form number: ca 12-12a

Form Number: CA 12-12aSection/division Occurrence Investigation Form Number: CA 12-12a
AIRCRAFT ACCIDENT REPORT AND EXECUTIVE SUMMARY
Reference: CA18/2/3/9487
Aircraft Registration
ZS-GYY Date of Accident 04 October 2015 Time of Accident 1430Z
Type of Aircraft Speed Astir IIB (Sailplane) Type of Operation Part 149
Pilot-in-command Licence Type
Pilot-in-command Flying Experience
Last point of departure Potchefstroom aerodrome (FAPS): North West province
Next point of intended landing
Potchefstroom aerodrome (FAPS): North West province
Location of the accident site with reference to easily defined geographical points (GPS readings if possible)
On a field at GPS co-ordinates determined to be S26° 40″ 30 .7 E027° 04″ 09.4 at an elevation of
approximately 4 495 ft above mean sea level (AMSL).
Meteorological Information
Temperature- 34°C: Dew-point was 06°C: QNH- 1024: Visibility- 10 km: Wind
direction-360@15 knots: Pressure altitude- 9 000 feet AMSL.
Number of people on board
1 + 0 No. of people injured
0 No. of people killed
1
Synopsis
On Sunday 04 October 2015, the pilot who was the sole occupant on-board the glider was
conducting a private flight from Potchefstroom (FAPS) aerodrome to Orkney and back when
the accident occurred. Visual meteorological conditions (VMC) prevailed in the area. The
launching began at about 11H30Z. ZS-GYY was successfully launched upon which it climbed
and headed towards Orkney area as planned. In approximately three hour’s flight time on
returning to FAPS at about 1 000 feet above ground level (AGL), the pilot reported his
position to FAPS ground advisor “downwind active runway 03” and his intension to land,
which was acknowledged. The aircraft did not show up as expected and an aerial search was
launched upon which ZS-GYY wreckage was spotted opposite the South African army base,
approximately 1.4 km south west of FAPS. The aircraft was destroyed by impact forces and
the pilot was fatally injured. Post-accident examination of the wreckage established that no
pre-impact failures had occurred in any of the primary flight control systems. The investigation
concluded that the accident was due to loss of control after the aircraft went into an
inadvertent spin that developed from excessive loss of airspeed after a turn.
Probable Cause
SRP Date 11 October 2016 Release Date
CA 12-12a 20 NOVEMBER 2015 Page 2 of 16
Section/division Occurrence Investigation Form Number: CA 12-12a
Telephone number: 011-545-1000
AIRCRAFT ACCIDENT REPORT
Model : Speed Astir IIB
Place : On a field
Date : 04 October 2015
Time : 1430Z All times given in this report are Co-ordinated Universal Time (UTC) and will be denoted by (Z). South African Standard Time is UTC plus 2 hours.
Purpose of the Investigation: In terms of Regulation 12.03.1 of the Civil Aviation Regulations (2011) this report was compiled in the interest of the promotion of aviation safety and the reduction of the risk of aviation accidents or incidents and not to establish legal liability.
Disclaimer: This report is produced without prejudice to the rights of the CAA, which are reserved.
1. FACTUAL INFORMATION: 1.1 History of Flight: 1.1.1 On Sunday 04 October 2015, the pilot who was the sole occupant on-board a non-
powered glider aircraft was conducting a private flight from Potchefstroom (FAPS)
aerodrome when the accident occurred. The official weather report showed visual
meteorological conditions (VMC) in the area at the time of the accident. No flight
plan was filed. According to the information gathered at FAPS during the
investigation, a team of aviators had gathered at the aerodrome’s club house in the
morning in preparation for the upcoming championship competition to be held the
following weekend. A comprehensive safety briefing was given by the chief flight
instructor (CFI) with all participants and role players where after thirty (30)
gliders/aircrafts were towed next to the runway in preparation for launching. The
CFI emphasised situational awareness and the importance of selecting several
possible landing sites should there be an emergency. A ground advisor was
appointed with the view to assist in coordinating the activity since the aerodrome
was unmanned with no control tower. Pre-flights checks were conducted by the
respective owners before the first glider was launched at 1130Z. The tow aircraft
was lined-up and ZS-GWE and ZS-GYY gliders were first to be launched.
