I looked into this myself a year or so ago. I tried to work with one of the respected agencies, and they “agreed to take me on” but were unable to provide any sales projections, even rough ones, for any of the projects we discussed, so I ended up never doing it…. I din’t want to front the money without knowing I had a chance to get it back. In the end I decided it was a no go.
However, I learned quite a bit… In particular, if you want to sell stock through an agency, you need to have every detail covered, and I mebna COVERED. This means LOCATION RELEASES, TALENT RELEASES, ETC. If you take a pricture of an airplane, they are going to want you tha have a release from US AIR and LAX, unless it is a completely generic shot. And believe me, my and your idea of generic is VERY different from theirs. They vetoed some shots of cars I had because they said you could just kind of make out the people inside…( I assure you, you could not make out the people inside).
Anyway, that’s what I know… good luck.
And PS, they probably don’t need shots of airplanes. If it’s nearby and easy, it’s already been done.