Transponders are required equipment that help air traffic control identify and track aircraft. They automatically send a unique four-digit identification code in response to interrogation from ATC radar. Transponders can operate in different modes to provide identification, altitude reporting, and collision avoidance. ELTs and EPIRBs are emergency locator beacons that transmit distress signals to help search and rescue teams locate downed aircraft. FDRs and CVRs are flight data and cockpit voice recorders, known collectively as the "black boxes," that record key flight parameters and cockpit audio to help investigate accidents.

1. Avionics Systems Day 6

2. Transponder
 Used to help ATC identify aircraft
operating in controlled airspace
 Transponders operate in the same
frequency range as ATC radar
 Required to be inspected & tested every
24 calendar months

3. The control head of an ATC transponder

4. Transponder
 When ATC radar interrogates the
aircraft, the transponder automatically
responds by sending a four digit
identification code

5. Transponder
 The four digit code is registered in the
ATC computer along with the aircraft
flight plan
 The controller will see the aircraft
registration number and four digit code on
the radar screen

6. Transponder Functions
 Identification (ident) – simply the four
digit coded reply
 Altitude reporting – transponder is
coupled to an encoding altimeter which
sends the aircraft altitude with the reply
 Collision avoidance – monitors other
aircraft transponders in the area & will
determine if a collision is possible

7. Transponder Operation
 Transponders operate in three modes
 Mode A
 Identification only
 Mode C
 Identification & Altitude reporting (required
in some airspace)
 Mode S
 Identification, Altitude reporting, & collision
avoidance

8. TCAS
 Traffic alerting & Collision Avoidance
System
 Used with mode S transponders
 Works independently of ground stations
 If a collision course is detected the system
will display appropriate directions to the
pilot to prevent the collision

10. ELT
 Emergency Locator Transmitter
 Battery powered transmitter required on
all general aviation aircraft
 Produces a locator signal which can be
used by search & rescue to locate
downed aircraft

12. ELT
 Inertia switch activated
 6 G forward
 Also has a manual switch on the ELT, &
usually in the cockpit
 Frequencies
 121.5 & 243 MHz
 International distress frequencies

13. ELT
 100 Mile range at 10,000 ft
 48 Hour capacity
 Installed in the tail of the aircraft
 Provides protection from crash damage
when placed as far aft as possible

14. ELT
 Must be tested on a regular basis
 Every 12 calendar months
 The test must be performed within the
first 5 minutes of any hour
 Log book entry should be made after test

15. ELT Testing
 Tune radio to 121.5
 With the ELT disconnected from the
antenna turn on the ELT using the switch
 You should hear the siren
 Turn switch to arm position & shake
 You should hear the siren again
 Turn off ELT using the switch
 Do not let the ELT operate for more than 3
seconds at a time

16. ELT Battery Check
 Battery must be replaced at the time of
the expiration date found on the battery
case
 Or if more than one hour has been
depleted from the battery
 Check maintenance records in the aircraft
logbooks

17. EPIRB
 Emergency & Position Indicating Radio
Beacon
 New replacement for the ELT
 Will be required by Feb. 2009
 5 Watts of power not ½ watt
 Digital signal
 Identifies owner and aircraft
 Fewer false alarms
 Must be registered with the FAA

19. EPIRB
 Picked up by satellites
 Can be interfaced with aircraft GPS
 Pinpoint accuracy .031 kilometers
 Old ELT 1260 sq kilometers
 More rapid response time for rescuers

21. FDR
 Flight Data Recorder
 Device which monitors & records specific
flight operation parameters for analysis
after an accident
 The “BLACK BOX”
 Which is actually bright orange

22. FDR
 Required on all commercial airliners
since 1958
 Records the last 25 hours of flight
 Located in the aircraft tail
 Fire & “G” resistant
 Transmits a locator signal so it can be
found in the wreckage

23. FDR
 Parameters
 Altitude & Airspeed
 Attitude & Direction
 Vertical acceleration
 Landing gear position
 Flight control position
 Engine power
 Greenwich mean time “ZULU time”

24. CVR
 Cockpit Voice Recorder
 Records the last 30 minutes of the flight
deck voice communications
 Microphone in the cockpit
 Recorder in the tail
 Crush & fire resistant
 Transmits a locator signal so it can be
found

25. Intercom System
 Cabin interphone system
 Amplified audio signals allow
communication between members of the
flight crew or with the passengers
 Public address system

28. Intercom System
 Service Interphone System
 Allows communication between flight crew
& ground personnel or mechanics

31. The End!
(for today)
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