The aviation industry’s concerns revolve around a piece of equipment called a radar altimeter, used by all kinds of aircraft to measure altitude, the distance between the aircraft and the ground, working by transmitting a signal toward the ground then determining altitude based on the time it takes the signal to reflect off the ground and back to the aircraft.

The aviation industry's concerns revolve around a radar altimeter, used by all kinds of aircraft to measure altitude, and determine altitude based on the time it takes the signal to reflect off the ground and back to the aircraft. The FCC warned that if C-band services interfere with radar altimeters, major disruptions to passenger air travel, commercial transport, and critical helicopter services.