ministry of defence defence standard 00-101

Ministry of Defence Defence Standard 00-101 Issue 1 Publication Date 27 June 2008

Design Standards for Explosives Safety in MOD Ships and

Submarines

Part 5 Ship Weapon Dynamic Safety

Category 1

Reprinted 28 August 2008 to Incorporate Amendment 1

DEF STAN 00-101 PART 5 Issue 1

AMENDMENT RECORD

Amd No

Date Text Affected Signature and Date

1 20/08/08 Clause 1.9 re-written to latest legislation R Leary 20/08/08

Revision Note

The previous magazine design standards have been protectively marked RESTRICTED, this standard is UNCLASSIFIED. Classified material associated with Response to ATTack on AMmunition (RATTAM) threat levels and mitigation techniques is published separately under classified Naval Authority Notice (NAN) EXP/03 in support of this standard. This document is available from DSS NAExp, it currently is protectively marked RESTRICTED.

Historical Record

This standard supersedes the following:

NAN EXP/05


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CONTENTS 0. INTRODUCTION ...................................................................................................7 1.SCOPE……………. ..................................................................................................8 2.WARNING…………..................................................................................................9 3.RELATED DOCUMENTS.......................................................................................10 4.DEFINITIONS AND ABBREVIATIONS..................................................................10 5.AMENDMENT .................................................................................................10 6.SPONSORSHIP OF THE REQUIREMENT AND SECURITY ................................11 7.SHIP WEAPON DYNAMIC SAFETY .....................................................................12 APPENDIX A DESIGN FOR SHIP WEAPON EQUIPMENT DYNAMIC SAFETY .................................................................................................15

A.1. Description............................................................................................... 15 A.2. Performance Requirements for Ship Weapon Equipment Dynamic Safety ................................................................................................................... 15 A.3. ACOP for Weapon Equipment Dynamic Safety Assessment .............. 16 A.4. Guidance on Ship Weapon Firing Hazards ........................................... 19 A.5. Guidance for Ship Weapon Equipment Dynamic Safety Assessment (Surface Ships)........................................................................................................ ................................................................................................................... 23 A.6. Guidance for Ship Weapon Equipment Dynamic Safety Assessment (Submarines) ........................................................................................................... ................................................................................................................... 24 A.7. Guidance for the SWEDS in the SESCR ................................................ 25

APPENDIX B CLEARANCE DISTANCES AND CUT-OFF ANGLES............28 B.1. Description............................................................................................... 28 B.2. Performance Requirements For Clearance Distances and Cut-Off Angles.................................................................................................................. 28 B.3. ACOP for Clearance Distances and Cut-Off Angles ............................. 28

APPENDIX C CUT-OFF LINES......................................................................33 C.1. Description............................................................................................... 33 C.2. Performance Requirements For Cut-Off Lines...................................... 33 C.3. ACOP for Cut-Off Lines........................................................................... 33

APPENDIX D TOLERANCING AND PHYSICAL CHECKING OF CAMS......38 D.1. Description............................................................................................... 38 D.2. Performance Requirements for Tolerancing and Physical Checking of Cams ................................................................................................................... 38 D.3. ACOP for Tolerancing and Physical Checking of Cams ...................... 38 D.4. Guidance for Physical Checking of Cams............................................. 41

APPENDIX E ESTABLISHING CUT-OFF LINES FOR ROTATABLE STRUCTURES .................................................................................................45

E.1. Description............................................................................................... 45 E.2. Performance Requirements for Establishing Cut-Off Lines for Rotatable Structures........................................................................................... 45 E.3. ACOP for Rotatable Aerial Systems....................................................... 45 E.4. ACOP for Guns and Missile Launchers ................................................. 48


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APPENDIX F ESTABLISHING CUT-OFF LINES FOR WHIP AERIALS.......52

F.1. Description............................................................................................... 52 F.2. Performance Requirements for establishing Cut-Off Lines for Whip Aerials .................................................................................................................. 52

APPENDIX G Polar Diagrams.......................................................................55 G.1. Description............................................................................................... 55 G.2. Performance Requirements for Polar Diagrams................................... 55 G.3. ACOP for Polar Diagrams ....................................................................... 55 G.4. Guidance for POLAR DIAGRAMS........................................................... 55

APPENDIX H PROCEDURES FOR DETERMINATION OF SHIP ACTUAL SAFETY FIRING BOUNDARY..................................................................................61

H.1. Description............................................................................................... 61 H.2. Performance Requirements for Determination of Ship Actual Safety Firing Boundary .................................................................................................. 61 H.3. Performance Requirements for Silhouette Cams and Diagrams......... 64 H.4. Performance Requirements for the Installation Trial of Firing Arcs ... 66

Annex A – REFERENCED DOCUMENTS ...............................................................67 Annex B – ABBREVIATIONS ..................................................................................68 Annex C – GLOSSARY OF DYNAMIC SAFETY TERMS........................................71 Annex D – SAMPLE SAFETY FIRING TEST SHEET..............................................75


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PREFACE

Sponsorship

a. This Defence Standard (Def Stan) 00-101 is sponsored by the Directorate Sea Systems (DSS) Naval Authority Explosives (NAExp), Defence Equipment & Support (DE&S), Ministry of Defence (MOD).

b. The complete standard is titled: Design Standards for Explosives Safety in MOD Ships and Submarines, and comprises:

Part 1: Surface Ships

Part 2: Submarines

Part 3: Electrical Equipment and Installation

Part 4: Generic Naval Environment

Part 5: Ship Weapon Equipment Dynamic Safety

c. If it is found to be unsuitable for any particular requirement the MOD is to be informed in writing of the circumstances.

d. Any user of this Defence Standard either within MOD or in industry may propose an amendment to it. Proposals for amendments that are not directly applicable to a particular contract are to be made to the publishing authority identified on Page 1, and those directly applicable to a particular contract are to be dealt with using contract procedures.

e. No alteration is to be made to this Defence Standard except by the issue of an authorized amendment.

f. Unless otherwise stated, reference in this Defence Standard to approval, approved, authorised or similar terms, means the Ministry of Defence in writing.

g. Any significant amendments that may be made to this Defence Standard at a later date will be indicated by a vertical sideline. Deletions will be indicated by 000 appearing at the end of the line interval.

h. Extracts from British Standards within this Defence Standard have been included with the permission of the British Standards Institution.

Conditions Of Release

i. This Defence Standard has been devised solely for the use of the MOD, and its contractors in the execution of contracts for the MOD. To the extent permitted by law,


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the Crown hereby excludes all liability whatsoever and howsoever arising (including but without limitation, liability resulting from negligence) for any loss or damage however caused when the Defence Standard is used for any other purpose.s document is Crown Copyright and the information herein may be subject to Crown or third party rights. It is not to be released, reproduced or published without written permission of the MOD.

k. The Crown reserves the right to amend or modify the contents of this Defence Standard without consulting or informing any holder.

MOD Tender Or Contract Process

l. This Defence Standard is the property of the Crown and unless otherwise authorised in writing by the MOD must be returned on completion of the contract or submission of the tender in connection with which it is issued.

m. When this Defence Standard is used in connection with a MOD tender or contract, the user is to ensure that he is in possession of the appropriate version of each document, including related documents, relevant to each particular tender or contract. Enquiries in this connection may be made of the Authority named in the tender or contract.

n. When Defence Standards are incorporated into contracts, users are responsible for their correct application and for complying with contractual and other statutory requirements. Compliance with a Defence Standard does not of itself confer immunity from legal obligations.

Categories Of Defence Standard

o. The Category of this Defence Standard has been determined using the following criteria:

a) Category 1. If not applied may have a Critical affect on the following:

Safety of the vessel, its complement or third parties.

Operational performance of the vessel, its systems or equipment.

b) Category 2. If not applied may have a Significant affect on the following:

Safety of the vessel, its complement or third parties.

Operational performance of the vessel, its systems or equipment.

Through life costs and support.

c) Category 3. If not applied may have a Minor affect on the following:

MOD best practice and fleet commonality.


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Corporate experience and knowledge.

Current support practice.

Related Documents

p. In the tender and procurement processes the related documents in each Section and Annex A can be obtained as follows:

a) British Standards British Standards Institution, 389 Chiswick High Road, London, W4 4AL

b) Defence Standards UK Defence Standardization, Kentigern House 65 Brown Street, Glasgow, G2 8EX

c) Other documents Tender or Contract Sponsor to advise.

q. All applications to Ministry Establishments for related documents are to quote the relevant MOD Invitation to Tender or Contract Number and date, together with the sponsoring Directorate and the Tender or Contract Sponsor.

r. Prime Contractors are responsible for supplying their subcontractors with relevant documentation, including specifications, standards and drawings.

Health And Safety

Warning

s. This Defence Standard may call for the use of processes, substances and procedures that may be injurious to health if adequate precautions are not taken. It refers only too technical suitability and in no way absolves either the supplier or any user from statutory obligations relating to health and safety at any stage of manufacture or use. Where attention is drawn to hazards, those quoted may not necessarily be exhaustive.

t. This Defence Standard has been written and is to be used taking into account the policy stipulated in Joint Service Publication (JSP) 430: MOD Ship Safety Management System Handbook.

Additional Information

u. This standard provides mandatory Performance Requirements for the design, construction and ship fitting of MOD ships in respect of explosives safety issues arising from stowage, handling and use of explosives onboard. The Performance Requirements are supplemented by Approved Codes of Practice (ACOP) and


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Guidance, which provide design best practice and corporate knowledge and experience.

v. This standard has been produced by DSS Naval Authority Explosives, Defence Equipment & Support, Ministry of Defence. The Point of Contact for matters pertaining to the technical content of the standard is NAExp, Ash 3c, #3311, MOD Abbey Wood, BRISTOL BS34 8JH.

w. This standard has been agreed by the authorities concerned with its use and is intended to be used whenever relevant in all future designs, contracts etc. and whenever practicable by amendment to those already in existence. If any difficulty arises which prevents application of the Standard, the sponsor shall be informed so that a remedy may be sought.

x. Any enquiries regarding this standard in relation to an invitation to tender or a contract in which it is incorporated are to be addressed to the responsible Platform Duty Holder (PDH), normally the Platform Integrated Project Team (IPT), named in the invitation to tender or contract.

y. Compliance with this Standard shall not in itself relieve any person from any legal obligations imposed upon them.

z. This standard has been devised solely for the use of the MOD and its contractors in the execution of contracts for the MOD. To the extent permitted by law, the MOD hereby excludes all liability whatsoever and howsoever arising (including, but without limitation, liability resulting from negligence) for any loss or damage however caused when the standard is used for any other purpose.

aa. The mandatory requirements and associated guidance in this Standard are intended to meet the policy of the Secretary of State for Defence to put in place regulations that are at least as good as civil requirements, so far as is reasonably practicable, where MOD has exemption from civil legislation. Use of this Standard in maritime platform acquisition programmes is also intended to contribute towards optimisation of capability.


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DESIGN STANDARDS FOR EXPLOSIVES SAFETY IN MOD SHIPS AND SUBMARINES - STANDARDS FOR DEFENCE

PART 5: SHIP WEAPON DYNAMIC SAFETY

0. INTRODUCTION

0.1. This standard is authorised by the Naval Authority (Explosives) by delegated authority from Controller of the Navy and Chairman of the Ship Safety Board on behalf of the MOD Ship Safety Board, and its use is a mandatory requirement of JSP 430 Part 3, Naval Authority Regulations (NAR) Chapter 8 (Explosives).

0.2. The aim of this Standard is to provide requirements and guidance to assist in providing an acceptably safe integration of Ordnance, Munitions and Explosives (OME) into MOD ships.

0.3. This Standard has been issued to identify the mandatory Performance Requirements for the design, construction and ship fitting of all JSP 430 applied ships in respect to safety issues arising from stowage, handling and use of explosives. It incorporates the best practice contained in previous magazine standards Naval Engineering Standard (NES) 183 and Def Stan 08-101 but is written to both support the risk based SMS introduced by JSP 430 Pt 3 Chapter 8 (Naval Authority Regulations) and allow prescriptive design features to continue under specified Approved Codes of Practice or Guidance.

0.4. Discrete sections cover specific topics providing Descriptions, Performance Requirements, Approved Codes of Practice (ACOP) and Guidance for each. This Standard is a component of the Safety Management System process mandated by Naval Authority Regulations Chapter 8 (Explosives) (NAR Ch 8) which defines how Ordnance Munitions and Explosives (OME) should be integrated and used safely in ships. It is essential that Def Stan 00-101 is read in conjunction with Naval Authority Regulations Chapter 8 (Explosives). In addition, Maritime Acquisition Publication (MAP) 01-103, Ship Explosives Safety Case (SESC) – Guidance For Platform Duty Holders, Part 1 provides further guidance on the process for developing an SESC.

0.5. This Standard is to be specified in the User Requirements Documentation and System Requirements for all MOD Ships that embark munitions. Def Stan 00-101 is authorised by the Naval Authority Explosives and its use is a mandatory requirement of the Naval Authority Regulations, Chapter 8 (Explosives).

0.6. The user of this standard is directed to ANNEX C that should be read early in the use of this standard to ensure that the terminology is understood and to avoid misinterpretation.


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1. SCOPE

1.1. The MOD Ships to which this standard applies are defined in JSP 430 and JSP 430 Part 3 Naval Authority Regulations, Chapter 8 (Explosives). These include HM Ships and Submarines, Royal Fleet Auxiliaries (RFA), Marine Services, other ships owned by MOD, Government Owned Contractor Operated (GOCO) vessels (where these are owned by MOD), and ships on MOD charter. The term “ship” is intended to include vessels, launches, tenders, lighters and any other craft carrying any explosives. The Naval Authority may determine that a specific platform is not required to comply where no hazard exists but does not issue exemption certificates. All such maritime platforms are described as MOD Ships in the remainder of this document.

1.2. This Standard applies to the design, construction and ship fitting of all MOD Ships built to MOD or Classification Society constructional standards and operated by the Royal Navy, Army (including Special Forces), Royal Air Force, RFA or Marine Services. The standard also applies to Marine Services vessels supplied as Government Furnished Equipment for contract operations and MOD authorised modifications undertaken to charter vessels.

1.3. It is to be applied to contracts that specify requirements that have any effect upon the explosives safety of the platform. This will include the magazines, adjacent compartments and ammunition routes and handling equipment within MOD ships in which explosives will be embarked, moved, stowed and used. It is also to be applied to all Refit and Repair work affecting any of these including Alterations and Additions and Modifications. It may also include other design issues throughout the platform that impact on explosives safety.

