If you have both launchers deployed, its sometimes useful to shoot in turns. This way its harder for enemy planes to pin point your exact location.
There is key command for this:
Controls > Ground vehicles > Miscellaneous > "Prohibit fire for the first launcher" and "Prohibit fire for the second launcher".
This can also be done manually, by switching to that specific launcher, using key command: "switch to auxiliary vehicle" and launching once you are controlling one of the two launchers.