There is a bug that sometimes causes you to get the message that the Midway has been destroyed -- before you can even launch.
The solution is to go to the simulator and play mission 6 or mission 7 for about fifteen seconds. That resets whatever causes the bug to activate.
Also, if you let the Midway take to much damage early on, it is pretty hard to defend it from any damage later. If you let too many wingmen get killed early on, you can run out later.
The solution for those two problems is to replay earlier missions until you have less damage to the Midway, more wingmen who survive.