The trails that aeroplanes leave across the sky are obviously created by pilots leaning out of the windows holding a piece of chalk, so they know where they've been. That's what I was told anyway.
A childhood belief about aeroplanes

others believed things like this
- I used to believe that the "shark mouth" nose art painted on military planes was to scare enemy pilots away.Anon
- I used to think that the trails that Airplanes left in the sky, that's how clouds were made.Anon
- I used to think that aeroplanes came to your house to pick you up.Anon
- I used to believe that aeroplanes could reverse when they are flying. Anon
- When I was little, I believed that aeroplanes were sent into the air by giant slingshots.— Now I Know Better
- I thought the dog poo in the street was human poo dropped from aeroplanesAnon