When must anti-collision or strobe lights be illuminated on an aircraft?

Anti-collision or strobe lights on an aircraft are required to be illuminated from engine start until engine shutdown. This practice enhances the visibility of the aircraft to other pilots, ground personnel, and air traffic controllers, which is especially important during movement operations on the ground, in the air, and during critical phases of flight such as takeoff and landing.

Using these lights during this entire period maximizes safety by ensuring that the aircraft is conspicuous at all times, reducing the risk of accidents. The lights serve as a warning to other aircraft and vehicles that the aircraft is either about to take off, is in transit on the taxiway, or is in any other phase of flight.

Unlike the other options, which limit the use of these lights to specific times or phases, the correct answer reflects the best practice for aircraft safety throughout all operational contexts.