1.4. The complete standard is titled: Design Standards for Explosives Safety in MOD Ships and Submarines, and comprises:

Part 1 – Surface Ships Part 2 – Submarines Part 3 – Electrical Equipment and Installation Part 4 – Generic Naval Environment Part 5 - Ship Weapon Dynamic Safety

1.5. Classified material associated with RATTAM threat levels and mitigation techniques is published separately under classified (NAN) EXP/03 in support of this standard. This document is available from DSS NAExp; it is currently protectively marked. .

1.6. This standard has been written primarily to support the risk based shipborne explosives Safety Management System (SMS) introduced by NAR JSP 430 Part 3 Chapter 8 Explosives. Where legacy vessels have been certificated under previous transition procedures, it is not necessary to implement additional work to meet this


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standard, unless major modifications are undertaken to a magazine or weapon system. In that case, this Defence Standard must be implemented.

1.7. Supplementary information, information requiring a higher protective marking and temporary instructions will be issued in the form of Naval Authority Notices (NAN). NANs relating to explosives safety in MOD ships and submarines are available from Naval Authority System Library website (www.nakmo.co.uk) or the Sponsor of this Standard.

1.8. For the storing and handling of petroleum, oils, lubricants (POL) and certain other hazardous stores in HM Ships, BR1754 is to be consulted (Navy Service Authority: Systems Fuels & Lubricants, WSA, MPS216, Abbey Wood , Bristol).

1.9 Regulations governing the safe stowage and handling of explosives in Magazines in RFAs are covered in JSP 862 Chapter 13. Regulations covering the safe stowage and handling of explosives in Charter shipping are included in the IMDG Regulations.

2. WARNING

2.1. The Ministry of Defence (MOD), like its contractors, is subject to both United Kingdom and European laws regarding Health and Safety at Work. All MoD Standards either directly or indirectly invoke the use of processes and procedures that could be injurious to health if adequate precautions are not taken. MoD Standards or their use in no way absolves users from complying with statutory and legal requirements relating to Health and Safety at Work.

2.2. This is a mandatory Category 1 Standard. If not applied it may have a Critical affect on the following:

a) Safety of the ship, its complement or third parties.

b) Operational performance of the ship, its systems or equipment.

c) Through life costs and support.

2.3. If the Platform Duty Holder (PDH) proposes not to apply this mandatory Category 1 Standard, agreement must be obtained from Naval Authority Explosives and the relevant Director of Equipment Capability (DEC). Details of any such agreement is to be formally recorded in the Safety Case. In the event of a MOD enquiry or any prosecution under Health and Safety legislation, if it is proved that the relevant requirements were not followed, the PDH will need to show that he has complied with the Naval Authority Regulations in some other way or an enquiry or court may find him at fault.

2.4. In this standard, Performance Requirements are mandatory (Category 1) requirements. Additionally clauses including the words “shall”, “must”, “is to”, “are to” also are mandatory.


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2.5. This standard contains Approved Code of Practice (ACOP), which has been approved by the Naval Authority (Explosives) as good practice. It gives practical advice that may be used to assist in complying with this standard.. Alternative methods to those set out in the ACOP may be used providing they are justified in the safety case.

2.6. This standard also contains other, more general Guidance. This guidance reflects corporate knowledge and experience and is issued by the Naval Authority Explosives to assist duty holders’ understanding of the subject area. It may not be exhaustive and all users are recommended to contact SSG NAExp for the latest information.

3. RELATED DOCUMENTS

3.1. The publications listed in Annex A are referred to in the text of this standard.

3.2. Reference in this standard to any related document means that in any invitation to tender or contract the edition and all amendments current at the date of such tender or contract apply unless a specific edition is indicated.

3.3. In consideration of 3.1.2 above, users shall be fully aware of the issue and amendment status of all related documents, particularly when forming part of an invitation to tender or contract. Responsibility for the correct application of standards rests with users.

3.4. The Directorate of Standardisation (DStan) can advise where related documents are obtained. Requests for such information can be made to the DStan Helpdesk.

4. DEFINITIONS AND ABBREVIATIONS

4.1. For the purpose of this standard the abbreviations and definitions listed in Annex B and Annex C apply. The user of this standard is directed to Annex C that should be read early in the use of this standard to ensure that the terminology is understood and to avoid misinterpretation.

5. AMENDMENT

5.1. If this Standard is found to be unsuitable for any particular requirement, the sponsor is to be informed in writing with a copy to DSS NAExp, Ash 3c #3311, MOD Abbey Wood, BRISTOL BS34 8JH.

5.2. Any user of this Standard either within MOD or in industry may propose an amendment to it. Proposals for amendments that are not directly applicable to a particular contract are to be made to the MOD and those directly applicable to a particular contract are to be dealt with using existing procedures or as specified in the contract.


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5.3. No alteration is to be made to this Standard except by the issue of an authorised amendment. Amendments, supplementary information and temporary instructions will be issued in the form of Naval Authority Notices (NAN) by DSS NAExp.

5.4. Unless otherwise stated, reference in this Standard to approval, approved, authorised or similar terms, means by the Ministry of Defence in writing.

6. SPONSORSHIP OF THE REQUIREMENT AND SECURITY

6.1. JSP 430 introduces the concept of Key Hazard Safety Management by MOD Platform Duty Holders (PDH) who are normally the associated Platform Integrated Project Team Leaders (PIPTL). JSP 430 defines a Key Hazard to represent a significant danger to the lives of several persons and whose consequence may cause the loss of the ship or significant damage to the environment. JSP 430 mandates the Regulation of these key hazards by an independent assurance body and for explosives the Naval Authority Explosives (NAExp) in SSG undertakes this role, with delegated authority from the Ships Safety Board. DSS NAExp sponsors this Category 1 mandatory Standard. It is approved by the Naval Authority Explosives Advisory Committee (NAEAC).

6.2. Throughout this document the following convention is used when referring to the Regulatory body or its incumbents. NAExp relates generically to Naval Authority Explosives and its policies, DSS NAExp relates to the Secretariat.

6.3. NAExp has published a suite of documents relating to the use of this Standard, that comprise JSP Part 3, Naval Authority Regulations Chapter 8 – Explosives, JSP 862 – MoD Maritime Explosives Regulations (Operator Requirements) and Maritime Acquisition Publication (MAP) 01-103, Ship Explosives Safety Case (SESC) – Guidance For Platform Duty Holders. They will be referenced in the Acquisition Management System (AMS) and are available via the Naval Authority System Library website at www.nakmo.co.uk.


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7. SHIP WEAPON DYNAMIC SAFETY

7.1. General

7.1.1. The policy for the Dynamic Safety of Weapon Equipment integrated into Ships is developed to protect ships and submarines, personnel and the environment as required by the Secretary of State’s policies on Health and Safety for Ships and associated equipment. It is also developed to protect the material condition of the Ship and equipment whilst providing maximum defence capability. Current policy is that the legal requirements of the Health and Safety at Work Etc., Act 1974, and JSP430, the Ship Safety Management System Handbook, shall be complied with. This requires that Duty Holders responsible for design, development and supply of equipment shall be able to prove through all investigations and analyses necessary that the known equipment risks have been reduced to ALARP.

7.1.2. Weapon equipment dynamics shall be such as to prevent ship weapons firing into physical obstructions, or damaging ship’s structure or equipment by blast or efflux, or, for both ship and submarines, causing injury to personnel and third parties.

7.1.3. e Ordnance Munitions and Explosives (OME) DH is responsible for establishing that weapon & OME-specific safety information (such as arc control measures, cut-off angles and ammunition dispersions including, where necessary, computer modelled sabot trajectory curves) are generated. The OMEDH is responsible for generating a Weapon Equipment Safety Case Report in accordance with the requirements of JSP520 during the process of achieving Defence Ordnance Safety Group OME Safety Review Panel (DOSG-OSRP) endorsement in a Certificate of Safety Ordnance, Munitions and Explosives (CSOME) that will be used subsequently by Platform DHowever, for Close In Weapon Systems (CIWS) and following assessment of individual installations, it may be considered acceptable to accept some degree of self damage in order to maximise operational effectiveness, providing such extension is justified fully.

7.1.4. Performance Requirements, Approved Code of Practice (ACOP) and Guidance for Ship Weapon Dynamic safety can be found at the Appendices.

7.2. Responsibilities for Ship Weapon Equipment Dynamic Safety

7.2.1. For ships, safe-firing arcs shall be designed to achieve the maximum areas of fire possible within the constraints of the weapon system and this standard, and be considered throughout the design stage. The process that should be followed for the management of ship weapon equipment dynamic safety is two-stage, with initially the Ordnance Munitions Explosives (OME) Duty Holder developing a weapon equipment that will subsequently be integrated (second stage) into a variety of Ships. The responsibilities of the authorities involved are detailed below:

a. OME Duty Holder.(OMEDH) – Thuty Holders (PDH) when integrating the weapon into a Ship.


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b. DOSG OME Safety Review Panel (OSRP). The DOSG, through the OSRP, is responsible for providing a service of safety assurance that demonstrates that OME safety is being managed effectively by OME DHs such that residual Explosives, OME safety and environmental risks are mitigated to ALARP. The OSRP review of OMEDH Weapon Equipment Safety Case Reports (WESCR) will include an assessment of the suitability and integrity of the arrangements for safe weapon equipment dynamics safety.

c. Platform Duty Holder (PDH). The PDH is responsible for the following mandatory aspects:

i) To ensure that levels of inherent OME safety, as assured by the DOSG/OSRP, are not compromised when weapon equipment is integrated into Ships.

ii) Utilisation of the OME IPT Weapon Equipment Safety Case Report (WESCR) and the weapon equipments inherent safe firing arc control measures and data in the development of safety case reports for each installation on the ship. NOTE: Each installation means that each weapon (i.e. gun) on a platform is to be justified. This can be achieved either individually or collectively.

iii) Risk management in accordance with JSP 430 (with detailed guidance in Defence Standard 00-56 and MAP 01-103) should be conducted for the integration of weapon equipment into individual Ships. To ensure that risks from the integration of weapon equipment are ALARP, and justified in the Ship Explosive Safety Case (SESC) produced for each weapon equipment integrated into the Ship.

iv) To ensure appropriate and safe integration of individual weapon equipment shall meet the requirements of JSP 862, other relevant SEMS and other relevant Key Hazard Area Certification requirements. The PDH shall take measures to ensure that all relevant requirements are identified and satisfied.

v) Risk Analyses shall address integration of Weapon Equipment Control Systems into Ships’ Command and Control Systems.

vi) Verification of the operation of the appropriate method of restriction of arcs of fire / weapon equipment dynamics for guns and missile launchers. After initial setting to work or following the rectification of defects in the safety firing arrangements and prior to presentation for acceptance and after any alteration to the Ship’s structure and/or equipment.

vii) During installation trials verification by an appropriately qualified inspection authority acting on behalf of the PDH (e.g. Maritime Commissioning, Trials and Assessment (MCTA).


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viii) The production of procedures for Ship’s Staff to conduct periodic checks on the weapon equipment.

ix) The PDH arranges for the ship’s profile points to be measured from the mounting by the setting to work authority.

x) It is the PDH responsibility to ensure that drawings/readings necessary for establishing the installation’s ship’s safety firing silhouette, production of the firing cams (in whatever form) and/or for inspection by an appropriately qualified authority (e.g. MCTA), are produced. The former requirements can be satisfied for many installations by the production of a Polar Diagram (which indicates the firing cut-off line) and the associated Silhouette Drawing (showing a smoothed version of the cut-off line).

xi) The PDH makes arrangements for producing the firing cams or installing ship’s safety firing silhouette into the firing control software of the weapon system.

xii) Compliance with the ship’s safety firing silhouette is confirmed by trials conducted by an appropriately qualified authority (e.g. MCTA) on behalf of the PDH.

d. NAExp is responsible for establishing and maintaining policy on Weapon Equipment Dynamic Safety for ships and submarines, advising where necessary on the interpretation of that policy. The NAExp Secretariat undertakes reviews of the Weapon Equipment Dynamic Safety element of PDH ship specific safety case reports during the process of certification of Ship Explosives designs in accordance with JSP 430, Part 3, Naval Authority Regulations (NAR) Chapter 8 where a Certificate of Safety – Explosives (CSE) is sought.

e. Ship’s Staff. Ship’s Staff are responsible for checking the operation of the appropriate method of restriction of arcs of fire for guns and missile launchers as pre-firing, periodical and pre-refit checks in accordance with procedures written by the PDH.


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APPENDIX A DESIGN FOR SHIP WEAPON EQUIPMENT DYNAMIC SAFETY

A.1. Description

A.1.1. Ship Weapon Equipment Dynamic Safety (SWEDS) is a collective term applicable to ordnance systems that discharge munitions. It covers all events that occur between launch initiation (intentional or otherwise) and termination of motion. This includes the trajectories of the munitions and any associated projectiles, their interaction with terrain or objects (including the platform), together with ricochet, warhead events, and terminal effects. It excludes any consideration of events after termination of motion including post conflict Explosive Ordnance Clearance (EOC) or Explosive Ordnance Disposal (EOD). [FROM JSP 520 Part 2 Section 5 Page 10 para 30]

A.1.2. SWEDS can be affected by factors associated with the platform, systems that interface with launch (including software), flight control systems (including software), the characteristics of the munition, as well as environmental and operational conditions. [FROM JSP 520 Part 2 Section 5 Page 10 Para 31]

A.1.3. SWEDS is assured in a two-stage process where initially the Weapon Equipment (including the Command and Control System) safety assurance generated by the OME IPT is assessed by the DOSG OSRP and reported on in the CSOME; the JSP520 process. The second stage involves the Platform IPT integrating the Weapon Equipment into the Ship and its Command and Control System and demonstrating the safety assurance of the integrated system in the ship; the JSP430 Part 3 Chapter 8 process.

A.1.4. The requirement to establish SWEDS hazards will result from the change to a ship’s silhouette, installation of a new weapon system to a Ship, or the introduction of a new Class of Ship.

A.1.5. This standard provides mandatory Performance Requirements for the design, construction and ship fitting of MOD ships in respect of explosives safety issues arising from stowage, handling and use of explosives onboard. The Performance Requirements are supplemented by Approved Codes of Practice (ACOP) and Guidance, which provide design best practice and corporate knowledge and experience for the safety assessment of weapon equipment dynamic hazards onboard Ships.

