When operating at night or in poor visibility, ensure that a green flashing light on the unmanned aircraft is activated.

Definition of night
The hours between the end of evening civil twilight and the beginning of morning civil twilight. Civil twilight ends in the evening when the centre of the sun’s disc is 6 degrees below the horizon and begins in the morning when the centre of the sun’s disc is 6 degrees below the horizon.
(Implementing regulation (EU) 923/2012 - SERA, article 2(97))