1.1.2 A sixty (60) meters towline was secured to ZS-GWE glider and then ZS-GYY.
Before aero-launch, the wing holder spoke with the pilots to check whether they
were ready. When the pilots indicated that they were ready, the wing holder gave
the “thumbs up”, followed by the all clear signal. Events proceeded in this manner
up to the last launch. After approximately two hour flight time, ZS-GWE landed
without incident on asphalt runway 03. An hour later, ZS-GYY reported his position
“downwind runway 03 from Orkney, South Westerly” at about 1 000 feet AGL and
his intention to land, which was acknowledged by the ground advisor. According to
the ground advisor “an appointed gliding club safety officer”, ZS-GYY did not show
up as expected after reporting his position and the matter was communicated and
conveyed to all in the air via the two way hand held radios. The ground advisor
reported that attempts were made to establish ZS-GYY location, but without
success. An aerial search was launched and the wreckage was spotted opposite
the South African army military base, approximately 1.4 km south-west of FAPS.
Potchefstroom police station was notified and police officers were promptly
dispatched to the scene. The aircraft had been destroyed by impact forces and the
pilot was fatally injured.
1.1.3 The accident happened in day light conditions approximately 1.4 km south west of
FAPS at GPS co-ordinates determined to be S26° 40″ 30 .7 E027° 04″ 09.4 at an
elevation of approximately 4 495 ft above mean sea level (AMSL).
Figure 1: Google Earth map depicting the aerodrome layout relative to the accident site
1.2 Injuries to Persons:
Fatal 1 - - -
Serious - - - -
Minor - - - -
None - - - -
1.3 Damage to Aircraft: 1.3.1 The glider was destroyed by impact forces during the accident sequence.
Figure 2: The wreckage as found at the accident site
1.4 Other Damage: 1.4.1 Minor environmental damage was caused. Nonetheless, because the accident took
place within the boundaries of Tlokwe Municipality, the scene was subjected to a
thorough clean-up afterwards.
1.5 Personnel Information:
Licence Number 0279006316 Licence Type National pilot licence
Licence valid Yes Type Endorsed Yes
Ratings Glider instructor
Previous Accidents Nil
Experience:
*NOTE: The pilot was in possession of a valid national pilot licence issued by the
Recreation Aviation Administration of South Africa (RAASA). The pilot had been
gliding for quite a number of years and had never been involved in any form of
aviation regulation transgression. He was the sole owner of ZS-GYY glider and had
listed about five sorties on it operating from FAPS before the accident flight. His
profile revealed no accident or incident history, enforcement actions, pilot certificate
or rating failure, or retest history. According to the pilot’s profile found at recreation
aviation administration of South Africa (RAASA), the pilot had conducted his
practical flight test through an approved reputable aviation training organization
(ATO). The pilot also completed a language proficiency test for his radiotelephony
communication at an approved ATO. Following accident procedure, the deceased
next of kin was contacted in order to obtain the pilot’s logbook. The pilot’s logbook
was made available and thoroughly scrutinized. All the pilot’s accumulated flight
hours were calculated and included on the pilot’s experience table above. According
to the pilot’s medical profile; there was no evidence of any sickness from which the
pilot may have suffered.
Total on Type Past 90 Days
3.9
1.6 Aircraft Information:
1.6.1 A Speed Astir IIB is a single seat high performance glider built from modern fibre
reinforced composites. It is equipped with devises such as spoilers, dive brakes and
flaps that modify the lift/drag of the wing. The spoilers extend from the upper
surface of the wing, interrupting or spoiling the airflow over the wings. The dive
brakes extend from both the upper and lower surfaces of each wing and help to
increase drag. The flaps are located on the trailing edge of each wing, inboard of
the ailerons and are used to increase lift, drag and descent rate of the glider during
the flight. The elevator which is attached to the back of the horizontal stabilizer
controls movement around the lateral axis, known as pitch. In-flight this elevator is
used to move the nose up and down, which controls the pitch attitude. The elevator
is primarily used to change or hold the same angle of attack. The trim tap which is
located on the elevator of this glider decreases the resistance felt on the flight
controls due to the airflow over the associated control surface. The rudder is
attached to the back of the vertical stabilizer and controls movement about the
vertical axis, known as yaw. This rudder is used in combination with the aileron and
elevator to coordinate turns during flight. This glider is equipped with the stabilizer
which is used in lieu of an elevator and horizontal stabilizer. Of which its function is
to pivot up and down on a central hinge point. Attached below is a Speed Astir IIB
glider type photographs.
IIAstand amaged memory chip
Airframe:
Serial Number 4107
Manufacturer Grob Flugzeugbau
Maximum speed 270 km/h
Year of Manufacture 1980
Total Hours Flown ±30
C of R (Issue Date) (Present owner) 26 March 2015
Operating categories Standard Part 149
*NOTE: The aircraft airframe hours at the time of the accident could not be
determined with accuracy because the flight folio could not be found. The hours
entered in the table above were obtained from a last maintenance documentation
found at the aircraft maintenance organization located at FAPS. Records showed
that the aircraft was manufactured in West Germany on 15 January 1980 and
imported second hand into South Africa in 2014. The aircraft was sold to and
transferred to the new owner on 20 March 2015. Following the investigation, it
became evident that the approved person (AP) who performed the last annual
inspection on the aircraft prior to the accident flight was in possession of a valid
approval certificate No 322. All the relevant manufacture’s aircraft service bulletins
(SBs) were conformed to, or complied with during maintenance. All relevant aircraft
certification such as the C of R, the Authority to Fly and the mass and balance
certificates were scrutinised were found to be valid. The aircraft logbook was found
from the AMO and scrutinised and all maintenance entries made were appropriately
certified in accordance with the applicable regulations. The aircraft profiled showed
that the aircraft was repaired 10 years ago after sustaining damages on the
fuselage; but the specifics of work done couldn’t be found during the investigation.
