From everything I've read on the Forums we can only assume that the Aero's in MW:LL will act like Battletech ASF should.
Understand that just like with 'mechs, every unit can cause you damage on the battlefield, few things will knock you out of the sky in one salvo though. So if you flew low over a bunch of Harassers expect to take SRM Hits, you get LoS with an Awesome and your dodging PPC bolts.
ASF have thick armour, a lot less usually than 'mechs of equivalent tonnage, but still capable of soaking up at least one hit from most anything you can throw at it. There's not much in the cannon for countermeasures IIRC, and LRMs are the least of an ASFs worries the faster ASF should easily run past the LRMs range or turning circle quite safely if we look at the TAG video to get an idea of LRMs speed.
Some vehicles are also designed to kill ASF and they tend to rely on clusters of LBX-AC2s and so on for fast firing rate and hits at extreme range. As another poster pointed out, Lasers of all variety are your enemy!