Why, when planes are taking off and landing at night, do the lights have to be dimmed? | Notes and Queries (2024)

Why, when planes are taking off and landing at night, do the lights have to be dimmed?

Brendan O'Brien, Rickmansworth UK

• I remember reading somewhere that the reason the interior lights of an aircraft are dimmed/switched-off on landing and taking off is that these are the times the plane is most likely to crash. In the event of a crash, survivors will have a better chance of escape with their eyes adjusted to the dark already.

  Tim, London

• I was told by cabin crew on a BA flight that it was in case of an accident or incident that would require evacuation of the aircraft. With the likelihood that the interior lighting would fail the passengers eyes would already be some way to being accustomed to the dark.

  William Gosling, Dommeldange Luxembourg

• The lights are dimmed in order to reduce electrical load.At takeoff, you want all the power possible in order to shorten the takeoff roll and the more electrical load, the more engine power is sapped off to generate electricity. The same is true on landing, though it is power is reserve in case the flightcrew need to abort the landing in a hurry. They would not want to be messing about with electrical switches at such a busy time.

  Jim Cross, Bristol UK

• The "dimming of cabin lights" only happens when it is dusk, dawn or dark outside the aircraft. This is a safety measure, and is to ensure your eyes are adjusted to the gloom enough to see the floor lights leading you to safety along the aisle in the event of a crash or emergency evacuation. If the cabin lights were on, but then went out your eyes would need a while to adjust to the lower light levels.

  Jamie McDonald, UK

• I tend to agree with the reason that they are dimmed so that in the event of a crash, your eyes don't need any extra time to get adjusted to the darkness. For the same reason, during a day flight, it is insisted that all the windows are kept open so the brightness of the cabin matches the brightness of the day outside.

  Conal Charles, Bombay India