Final answer:
The phrase 'mode C' indicates that a transponder has the capability to transmit altitude information, which is essential for air traffic controllers to maintain aircraft separation.
Step-by-step explanation:
The phrase 'mode C' in the context of a transponder refers to the capability of the transponder to relay information about the aircraft's altitude to air traffic controllers. This is important for maintaining safe separation between aircraft in controlled airspace. The transponder's 'mode C' function does not transmit information on airspeed, heading, or radio frequency. Instead, it specifically encodes and sends altitude information, based on pressure altitude readings from the aircraft's altimeter, which air traffic controllers can then see on their radar screens.
Frequency modulation (FM) detailed in the provided information is relevant to radio communications technology, which allows for the transmission of signals by varying the frequency of a carrier wave, but is not directly related to the transponder's 'mode C.' The modulation of a carrier wave's frequency, as explained, is an essential technique for FM radio communications.
The operation and uses of transponders are crucial in the fields of aviation and aerospace engineering. By understanding how these devices work, pilots and air traffic controllers can effectively communicate crucial information that ensures the safety and efficiency of air travel.