Can aircraft equipped only with Mode A transponders be detected by ACAS II?
Aircraft equipped with Mode A transponders only are not tracked and detected by ACAS II because ACAS II does not use Mode A interrogations. However, if the aircraft is equipped with Mode A/C transponder but does not provide altitude information (Mode C) this aircraft will be tracked as non-altitude reporting using range and bearing information and shown on ACAS II traffic display. Neither a data tag nor a trend arrow will be shown for traffic symbol for an intruder that is not reporting altitude. TAs will be generated against non-altitude reporting aircraft when the range test for TA generation is satisfied. Non-altitude reporting aircraft are deemed to be at the same altitude as own aircraft.
