Navigation lights in civil aviation are required to be turned on from sunset to sunrise. High-intensity white strobe lights are part of the anti-collision light system, as well as the aviation red or white rotating beacon. The anti collision light system (either strobe lights or rotating beacon) is required for all airplanes built after March 11, 1996 for all flight activities in poor visibility, and recommended in good visibility, where only strobes and beacon are required. An example of this would be just before push back, (push and start) the beacon lights are required, to notify ground crews that the engines are about to be started. These beacon lights will stay on for the duration of the flight. While taxiing, the taxi lights are activated. When coming onto the runway, the taxi lights are deactivated and the landing lights and strobes are activated. When passing 10000 feet (or FL100), the landing lights are no longer required, and can be turned off at the pilot's discretion.