How do I get engineer specialist 2 if everyone Flys like their in the airforce?

I noticed in the end you can use regular weapons like a LMG, DMR, Sniper to damage helicopters etc. too to get the assignment done. But I managed to finish it with the regular Stinger AA launcher. I finished most assignments in "Casual Breakthrough" but lots of them you have to do in a regular Conquest match because you have to take down aircraft and such.