A.2. Performance Requirements for Ship Weapon Equipment Dynamic Safety

A.2.1. It is the responsibility of the Platform IPT Duty Holder to ensure that levels of inherent OME safety, as assured by the DOSG/OSRP, are not compromised when weapon equipment is integrated into Ships. Also that risks from their integration are ALARP, and justified in the Ships Explosive Safety Case (SESC).


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A.2.2. Weapon Equipment Dynamic Safety installations (including Safe Firing Arcs) are to be installed by competent individuals, and physically verified by a SQEP authority (e.g. MCTA), in accordance with the requirements of this standard.

A.2.3. The Platform Duty Holder shall ensure that appropriate and safe integration of individual weapon equipment meet the requirements of this standard, JSP430, JSP 862, other Safety and Environmental Management Systems (SEMS) and other Key Hazard Area Certification requirements. The Platform Duty Holder shall take measures to ensure that all relevant requirements are satisfied.

A.3. ACOP for Weapon Equipment Dynamic Safety Assessment

A.3.1. Physical Obstructions in the Weapon Firing Arc

a. These include exposed personnel, fixed structures, missile launchers, guns and mountings, aerials, and aircraft when these are parked on deck. In all cases it will be necessary to establish some minimum clearance distance by which the projectile must clear the obstruction.

i) Personnel. Allowance shall normally only be made for exposed personnel necessarily at or in transit to, action stations or flying stations.

ii) Material. Allowance shall be made for fixed structures and equipment in all configurations, in its action condition.

iii) Missile Launchers. Allowance shall be made for missile launchers under all conditions and for the swept arcs of structure and loaded missiles where appropriate.

iv) Gun Mountings. Allowance shall be made for the gun house or shield of gun mountings under all operational conditions and in all possible positions and also for the swept arc of the gun muzzle at all possible training angles between minimum and maximum elevation.

v) Aerials. Allowance shall be made for aerials including aerial rotation envelopes where appropriate and for whip and wire aerials except for emergency rigs.

vi) Aircraft. Allowance shall be made for aircraft on deck ranged, armed and lashed in position on their designated landing spots, and for structure and equipment deployed in the aircraft operating condition.

vii) Replenishment at Sea Gear. Allowance shall be made for replenishment at sea gear in its stowed condition, and also for roller fairleads and similar items which, due to non-portability, are not de-rigged.

viii) Jack and Ensign Staff Tripods. These are to be struck before weapon firing takes place.


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ix) Guard Rails. Guard rails in the cleared away area of guns and missile launchers shall be struck to ensure that they do not reduce the maximum firing arc of the mounting. If this is undesirable for personnel safety reasons the Platform Duty Holder is to justify in the SESC for the guardrails to remain standing.

x) General. Where necessary to meet overriding operational requirements, proposals for special arrangements permitting weapons less restricted arcs of fire (such as across flight decks when clear of aircraft) are to be justified by the Platform Duty Holder in the SESC.

A.3.2. Limitations to Weapon Firing Arcs

a. Blast and Efflux. A further restriction of firing arcs may be necessary to prevent damage by blast and efflux. The blast-proof pressures of various structures and the blast curves of 76mm and larger guns are given in BR 1031 and are used to give the approximate restrictions required, the exact arcs being confirmed, if necessary, by blast and efflux trials. Advice on blast and efflux restrictions will normally be supplied by NAExp. A much greater restriction of a firing arc may be necessary to prevent blast and efflux damage to exposed personnel necessarily closed-up adjacent to the line of fire. In this case the limiting blast pressure or efflux dispersion is dependent on the type of gun and rate of fire or the type of missile being considered. Details of restrictions imposed will be found in manuals, handbooks and / or OMEDH WESCR as appropriate to the individual gun or missile system. The degree of exposure of personnel to blast and efflux shall be limited to a level that prevents injury and allows duties to be carried out without undue loss of efficiency. It should be noted that shock waves and efflux could be reflected from, for example, a screen bulkhead thereby subjecting personnel to secondary effects within a few milliseconds of the direct wave. It is therefore important to consider local topography when considering the type of hazard to which personnel will be exposed. In all problems concerned with the effect of blast or efflux on structure or personnel it is important to work from a three dimensional model.

b. The effects of inhalation of particles and vapour from blast and efflux should also be considered as part of the overall Ship Safety Case, but are not covered by this Defence Standard.

c. Ammunition Debris from CIWS. Firing arcs for close in weapon systems using sub calibre ammunition shall be limited to minimise the risk of damage by sabot and pusher debris. The risk of injury to personnel or damage to equipment shall be as low as reasonably practicable (ALARP). Where judgement is required to evaluate and allocate priorities to the probability of damage or loss caused by the weapon failing to defend the ship adequately, the case for widening safe arcs of fire shall be fully explored and justified in the Ship Explosive Safety Case Report (SESCR).

d. Limit Stops. These physically limit the ‘training’ and/or ‘elevation’ or ‘depression’ of the gun or launcher mounting and include some means of


18

cutting off or reducing the driving torque as it comes up against a buffer or stop. In relatively unobstructed mountings, limit stops provide the simplest and safest method of the normal firing arc. Where the firing arc of a mounting is limited by limit stops, these should be fitted so that, with the buffer fully compressed, the axis of the nearest gun barrel or missile on the launcher clears the obstruction. NOTE: Care should be taken to ensure that any backlash that could be present at the arc stops is removed prior to finalising and cutting the cams. This clearance should only be by the appropriate clearance distance for physical obstructions, blast and efflux or sabot limitations whichever is the greater. Where necessary, this clearance shall include an allowance for the effects of ship motion and missile dispersion. In some mountings, it may be necessary to provide a removable ‘training’ limit stop so that the mounting may be trained into wider arcs, e.g. for maintenance or when securing. Where a hydraulic buffer is used to limit the normal firing arc of the mounting, it may be necessary to remove the buffer to assist with the determination of the clearance angle. When subsequently determining this clearance angle, after refitting the buffer, the reading should be taken with the buffer just touching the stop. Guidance on the procedural aspects of how to install the arc stop is available from the inspecting authority (e.g. MCTA).

e. Safety Firing Gear. This is arranged to interrupt weapon-firing mechanisms/circuits within restricted arcs of remotely operated guns by means of a combination of ‘elevation’ and ‘training’ cams that are suitably cut to allow for the various obstructions. Where safety-firing gear is fitted, it shall be arranged to stop the weapon firing by the appropriate clearance distance from an obstruction, the extent of this clearance depending upon whether physical obstruction or blast and efflux or sabot limitation is the predominant factor. Since, when controlled by safety firing gear, the weapon can continue to train into the restricted arc, a cut-off angle shall additionally be applied by which the firing gear of the mounting is interrupted before the clearance distance from the obstruction is reached. The magnitude of this angle is dependent upon the maximum training and elevation speeds of the mounting and the inherent delays in the firing mechanism.

f. Software Cams. Where software is used to control arcs of fire, the software arc is generated from the system rules and is used, in conjunction with the fire control solution, to produce the best point of aim for firing. The requirements of Def Stan 00-56 shall be applied. Facsimiles of the safe to fire arc silhouettes of a software controlled weapon are stored in the weapon’s fire control system and are used to control the actual firing angles of the gun or launcher. Any fault in software will have been there since its design and will only become apparent when the feature containing the fault is called into use. The risk of software errors will be minimised through compliance with Def Stan 00-56 for system safety.

g. General Limitations. The requirement to establish safe-firing arcs is not limited to ‘trainable’ mountings employing the above methods of restriction. Many fixed launchers require clearance distances to be imposed either to the rear of the launcher due to blast and efflux considerations or in the arc of fire.


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Guidance should be sought from the OMEDH. Where software is used to control the firing arcs of weapons it shall be programmed in accordance with the system documentation and Def Stan 00-56 to restrict the firing capability of the weapon to the safe arcs of fire. The safe-firing silhouette shall be determined using the same allowances as those for weapons controlled by mechanically operated safety firing gear. It should be noted that software controlling weapon arcs of fire and munitions firing is likely to be safety related and highly likely to be safety critical, requiring a high level of integrity. In such cases, software development shall be in accordance with the requirements of Def Stan 00-56. For further guidance on software contact DOSG-ST3b .

A.4. Guidance on Ship Weapon Firing Hazards

A.4.1. Inadvertent Weapon Firing

The safety case should discuss all identified eventualities that could culminate in inadvertent and incorrect launch, including Hangfire, Misfire, jettison, underwater shock, damage from fire or explosion in the vicinity of the equipment, and corrupted inputs from other systems. Features designed to prevent such an eventuality, for example, physical protection of launchers, software partitioning, physical interlocks and diversity in the design of parallel systems, should be specified.

A.4.2. Self Hit

One of the major hazards associated with Dynamic Safety is the risk of contact between the Munition and the firing Ship or consorts during the launch process. For surface ships, it is essential to maintain a miss distance between the line of fire and obstacles on the launch platform. There are, however, other eventualities which need to be considered, including the possibility of missiles and torpedoes performing circular runs, failing to clear the launch vessel and contacting control and propulsive systems, or discarding sabots or boost motors in the vicinity of the launch platform or consorts. Finally, there is the risk posed by munitions that miss-fire, inflict damage on close-sited munitions (particularly in the event of salvo firings), or fail to return to a safe state after an aborted firing.

A.4.3. Ship Environment

a. The ship environment can be quite hostile to modern weapon equipment. All external stimuli such as Electromagnetic Radiation Hazards (RADHAZ), ElectroMagnetic Pulse (EMP) / Transient Radiation Effects on Electronics (TREE), electrostatic and magnetic field effects should be considered and their effects on the dynamic safety of the ship and weapon equipment ascertained.


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b. The underwater environment can be quite hostile to modern weapon systems. All external stimuli such as motion through the water and submarine manoeuvre during launch, electrostatic and magnetic field effects should be considered and their effects on the dynamic safety of the submarine and weapon systems ascertained.

c. Hazards to Personnel - In addition to external influences affecting the weapon equipment and Explosives, the risk of their emissions endangering Ships Staff (and third parties) must also be considered.

d. Interface Hazards - A consequence of fully integrated combat systems is that factors outside the boundary of the weapon equipment can have a direct influence on dynamic safety. A typical example may be a weapon or decoy equipment operating in fully automatic mode, where inputs from various sensors are processed by the combat system to determine the most effective way of dealing with a potential threat. This is known as the Threat Evaluation and Weapon Assignment (TEWA) process. In such cases, with no human involvement leading to the decision to fire, each individual element involved in the process has the potential to introduce an error. Ultimately, this could lead to an unintended launch or the operation of the wrong weapon equipment. Clearly this has a direct influence on dynamic safety and must be considered.

A.4.4. Missile Systems

a. Missile systems comprise a range of sub-systems that integrate the logic, command and control functions. Typical sub-systems that are likely to have a bearing on the assessment of dynamic safety include:

i) For ships: a data processor for TEWA, sometimes integrated with a second data processor for target acquisition, tracking, missile pointing and missile guidance. For submarines: a data processor for mission profile data, sometimes integrated with a second data processor for target acquisition.

ii) A launcher pointing sub-system that has the capability to slew and position the launcher in training and elevation or for submarines’ a launcher sub-system that controls the pre-launch preparation and firing sequence.

iii) A missile firing unit which initiates the missile propulsive and pyrotechnic devices. It may also relay information from a control unit and provide information transfer from a tracking system to initialise the missile and determine its initial trajectory.

iv) A guidance sub-system within the missile. This may be autonomous within the missile or respond to external guidance signals from the target tracker and missile guidance unit. The missile guidance unit processes these signals and converts them into commands to the autopilot and flight


21

control systems within the missile. In some systems the unit may check the validity of incoming data prior to launch.

b. For ships: The initial launch trajectory may be controlled by silo tube or launch rail orientation and thereafter the missile is required to follow an initial launch trajectory within a specified envelope governed by the ship’s configuration. A number of alternative mechanisms may be used to control the trajectory, ranging from vectoring of the thrust to manipulation of aerodynamic surfaces. Actuators powered by hydraulics, gas pressure or electricity with their control increasingly effected by software in modern systems usually accomplish this. The principal factors that will influence the trajectory on and immediately after launch are:

i) Location and orientation of the silo/launch rail.

ii) Initial setting of the control surfaces.

iii) Any programmed initial flight profile.

iv) The orientation of the target to the ship's heading.

v) Correct functioning of the propulsion system.

vi) The external environmental influences.

vii)The separation flight profile for a multi-stage system.

viii)The functioning of all command and control sub-systems.

b. For submarines: The initial launch trajectory is controlled by launch tube orientation. Thereafter the missile is required to follow an initial launch trajectory within a specified envelope to achieve broach at the sea surface. A number of alternative mechanisms may be used to control the trajectory. An assessment must be made of the probability of failure to broach or ‘fall back’ and of the potential risks to the submarine.

A.4.5. Torpedo Systems

a. Torpedo systems may be fitted to both submarines and surface ships. In both cases the weapons are fired at a fixed relative bearing. Typical logic, command and control sub-systems that are likely to have a bearing on the assessment of Probability of Self Hit (PSH) include:

i) A homing and tactics sub-system that monitors the location of the target, directs the torpedo’s course, speed and depth, and may set the point of warhead detonation.

ii) A firing chain sub-system that encompasses the safety and arming unit and associated safety breaks.


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iii) A manoeuvring sub-system that computes the weapon position, maintains its course, speed and depth and incorporates an anti-circling system to inhibit the torpedo from circling back whilst still within the safety distance from the firing vessel.

iv) A guidance and telemetry sub-system that accepts data from the vessel mounted fire control system, usually via a wire link, and from the homing and tactics sub-system.

v) A propulsion sub-system through which the start up of the torpedo motor is controlled with respect to critical launch parameters.

vi) A dispenser sub-system to control, where applicable, the dispensing of the guidance wire.

vii) A vessel mounted fire control system that control the start up sequence, passes initial target and control data to the torpedo, and sets the necessary torpedo engine start up distance.

viii) An independent, vessel mounted tube/bow cap opening system with its own inhibits to ensure safe operation and in the case of submarines additionally, a bow shutter mechanism.

c. For torpedoes launched from test vessels, the launch and sub-surface phases should be individually assessed to determine the potential failure modes that could lead to self-hit. The probability of self hit following return of the torpedo below the surface under fault conditions will need to be addressed separately, with assessments made on energy of hit and the associated potential for damage.

d. For torpedoes that require recovery to surface vessels, the end of run phase should be assessed to determine the potential failure modes that could lead to safety related faults. The procedure for recovery and the equipment required should be designed, installed, tested and proved in accordance with the requirements of Def Stan 00-101 Part 1, for ships and Part 2, for submarines where applicable.


