Transponder with IvAc[PDF]


In his area of control, an active controller is responsible to assign a transponder code to all aircraft. It is the responsibility of the pilot in command to tune this transponder code in his aircraft.

To reduce pilot and controller workload and the need for controller/pilot communication, the number of code changes required of the pilot should be kept to the minimum.

Transponder code

As the system of discrete transponder codes is very complex in real aviation, there are no IVAO global rules to assign specific series of transponder codes to a specific activity or type of flight.

Outside of specific cases given in this documentation, the transponder code assignment is free.

As ATC, be aware that you cannot assign a particular code to an aircraft outside your airspace.

Some countries have their own transponder code allocation. Contact the ATC Operations Coordinator of the related division or ATC Operations Director.

Except for aircraft in a state of emergency, or during radio communication failure, the transferring unit shall assign transponder code A2000 to a controlled flight prior to transfer of communications except before a transfer to an accepting ATC unit.

Caption Aircraft squawking 2000 in non controlled area

Specific Transponder display

CaptionAircraft squawking 7700 transponder code in state of emergency

CaptionAircraft squawking 7600 transponder code in state of loss of communication

CaptionAircraft squawking 7500 transponder code. (forbidden to use)

This image was created with special authorization from a supervisor in order to make this documentation.

Transponder status with IvAc

It is the responsibility of the active controller to check that a pilot correctly uses the STDBY/TX position of his transponder. He shall instruct the transponder change only if the pilot forgets to select the correct position.

All pilots must:

  • Set transponder to STDBY position before connecting to the IVAO network
  • Set transponder to STDBY position on apron and during taxiing
  • Set transponder to TX position when cleared entering on runway for departure, and at the latest before take-off
  • Keep transponder to TX position while flying
  • Set transponder to STDBY position after vacating the landing runway

Caption aircraft taxiing in STBY mode

Aircraft call sign may be displayed, depending on the IvAc settings

Caption aircraft in TX or alticoder mode

There are only two representations of the transponder mode when the aircraft is in TX or alticoder mode:

  • Mode A transponder with no pressure altitude information

Ivac aircraft mode a.PNG

This representation is also valid for N, X and I modes. The aircraft identification is always active in IvAp.

  • Mode C or Mode S transponder with pressure altitude information

Ivac aircraft mode s.PNG

This representation is also valid for P mode. The aircraft identification is always active in IvAp.

Aircraft Identification with transponder

As an air traffic controller in a large zone, you may not easily locate an aircraft quickly.

In order to speed up identifying an aircraft location, the air traffic controller can use the IDENT procedure by giving a “transponder IDENT” or “squawk IDENT” command to the pilot.

When receiving a transponder IDENT request, a pilot will press the IDENT button on his instrument. When the radar equipment receives the IDENT, it results in the aircraft's blip blinking on the radar scope.

Note that IDENT should be performed on request of ATC only.

Ivac aircraft ident.PNG the 2 aircraft states during the blinking IDENT

IDENT can also be used in case of a reported or suspected radio failure to determine if the failure is only one way and whether the pilot can still transmit or receive, but not both, e.g., "Air France 8542, if you read, squawk IDENT".

See also


  • none


  • VID 150259 - Creation
  • VID 150259 - Wiki integration


  • 23:57, 19 January 2022


  • This documentation is copyrighted as part of the intellectual property of the International Virtual Aviation Organisation.


  • The content of this documentation is intended for aviation simulation only and must not be used for real aviation operations.