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Message: <blockquote data-quote="typo" data-source="post: 3348079" data-attributes="member: 83808">I'll juggle some numbers. Just taking the wing span as 80cm and the distance as 6.25 km, that would be 26.4arcseconds to the unaided eye. Even unaided, there is a good chance you would spot s a dark object that size on a white background  or vice versa, but you wouldn't be able to see it as a bird.  An 8cm wing width would be 2.64".  At 27x that would be 71.3" which is still somewhat smaller than your 120" optician diagnosis but you should might make out a cross shape if it presented at the right angle. You wouldn't see the wings clearly, or discern other features. I'm pretty sure you couldn't tell grey from brown at that range either, but I wouldn't rule out seing indistinct light/dark flashes, but the light would have to be very good indeed. Is that enough?David</blockquote>