TT31 Mode S Transponder Operating Manual 00454-00-AA 1 September 2006 Trig Avionics Limited Heriot Watt Research Park Riccarton, Currie EH14 4AP Scotland, UK © Copyright 2006
Front Panel Display The display shows the operating mode of the transponder, the reported pressure altitude, and the current squawk code and Flight ID. The reply indicator is active when the transponder replies to interrogations. The pressure altitude is displayed as a Flight Level, which is the pressure altitude in hundreds of feet. When non-standard atmospheric conditions apply, this may not match the altimeter indicated altitude, but will be correctly displayed by the ATC radar.
Push Buttons IDENT Press the IDENT button when ATC instructs you to “Ident” or “Squawk Ident”. This activates the SPI pulse in the transponder replies for 18 seconds. IDENT will appear in the display. FUNC Pressing the FUNC button provides access to the flight timer, stopwatch and altitude monitor function. VFR Pressing the VFR button sets the transponder to the preprogrammed conspicuity code. Pressing the button again restores the previous squawk code.
Stopwatch The stopwatch can be used as a convenient timer. Press the FUNC button to display the stopwatch. Pressing ENT will reset and start the timer. Pressing ENT again will stop the timer. Altitude Monitor The Altitude Monitor activates an audio annunciator or annunciator light (depending on installation) when the aircraft pressure altitude differs from the selected altitude by more than 200 feet. Press the FUNC button to display the altitude monitor enable screen.
