When must anti-collision lights be illuminated while airborne?

Anti-collision lights serve an essential purpose in aviation safety by enhancing the visibility of an aircraft to other pilots and ground personnel. The requirement for these lights to be illuminated from takeoff to landing is grounded in the need to ensure that the aircraft is conspicuous during operations like departures and arrivals, which are critical phases of flight where the risk of collision is heightened.

During takeoff, these lights help other aircraft on the ground or in the air-to-see the departing aircraft, while during landing, the lights indicate the aircraft's position and intentions. Illuminating these lights during the entirety of the takeoff and landing phases promotes safety by reducing the chances of accidents due to visibility issues.

The other options relate to incorrect assumptions about the flight stages or conditions when anti-collision lights are necessary. The emphasis on takeoff and landing ensures that visibility during these critical phases is prioritized, aligning with standard procedures recommended by aviation authorities.