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A.5. Guidance for Ship Weapon Equipment Dynamic Safety Assessment (Surface Ships)

A.5.1. The following process (Figure 1) is one method of achieving satisfactory resolution of identified Dynamic Hazards when integrating weapon equipment into surface ships.

P R O C E S S E X P L A N A T IO N

R e q u i re m e n ts fo r s h ip s a rc c o v e ra g e w i l l b e d e c la re d b y th e E q u ip m e n t C a p a b i l ity B ra n c h .

T h e W e a p o n E q u ip m e n t S a fe ty C a s e R e p o r t p ro v id e s d e ta i ls o f th e s a fe ty a s s e s s m e n t o f th e w e a p o n e q u ip m e n t c o n d u c te d b y th e o r o n b e h a lf o f th e O M E D u ty H o ld e r in a c c o rd a n c e w i th J S P 5 2 0 . It p ro v id e s th e d a ta r e q u i r e d to in te g ra te th e w e a p o n e q u ip m e n t in to th e p la t fo rm .

[ In te r r o g a te W E S C R to a sc e r ta in g e n e r ic w e a p o n e q u ip m e n t D y n a m ic S a fe ty a r ra n g e m e n ts .

T h is h a s to c o n s id e r th e sa fe f i r in g a rc a n d th e v a r io u s o th e r d e s ig n c o n s t r a in t s o f s i t in g ( e g o th e r s y s te m s a n d c o m p a r tm e n t la y o u t ) s o th a t th e o p e ra t io n a l f i r in g a rc i s m a x im is e d .

T h is i s re q u i r e d fo r e a c h w e a p o n e q u ip m e n t to b e in s ta l le d .

T h is sh o u ld b e c o n d u c te d u s in g r i sk a s s e s s m e n t p ro c e d u re s in a c c o rd a n c e w i th D e fe n c e S ta n d a rd 0 0 -5 6 a n d th e g u id a n c e in A p p e n d ix B o f th i s s t a n d a rd .

E s ta b li sh th e s e fo r e a c h W e a p o n E q u ip m e n t f ro m th e W E S C R . R e fe r to th e g u id a n c e in A p p e n d ix B .

T h e s e a re e s ta b li s h e d b y r e fe re n c e to th e W E S C R a n d th e M u n i t io n d a ta . T h e s e a l lo w a n c e s a re to b e ju s t i f i e d b y r i s k a s s e s s m e n t . R e fe r to th e g u id a n c e in A p p e n d ix B .

T h is d ia g ra m in c lu d e s th e v a r io u s a l lo w a n c e s a n d c le a ra n c e s e s ta b lish e d f ro m th e s te p s a b o v e , ie c le a ra n c e d i s ta n c e , c u t o f f a n g le s , b la s t , e f f lu x a n d s a b o t a s a p p lic a b le . It a ls o t a k e s in to a c c o u n t th e a p p lic a t io n o f C u t O f f L in e s . R e fe r to th e g u id a n c e in A p p e n d ic e s B , C , D , E & F a s a p p lic a b le .

T h e p u rp o s e o f th i s s t e p i s fo r th e P D H to n o w v e r i f y th e S S D p ro d u c e d f ro m th e S h ip d e s ig n a g a in s t th e a c tu a l S h ip S i lh o u e t te b e fo re in s ta l l in g th e W E o r m a n u fa c tu r in g c a m s (m e c h a n ic a l o r s o f tw a re ) .

S T E P 1 E s ta b li s h th e r e q u ir e m e n t f r o m th e

U R D /S R D

S T E P 2 O b ta in th e W E S C R fr o m th e

O M E D H .

S T E P 3 D e te r m in e th e in tr in s ic sa f e f i r in g

a r c c o n tr o l m e a s u r e s a n d d a ta .

S T E P 4 E s ta b lis h s h ip p o s i t io n fo r th e

W e a p o n E q u ip m e n t .

S T E P 6 D e te r m in e ‘C le a r a n c e

D is ta n c e s ’ .

S T E P 7 D e te r m in e ‘C u t O f f A n g le s ’

S T E P 8 D e te r m in e B la s t , E f f lu x a n d S a b o t

a llo w a n c e s .

S T E P 9 P r o d u c e a s m o o th e d c o m b in e d S h ip

S i lh o u e t te D ia g r a m (S S D ) .

S T E P 1 0 D e s ig n A u th o r i ty to v e r ify th e

c o m b in e d S S D .

S T E P 5 E s ta b lis h S h ip S ilh o u e t te

D ia g r a m .

Figure 1 - Process for Dynamic Hazards in Ships


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A.6. Guidance for Ship Weapon Equipment Dynamic Safety Assessment (Submarines)

A.6.1. The following process (Figure 2) is one method of achieving satisfactory resolution of identified Dynamic Hazards when integrating weapon equipment into submarines.

P R O C E S S E X P L A N A T IO N

R eq uirem en ts fo r sh ips a rc coverage w ill b e d ec la red b y th e E qu ip m ent C ap ab ility B ran ch .

T h e W eap on E q uip m en t S a fety C ase R ep ort p rovid es d eta ils of th e sa fety a ssessm en t o f th e w eap on eq uip m en t con du cted b y th e o r on b eh a lf of th e O M E D u ty H old er in accordance w ith JS P 520 . It p rovid es th e da ta req u ired to in teg ra te th e w eap on eq u ip m en t in to th e p la tform .

In terro ga te W E S C R to ascerta in gen eric w eap on equ ip m ent D yn am ic S a fety arran gem en ts.

T h is w ill in c lud e th e n ecessa ry a lign m en t b etw een th e torp ed o load -lin e eq u ip m ent and th e resp ec tive to rp ed o tub e axes.

N A E xp issu es a C ertifica te of S a fety E xp losives (C S E ) if p la tform safety is m an aged in th e JS P 430 P art 3 C hap ter 8 risk -based p rocedu ra l req u irem en t.

S TE P 1 E sta b lish th e req uirem en t fro m th e

U R D /S R D

S TE P 2 O b ta in th e W E S C R fro m th e

O M E D H .

S TE P 3 D eterm in e th e in tr in sic sa fe fir in g

a rc co n tro l m ea su res a n d da ta .

S TE P 4 P D H a u tho rises th e in sta lla tio n

o f th e W E .

S TE P 6 P D H p ro d u ces th e S W E D S C R .

S TE P 7 S u b m it S W E D S C R to th e R eg u la tory A u th o rity for

C ertifica tio n .

S TE P 8 R eg u la tory A u th o rity review s th e

S W E D S C R .

S TE P 9 R eg u la tory A u th o rity certif ie s th e

S h ip W ea po n E q uip m en t.

S T E P 10 S W E D S C R a n d th e C ertif ica te are

su b su m ed in to th e S E S C .

S TE P 5 C o n d u ct S h ip In sta lla tio n T ria l

o f th e W ea p o n E q u ip m en t.

Figure 2 – Process for Dynamic Hazards in Submarines


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A.7. Guidance for the SWEDS in the SESCR

A.7.1. As stated above, in addition to any diagrammatic representation of the firing arcs, the PDH is to produce a SESCR. The SESCR is to illustrate an understanding of all hazards identified as being posed by the installation (including firing arcs for ships) and the firing dynamics. Also, to justify the controls introduced to reduce residual risks to levels tolerable and as low as reasonably practicable (ALARP) during its operational life. Due to the weapon-specific nature of much of the information, close liaison with the OMEDH is strongly recommended. The format and content of individual weapon SESC submissions will vary according to the particular characteristics of the installation. For instance, where firing arcs need to be established due to alterations to a vessel’s silhouette, it may be acceptable to update the existing SESCR to take account of the changes. The SESCR should typically include information and, where appropriate, justifications under the following headings:

a. Introduction.

This is to include a brief description of each of the weapon equipment installations and their location on/in the Ship.

b. Requirements for Ship Weapon Equipment Dynamic Safety.

This section is to summarise the requirements that relate to Ship Weapon Equipment Dynamic Safety.

A copy of those URD/SRD requirements applicable to the weapon equipment.

The safety case should state which standards have been used for the ship weapon equipment dynamic integration and safety assessment. This is to include those applicable to software where that is the method of control used for the weapon equipment. In addition, the standard(s) used for Human Factor integration shall be identified.

The safety case should state which International, European and National Statutory Legislation is applicable to the integration of the Weapon Equipment into the Ship.

c. Ship Weapon Equipment Descriptions.

i) This section is to provide a detailed description of the Ship weapon equipment sufficient for the justifications within the SESCR to be understood. It should also include details of their location and means of operation. Where possible, a diagram of the installations should be included. Where greater detail is available in other documentation it is to be referenced. The following aspects should also to be included:


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Weapon system characteristics. Weapon and launcher dimensions, acceleration, dispersion, yaw etc, and method of determination.

Safe Firing Arc control gear. A description of the mechanism used to limit firing arcs, for example, hard or soft cams, physical stops, additional switches etc, and details of any other safety features incorporated.

Software cams. Where software controlled cams are employed, a brief description of the firing arc control mechanism is to be provided.

Bearing and elevation over-runs. These are to be quantified and their method of determination outlined.

d. Ship/Weapon Equipment Interface

i) This section is to detail the interfaces between the ship and weapon:

Ship Data. How the ship structure and equipment exposed points were chosen and measured. The data points must include, where applicable:

i. Fixed Structure

ii. Movable Equipment

iii. Personnel

Clearance Distance. The minimum clearance distance required between ship structure/equipment/personnel and the projectile and method of determination.

Ship Motion and Wind. What ship motion and wind allowances have been used and how they have been applied.

Safe Firing Arc Determination. How the safe arc silhouette has been determined, with justification that the results are correct and that the figures have been properly applied, resulting in a Silhouette diagram showing the ‘as designed’ firing profile and the silhouette of all exposed equipment. In the case of computer generated arcs, confirmation that the software used in the calculations conforms to the safety requirements of Def Stan 00-56 will be necessary.

e. Safety Targets

Identify the safety criteria, whole ship safety targets and specific weapon equipment safety targets and the basis for their definition of applicability to the weapon equipment integration into the Ship.


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f. Hazard Identification, Mitigation and Recording

The SESCR should include evidence that, where appropriate, a hazard analysis of the Weapon Equipment, including the fire control system, including any software, has been carried out in accordance with Def Stan 00-56. The hazards specifically associated with the dynamic safety of the Ship Weapon Equipment integration should be stated together with their controls introduced to reduce the risks to an acceptable level and demonstrated by Formal Safety Assessment (FSA). This FSA is to include demonstration of compliance with Statutory Legislation. Procedures for carrying out hazard identifications and risk assessments are detailed within JSP 430 and Def Stan 00-56. Hazard Controls are not restricted to initial installation: they should also include safeguards necessary to prevent subsequent actions, such as changes to the vessel’s silhouette, from compromising the safety of the firing arcs. The firing arcs of certain installations, such as Close In Weapon Systems, may need to be further limited to take account of sabot dispersion or relaxed to take into account any widening of safe arcs of fire to maximise protection against in coming missiles as discussed in Appendix A.3.2.c. In such cases, the adequacy of the additional limitations employed must also be justified.

g. Independent Safety Auditor (ISA)

A summary of the findings of the ISA, and the PDH response thereto should be included.

h. Inspections and Trials

Details of SQEP Inspection Authority (e.g. MCTA) reports that confirm that arcs have been satisfactorily established in accordance with the installation requirements set by the PDH.

i. References

Details of documents referred to in the SESCR.

j. Statement of Compliance

The PDH is required to make a clear unambiguous statement to the NAExp that confirms that the Ship weapon equipment dynamic arrangements submitted as an element of the SESCR are satisfactory and compliant with the requirements of this Def Stan. NAExp will signify acceptance by listing all those weapon installations, where the assurances provided are agreed to be ALARP, in the Certificate of Safety Explosives (CSE).


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APPENDIX B CLEARANCE DISTANCES AND CUT-OFF ANGLES

B.1. Description

B.1.1. Clearance distances and cut-off angles are important aspects of Ship Weapon Dynamic Safety.

B.2. Performance Requirements For Clearance Distances and Cut-Off Angles

B.2.1. Clearance distances and cut-off angles shall be determined and installed for each Weapon Equipment integrated into a Ship. The level of risk from hazards, identified from risk management techniques, are required to be reduced to ALARP and shall be justified and reported in the SESCR.

B.3. ACOP for Clearance Distances and Cut-Off Angles

B.3.1. Clearance Distances - Guns

a. These dimensions are for guidance insofar as justification is required that they meet ALARP criterion in terms of exposure of personnel to noise legislation. Except for the special requirements of CIWS to which paragraph 7.1.3 and Appendix A.3.2.c refer, the axis of the barrel on a gun mounting nearest to an obstruction shall clear it by the following clearance distance:

i) Physical Obstruction

Exposed personnel - by half the calibre of the subject OME plus 325mm.

NOTE: For assessment purposes the standard man should be assumed to be 2m tall. However risk assessment is to discuss how individuals taller than 2m or those who reach-up will be addressed.

Structure other than whip aerials - by 75mm or 1½ calibres, whichever is the greater.

Whip aerial - by half calibre plus 1½° after allowance has been made for aerial flexibility.

Aircraft - by half calibre plus 450mm except for the main rotors of helicopters for which the clearance distance shall be half calibre plus 900mm with the rotor in the fully dished (i.e. ready to take off) condition.

The swept arc of any guided weapon launcher (loaded with missiles, i.e. the largest space envelope.)- by half calibre plus 450mm.


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The gun house or shield and the swept arc of the barrel of any other gun mounting - by half calibre plus 450mm.

NOTES:

1. Exceptionally for 20mm mountings, the clearance distance from structure shall be 75mm for obstructions at distances up to and including 6m from the end of the barrel and 300mm for obstructions at distances greater than 6m.

2. Additional considerations to be taken into account when establishing clearance distances for guns using ammunition incorporating sabots are outlined below:

a) The following guiding principles shall be applied when determining firing arcs, the method of application depending on the primary function of the ship and equipment concerned.

b) It should be noted that, when considering the safe firing arcs of guns firing sub calibre ammunition, eg Close In Weapon Systems (CIWS), account must additionally be taken of pusher and sabot dispersion. Pushers/base plugs often remain intact and tend to follow the penetrator (round) in its slipstream, remaining lethal for some distance whilst petals from a sabot disperse away from the line of fire and are dangerous to both structure and personnel. Dispersion/deviation characteristics must be assessed for each system individually, but any framing of rules, or choice of parameters, for use in modelling and dispersion cones which are to be included in the overall safety allowance shall include consideration of the following factors:

i) Cease fire time delay whilst the mounting is slewing.

ii) Lateral acceleration of round due to mounting slewing.

iii) Lateral acceleration of round due to rotation of barrels.

iv) Pusher gravity drop.

v) Aerodynamic performance of sabots and pushers in prevailing winds.

ii) Blast Limitations

76mm mountings and above - by the appropriate distance obtained from BR1031.

