Airlines dim cabin lights during takeoff and landing for a critical safety reason that has nothing to do with creating ambiance. Your eyes need time to adjust to darkness, and in an emergency evacuation, those precious seconds could mean the difference between life and death.
It takes your eyes approximately 10-30 minutes to fully adjust from bright light to darkness. If the plane loses power during takeoff or landing and you need to evacuate in smoke-filled or dark conditions, pre-adjusted eyes can see emergency exit signs and obstacles that would be invisible to someone coming from a bright cabin.
The dimmed lights also help flight attendants spot any external fires, sparks, or other hazards that might be obscured by bright interior lighting reflecting off the windows. During the most dangerous phases of flight, crew members need maximum visibility both inside and outside the aircraft.
This is why window shades must also be raised during takeoff and landing - it allows passengers and crew to see outside conditions and potential evacuation routes. In daylight, the dimmed interior lights help your eyes adjust to the brighter conditions outside that you'd encounter during an emergency exit.
The science behind this safety measure is fascinating. Your pupils can dilate up to 4 times their normal size in low light conditions, dramatically increasing the amount of light that reaches your retina. But this adjustment process takes time - which you don't have during an actual emergency.
Airlines discovered this the hard way through accident investigations where survivors reported being completely blind for crucial minutes after exiting bright cabins into dark evacuation scenarios. Studies showed that passengers who evacuated from dimmed cabins could navigate emergency slides and find exits significantly faster than those coming from brightly lit interiors.
The rule is so critical that it's mandated by aviation safety regulations worldwide. Airlines can face serious penalties for not following proper lighting procedures during these crucial flight phases.
Even the timing is precisely calculated - lights dim exactly when the plane begins its takeoff roll or descent approach to give passengers' eyes maximum adjustment time during the most statistically dangerous moments of any flight. Flight attendants are trained to monitor compliance because even a few minutes of proper eye adjustment can be the difference between a successful evacuation and tragedy.