aircraft avionics

8/12/2019 Aircraft Avionics

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Aircraft Electrical & Electronic Systems

What is Avionics?

Avionicsis actually a combination of Aviation & Electronics.

Represents the field of technology that encompasses the electronic equipment and

systems that are used on aircraft and aircraft components.

Avionics equipment is usually thought of as different from electrical orelectromechanical aircraft equipment but the lines between electrical systems and

avionics systems are not always distinct, especially in the more modern aircraft.

Supports the goal of helping flight crews get safely from pint to point.

Avionics helps pilots with their responsibilities in the cockpit to

Aviate (Tracking and Controlling Aircraft Pitch, roll and yaw)

Navigate (track position, way point estimates, deviation from desired course,

avoiding collision with obstacles, in all weather conditions)

Communicate (communicate flight progress with others who need to know

other crew members, ATC, other aircraft, Flight Service Stations and airlines).

What are the functions of Avionics?

Function of Avionics Systems is to receive, compute and display

Navigation data,

sense flight parameters,

correlate information,

consolidate and present information to crew,

support crew by automating functions like flight control and flight management,

enhance safety,

improve flight performance,

permit communication with external elements.

Help crews manage their workload, onboard systems and the flight situation

Terminologies used in AvionicsADF Automatic Direction Finder. An aircraft radio navigation which senses and indicates the

direction to a Low/Medium Frequency non-directional radio beacon (NDB) ground transmitter.

DME Distance Measuring Equipment. Ground and aircraft equipment which provide distance

information and primary serve operational needs of en-route or terminal area navigation.

EAT Estimated Approach Time

EFISElectronic Flight Instrument System , in which multi-function CRT displays replace traditional

instruments for providing flight, navigation and aircraft system information, forming a so-called "

glass cockpit ".

ETA Estimated Time of Arrival

GPS Global Positioning System. A navigation system based on the transmission of signals fromsatellites provided and maintained by the United States of America and available to civil aviation

users.

HDGHeading. The direction in which an aircraft's nose points in flight in the horizontal plane,

expressed in compass degrees (eg. 000 or 360 is North, 090 is East)

HSIHorizontal Situation Indicator. A cockpit navigation display, usually part of a flight-director

system, which combines navigation and heading.


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IFRInstrument Flight Rule . prescribed for the operation of aircraft in instrument meteorological

condition.

ILS Instrument Landing System . consists of the localizer, the glideslope and marker radio

beacons (outer, middle, inner). It provides horizontal and vertical guidance for the approach.

INS Inertial Navigation System. It uses gyroscopes and other electronic tracking systems to

detect acceleration and deceleration, and computes an aircraft's position in latitude andlongitude. Its accuracy, however, declines on long flights. Also called IRS, or Inertial Reference

System.

KNOT (kt) Standard Unit of speed in aviation and marine transportation, equivalent to one

nautical mile per hour. One knot is equal to 1.1515 mph., and one nautical mile equals to 6,080

feet or 1.1515 miles. One knot is equal to one nautical mile per one hour.

LORAN C Long Range Navigation is a Long-Range low frequency Radio Navigation. Its range is

about 1,200 nm by day to 2,300 nm. by night.

MAGNETIC COURSE Horizontal direction, measured in degrees clockwise from the magnetic

north.

MACH NUMBERRatio of true airspeed to the speed of sound. Mach 1 is the speed of sound at

sea level. Its values is approximately 760 mph.

NDB Non-Directional Beacon. A medium frequency navigational aid which transmits non-

directional signals , superimposed with a Morse code identifier and received by an aircraft's ADF.

RMI Radio Magnetic Indicator. A navigation aid which combines DI ,VOR and /or ADF display and

will indicate bearings to stations, together with aircraft heading.

RNAV Area Navigation. A system of radio navigation which permits direct point-to-point off-

airways navigation by means of an on-board computer creating phantom VOR/DME transmitters

termed waypoints.

TACAN TACtical Air Navigation. Combines VOR and DME and used by military aircraft

only.System which uses UHF frequencies , providing information about the bearing and distance

from the ground station we have tuned into.TCAS Traffic Alert and Collision Avoidance System. Radar based airborne collision avoidance

system operating independently of ground-based equipment. TCAS-I generates traffic advisories

only. TCAS-II provides advisories and collision avoidance instructions in the vertical plane.

TRANSPONDERAirborne receiver / transmitter which receives the interrogation signal from the

ground and automatically replies according to mode and code selected. Mode A and B wre used

for identification, using a four digit number allocated by air traffic control. Mode C gives

automatic altitude readout from an encoding altimeter.

VFR Visual Flight Rules. Rules applicable to flights in visual meteorological conditions.

VHF Very High Frequency. Radio frequency in the 30-300 Mhz band, used for most civil air to

ground communication.VOR Very High Frequency Omnidirectional Range. A radio navigation aid operating in the 108-

118 Mhz band. A VOR groun station transmits a two- phase directional signal through 360

degrees. The aircraft's VOR receiver enables a pilot to identify his radial or bearing From/To the

ground station . VOR is the most commonly used radio navigation aid in private flying.