40mm and below - by 1.25m for exposed personnel at distances up


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to and including 6m and by 625mm for personnel at distances greater than 6m. Guns of 40mm and below have no blast limitation for structure.

B.3.2. Clearance Distances - Missiles

a. The axis of the line of fire of the missile nearest to an obstruction shall be calculated to ensure that the closest part of the missile clears the obstruction by the following clearance distances after allowance has been made (using statistical techniques to determine probability where appropriate) for dynamic forces acting on missile and ship during launch. The principles governing the determination of clearance distances applicable to all physical obstructions, and also to blast and efflux limitations and personnel safety margins, shall equally apply to missiles fired from vertical and fixed angle launch systems. All factors affecting missile dispersion and ship motion shall be considered.

i) Physical Obstruction

Exposed personnel - by 450mm.

NOTES:

1. A larger clearance will probably be required due to blast and efflux limitations.

2. For assessment purposes the standard man should be assumed to be 2m tall.

Structure other than whip aerials - by 300mm.

Whip aerial - by 1½° after allowance has been made for aerial flexibility (See APPENDIX F.

Aircraft - by 450mm except for the main rotors of helicopters for which the closest part of the missile shall clear by 900mm with the rotor in the fully dished (ie ready to take off) condition.

The swept arc of any other guided weapon launcher (loaded with missiles) - by 450mm.

The gun house or shield and the swept arc of the barrel of any gun mounting - by 450mm.

ii) Blast and Efflux Limitations

An additional blast and efflux allowance shall be added to the clearance distances where necessary to prevent damage to structure or personnel. This allowance is specific to each missile system. Clearance dimensions of actual Blast and Efflux allowances are to be justified by the PDH in the SESCR.


31

iii) Cut-Off Angles

Cut-off angles appropriate to individual weapons are to be justified by the PDH in the SESCR. Cut-off angles are an allowance derived from the speed of elevation and training of the mounting and inherent delays in the firing mechanism. Cut-off angles are additional to the clearance distances that prevent projectiles striking an obstruction.

iv) Allowance for ship motion and wind

An allowance shall be included to allow for ship motion under the following conditions:

a) Sea State 8 or other Sea State specified in the ship or weapon requirement document, URD/SRD.

b) All ship headings.

c) All likely ship speeds.

v) Allowances for Missile Deviation

Allowances shall be included to allow for:

a) Wind of strength 60 knots or the maximum missile launch wind strength if lower.

b) Gravity.

c) Missile dispersion.

B.3.3. Use of Probabilistic Methods

a. The PDH may choose to utilise probabilistic methods to justify the safety of an installation rather than developing a SESCR based solely on the clearance distances defined in this Chapter. When probabilistic methods are used to justify the safety of an installation it should be noted that the likelihood of a projectile passing closer to personnel or ship structure than the clearance distance defined by the combined non-probabilistic methods is to be no greater than:

o Missiles – 1x10-3 per missile

o CIWS (Guns) – 1x10-3 per engagement

NOTE: Where the above result in over-restrictive firing arcs, the case for higher probabilities shall be justified fully in SESCR. It is recommended


32

that the PDH discusses any such proposals with the NAExp Secretariat as soon as possible.


33

APPENDIX C CUT-OFF LINES

C.1. Description

C.1.1. Cut-Off lines are the limits within the firing arc of a weapon into which the weapon must not be allowed to fire due to obstructions such as ships superstructure, access areas, manned areas, etc. However, Cut-Off lines can also limit the effectiveness of the weapon by reducing its potential firing arc if they are not correctly optimised.

C.2. Performance Requirements For Cut-Off Lines

C.2.1. Cut-off lines shall be determined for each Weapon Equipment integrated into a Ship. It is required that the level of risk from hazards, identified from risk management techniques, to which Cut-Off Lines relate have been reduced to ALARP shall be justified and reported in the SESCR.

C.3. ACOP for Cut-Off Lines

C.3.1. The procedures to be followed in establishing the required cut-off line shall be in accordance with the principles set out in this Appendix.

C.3.2. Application of Tolerances

a. Safety firing cams shall be designed, manufactured and tested to tolerances applied to take account of the operation of switch mechanisms, mechanical backlash in the safety firing gear, synchronisation between multiple gun firing circuits etc, details of which are contained in the documentation of individual weapon mountings. Guidance on the application of tolerances is given in section APPENDIX D.

C.3.3. Checking Firing Arcs

a. Procedures to be followed when checking safety firing arcs are contained in the documentation of individual weapon equipment. When checking safety firing arcs, inspecting authority (e.g. MCTA) shall satisfy themselves that no changes to the positions or distances of the items used in the establishment of the firing arcs have occurred. It shall also be ensured that no additional fittings have been introduced which could affect the clearance distances. If discrepancies are found then installation Safe Firing Arcs (SFA) should be re-set and the inspecting authority called in to re-inspect.

C.3.4. Determination of Hard Safety Firing Cam Profile

a. When determining a safety firing cam contour, the principle requirement shall be to achieve the maximum practicable firing arcs consistent with ship and personnel safety. Ideally, this would allow the weapon system to fire right up to the cut-off lines. In practice, this is rarely possible because of the inherent


34

characteristics of the firing cam. The following factors shall be taken into account when establishing a cam profile:

i) For reasons of engineering practicability, the safety firing gear mechanics of most weapon equipment will not allow a cam slope of more than 30 degrees.

ii) The cam shall contain no hollows which cover less than 3 degrees of training arc measured at the base of the hollow.

NOTE : Figure 3 to Figure 7 show methods whereby the cam may be contoured around single and multiple obstructions observing the limitations set out above.

Figure 3 – Single Obstruction showing CAM contoured around Obstruction

Figure 4- Multiple Obstructions showing CAM contoured from obstruction to obstruction


35

Figure 5 – Multiple obstructions showing CAM contoured to avoid a stepped distance of less than 3º Training Arc

Figure 6 – Multiple obstructions showing CAM contoured to give a minimum 3º Training Arc at constant elevation


36

C.3.5. Systems Employing Software Cams

Soft cams in general allow a weapon system to follow the cut-off lines more closely. Although the clearances and main requirements for both hard and soft cams are identical, the following conditions must be satisfied when establishing firing arcs for software controlled cams:

i) Logging training/elevation readings - The training/elevation readings obtained when establishing the cut-off lines shall be logged automatically, in an electronic form, directly from the surveying mechanism. The information shall then be transferred automatically into the system employed to calculate the safe firing arcs, which shall be produced, after consideration of the weapon equipment dynamics, using software means.

ii) Hazard Analysis - A hazard analysis shall be performed on the whole weapon equipment that generates the safe firing arcs, in accordance with Def Stan 00-56, and the software developed to the appropriate level of integrity. Wherever possible MOD approved software applications should be used.

iii) Storage of output data - The resulting output data is to be stored automatically in an electronic form, and loaded into the weapon equipment via automatic means.

iv) Checking Software-generated Firing Arc - The generated safe firing arcs shall be checked on installation using equipment identical to that employed initially to establish them. Due to the increased complexity of soft cams over hard cams, a greater number of samples must be taken when testing the integrity of the no fire zone. The exact number and positions of samples shall be justified in the SESCR, prepared by the PDH. As well as confirming that the weapon equipment ceases firing at the specified position, checks should also be made randomly within the no fire zone. These tests will help to provide evidence that the fire control software of the gun is fit for purpose and meets the requirements of the JSP 430 risk management process.

v) Environmental Data - Environmental data that is used by the weapon equipment during the firing sequence, such as wind and ship speeds, shall be entered automatically from the measuring equipment via a communication link.

vi) Storage and Communication of Data - Evidence shall be provided to show that the communication protocol used in the transferral of data between different systems/subsystems preserves the integrity of the data. This evidence may be of the form of showing the use of a Cyclic Redundancy Check (CRC) or an alternative.

vii) Audit Trail - A copy of the generated arcs of fire shall be stored along with any changes made to the parameters during the systems life. This


37

may be in hardcopy or preferably in non-volatile memory on the weapon equipment, and is in order to provide an auditable trail of the life of the parameters. In addition, they will be a ‘live file’ of the SESCR.

Figure 7 – Required Cut Off Line and associated CAM Contour


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APPENDIX D TOLERANCING AND PHYSICAL CHECKING OF CAMS

D.1. Description

D.1.1. The angles allowed as tolerances in the cutting/contouring of safety firing cams are a compromise between obtaining the maximum firing arc and achieving a practical and cost effective engineering solution. In considering the engineering problem, due regard shall be paid to the effect of the scaling of the cam contour due to the linkages, to the type of work/tools involved in the contouring of the cam and to the repeatability of readings with any particular arrangement.

D.2. Performance Requirements for Tolerancing and Physical Checking of Cams

D.2.1. Tolerancing of Safety Firing Cams (SFC) shall be determined for each Weapon Equipment integrated into a Ship such that the level of risk from hazards to which they relate have been reduced to ALARP. As tolerances are a compromise the ‘actuals’ chosen for each weapon equipment integrated into a ship shall be justified and reported in the SESCR.

D.3. ACOP for Tolerancing and Physical Checking of Cams

D.3.1. Scaling Relationships

If, at a weapon mounting, a movement of 1° in training is represented by a lateral distance of 25mm on the safety firing cam and a movement of 1° in elevation is represented by a vertical distance of 1.5mm on the cam, the elevation/training scaling relationship is represented as 1.5:25 or 1:16.7. The shape of a cam contoured to produce a cut-off line with a rise of approximately 60° and drawn to the approximate elevation/training scaling relationship of 1:16.7 is shown in Figure 8.

D.3.2. Cam Checking and Application of Tolerances

a. When a cam is contoured at an approximately constant elevation, or with a slight rise, the critical tolerance is on elevation (Figure 8). In this case, if the cam were checked at point X in training or elevation the result could be found within tolerance had the cam been contoured to take up almost all the allowed tolerance in both motions. This is not necessarily the case when the safety firing boundary/cut-off line has a marked change in elevation, i.e. a high rise condition exists.


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Figure 8 - Safety Firing CAM Tolerances in contouring

b. A typical section of a safety firing cam with an elevation/training scaling relationship of 1:1 is shown in Figure 9. In this example, the cam, which is contoured to be 1° safe when checked in training at A will be only 30’ safe when checked in elevation at B. Similarly, a cam contoured to be 1° safe when checked in elevation at D will be 2° safe when checked in training at C.

c. The effect will change with different elevation/training scaling relationships, e.g. 1:4 (Figure 9). In this example if a cam has been contoured to be 1° safe when checked in training at A, it would be 2° safe when checked in elevation at B. Similarly, a cam contoured to be 1° safe when checked in elevation at D will only be 30’ safe when checked in training at C. With an elevation/training scaling relationship of 1:16.7, the effects illustrated in Figure 9 are even more marked.

d. Examples of safety firing boundaries and cut-off lines are illustrated in Figure 8. Table 1 also gives guidance on whether a particular point on a cam should be checked in training only, elevation only or in both training and elevation. The contour of any particular cam relating to the illustrations may change according to the elevation/training scaling relationship but this in no way changes the outlined principles.

e. Observation of the relationship of the adjacent obstructions to be cleared and an examination of the cam contour before commencing the check will


40

normally make clear the application of the principles involved. If any doubt exists, points should be checked in both motions.


41

Figure 9 - Safety Firing CAMS – Application of Tolerances

f. Where, exceptionally, strict adherence to tolerances would result in uneconomical or unacceptably difficult engineering practices being necessary for the production of the cam, concessions may be sought from the PDH. For example, a cam contoured to be within the training tolerances and normally checked in training only at the required elevation, may be oversafe in elevation. This may be acceptable in order to maintain safety principles. It may also be possible to make a concession where achieving stringent tolerances on both motions will involve futile work due to un-repeatability of readings.

D.4. Guidance for Physical Checking of Cams

Table 1 provides the guidance for the physical checking of weapon cams.

NOTES for: Table 1: 1. A cut-off angle of 1° 30’ is assumed for training and elevation. 2. Abbreviations: OB – Obstruction; SFB – Safe Firing Boundary; CL – Cut-off line.

Example Described Checking Motion Example Illustrated

1. The Safe Firing Boundary (SFB) is a straight line at more than 45º to the horizontal.

Check at point X in training only


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2. The SFB goes round a corner from a line at 45º to the horizontal to another line at over 45º to the horizontal

Check at point X in training only

3. The SFB is a straight line at less than 45º to the horizontal

Check at point X in elevation only


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4. The SFB goes round a corner from a line at less than 45º to the horizontal to another line at less than 45º to the horizontal

Check at point X in elevation only



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5. The SFB goes round a corner from a line at more than 45° to the horizontal to a line at less than 45° to the horizontal.

NOTE: In this example there is a large change in direction of the SFB and the cam will be contoured. The only check that can be made is that the safety firing gear is not dangerous at this point and at the same time that it is not unreasonably oversafe.

Check at point X in training or in elevation that the gun is oversafe.

6. The SFB goes round a corner from a line at less than 45° to the horizontal to a line at more than 45° to the horizontal.

Check at point X in elevation and in training.

Table 1 – Checking Safety Firing CAMS


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APPENDIX E ESTABLISHING CUT-OFF LINES FOR ROTATABLE STRUCTURES

E.1. Description

E.1.1. Rotatable structures, such as aerials and other gun / weapon systems provide an additional challenge when establishing cut-off lines due to their Independent movement.

E.2. Performance Requirements for Establishing Cut-Off Lines for Rotatable Structures

E.2.1. When establishing the cut-off lines for rotatable structures, great care shall be taken to ensure that the cut-off line affords protection to the structure on all bearings to which that structure may be trained.

E.3. ACOP for Rotatable Aerial Systems

E.3.1. The front elevation and plan of a typical rotatable aerial system are outlined in Figure 10. The system indicated comprises a main rotatable aerial with an associated aerial mounted on it and therefore rotating with it.

E.3.2. The main aerial is shown as ABCD in the front elevation and as ABEF in the plan.

E.3.3. The associated aerial is shown as JKLM in the front elevation and as JKNP in the plan.

