ATPL Online question bank
Question 1 of 14 Number: 12208

Aircraft equipped with red anti-collision lights may display them:

  1. on the ground when the engines are running.
  2. outside the daylight-period in flight, but not on the ground when being towed.
  3. outside the daylight-period at engine-start. During the daylight period this procedure is not applicable.
  4. while taxiing, but not when being towed.

Fixed wing aircraft must have at least one anti-collision light which may be either red or white.

If fitted with a white anti-collision light, this may be displayed for engine start but it must be displayed during taxiing. (This rule has possibly come about because a white anti-collision light has a 'strobe-style' effect and could be distracting for the start crew.)

If fitted with a red anti-collision light then this must be displayed for engine start and taxiing.

(Helicopters only have red anti-collision lights!)