The FAA runs the airspace for the airlines. The airlines use a transponder-based detection system as a collision avoidance system. They want to keep this system as a backup to ADSB based collision avoidance.
Sort of a related thought question: With ADS-B out transmitting your tail number (or flight ID), thus uniquely identifying you, why is it necessary to squawk a 4 digit code? Seems ATC should already have a unique identifier for your "target" already.
Sort of a related thought question: With ADS-B out transmitting your tail number (or flight ID), thus uniquely identifying you, why is it necessary to squawk a 4 digit code? Seems ATC should already have a unique identifier for your "target" already.
If every aircraft was operating with ADSB that might actually work. Right now even with ADSB giving them a tail number for the airplane, that doesn't tell ATC if you are receiving services or not - you could be VFR and not talking to anyone - but if you a squawking a discrete code they know you are in the system and receiving services, either VFR or IFR.