1.7 Meteorological Information: 1.7.1 An official weather report was obtained from the South African Weather Services
(SAWS). The weather data on the report were extracted from a SAWS Automatic
Weather Station located at Johannesburg. The data below were for 04 October
2015 at the estimated time of the accident.
Temperature - 34°C, Pressure altitude- 9 000 feet AMSL
Dew-point - 06°C, Wind direction -360@15 knots
QNH - 1024 Visibility - 10 km,
Figure 4: Satellite image taken on 04 October 2015
1.8 Aids to Navigation:
1.8.1 The glider was equipped with basic navigational aids, which consisted of the
magnetic compass, vertical speed indicator, turn indicator, altimeter and the
airspeed indicator. The glider was also equipped with a cell phone GPS with a data
logger which was supposed to record the position and pressure altitude during the
flight. The cell phone was recovered from the accident site, but the data recorded
couldn’t be retrieved or downloaded because the memory chip was broken or
damaged during the accident sequence. Attached below are the pictures of the cell
phone and the damaged memory chip.
Figure 5: Impact-damaged cell phone recovered at the accident site
1.9 Communications: 1.9.1 The communication equipment installed in the glider was found to comply with the
approved equipment list. There were no defects reported with the communication
equipment prior to the accident. No distress call was received from the accident
aircraft at any stage of the flight.
1.10 Aerodrome Information: 1.10.1 The aircraft was expected to land at Potchefstroom aerodrome (FAPS), but never
arrived at the aerodrome. It was later determined that the aircraft had crashed onto
the field next to the army military base approximately 1.4 kilometers south west of
the aerodrome.
Aerodrome Elevation 4 520 feet AMSL
Aerodrome Status Licensed
Accident
damaged
memory
Runway Dimensions 15/33 1000 x 30
Runway Used None
Runway Surface Asphalt
Approach Facilities Runway Lighting
1.11 Flight Recorders: 1.11.1 The glider was not equipped with a flight data recorder (FDR) or a cockpit voice
recorder (CVR) nor was it required by the regulation to be fitted.
1.12 Wreckage and Impact Information: 1.12.1 A detailed examination of glider revealed multiple overload failures of the flight
control system in the fuselage and cockpit area. The flight controls after impact
could not be relied upon as evidence of the aircrafts pre-impact configuration. The
glider impacted the ground nose low in an inverted position. The position of the
primary flight controls was examined; no evidence of restriction, jamming or pre-
impact damage was identified in the flap, spoiler or elevator circuits. The connecting
turnbuckle which transmits aileron inputs into the mixer unit had failed. Analysis of
the failure showed the characteristics of a single overload failure with no evidence
of fatigue or pre-existing defect. The self-connecting mechanisms on the mixer unit
and the wings were examined and no evidence of incorrect connection or a
mechanical disconnect in flight was identified. The wing control surfaces were
examined through their full range of movement from the wing root connection points
and no binding or jamming of either the flaperons or the spoilers was identified. The
flap lever was destroyed by post impact and its position prior to impact could not be
determined. The glider was equipped with primary flight instrumentation consisting
of an air speed indicator, artificial horizon, and altimeter, compass and a turn and
slip indicator. All of these instruments were destroyed by post impact. In addition
the glider was fitted with two variometers and a data logger. One of the variometers
was used in conjunction with pressure tapings close to the wing roots to provide a
stall warning system for the glider. The glider was fitted with a tail mounted pitot
orifice which provided a total pitot pressure supply to the instruments; this was
found to be in good condition and free from dirt. The aft fuselage broke or failed due
to overload and the elevator detached from the horizontal stabiliser. Attached below
are the photographs.
Figure 6: The cockpit remains as found at the accident site
Figure 7: The wreckage at the accident site with the detached tail section visible and the wings in an
inverted position
Figure 8: Witness marks left by the wings at the accident site
Figure 9: Shattered left wing
1.12.2 The wreckage was examined before being recovered from the site of the accident;
the assessment showed that the main wheel gear was selected into the DOWN
position, which was consistent with the pilot’s intention to land. Attached below are
the pictures.
