Which program do i use to view .AIR files, i am using FS Tweaks and it is asking for a directory to my .AIR viewing Program.
Use notepad.
Notepad is used to open the aircraft.cfg file NOT the .air file. You'll need something like AirEd:
http://pagesperso-orange.fr/hsors/fsairfile.html
I can't verify that this app works with the FSX .air files, just give it a try. Make sure you keep a copy of the original before you start tweaking.
If the question and answers provided above do not answer your specific question - why not ask a new question of your own? Our community and flight simulator experts will provided a dedicated and unique answer to your flight sim question. And, you don't even need to register to post your question!
Be sure to search for your question from existing posted questions before asking a new question as your question may already exist from another user. If you're sure your question is unique and hasn't been asked before, consider asking a new question.
Flight Sim Questions that are closely related to this...