Hey! What's wrong with plane spotting??
I wouldn't class myself as an anorak and yet when I lived in Hong Kong some four years ago it used to be great fun to take my (then three year old) up to Kai Tak and stand on the top of the car park watching you guys performing split-arse turns over Kowloon.
I must admit though, after 30 minutes, it would be off to the bar for sustenance.