(a) (b)
Figures10/11: The gear locking mechanism showed on Figure (a) in the down and locked position and the
shattered rudder rudder pedals/control column on Figure (b) as found at the accident site
1.13 Medical and Pathological Information:
1.13.1 The post-mortem report indicates the cause of death to be multiple injuries
sustained during the accident sequence. The pathologist also reported that there
was no evidence of drugs or alcohol having been consumed, or indication that
incapacitation or physiological factors may have affected the pilot.
1.14 Fire: 1.14.1 No evidence pre or post impact fire was reported.
1.15 Survival Aspects: 1.15.1 The impact forces associated with this accident were regarded to be well above that
of human tolerance. The accident was therefore not considered survivable. A
parachute was located on the scene of the accident but it was not used. The
parachute was an emergency device, which the pilot could have utilized to bail out
of the aircraft during an emergency phase of the flight where he felt it to be unsafe
to continue with such a flight. The glider was not fitted with an emergency locator
transmitter (ELT). The emergency medical service team was dispatched to the
scene of the accident, however the pilot was found to have been fatally injured. The
pilot’s body was handed into the care of the forensic pathology services located at
Potchefstroom and the local police station has opened an inquest investigation
docket.
1.16 Tests and Research: 1.16.1 Gliders are propelled mainly by flying in thermals or rising air. Due to the fact that
they do not have an engine they are designed purely to be flown when there is
sufficient lift for them to stay in the air. Glider pilots depend on the variometer, a
very sensitive vertical speed indicator, to measure the climb or sink rate of the
aircraft. This information enables the pilot to detect the minute changes that occur
when the glider enters rising or sinking air or stall conditions. Following the accident
and subsequent on-site investigation, the investigating team thoroughly examined
the entire wreckage and it was established to be complete with no single flight
control component missing. In addition, all flight controls were properly rigged and
fully functional when it collided with the ground. On-site examination showed that
the glider collided with the ground nose-low in an inverted attitude, consistent with a
spin after effecting a right hand turn from Orkney. According to the investigation it
was unlikely that the pilot might have intentionally spun the glider at low altitude
upon which he was unable to effect recovery. Attached Google Earth map below
showed the estimated aircraft flight path.
Figure 12: The map depicting the aircraft flight path relative to the aerodrome and the accident site
1.17 Organizational and Management Information:
1.17.1 This was a private gliding flight; the owner of the aircraft was also the pilot.
1.17.2 The last annual Inspection prior to the accident flight was certified on 20 October
2015 at 1908.3 airframe hours. The approved person who performed the inspection
was accredited by the Aero Club of South Africa.
The aircraft
flight path
1.18 Additional Information:
1.19 Useful or Effective Investigation Techniques:
1.19.1 None. 2 ANALYSIS: 2.1 On Sunday 04 October 2015, the pilot who was the sole occupant on-board the
glider was conducting a private flight from Potchefstroom (FAPS) aerodrome to
Orkney and back when the accident occurred. The launching began at about
11H30Z. ZS-GYY was successfully launched upon which it climbed and headed
towards Orkney area as planned. In approximately three hour’s flight time on
returning to FAPS at about 1 000 feet above ground level (AGL), the pilot reported
his position to FAPS ground advisor “downwind active runway 03” and his intension
to land, which was acknowledged. The aircraft did not show up as expected and an
aerial search was launched upon which ZS-GYY wreckage was spotted opposite
the South African army base, approximately 1.4 km south west of FAPS. The
aircraft was destroyed by impact forces and the pilot was fatally injured. Following
the investigation, it was concluded that the glider was structurally intact before the
accident. The official weather report showed visual meteorological conditions (VMC)
in the area at the time of the accident. No flight plan was filed. There was no
indication that incapacitation or physiological factors may have affected the
performance of the pilot. The investigation concluded that the accident was due to
loss of control after the aircraft went into an inadvertent spin that developed from
excessive loss of airspeed after a turn.
3. CONCLUSION: 3.1 Findings: 3.1.1 The pilot held a valid gliding pilot’s licence and had the aircraft type endorsed in his
logbook.
3.1.2 The pilot’s medical certificate was valid with restrictions to wear suitable corrective
lenses.
3.1.3 The flight was operated as a general aviation flight under VMC.
3.1.4 The aircraft was in possession of a valid authority to fly at the time of the accident.
The condition of the cell phone and the memory chip as found at the accident site
3.1.5 The AP who performed the annual maintenance inspection on the aircraft prior to
the accident flight was in possession of a valid approval certificate.
3.1.6 The accident was not considered survivable.
3.2 Probable Cause/s:
4. SAFETY RECOMMENDATIONS: 4.1 None.
5. APPENDICES: 5.1 None.

form number: ca 12-12a

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