Lights, Please!

Question:  I have a question regarding lights, specifically landing and strobe lights.  Is it mandatory to have the landing and strobe lights on when on an active runway, or can they be turned off if they hinder the pilots vision (i.e. reflection in low visibility)?

Chris Moroney, Biloela, Australia

Answer:  Some lights are required to be on all the time, such as the "navigation lights," including a red one on the left wingtip, a green one on the right wingtip and a white one on the tail, visible to the rear of the aircraft.  This type of light doesn't interfere with pilot vision.  At night it can sometimes be difficult to tell what direction another aircraft is headed and the colored lights help with orientation.  There are often two of each light installed, in case one burns out.

The red anti-collision beacons are required to be on when a plane is about to be moved or any time an engine is running or about to be started.

Some lights, such as white anti-collision strobes and landing lights, may be turned off in flight when they adversely affect cockpit vision.

While taxiing, pilots crossing runways, day or night, turn on all available lighting, including landing lights and strobes, until clearing the runway.  This is to improve visibility for other aircraft.  Strobes can be blinding and are otherwise not used on the ground. 

When aircraft are stopped on the ground at night, pilots will often turn off their landing and taxi lights as a courtesy to other pilots whose aircraft are facing the opposite direction.

When a pilot taxis onto the runway for takeoff, all the exterior lights are turned on and normally stay on until the aircraft climbs out of at least 10,000 feet.  Speed is restricted by Federal Aviation Regulations to 250 knots below 10,000 feet, but above 10,000 feet speed is normally increased.  Some aircraft, such as the Airbus I flew, has a speed restriction of 250 knots for the landing lights, which should be retracted at higher speeds, so above 10,000 feet the landing lights are turned off (the lights extend when turned on and retract when turned off).

Some airlines have a policy for pilots to leave all exterior lights on until reaching 18,000 feet unless the airplane, such as the Airbus, has a speed restriction with regard to lights.

It is a pilot's option to turn off the landing lights and/or strobes if they interfere with visibility.  The purpose of the lights is to improve visibility to other aircraft.  Landing lights only improve visibility to the pilot while on the takeoff roll or just prior to landing, and while on the landing roll.

Both Federal Aviation Regulations and airlines' policies govern exterior light operations.