The REAL issue is the MANPADS --THAT is what to prevent you from focusing on.
400 were stolen on 9-11 but the total load was 21,000 of which 5,000 were non-servicable and destroyed.
That leaves 15,600 MANPADS, some of which transited Bengazi prior to 9-11.
They were mostly SA-7's --old and very vulnerable to such simple countermeasures as flares. BELOW:
https://upload.wikimedia.org/wikipedia/commons/9/97/Sa-7.jpg
Also with the SA-7 featured above the target must be silhouetted against bare sky for the seeker to "see" the target. So if I'm a hilltop rebel trying to fire on a helicopter approaching from low in a valley using the SA-7 Grail, then forget it, the missile sees nothing, since there is a mountain behind him.
But After Reagan's air attack against Khadaffi (much later it turned out his daughter was not killed in the raid, as he'd claimed for many years), Khadaffi imported newer Soviet AA missiles, also, like the SA-24 Grinch, below, and THIS is the real problem:
http://4.bp.blogspot.com/-j5TUVPrTpqA/Tmh48bS0bOI/AAAAAAAAAXM/T2e2iOPYRrw/s400/SA-24_Grinch_9K338_Igla-S_portable_air_defense_missile_system_Libya_Libyan_army_001.jpg
It flies at Mach 2, reaches up above 10,000 feet, and the aircraft needn't be seen against empty sky for targeting. Also the Grinch needn't score a physical hit for detonation --it also comes equipped with proximity fusing, so if senses an impending bypass, it will still trigger. Also if there is remaining fuel, this, too, will be blown in the explosion as a kicker. Even with jamming and flares, about one in four Grinches will score a hit, generally.
What type of success might it get against commercial aircraft in their current form...? The Obama Admin does NOT want to talk about this at all.
The Libyan smugging was a WH/JSOC op, which means VJ BHO Hillary and John Brennan giving orders to a bunch of really secret squirrels who don't ask questions and won't squeal.
They killed some people who got mad, got outside help and fought back, zapping our four guys.