08-17-2012, 05:11 PM
quote:
Posted by ckaupp:
If the facility has digitized radar they can review the files and check the flight paths of the aircraft. If they aircraft have mode C transponders they can also check their altitudes. Does anyone know if the local ATC facility has digitized radar? Does anyone know if the helicopters have mode C transponders?
Mode C transponders transmit/display approximate aircraft altitude (I believe in hundreds of feet) above sea level and it's difficult for ATC to know the precise ground level where aircraft are flying. I doubt if Mode C altitude and radar position displays would be considered accurate enough to determine if pilots are violating altitude restrictions for enforcement purposes. Routine flight in most airport airspace and other high-traffic areas is not very practical without mode C transponders, though I believe some areas controlled by the FAA still permit entry to aircraft without transponders with prior permission. All commercial aircraft (other than some ag-planes and perhaps some other utility aircraft), and virtually all private aircraft other than some ultralights and other planes have mode C transponders which transmit altitude information to controllers monitoring radar displays. Pilots have the option to turn transponders (or just the altitude information transmissions) off in flight when clear of certain controlled airspace but rarely do so since safety is enhanced when controllers can monitor the altitudes of aircraft sharing airspace where collisions may occur and then can help pilots whose position and altitude are known avoid collisions.