First off as soon as the level starts you need to beat feet to your AT-PTs and take down the AT-AT. Leave the gate to your wing men and then go to the walker that is by the generators, take him out go towards your AT-PTs and hang a left down the path and you will see one more AT-AT. take him out and then you will start to see the tanks coming for your AT-PTs now. Start shotting at them as soon as you see them coming over the ridge, don't wait till they are down in the path. there is at least 8-10 of them. When they are all killed(the tanks) look for the Tie bombers to now come over the ridge. They come in groups and fly down the path towards the transport, turn around and then fly back up the path again. So when you are done with the tanks keep your eye on the the ridge, you will hear them before you see them, so when you year them coming go look for them right away. when you get the first ones turn around towards the ridge and look for the next wave. They are in groups of 2 I think, maybe 3. When you hear Riekeen say the AT-PTs are safe go shoot the generators that are by the 2 AT-AT you took out (if you didn't already do this) the go to the research facility, but before you blow it up go up the ridge behind it and shoot he bunker for your bonus.
http://www.roguesquadron.net/forums/smile.gif) Then continue to destroy the facility, killing everything.
http://www.roguesquadron.net/forums/smile.gif)
When I did it if there was ever a time I noticed I has lost one of my AT-PTs I just would start over.
Good luck credenda