Thanks everyone

Not very..

His books are filled with inaccuracies but the gist of the idea is plausible. One has to just look at Cargo Cults in the Pacific, building runways, wooden airplane symbols and emulating the pilots in dress and attitude. I cannot rule it out.

The theory can't be entirely ruled out - it's so very unlikely that it's not really worth spending too much time thinking about it, but it's remotely possible. Von Däniken himelf, meanwhile, is rather less than trustworthy - his books feature a lot of bad science and bad history selectively edited in order to be presented as respectable research, and numerous parts of his books are plagiarised. What's more, his original research was funded through financial fraud - after being found guilty in 1970, he was sentenced to 42 months in prison. That wasn't the first time he'd been in prison - he'd served 9 months for fraud in 1964, too.