Normally, a squadron will be made up of 12 ships, so that would be three wings of four. But any squadron will have a small number of reserve pilots to fly additional fighters when pilots who are wounded in acion can't fly. So I figure an average squadron will have 12 regulars and up to 6 reserve pilots, for a total of (maybe) 18 ships.
However, in the SOC mission in FS2 where you are hijacking the NTT Sunder, the 185th NTF squadron (the one that you and Snipes betray), there are about 16 or so ships in the squadron (including you and Snipes), instead of the regular 12. My guess is that Snipes decided to put the whole 185th (including the reserve pilots) in the mission, so that more NTF pilots would be "sanitized" during the covert op.
With you and Snipes as the only survivors of the 185th, who would dispute your word about being ambushed?
What Snipes didn't forsee was that he would get transferred immediately afterward, leaving you alone and holding the bag....
But to get back to your original question, a squadron "officially" has 12 ships, so three wings of four.