Locks keep honest people honest... They might make a less determined crook
go to a easier target... A crook that is determined to steal a
particular
plane will find a way to do it... All you can hope for is to make it a
lengthy and noisy enough process that he either goes elsewhere or
someone
discovers him prior to him completing the act...

Okay, maybe a stinky week-old tuna & swiss hidden in a map pocket might
be a better deterrent?