E.3.4. The following requirements shall be observed when establishing cut-off lines:

a. Good communications shall be provided between the weapon equipment and the aerial control position i.e. 2 Way Radios, in order to avoid hazards arising to those personnel involved with the assessment process.

b. On a multiple mounting, the left axis of fire must be used when training left into danger and vice versa.

c. When it is not possible to use a 1½ calibre batten, the allowance for 1½ calibres may be calculated using measurements of distance from ship’s drawings.


46

Figure 10 – Rotatable Aerials System – Diagrammatic

E.3.5. When establishing training cut-off lines the maximum apparent width of the main aerial, as seen from the mounting, will be when the aerial is rotated so that either diagonal AE or diagonal BF is at 90° to the vertical plane containing the axis of fire (Figure 11) . The cut-off line for these positions can be established by adding or subtracting the clearance distance plus the cut-off angle for the mounting or structure under test.

Figure 11 –Rotatable Aerial System – Establishing Training Cut-Off Lines


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E.3.6. When establishing elevation cut-off lines the highest point of the aerial system as seen from the mounting will appear when the aerial system is trained so that either diagonal AE or diagonal BF lies in the vertical plane containing the axis of fire (Figure 12). Both points on each diagonal shall be sighted from each axis of fire of a multiple mounting to establish the greatest elevation. Should the smaller associated aerial present the highest point when viewed along the axis it shall be used as the datum, and the points of the diagonals JN and PK (Figure 10) used to establish the greatest elevation. Having established the greatest elevation as viewed from the mounting, the cut-off line can be established by adding the clearance distance plus the cut-off angle.

NOTE: In this example, the smaller associated aerial is covered by the main aerial.

Figure 12 – Rotatable Aerial System – Elevation Cut-Off Line

E.3.7. The cut-off lines are defined by one elevation and two training readings (Figure 13), both motions being checked at points X. The safety firing cam is not cut for intermediate aerial positions.


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Figure 13 – Rotatable Aerial System – Cut-Off Lines

E.3.8. When establishing the safety firing boundary of a stabilised aerial it will be necessary to take into account that the aerial will change orientation with respect to the ship and may topple when power is off. The safety firing boundary shall therefore be established with the aerial in its worst position, i.e. toppled for elevation, horizontal for training, for 360° of arc.

E.4. ACOP for Guns and Missile Launchers

E.4.1. When establishing the cut-off lines required to clear a gun or missile launcher, it must be ensured that the mounting to be cleared is trained to bearings which present the greatest obstacle to the line of fire before measuring the training and elevation angles at the firing mounting which are to be used as a datum for applying cut-off angles and clearance distances.

E.4.2. Good communications are required between the two mountings since it is necessary to train and stop both mountings simultaneously.

E.4.3. The procedure for establishing the cut-off line for a twin gun mounting is detailed in Table 2 and Figure 14. The same principles should be applied to a single gun mounting.


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Figure 14 – Gun Mounting – Cut-Off Lines


50

Step A Mounting B Mounting

1 Trained fore and aft. Trained fore and aft. Left gun bore telescope manned.

2 Train left. Train right. Sight highest farthest right point of A mounting.

3

Continue training left slowly until ordered to stop and/or reverse.

Continue to train right following selected point until obstruction is farthest right.

4 Stop training (Figure 14 position X).

Stop training.

5 Record training GPI reading.

Allow clearance distance. Record training GPI reading. Allow cut-off angle. Record training required reading and achieved reading.

6 Train fore and aft. Train fore and aft. Man right gun bore telescope.

7 Train right. Train left. Sight highest farthest left point of A mounting.

8 Continue training slowly until ordered to stop and/or reverse.

Continue to train left following selected point until obstruction is farthest left.

9 Stop training (Figure 14 position Y).

Stop training.

10 Record training GPI reading.

Allow clearance distance. Record training GPI reading. Allow cut-off angle. Record training required reading and achieved reading.

11 Train to present the highest point at its maximum elevation when viewed from B mounting.

Using either gun bore establish the highest point of the gunhouse or shield.

12 Stop training (Figure 14 position Z). Record training GPI position.

Check on other gun bore that the elevation is the same, if not use the gun having the highest reading. Allow clearance distance. Record elevation GPI reading. Allow cut-off angle. Record elevation required reading and achieved reading.

Table 2 - ESTABLISHING CUT-OFF LINES FOR GUN MOUNTINGS


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WARNING: Where software is used to control weapon arcs of fire, it may incorporate slew prediction, therefore slow training is essential.


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APPENDIX F ESTABLISHING CUT-OFF LINES FOR WHIP AERIALS

F.1. Description

F.1.1. Whip aerials are vulnerable to damage due to their exposed position and potential to move in the wind or as the vessel manoeuvres, but they are often critical to the operation of the vessel.

F.2. Performance Requirements for establishing Cut-Off Lines for Whip Aerials

F.2.1. When establishing the cut-off lines required for a mounting to clear whip aerials, the following shall be considered:

a. The clearance distance is - half calibre plus 900mm.

b. The clearance distance must allow for the top of the whip aerial bending towards the mounting (more elevation required to clear) or at 90° to the line of sight (more training required to clear).

c. Whip aerials can bend considerably in strong winds. If the bend is obvious to the eye and/or the required readings cannot be established with confidence, the test shall be postponed until conditions improve.

d. When the whip aerial to be cleared is on top of a gun mounting, the appropriate procedure may be a combination of the above instructions and those in Table 2.

e. The procedure consists of the following steps for each whip aerial:

i) Establish and record the angles of elevation and training of the top of the whip aerial.

ii) Establish from drawings or by measurement, the horizontal distance from the centre of rotation of the mounting to the base of the whip aerial.

iii) Calculate the required elevation cut-off line.

iv) Calculate the required training cut-off line.

F.2.2. Elevation Cut-Off Line

a. The calculations required to establish the elevation cut-off line are based on Figure 15 using the following data; all linear measurements must be in the same units:

c = Clearance distance of half calibre plus 900mmd Horizontal distance, mounting to whip aerial


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h = Height of top of whip aerial above weapon

γ = Observed elevation to top of whip aerial

φ = Elevation of the top of the whip aerial when the top is towards the mounting by an amount equal to the clearance distance c.

Figure 15 – Whip Aerial Establishing Elevation Cut-Off Line

Figure 16 – Whip Aerial Establishing Training Cut-Off Line


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b. The equations used for the calculations are as follows:

i) h = d tan γ

ii) cdh−

=φtan

iii) Elevation of required elevation cut-off line = φ + 1° 30’

F.2.3. Training Cut-Off Line

a. The calculations required to establish the training cut-off line are based on Figure 16 using the following data; all linear measurements must be in the same units.

c = Clearance distance of half calibre plus 9000 mm.

d = Horizontal distance, mounting to whip aerial.

Ψ = Angle subtended in the horizontal plane by the clearance distance c measured at the elevation cut-off line and projected onto the horizontal plane.

φ = Elevation of the top of the whip aerial when the top is towards the mounting by an amount equal to the clearance distance c.

b. The equations used for the calculations are as follows:

i) cdc−

=Ψtan

ii) Training of required training cut-off line = Trained angle of mount to whip aerial + Ψ + 1° 30’


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APPENDIX G POLAR DIAGRAMS

G.1. Description

G.1.1. Polar diagram development and production is not mandatory. However, these have been found to offer benefit in the development of safe firing arc solutions and assurances

G.2. Performance Requirements for Polar Diagrams

G.2.1. There are no Performance Requirements for polar Diagrams

G.3. ACOP for Polar Diagrams

G.3.1. There are no ACOP for Polar Diagrams.

G.4. Guidance for POLAR DIAGRAMS

G.4.1. Guidance is provided below to explain Polar Diagram development.

NOTE: Clearance distances referred to in this Appendix are for illustrative purposes only.

See the Notes following these Tables

Limiting

Safety Firing

Boundary

Cut-off line

Remarks

Obstruction Training Angle

Elevation Angle

Training Angle

Elevation Angle

1 2 3 4 5 6 7

1 Jackstaff lug on Bullring 0° -3° 30’ 4° 30’G R -1° 20’

2 Forward fairlead 5° 16’G -3° 31’ 9° 46’G -1° 21’

3H Forward fairlead 5° 49’G -3° 40’ 10° 19’G -1° 30’

3S Forward fairlead 6° 37’G -4° 23’ 11° 07’G -2° 13’

4H Forward bollard (forward set)

12° 08’G -5° 45’ 16° 38’G -3° 35’

Table 3: TABULAR STATEMENT FOR POLAR DIAGRAM


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See the Notes following these Tables Limiting Safety Firing

Boundary Cut-off line Remarks


Elevation Angle

Training Angle

Elevation Angle

1 2 3 4 5 6 7

4S Forward bollard (forward set)

14° 08’G -6° 45’ 18° 38’G -4° 35’

5H Forward bollard (forward set)

14° 43’G -6° 11’ 19° 13’G -4° 01’

5S Forward bollard (forward set)

16° 29’G -7° 14’ 20° 59’G -5° 04’

6 Collapsed handrail stanchion

17° 21’G -9° 12’ 21° 51’G -7° 02’

6A Collapsed handrail stanchion

20° 40’G -9° 33’ 25° 10’G -7° 23’

12 Starboard bollard (third set)

151° 29’G -9° 55’ 146° 59’G -7° 45’

13A

13B

After breakwater up and

over lamp box mounting

154° 50’ G

157° 47’ G

-8° 42’

-7° 23’

150° 00’ G

153° 17’ G

-6° 32’

-5° 13’

14 Roller fairlead and superstructure

159° 16’ G -6° 59’ 154° 36’ G -4° 49’

15(1) Bridge profile starboard 160° 46’ G -6° 27’ 156° 16’ G +8° 37’ }}

15(2) Bridge profile starboard

personnel

160° 46’ G +9° 16’ 156° 16’ G +11° 26’ }

}}


personnel

168° 34’ G +9° 59’ 164° 04’ G +12° 09’ } From wing of bridge

} up over bridge house


personnel

168° 59’ G +10° 27’ 164° 29’ G +12° 37’ }

}}

18 AWN for QYA(2) similar

to line of sight 26

170° 31’ G +16° 18’ 166° 31’ G +18° 28’

21 AWN at FR21 173° 13’ G +16° 18’ to

+24° 43’

168° 43’ G +18° 28’

to

+26° 53’

22 UHF FH5 aerial 178° 55’ G +24° 43’ to

+27° 37’

174° 22’ G +26° 53’ to

+29° 47’

Starboard side of UHF at widest position

23 UHF FH5 aerial 180° 00’ +27° 37’ 175° 30’ G R

-29° 47’



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Limiting

Safety Firing

Boundary

Cut-off line

Remarks


Elevation Angle

Training Angle

Elevation Angle

1 2 3 4 5 6 7

24 UHF FH5 aerial 178° 58’ R +24° 09’

to +22° 17’

174° 28’ R +28° 19’ to +24° 27’

Port side of UHF at widest position

24B 965 radar top athwart (port)

173° 09’ R +22° 17’

to +16° 18’

168° 39’ R +24° 27’ to

+18° 28’

26

AWN for QYA(2) port similar to line of sight 18

170° 31’ R

+16° 18’

166° 01’ R

+18° 28’

27(4) Bridge profile port top of wheelhouse

168° 59’ R +10° 28’ 164° 29’ R +12° 38’ }

}}

27(3) Bridge profile port personnel

168° 35’ R +10° 00’ 164° 05’ R +12° 10’ }

} From wing of bridge

} up over bridge house


160° 43’ R +9° 20’ 156° 13’ R +11° 30’ }

}

}


160° 43’ RG

+6° 53’ 156° 13’ G +9° 03’ }

}

}

29 Forward roller (Red) 159° 17’ R -7° 07’ 154° 47’ R -6° 57’

32 After breakwater (Red) lamp box

157° 57’ R -7° 19’ 153° 27’ R -5° 09’ Over top of emergency off switch

33 Corner after breakwater (Red)

154° 57’ R -8° 47’ 150° 27’ R -6° 37’

34 After bollard (Red) (third set)

152° 51’ R -9° 29’ 148° 21’ R -7° 19’

35 Forward bollard (Red) (third set)

150° 39’ R -9° 18’ 146° 09’ R -7° 18’



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Limiting

Safety Firing

Boundary

Cut-off line

Remarks


Elevation Angle

Training Angle

Elevation Angle

1 2 3 4 5 6 7


21° 05’ R -9° 20’ 25° 35’ R -7° 10’


17° 40’ R -8° 59’ 22° 10’ R -6° 49’

39P After bollard (Red) (first set)

16° 25’ R -7° 16’ 20° 55’ R -5° 06’

38H After bollard (Red) 15° 19’ R -6° 15’ 19° 49’ R -4° 05’

39P Forward bollard (Red) (first set)

14° 00’ R -6° 39’ 18° 30’ R -4° 29’

39H

Forward bollard (Red) (first set)

12° 26’ R -5° 46’ 16° 56’ R -3° 36’

40P Forward fairlead outboard (Red) (first set)

6° 35’ R -4° 26’ 11° 05’ R -2° 16’

40H Forward fairlead outboard (Red) (first set)

5° 47’ R -3° 36’ 10° 17’ R -1° 26’

41 Forward fairlead inboard (Red) (first set)

5° 14’ R -3° 30’ 9° 44’ R -1° 20’


NOTES :

1. Points on the ship’s structure within the safety profile or below the maximum depression of the gun (10°) are not listed.

2. The training and elevation angles defining the safety firing boundary (columns 3 and 4) include allowances for clearances and blast as stated in Notes 4. and 5.

3. The training and elevation angles defining the cut-off line (columns 5 and 6) are the columns 3 and 4 angles with the allowances for cut-off angles added as stated in Note 6.


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4. The polar diagram (Figure 17) and tabular statement (Table 3, Table 4, Table 5 & Table 6), used as examples, are typical for a 4.5in Mk 8 mounting installed in a Type 42 Destroyer for which the following Clearance Distances for Physical Obstructions (derived from Imperial units) are applicable:

(1) Exposed personnel by 305mm (1ft).

(2) Whip aerials by 914mm (3ft).

(3) Swept arc of the SEA DART launcher (loaded with missiles) by 457mm (1ft 6in). This distance gives the requisite blast limitation clearance.

5. Blast Limitation - The limiting peak pressure for exposed personnel adjacent to the 4.5in Mk 8 mounting is 0.24 bar (3.6 lb/in²).

