360BakTrak
True, but what if the police/SAR aircraft is approaching the lights-out aircraft from the rear? Who would be held to blame should a collision or airprox occur?
H Peacock
There is nothing in aviation law that prevents you from displaying nav lights by day. It is a very sensible flight safety precaution, particularly in dull weather conditions. It also stops you forgetting to switch them back on at dusk.
There are, however, some cheapskate operators that encourage their crews not to use them in order to save light bulbs.