Quote:
Originally Posted by A Squared View Post
Yes: Reported altitude + Climb rate X ( Transmitting Transponder system latency + Radio propagation delay + Receiving TCAS system latency)
That formula will give you the altitude of the other aircraft at any moment. The difficulty is determining the value of those variables.
Thanks, makes sense.
Transmitting Transponder system latency < 100 milliseconds (mainly the refresh rate of the altitude from the air data computer. The internal interrogation / reply processing of the Transponder will be small in comparison)
Radio propagation delay <1millisecond
Receiving TCAS system latency [the display works on a 1s refresh so that is the maximum latency]
So potentially the height data is maximum 1101milliseconds old.
At 5000ft per minute that's around 92ft as a maximum. But as an average probably much less.
This is simply for the display of course. The internal tracking algorithms of the TCAS unit are not constrained to the 1s refresh rate.