Ask the Captain: Landing lights in my bedroom window

Question: Can you explain all the different lights on a commercial aircraft and their purpose?

-- Joel Leckie, Clinton, S.C.

Answer: Lights vary on airplanes, but all have red and green lights on the wing tip, and a white light visible from behind (it can be on the tail or aft part of the wing tip). Additionally there are landing lights to provide illumination of the runway during landing. A taxi light provides a lower-power light to see taxiways; the taxi light can be supplemented by special lights to help make sharp turns. There are often lights that illuminate the wings so the pilots can inspect for ice build-up. The red flashing lights on the top and bottom are known as anti-collision lights. Many airplanes have bright flashing white lights called strobes making them easier to see.

Q: I recently saw a Southwest 737 landing around 4:30 p.m. on a cloudy day. It had lights flashing back and forth between the right and left sides. What is the purpose of this?

-- Brian, Tampa, Fla.

A: Some operators, including Southwest on some of their 737s, have pulsing landing lights as an attempt to decrease bird strikes.

Q: How far out from the airport are the landing lights turned on, and also how long after departure are the lights turned off?

-- Sara George, Concord, N.C.

A: It varies by operator and individual captain. I usually left the landing lights on until reaching 10,000 feet and switched them on descending at 10,000 feet. Some operators use 18,000 feet.

If we were in the clouds I switched the landing lights off.

Q: I commented to a FedEx pilot about how the upward rotation of landing lights on planes approaching the Memphis airport were flashing light right into my bedroom window. He said landing lights come on at 5,000 feet, not at a location relative to the airport. Is this true?

A: No, the landing lights come on when the pilots switch them on. I do not know where the 5,000 feet comment would apply.

As for the lights in your bedroom window, it sounds like you live on the approach course to a runway. If so, then airplanes will inevitably have their lights on when they pass by your home for night landings.

John Cox is a retired airline captain with US Airways and runs his own aviation safety consulting company, Safety Operating Systems.