EOD stands for end of daylight. It marks the precise moment when evening civil twilight ends and the sun drops far enough below the horizon that visual reference to the ground is lost. Pilots operating under visual flight rules must either land their aircraft before this time or switch to an instrument flight plan if suitably equipped and rated. The exact minute shifts daily and depends heavily on the local latitude and altitude.
Heard on the job
We need to be wheels down at the alternate airfield before EOD or we're going to be violating our visual clearance.
Insider tip
Dispatchers calculate EOD using official tables rather than looking outside, as atmospheric conditions can make it appear dark long before the legal threshold is reached.