6. The design cut-off angle is 4° 30’ for training and 2° 10’ for elevation.

7. Different allowances may be required for other ship installations, e.g. the blast limitations for GWS 50 containers is 0.69 bar (10 lb/in²); hence for Type 21 Frigates fitted with this system it is necessary for a 0.69 bar (10 lb/in²) blast limitation boundary to be added to the polar diagram.

G.4.2. The polar diagram and its associated tabular statement provide the following data:

a. The points defining the safety firing boundary, i.e. physical obstruction silhouette points with appropriate clearance distances added and with any applicable blast limitations included.

b. The points defining the cut-off line, i.e. the safety firing boundary with allowances made for the cut-off angles.


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Figure 17 – Typical Polar Diagram for 4.5 in Mark 8 Mounting On Type 42 Destroyer


61

APPENDIX H PROCEDURES FOR DETERMINATION OF SHIP ACTUAL SAFETY FIRING BOUNDARY

H.1. Description

H.1.1. Once the weapon systems and all other potential obstructions are fitted to the vessel, it is necessary to ensure that the actual cut-off lines are in the most appropriate place so that the weapon system has a clear arc of fire, but that it is also not limited excessively reducing the capability of the weapon system.

NOTE: Reference to 1½ calibre in this chapter refers to the clearance required from structure for guns of 50mm calibre or greater. Its use here is illustrative.

H.2. Performance Requirements for Determination of Ship Actual Safety Firing Boundary

H.2.1. The design and manufacture of the safety firing cam shall be undertaken after the installation of the weapon equipment. The true silhouette of the ship shall then be plotted using the appropriate equipment, e.g. a bore telescope for guns or specialist equipment for missile launchers, as required by the installation specifications and the elevation and training angles measured by the Gun Position Indicators (GPIs) or missile launcher equivalents.

H.2.2. A 1½ calibre square or T-shaped batten shall be used to obtain the correct clearance distance when measuring the elevation and training angles to determine the safety-firing boundary. Where this is impracticable, e.g. aerials and fittings on masts the appropriate angle for 1½ calibre clearance shall be obtained by calculation, using distances taken from the relevant drawings. The calculated clearance angles shall then be added to or subtracted from, as appropriate, the training and elevation positions measured by the GPIs.

H.2.3. The installation and/or setting to work authority shall assist the shipbuilder/refitting authority and the Inspection Authority (e.g. MCTA) representatives in obtaining and recording the readings from which the shipbuilder/refitting authority will produce the polar diagram.

H.2.4. Before commencing the procedure for determining the safety firing boundary (Figure 18) the shipbuilder/refitting authority shall:

a. Be satisfied that all ship’s structure which could affect weapon firing arcs is complete and provide a written assurance that no alteration to ship’s structure will be undertaken after safety firing boundary readings have been taken and recorded.

b. Ensure that elevation and training GPIs and gun bore, or missile launcher equivalents, are correctly aligned to Ship’s Datum’s, Bench Marks or scribed lines.


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H.2.5. Before measuring the elevation and training angles to determine the safety-firing boundary, the following preparations are required:

a. Fully clear away the mounting (jackstaff, guardrails, etc to be struck).

b. Provide a 1½ calibre square or T-shaped batten.

c. Fit bore telescope and muzzle cross wires to gun or deploy equivalent equipment for missile launcher.

d. Provide suitable communication arrangements between mounting and upper deck.

H.2.6. The following procedure is typical and variation may be needed to suit local conditions, e.g. weapons mounted under overhead gantries. Although written for guns the underlying principle is equally applicable to missile launchers:

Figure 18 – Determination of Safety Firing Boundary

a. Start on the starboard beam with the gun lay at maximum depression and train forward until the line of sight through the bore telescope just clears the ship’s structure by the clearance distance, i.e. the width of the batten, and record training GPI reading. With the gun still at full depression, train aft until the line of sight just clears the ship’s structure by the clearance distance and record training GPI reading.

b. Repeat the procedure in (a) on the port side, again recording forward and after training GPI readings.


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c. Return the mounting to the starboard beam and train left to the first obstruction. Using the bore telescope, record the elevation and training of the obstruction by elevating and training on to the outboard end of the 1½ calibre batten placed on the obstruction in a plane normal to the axis of the gun bore. Repeat for all other obstructions to the bow, and similarly from the starboard beam to the stern.

d. Repeat the procedure in (c) on the port side, again listing each obstruction and the relevant elevation and training GPI readings. Each individual ship installation shall be treated as described above because it cannot be assumed that ships of the same class will have identical profiles. When sighting through the bore telescope it is of particular importance that, where there is a change of profile, all points should be covered and the limits of each obstruction determined. Elevation and training readings must be obtained for all obstruction points considered, ie it is incorrect to record the elevation GPI reading of the highest point of the obstruction and the training GPI reading of the lowest point of the obstruction. Each point considered must have its own elevation and training GPI reading. When an obstruction can be approached either training right or left, e.g. the top of the bullring, GPI readings in each direction shall be recorded.

e. Compile a tabular statement from the elevation and training GPI readings obtained.

H.2.7. From the information recorded in (f) the shipbuilder/refitting authority shall prepare the polar diagram drawing which shall show the additions necessary for blast and efflux limitation, cut-off angles, etc and must be supported by the tabular statement. The ship’s name and the relevant drawing and issue numbers shall be clearly marked on the drawings, (NOTE - these details have been omitted from the polar diagram example in Figure 17).

H.2.8. In ‘First of Class’ Ships the shipbuilder shall calculate any blast clearances that may be necessary and show them on the silhouette diagram or polar diagram. These clearances will be verified by ‘First of Class’ Blast Trials. For subsequent ships of the same class, blast clearances established for the first of class shall be utilised and justified for continuous use.

H.2.9. Any completed silhouette diagram/polar diagram and tabular statement shall form part of the SESCR.


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H.3. Performance Requirements for Silhouette Cams and Diagrams

H.3.1. When required for the manufacture of a type of safety firing cam known as a silhouette cam, it is necessary to produce a silhouette diagram from which the cam can be manufactured.

H.3.2. The silhouette diagram (Figure 19) shall contain details of:

a. The cut-off line, i.e. a plot of the obstruction to which the clearance distance, cut-off angles and blast and efflux allowances have been added.

b. The safety firing silhouette, i.e. the smoothed designed safety cut-off line.

c. Switch operating elevations and bearings (where applicable).

d. A table of co-ordinates which clearly defines the safety firing silhouette.

e. The drawing number of the polar diagram, if produced, from which the silhouette was drawn.

H.3.3. When the safety firing silhouette diagram has been verified by the PDH, the shipbuilder/refitting authority shall produce a safety firing test sheet for the ship, based on the details shown on the silhouette diagram.

H.3.4. The shipbuilder/refitting authority shall complete a standard blank safety firing test sheet, showing the designed cut-off and switch operating angles for elevation and training, for use at the ship installation trial.

H.3.5. The silhouette cam shall be manufactured to the silhouette cam drawing, assembled in its safety firing unit and bench tested. The achieved readings shall be recorded on a test sheet, ultimately to be recorded on the safety firing test sheet. On installation in the mounting, the safety firing unit shall be aligned to the mounting GPIs and the cut-off points checked against the safety firing test sheet.

H.3.6. The completed silhouette diagram and associated safety firing test sheet shall form part of the Safe Firing Arc Safety Case Report (SFASCR).

NOTE: An example of a typical safety firing test sheet completed for a 4.5in Mk 8 mounting in a Type 42 Destroyer is at Annex D.


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Figure 19 – Typical Silhouette Diagram for 4.5 in Mark 8 Mounting on Type 42 Destroyer

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H.4. Performance Requirements for the Installation Trial of Firing Arcs

H.4.1. General

a. Weapon firing arcs shall be checked by a qualified inspecting authority (e.g. MCTA) Trials Officers as part of the Weapon Equipment Installation Trial. The safety firing test sheet is to be used as a means of testing for acceptance but it is to be noted that the trials officer may re-check any obstruction point should he consider it to be necessary. Should there be any requirement to test at points other than those shown on the test sheet, care must be taken to ensure that the safety firing cut-off is tested in the correct motion i.e., the cut-off is to be tested on elevation only when the slope of the cut-off line is 45° or less to the horizontal or in training only when the slope is greater than 45°. Where additional points are tested, tolerances are to be applied with reference to the smoothed cut-off line and not the unsmoothed cut-off line.

b. The test procedure to be followed during the installation trial shall be detailed in the safety firing test sheet (see Annex D).

c. On satisfactory completion of the safety firing tests a table of the results obtained is to be produced and presented in the SESCR. The safety firing gear is required to be correct and acceptable before a SESCR submission is made to NAExp. NAExp certification is required before Installation Test Firings, First of Class Blast and Efflux Trials or Ship Blast and Efflux Trials.

H.4.2. As Fitted Safety Firing Test Sheet

a. On verification of the safety firing arrangements by the Inspecting Authority (e.g. MCTA), the weapon mounting contractor/ refitting authority shall produce completed copies of the safety firing test sheet showing the bench test achieved readings and the ship achieved readings including a tabular statement of the total firing limitations as proved at the Installation Trial.


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Annex A – REFERENCED DOCUMENTS

Ref No

Reference Title Sponsor/Contact

1 JSP 430 Ship Safety Management System Handbook

SSMO

2 JSP 862 MOD Maritime Explosives Regulations

NAExp

3 Def Stan 00-56 Safety Management Requirements for Defence Systems

DStan

4 JSP 430 Part 3 (NAR)

Naval Authority Regulations (now JSP 430 Pt 3)

SSMO


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Annex B – ABBREVIATIONS

For the purpose of this MAP the following abbreviations apply:

ACOP Approved Code of Practice

ALARP As Low As Reasonably Practicable

BR Book of Reference (RN)

CIWS Close-In Weapon System

CL Cut-off Line

COT Captain Of Turret

CRC Cyclic Redundancy Check

CSE Certificate of Safety Explosives

CSOME Certificate of Safety Ordnance, Munitions and Explosives

Def Stan Defence Standard

DOSG Defence Ordnance Safety Group

DStan Directorate of Standardisation

EMP Electromagnetic Pulse

FSA Formal Safety Assessment

GOCO or GoCo Government Owned Contractor Operated

GPI Gun Position Indicators

GWS Guided Weapon System

HMS Her Majesty’s Ship

ISA Independent Safety Auditor

JSP Joint Service Publication

MAP Maritime Acquisition Publication

MCTA Maritime Commissioning, Trials and Assessment

mm Millimetre


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MOD Ministry of Defence

NAExp Naval Authority Explosives (Regulator)

NAR Naval Authority Regulations

NAR Chapter 8 Naval Authority Regulations Chapter 8 (Explosives)

OB Obstruction

OME Ordnance, Munitions and Explosives

OMEDH OME Duty Holder

OSRP OME Safety Review Panel

PDH Platform Duty Holder

PSH Probability of Self Hit

RADHAZ Radiation Hazard

RFA Royal Fleet Auxiliary

SEMS Safety and Environmental Management System

SESC Ship Explosives Safety Case

SESCR Ship Explosives Safety Case Report

SFA Safe Firing Arc

SFASCR Safe Firing Arc Safety Case Report

SFB Safe Firing Boundary

SFC Safety Firing Cams

SQEP Suitability Qualified & Experienced Personnel

SRD System Requirements Document

SWEDS Ship Weapon Equipment Dynamic Safety

TEWA Threat Evaluation and Weapon Assignment

TREE Transient Radiation Effects on Electronics

URD User Requirements Document

WESCR Weapon Equipment Safety Case Report


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Annex C – GLOSSARY OF DYNAMIC SAFETY TERMS

1½ CALIBRE The clearance required from structure for guns of 50mm calibre or greater.

BORE TELESCOPE A bore telescope is an optical device which, when fitted to the bore of a gun barrel and centred, will enable the operator to view accurately the axis of the line of fire of the gun at any given elevation or training angle.

BREECH LAMP A breech lamp is an indicator fitted to some guns when checking safety firing profiles, it indicates when the safety firing switch is operated by the firing cams. The lamp will burn when, with the firing circuits continuously energised, the gun is trained within the zone bounded by the safety firing silhouette and extinguish when elevation or training cams operate the safety firing switch as a restricted arc is entered.

CLEARANCE DISTANCE

The clearance distance is the distance by which the projected axis of the nearest gun barrel or missile launcher rail system shall clear an obstruction. The locus of the points thus defined form the safety firing boundary. Different clearance distances are specified for hard and soft structures.

CUT-OFF ANGLE The cut-off angle is an angular allowance added to the safety firing boundary so that the firing circuits will be broken sufficiently early to ensure that no projectile infringes the safety firing boundary due to speed of elevation and training of the mounting.

CUT-OFF LINES Cut-off lines are the lines produced by adding the cut-off angle allowance to the safety firing boundary in elevation and training.

CYCLIC REDUNDANCY CHECK

A Cyclic Redundancy Check is an Error Checking Algorithm That undertakes a numerical comparison of the data transferred versus what has been received. There are other similar acceptable tools that can be used.

EFFLUX Efflux is an exhaust gas plume of high temperature, pressure and flow accompanied by smoke, discharged by either a solid or liquid propelled missile.


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FIRING ARC POLAR DIAGRAM

The firing arc polar diagram is a radial diagram showing the shape and limits of the safety firing boundary and cut-off line for a weapon.

GPIs Gun Position Indicators

HANGFIRE When the time interval between initiation of a cartridge cap or the application of an electrical firing pulse and the initiation of the propellant charge is excessive. An undesired delay in the functioning of a firing system.

LAUNCHER RUN AWAY During firing it is theoretically possible, under fault conditions, for a launcher to remain travelling whilst a fire boost pulse is sent but the fact that the launcher is still travelling is not detected in time to prevent the boost pulse from being sent. Therefore an allowance (Launcher Run Away) is required to be applied for both training and elevation.

MISFIRE Failure to fire or explode properly or the failure of the primer of the propelling charge of a round or projectile to function wholly or in part.

MISSILE DISPERSION Missile dispersion is the deviation of the missile from the projected longitudinal centreline of the missile launcher rail system and is influenced by environmental forces and the missile guidance system. Missile dispersion and movement of shipborne structure into the missile flight path are dependent on ship motion, wind, gravity drop and aerodynamic forces and is further modified by the velocity imparted to the missile by ship motion at the instant of launch.

MISSILE DISPERSION ANGLE

The missile dispersion angle is the launcher rail system offset angle needed to allow for the dispersion of that part of the missile which passes closest to the ship’s structure

MISSILE INCIDENCE ANGLE

The missile incidence angle is the angle the missile centreline makes with the projected axis of the missile launcher rail system.

