If the airplane you wish to photgraph is is public space you can click
away, just as you can for cars, boats, people, etc. You can photo the
pilot, the N-number whatever you want. You can't enter private property
(e.g. walk up to the hangar, or trespass on the airport property -- not
that there is anything typically preventing that) to photograph, though.


If you intend to use the photos for commercial purposes, however, you
should obtain the party's written permission.