Which phase of flight requires a signal check for the aircraft?

During flight, particularly while the aircraft is airborne, a signal check is vital to ensure reliable communication with ground control and other air traffic services. This phase is critical as it involves maintaining situational awareness, which relies heavily on consistent and clear radio communications.

When an aircraft is airborne, it needs to continuously monitor its communication equipment to confirm that it is receiving and transmitting signals effectively. This involves checking radio frequencies, ensuring that the transponder is functioning correctly, and that pilots can communicate with air traffic control as well as other aircraft. The safety of the flight and the aircraft's adherence to its flight plan largely depend on effective communication during this phase.

While takeoff, after landing, and before departure are all important phases where checks are performed, the airborne phase necessitates ongoing vigilance for maintaining communication throughout the flight.