MISSILE/SHIP CLEARANCE ANGLE

The missile/ship clearance angle is the launcher elevation angle or bearing angle needed to allow for the clearance between the ships structure and that part of the missile which passes closest to the ship’s structure

NO FIRE ZONE The concept of software-controlled arcs is that the weapon installation is able to train in an unrestricted manner, so target tracking is maximised. Safe arcs are achieved by the use of firing gear interruption that prevents the gun from firing Hence the no-fire zone is simply the zone when the weapon is prevented from firing.


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PROFILE POINT A profile point is a point on a ship’s structure or equipment, prominent when viewed from the axis of the gun barrel or missile launcher rail system under consideration, and forming part of the outline which, with the addition of clearance distances, defines the safety firing boundary. Its position is defined and tabulated in the ship profile data in the form of range, bearing and elevation

PUSHER A pusher is an aluminium plug which forms part of the projectile of sub calibre ammunition. It is fitted behind the sabot petals and the penetrator to which it transfers the explosive energy of the propellant on detonation.

SABOT A sabot is a disposable plastic cap, fitted to the penetrator of sub calibre ammunition the purpose of which is to increase the effective diameter of the round at detonation. It is designed to split into ‘petals’ and disperse when clear of the gun barrel

SAFE FIRING ARC The safe firing arc for a gun or launcher is the arc of fire bounded, either in elevation or training, by the safety firing boundary

SAFETY FIRING BOUNDARY

The safety firing boundary is a line dividing the areas where a projectile may pass from those where it may not pass. It is the locus of the points at which the projected axis of fire clears the profile points by the clearance distance.

SAFETY FIRING CAM (SILHOUETTE CAM)

Safety firing cams are incorporated within the safety firing gear to prevent a weapon firing into the restricted arcs of fire. They comprise a combination of elevation and training cams suitably cut to restrict firing to the outline of the safety firing silhouette

SAFETY FIRING SILHOUETTE

The safety firing silhouette is the smoothed safety firing cut-off line forming the basis for a silhouette cam.

SHIP MOTION Ship motion comprises Pitch, Roll, Yaw, Heave Surge and Sway in various combinations. When assessing the effect of ship motion on missile firing arcs, a calculation based on maximum values for un-stabilised ship motion is applied.

SHIP MOTION EFFECTS

The imparted pitch and heave velocities affect only the vertical dispersion of a missile and the effect varies with launcher elevation. The imparted roll velocity affects vertical and horizontal dispersion and its effect depends on launcher elevation and bearing. Velocities imparted from yaw, surge and sway affect missile dispersion only in the horizontal plane and the effects vary with launcher elevation and bearing. Ship motion also causes movement of shipborne structure relative to the missile flight path after launch.


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SHIP’s OUTLINE DRAWING

An outline drawing of the ship which is produced from the class small scale drawings together with relevant weather deck and aerial rig drawings and on which the positions of all significant structures are marked.

SHIP SILHOUETTE ANGLE

The ship silhouette angle of any point is the bearing and elevation of the mounting when the projected axis of the gun barrel or missile launcher rail system passes through that point

SILHOUETTE CAM PROFILE

The silhouette cam profile, which is developed by the safety firing gear manufacturer using computer techniques, is derived from a diagrammatic sketch and table of results of profile point measurements plus allowances and provides manufacturing data for the cam

SILHOUETTE DIAGRAM A diagram showing the safety firing silhouette and cut-off line for a weapon

SOFT/HARD STRUCTURES

Structures which are considered to be particularly prone to damage from blast, sabots or the pressure and/or corrosive effects of missile efflux are termed ”soft” structures, eg aerials and radomes. Other structures are termed ”hard” structures

SOFTWARE Software includes all instructions and data which is input to a computer to cause it to function in any mode. Where software is used to control firing profiles, information, generated from the system rules and stored in the weapon fire control system, prevents the weapon firing unless it is trained within the defined safe arcs of fire

SWEPT ARC The swept arc of a weapon is the locus of its extremities (muzzle, structure, loaded missile, etc) at all angles of elevation and training to which it is capable of being manoeuvred


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Annex D – SAMPLE SAFETY FIRING TEST SHEET

4.5in MARK 8 MOUNTING - SAFETY FIRING TEST SHEET FOR TYPE 42 DESTROYERS

SHIP ................................................................... SILHOUETTE DIAGRAM ................................ POLAR DIAGRAM .......................................... DATE OF TEST ................................................ INSPECTION AUTHORITY REPORT No ....................

4.5in MARK 8 MOUNTING - SAFETY FIRING TEST SHEET

General

1. The test instructions and tables contained in this safety firing test sheet are provided as a means of checking the setting up and operation of the various cam operated switches within the safety firing unit.

2. The ‘Designed Cut-off Readings’ and ‘Achieved Readings’ recorded in the tables of this test sheet are applicable to the named ship only and must not, under any circumstances, be used to check the safety firing arrangements of any other ship.

3. Before commencing any of the tests contained in this test sheet the operator must either verify, or be assured that the mounting and the mounting GPIs are correctly aligned to the Ship’s Datum’s (Tolerance + 3’).

4. The test instructions provided with these tables call for the use of a breech lamp to indicate when the firing circuits to the gun make or break. For convenience, the indication lamp at the Captain Of Turrets (COT) Panel may be used in lieu of the breech lamp to provide the required firing circuit make and break indication, providing checks are first carried out to verify that the


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gun firing circuits are accurately synchronised with the indication circuits concerned. Similarly, when safety firing checks are carried out with mounting power ON and the mounting is controlled from the Test Cabinet, the elevation and training indicator dials at the Test Cabinet may be used to read off the achieved elevation and training cut-off angles providing the alignment of the Test Cabinet dials has been verified against mounting GPIs before commencing the safety firing checks.

5. Dependent on the layout of the Power Room, it may be more convenient and advantageous to the operator if a temporary extension test lead with lamp is rigged between the COTs Panel and the Test Cabinet to enable him to observe directly the operation of the indicator lamp at the controlling position. Adoption of this method will speed up the test procedure and also reduce the number of personnel required to carry out the tests.

NOTE : The tables in this Annex include typical test readings.

SHIP ................................................

TEST 1 - BACKLASH AND SWITCH DIFFERENTIAL TEST (ELEVATION)

1. Train the mounting on to the training test angle (Table: D1 column 2).

2. With the gun elevated into the firing arc, continuously energise the firing circuits and ensure that the breech lamp burns.

3. Depress the gun slowly and record the elevation at which the breech lamp is extinguished (Table: D.1 column 6).

4. Depress a further 3° to 4° then slowly elevate the gun and record the elevation at which the breech lamp burns (Table: D.1 column 7).

5. Repeat test for each switch listed in Table: D.1 .

Tolerances

Differences between readings when depressing into danger (column 6) and elevating out of danger (column 7) not to exceed 1° 30’.

Table: D.1

Bench Achieved

Test Readings

Ship Achieved

Readings

Switch

(1)

Training

(2)

Depr

(3)

Elev

(4)

Diff

(5)

Depr

(6)

Elev

(7)

Diff

(8) S1 0º 1º 11’E 1º 45’E 34’ 1º 15’E 2º 07’E 52’

E1 150º 00’G

2º 28’D 1º 53’D 35’ 2º 37’D 1º 30’D 1º 07’


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TEST 2 - BACKLASH AND SWITCH DIFFERENTIAL TEST (TRAINING)

1. Lay the gun to the elevation test angle (Table: D.2 column 2).

2. With the gun trained into the firing arc, continuously energise the firing circuits and ensure that the breech lamp burns.

3. Train the mounting slowly left towards danger and record the angle of training at which the breech lamp is extinguished (Table: D.2 column 6).

4. Continue training left a further 3° to 4°, then slowly train right and record the bearing at which the breech lamp lights (Table: D.2 column 7).

5. Repeat test on Green angles of training.

6. Repeat paragraph 1 to 5 for each listed switch.

NOTE : When testing S2 switch, the mounting should be trained right into danger on Red angles of training and left into danger on Green angles of training.

Tolerances

Difference between readings when training into danger (column 6) and training out of danger (column 7) not to exceed 1° 30’.

Table: D.2

Bench Achieved

Test Readings Ship

Achieved Readings

Switch

(1)

Elevation

(2)

Training

Into Danger (3)

Training out of

Danger (4)

Diff (5)

Training

into Danger (6)

Training out of

Danger (7)

Diff (8)

T1 5º 00’E 154º 10’ R 153º 30’ R 40’ 154º 20’ R 153º 15’ R 1º 05’

T1 5º 00’ E 154º 10’ G 153º 30’ G 40’ 154º 30’ G 153º 36’ G 54’

T2 6º 00’ D 145º 30’ R 144º 40’ R 50’ 145º 40’ R 144º 22’ R 1º 18’ T2 6º 00’ D 146º 20’ G 145º 50’ G 30’ 146º 55’ G 146º 02’ G 53’ S2 8º 00’ D 26º 18’ R 27º 10’ R 52’ 26º 06’ R 26º 58’ R 52’ S2 8º 00’ D 25º 35’ G 26º 40’ G 1º 05’ G 26º 03’ G 27º 09’ G 1º 06’


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TEST 3 - ELEVATION SWITCH TESTS

1. Train the mounting on to the training test angle (Table: D.3 column 2).


3. Depress the gun slowly into danger and record the elevation at which the breech lamp is extinguished (Table: D.3 column 6).

4. Complete column 6 for all training test angles in Table: D.3 .

Tolerances

Switches to operate within plus 1° and –minus 10’ of the designed cut-off readings (Table: D.3 column 3).

Table: D.3 Switch

(1) Training

(2) Designed

Cut-off (3)

Bench Test Achieved Readings

(4)

Error (5)

Ship Achieve

d Reading

s (6)

Error (7)

E1 147º 30’ G 2º 59’ D 2º 28’ D +31’ 2º 29’ D +30’ E1 153º 30’ G 2º 59’ D 2º 28’ D +31’ 2º 29’ D +30’ E1 147º 00’ R 2º 59’ D 2º 28’ D +31’ 2º 30’ D +29’ E1 153º 00’ R 2º 59’ D 2º 28’ D +31’ 2º 29’ D +30’


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TEST 4 - TRAINING SWITCH TESTS

1. Lay the gun to the elevation test angle (Table: D.4 column 2).

2. With the gun trained into the firing arc, continuously energise the firing circuits and ensure that the breech lamp burns.

3. Train the mounting slowly in the direction shown in Table: D.4 column 3 and record the angle of training at which the breech lamp is extinguished (Table: D.4 column 7).

4. Repeat the test for each of the various elevations and training directions listed in Table D.4 and record cut-off bearings in column 7.

5. Repeat paragraph 1 to 4 for each listed switch.

Tolerances

Switches to operate within plus1°and –minus 10’ of designed cut off readings (Table: D.4 column 4).

Table: D.4 Switch

(1) Elevation

(2) Training

Test Direction

(3)

Designed Cut-off

(4)

Bench Test Achieved Reading

(5)

Error (6)

Ship Achieved Reading

(7)

Error (8)

T1 1º 00’ D Left 154º 47’ R 154º 10’ R +37’ 153º 57’ R +50’

T1 5º 00’ E Left 154º 47’ R 154º 10’ R +37’ 153º 59’ R +48’

T1 12º 30’ E Left 154º 47’ R 154º 10’ R +37’ 153º 58’ R +49’

T1 1º 00’ D Right 154º 46’ G 154º 10’ G +36’ 154º 18’ G +28’

T1 5º 00’ E Right 154° 46’ G 154° 10’ G +36’ 154° 14’ G +32’

T1 14º 00’ E Right 154° 46’ G 154° 10’ G +36’ 154° 16’ G +30’

T2 4° 00’ D Left 146° 09’ R 145° 30’ R +39’ 145° 31’ R +38’

T2 9º 00’ D Left 146° 09’ R 145° 30’ R +39’ 145° 30’ R +39’

T2 4° 00’ D Right 146° 59’ G 146° 20’ G +39’ 146° 32’ G +17’

T2 9º 00’ D Right 146° 59’ G 146° 20’ G +39’ 146° 42’ G +17’

S2 7º 30’ D Left 25° 10’ G 25° 35’ G +25’ 26° 03’ G +53’

S2 7º 30’ D Right 25° 35’ R 26° 18’ R +43’ 26° 06’ R +31


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TEST 5 - ELEVATION CUT-OFF TESTS (S1 SWITCH)

1. Train mounting on to the training test angle (Table: D.5 column 1).


3. Depress the gun slowly into danger and record the elevation at which the breech lamp is extinguished (Table: D.5 column 5).

4. Complete column 5 for all the training test angles listed in Table: D.5 .

Tolerances

Achieved readings to lie within plus1° and –minus 10’ of designed cut-off readings.

Table: D.5

Training (1)

Designed Cut-off

(2)

Bench Test Achieved Reading

(3)

Error (4)

Ship AchievedReading

(5)

Error (6)

0°

00° 55’ E

1° 11’ E

+16’

1° 17’ E

+22’

2° 30’ R

00° 53’ E

1° 10’ E

+17’

1° 16’ E

+23’

5° 00’ R

00° 50’ E

1° 11’ E

+21’

1° 16’ E

+26’

7° 30’ R

00° 45’ E

1° 08’ E

+23’

1° 10’ E

+25’

10° 00’ R

00° 30’ E

00° 53’ E

+23’

00° 55’ E

+25’

12° 30’ R

00° 08’ E

00° 32’ E

+24’

00° 34’ E

+26’

15° 00’ R

00° 20’ D

00° 04’ E

+24’

00° 02’ E

+22’

NOTE : Elevation readings are to be taken in accordance with paragraph 3, at intervals of 2° 30’ throughout the full training arc of 360°.

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File Reference The DStan file reference relating to work on this standard is D/DStan21/101/5. Contract Requirements When Defence Standards are incorporated into contracts users are responsible for their correct application and for complying with contractual and statutory requirements. Compliance with a Defence Standard does not in itself confer immunity from legal obligations. Revision of Defence Standards Defence Standards are revised as necessary by up issue or amendment. It is important that users of Defence Standards should ascertain that they are in possession of the latest issue or amendment. Information on all Defence Standards is contained in Def Stan 00-00 Standards for Defence Part 3 , Index of Standards for Defence Procurement Section 4 ‘Index of Defence Standards and Defence Specifications’ published annually and supplemented regularly by Standards in Defence News (SID News). Any person who, when making use of a Defence Standard encounters an inaccuracy or ambiguity is requested to notify the Directorate of Standardization (DStan) without delay in order that the matter may be investigated and appropriate action taken.