Why Do Planes Turn Off Lights When Landing?
Many passengers are confused by the custom of dimming the cabin lights as the plane descends to land. This is a necessary safety protocol that protects pilots, air traffic controllers and passengers.
There are several reasons why airplanes dim their cabin lights for take-off and landing. The most important is passenger safety. When an emergency occurs, passengers need to be able to evacuate the aircraft quickly. It can be difficult to do this if the eyes are still adjusted to light.
The main reason airplanes dim their cabin lights during takeoff and landing is for safety reasons. It’s important for pilots and air traffic controllers to be able to see the aircraft clearly on the runway. Keeping the cabin lights on can distract the pilots and interfere with their vision.
Similarly, the passengers’ eyes must be adjusted to darkness before an emergency evacuation can take place. If passengers disembark into a pitch-black plane, they would have trouble finding their way around. The practice of dimming the cabin lights during take off and landing helps passengers become accustomed to darkness, allowing them to react quickly in an emergency situation.
Nevertheless, the cabin lights are not turned off completely during takeoff and landing. Some lights, including emergency exits and flight paths, remain illuminated. This allows passengers to still find their way out of the plane if necessary and also makes it easier for crew members to spot potential hazards.
A plane’s lights use up a lot of energy, and keeping them on during takeoff and landing adds to the stress on the engines. Dimming the cabin lights helps conserve power, and it also makes it easier for passengers to see the emergency exits in case of an evacuation.
Another reason for dimming the cabin lights is to allow passengers’ eyes to pre-adjust to the darkness. It can take up to 30 minutes for the human eye to adjust from a well-lit environment, and that time could make all the difference in a crisis.
Another way that airlines save power is by using white wingtip strobes (the flashing lights you see when looking up at airplanes in the night sky). The crew can toggle these lights between ON, OFF, and PULSE. Typically, the strobes are ON for cruise and OFF during descent, with a switch to PULSE at low altitudes and when approaching the runway.
As soon as the cabin lights dim, most air travelers know that their flight has cleared takeoff or is in the final stages of descent before landing. It’s a widely-known aviation safety procedure, and for good reason.
The main reason planes turn off their cabin lights is to give passengers the best visibility possible in the event of an emergency situation during the most dangerous parts of a flight. The human eye needs a moment to adjust from an illuminated environment to a dark one, and this visual adjustment could cost precious seconds in the case of an emergency evacuation.
The dimming of the cabin lights also helps passengers easily identify the “EXIT” signs located throughout the airplane. In addition, it makes the bright white anti-collision lights on the wing tips more prominent. This is especially important during nighttime takeoffs and landings when other aircraft may be flying in the vicinity. This way, the crew can quickly point out where to locate their emergency exits to save valuable seconds when it comes to an emergency situation on the ground.
The most important reason cabin lights are dimmed during takeoff and landing is a safety precaution. In the unlikely event that an evacuation is required at these critical stages, passengers would need to quickly adjust from a brightly lit cabin into pitch-black darkness. This can save valuable seconds as passengers follow the evacuation directions and find their way to the nearest exit door.
This is also why flight attendants ask passengers to keep their window shades open during these periods. It helps their eyes pre-adjust to the dark conditions outside the aircraft, so they can easily see emergency lighting and walkways in an emergency evacuation.
In addition, keeping the cabin lights off prevents glare from disrupting pilots’ night vision while navigating the runway for landing. Airplanes have a three-position switch for their landing lights: ON, OFF, and PULSE. The ON setting is used when the airplane is in cruise and the OFF and PULSE settings are used during takeoff and landing.