Check out the figures produced by Reheat Models. These are resin figures, and they have several types of pilot figures. Most of them are standing figures, but with some cutting and filling, you could transform them into sitting figures.
Look for Reheat models on:
http://www.historexusa.com
- or -
http://www.hannants.co.uk (This web site also has pictures of the models)
Success,
Dirk