That's true, I am refering to a precise case which occured a long time ago(24th of june 1947), in Oregon, in the vincinity of a moutain range including the mounts Rainier and Adams (with multiple high altitude glaciers: above 7500 ft, even above 9000 ft for some of them). The pilot (Kenneth Arnold) was at approx 20 miles at the 255° azimut from the mount Rainier, flight level 9200 ft, heading for Yakima. The sun was at 60° of elevation from the 230° azimut. This sighting gave birth to the notion of "flying saucers" and UFOs.
http://www.martinshough.com/aerialph...0analysis2.pdf
We are trying to revisit this case, and in the present case, we are looking for the possibility that nearby mounts and peaks could have created grazing beams of sunlight (specular reflections on the icy slopes) illuminating briefly the plane of K.A. and then nearby birds between him and the mount Rainier (they were crossing his trajectory) at grazing angles so as to make them appear like flashing mirrors (forward gloss).
J.F.B.