Awhile back I flew on a DHC-8 Q400. It was an early morning flight, and throughout the flight the flight crew would periodically flash the landing lights (bright lights on the wings used during takeoff and landing). I was just curious… what is the purpose of this?
They might have been checking for ice buildup.
Is that what those things are? Well, hell! I thought they were targeting lights for the stealth bombers…
It was in November and we were flying through some snow…
I had two hunches… one being that, and the other being some sort of signaling to a plane flying towards us but at another altitude…
They were probably doing it to alert other aircraft in the area and for ice buildup inspection.
From where to where was the flight?
aerospaceweb.org/question/el … 0263.shtml
I also came across a reference in another forum that said his (the poster’s) airline kept the lights on below 18,000 to “see and be seen”.
KELM to KPHL
That’s a relatively short flight so either or both of what I said probably applied (i.e. checking for ice, see-and-be-seen).
It was likely the pulse light system that you observed. Most modern aircraft have two modes available for use of the Landing Light System, “Steady” and “Pulse”. Steady is typically used for takeoff and landing at night for runway illumination. Pulse is used in the airport/terminal area while airborne. While smaller aircraft may have a single Landing Light with a pulse mode, most large aircraft/airliners have at least two Landing Lights positioned one on each side of the aircraft. In the two light set-up they pulse alternately when selected. Pulse lights provide a greater margin of safety to “see and avoid” as they are more conspicuous to the eye than a steadily illuminated light.
On the Dash-8 the Landing Lights are positioned in the wing just outside of the engine nacelle. Because of their brightness it may have appeared to illuminate the wing, but they are aimed to illuminate the area in front of the aircraft. There is a separate light system that steadily illuminates the length of the wing leading edge for ice detection.
Also, it wasn’t a Q400 if it was ELM-PHL. US Airways Express doesn’t operate that particular variant.
Looking at what’s operating the flight right now, it was likely a -100
If you were seeing lights shining down the length of the wing, illuminating the wing itself, they were indeed “ice lights”. These are, as mentioned above, used to allow the flight crew to visually inspect the wing for icing. If however the lights were shining forward, you were indeed seeing the landing or recognition lights described by Azav8r