this site to try understand more plane spottin, www.airliners.net.
Plane spotting it´s a hobby and main activites are, watching planes, take photos, take registrations of the planes.
Just this curiosity, In the wake of the targeting of airports by terrorists, enthusiasts' organisations and the police in the UK have co-operated in drawing up a code of conduct. This attempts to both allow enthusiasts to continue their hobby and increase security around airports, by asking enthusiasts to contact police if they believe something they see or hear is suspicious.