On Wednesday, July 15, 2015 at 11:39:38 PM UTC-4, Darryl Ramm wrote:
On Wednesday, July 15, 2015 at 9:34:31 AM UTC-7, wrote:


TCAS is certainly impressive and proven technology, but I don't think you can claim that an F-16 with TCAS would have "prevented" this collision. We don't know the important details about how/why the collision happened. AFAIK it is still not clear if the Cessna 150 transponder was actually operating--was it actually turned it on? Was the encoder reading the correct altitude? Was the Transponder correctly set to Mode-C/S (not Mode A aka "ON" on many transponders... then a TCAS would not "see" the Cessna at all).


Just a slight correction. TCAS does indeed see mode A transponder returns. It obviously can not see the altitude of said transponder as there is no mode C altitude information being interrogated. So the TCAS will display the target range and bearing information and if there is a potential collision it will issue a TA or Traffic Alert audio warning and the target turns yellow. Since TCAS needs the altitude information in order to compute a climb or descent escape maneuver or RA Resolution Advisory, TCAS will not provide that as it would if the target were mode C equipped and operating. So the pilots eyeballs are the only defense. This is often frustrating as you can be flying in the flight levels and be get a TA warning for non mode C traffic in a airport traffic pattern 10,000' plus below. That said I'd much rather get the warnings and drive the pilots eyes outside and in the direction of the threat to scan all close altitudes than not know about it. Cheers.