What camera is it? Basically if your after sharp pictures of jets flying and no arty motion blur you need a high shutter speed. I use Aperture Prority on my Nikon (AV on Canon) and leave it wide open to start with(the smallest f stop number). A shutter speed of 1/800 and above should suffice.
This is a good starting point for sharp images. (providing you've enough light to produce a high shutter speed for your given ISO which can be adjusted also)
For props and helis you need to slow your shutter speed down to at least 1/200th of a second so use Shutter Prority (TV on Canon) and a steady hand
(Mods: remove if this is too off topic
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