Transponder
From Debunk911myths
Transponder
A transponder, installed in aircraft, transmits an identifying code to air traffic controllers, enhancing their ability to track the aircraft on radar. Boeing 757 and 767 aircraft are equipped with Mode S transponders. Without a transponder signal to air traffic control, the aircraft merely appears as a blip (among many blips) on the radar with no identification or altitude provided.
Background
Aircraft transponders were developed during World War II, to help in identifying friend or foe. In the 1980s, this technology was enhanced with the advent of traffic alert collision avoidance systems (TCAS).[1]
References
- ↑ The Post 9/11 Transponder, Aviation Today, June 1, 2001.