.....if it was dark and he was 'dark', how do you know what it was?
There's a lot of light pollution here; it was a damp night, lowish cloudbase, so there was a background glow; he was clearly silhouetted; I teach ac rec to cadets; I live near a station where Pumas live; it was heading in that direction... need any more?
There were plenty of other ac around but he wasn't in formation - I saw him clearly against an otherwise empty patch of sky. There was nothing within, say, 1/4 mile in any direction, except possibly astern of him, but surely it's the lead who keeps lights on?
Tim