No way to tell how many aircraft thefts have been averted because of
the airport watch program. They probably go unreported. Naturally when
a plane is stolen the media jumps all over it.


How many aircraft were stolen before the airport watch program?

How many were stolen afterwards?

Not the perfect answer, but a big clue.


If securing an airplane means buying a $50 prop lock I doubt many
owners would object


But a prop lock does not secure the aircraft. It gives the illusion of
security.

Jose