If the light on a plane flashed and you saw it from the ground, that was because the pilot and/or co-pilot saw you. The polite things to do was wave back.
A childhood belief about aeroplanes

others believed things like this
- My friend's sister used to think the auto pilot on a plane was an inflatable man like the one in Airplane!— Richard Davies
- I thought a tidal wave was acutualy a title wave because if the wave was big enough it had its own title!— Nate
- I used to believe Airplanes were things that made air plane- like took out scents, took out impurities, etc...— Emile
- My friend believed that when lightening flashed, you better smile because God was taking your picture! — Linda from Southern California
- I remember back in sunday school that if you stomped on the ground you would hurt satan. Anon
- I thought ground beef was the meat they scraped off the ground at the slaughterhouse. Yuck.Anon