VORTAC A special VOR which combines VOR and DME for civil and military used . System

provides information about the bearing and distance from the ground station we have tuned

into.


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Aircraft Navigation Systems

Finding the way from one place to another is called NAVIGATION.

Moving of an aircraft from one point to another is the most important part for any kind

of mission. Plotting on the paper or on the map a course towards a specific area of the

earth , in the past, used to be a task assigned to a specialized member of the aircraft's

crew such a navigator. Such a task was quite complicated and not always accurate. Sinceit depended on the observation , using simple maps and geometrical instruments for

calculations.

Today, aerial navigation has become an art which nears to perfection. Both external

Navaids (Navigational Aids) and on-board systems help navigate any aircraft over

thousand of miles with such accuracy that could only be imagined a few decades ago.

Methods of Navigation

There are three main methods of air navigation. There are:

1. Pilotage , 2. Dead Reckoning , 3. Radio.

1. Pilotage or Piloting: is the most common method of air navigation. This method, the pilot

keeps on course by following a series of landmarks on the ground. Usually before take-off,

pilot will making pre-flight planning , the pilot will draws a line on the aeronautical map to

indicate the desired course. Pilot will notes various landmarks , such as highways , railroad

tracks, rivers , bridges . As the pilot flies over each of landmark , pilot will checks it off on

the chart or map. If the plane does not pass directly over the landmark , the pilot will know

that he has to correct the course.

2.

Dead Reckoning

Dead Reckoning is the primary navigation method used in the early days of flying. It is the

method on which Lindberg relied on his first trans-Atlantic flight. A pilot used this method

when flying over large bodies of water, forest, deserts. It demands more skill and

experience than pilotage does. It is based on time, distance, and direction only.

The pilot must know the distance from one point to the next, the magnetic heading to beflown. Pilot works on the pre-flight plan chart , pilot plan a route in advance. Pilot calculate

the time to know exactly to reach the destination while flying at constant speed. In the air,

the pilot uses compass to keep the plane heading in the right direction. Dead reckoning is

not always a successful method of navigation because of changing wind direction. It is the

fundamental of VFR flight.

3. Radio Navigation

Radio Navigation is used by almost all pilots. Pilots can find out from an aeronautical chart

what radio station they should tune to in a particular area. They can then tune their radio

navigation equipment to a signal from this station. A needle on the navigation equipment

tells the pilot where they are flying to or from station, on course or not Navigating Across Oceans Pilots have special methods for navigating across oceans.

Three commonly used methods are:

1. Inertial Guidance: This system has computer and other special devices that tell pilots

where are the plane located.

2.LORAN: Long Range Navigation The plane has equipment for receiving special radio

signals sent out continuous from transmitter stations. The signals will indicate the plane

location


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3.GPS Global Positioning System: is the only system today able to show your exact

position on the earth any time, anywhere, and any weather. The system receiver on the

aircraft will receives the signals from satellites around the globe.

Present information to Crew - Display system Purpose & Functions

Provides situational awareness to the pilot by displaying flight critical information forsuccessful completion of the mission.

Type of Information displayed

Primary flight performance - Airspeed, Attitude, Altitude, Heading, Vertical

Speed, Radio Direction & Distance, etc.

NavigationFlight plan, approach, VOR, moving map, Situation awareness,

Engines Torque, Np, Ng, ITT (Turbine inlet temperatures) , Oil Pressure, Oil

Temperature, Fuel Pressure, Fuel Flow, Fuel Qty (different tanks)

Aircraft Utility System

Pressurization/ air conditioning

Hydraulic Power

Auxiliary Power unit

Flight deck

Electronic Flight Instrument System (EFIS)

An Electronic Flight Instrument System (EFIS) is a flight deck instrument display system in

which the display technology used is electronic rather than electromechanical. EFIS

normally consists of a primary flight display (PFD), multi-function display (MFD) andEngine Indicating and Crew Alerting System (EICAS) display. Although cathode ray tube

(CRT) displays were used at first, liquid crystal displays (LCD) are now more common


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PFD/ND Format

EFIS Format


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Over/Under Engine Format

Side-By-Side Engine Format


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Navigation Aids

Air navigation needs

1. Earth model for reference

2. A co-ordinate system to identify position/fixes and to compute distances

3.

Navigational aids for reducing the workload of Navigator/pilot Basic Navigation aids

Aeronautical Charts: specialized maps that show more than geographical features -

1. Navigation aids and airways which are highways in the air

2.

Location of airports, Land marks like mountains, rivers, lakes etc.

3. National borders

Magnetic compass

CNSA Systems

Communication

Infrastructure providing connectivitybetween Air-Ground and Ground-

Ground systems

Navigation

Helps in en route navigation

Surveillance

Helps gathering weather reports,

collision detection etc.

Air Traffic Management

Managing Air Traffic

Integrated CNS Architecture to

improve ATM

NavigationSystemsMethods


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aircraft avionics

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