When does the Flight Data Recorder (FDR) start recording?

The Flight Data Recorder (FDR) is designed to begin recording data during critical phases of flight to ensure that vital flight information is captured from the moment the aircraft is prepared for takeoff until it is safely on the ground. This occurs when both the beacon or strobes are turned on, indicating the aircraft is active and preparing for departure, and when the weight is off the wheels, marking the transition from ground to flight.

Starting the recording upon activation of the beacon or strobes reflects the aircraft's readiness and signaling to the ground personnel that the flight is about to commence. Simultaneously, recording when the weight is off the wheels ensures that data is captured for all phases of flight, including takeoff, climb, cruise, descent, landing, and taxiing. This dual activation means the FDR records relevant data throughout the flight, providing crucial information in the event of an incident or accident.

Thus, the accurate moment of recording commences according to the activation of these two important signals, which is why the choice mentioning both conditions is the right answer.