Low speed is not a problem. Compared to missiles, all publicly known manned aircraft are really really slow. Even the SR-71 was kind of slow, and it no longer flies.

Radar profile is a minor issue. Normally, the A-10 would be facing unguided and perhaps IR-guided threats. The A-10 has flares and chaff.

I don't think modern radar-guided AAA is much of an issue given the use case. The radar gets taken out, either by the A-10 itself or by something high and stealthy or even by a cruise missile. The larger systems are not easy to move and hide. For the smaller systems, the A-10 can withstand 50mm shells hitting the cockpit armor.

>> the A-10 can withstand 50mm shells hitting the cockpit armor.

No. Wherever you read that is dead wrong. 0.50 caliber glancing rounds yes, the sort of thing from a machine gun. And it is meant to survive nearby air bursts from 37mm AA shells, their shrapnel, but not direct hits. A hit from a 50mm exploding shell would rip the plane into pieces no matter where it impacted.

0.50 caliber sounds more like the canopy.

Minor correction, from Wikipedia, with references: The armor has been tested to withstand strikes from 23 mm cannon fire and some strikes from 57 mm rounds.

References:

Donald and March 2004, p. 18

Jenkins 1998, pp. 47, 49

Note "strikes", not shrapnel. The armor thickness varies. From some angles, the cockpit can take a 57mm shell. From other angles, it's only good for 23mm.

I wouldn't describe it as delicate - these things are meant to make it home after taking multiple direct hits from 23mm+ or a hit from a man-portable AA missile - and they have tested that durability:

http://warthognews.blogspot.com/2011/07/from-archives-oif-st...

http://i155.photobucket.com/albums/s314/Lethal_014/EMLandv1a...

Nobody would debate that the A-10 is a beast. If you are going to be raked with ground fire it's where you want to be. But we have to look at the entire mission profile. The A-10 is slow, making it more susceptible to shoulder-fired missiles, causing it to have to fly higher on the way to and from the mission. Higher means greater exposure to radar-directed weapons, not the A-10's strong game. Or it can fly lower, reducing its range and requiring airfields closer to the fight, airfields which are more difficult to protect. Flying low also reduces tanker options. There are a hundred factors. The evaluation of weapon systems really does require a committee.

The speed of the A-10 wouldn't matter against MANPADs, sub/transonic light-attack/trainers wouldn't fare any better. A block-2 stinger missile travels at mach 2.5, the SA-18 Igla can do almost Mach 3, and the 9K333 "Pussy Willow" (no, I didn't made it up but GJ NATO) is presumed to be even faster, tho it's very new and still not a lot of operational information about it. If they get a lock on you within their interception range even a fighter aircraft would not outrun them.

Yes, but even a moderate increase in target speed dramatically reduces the range of the missile, along with increasing the time for the pilot to react. Small missiles do not travel at a constant speed. They hit top speed the moment their motor burns out and then coast. By the time they are near their effective range they may be moving slower than the target. If the missile has to chase the aircraft (all shoulder-fired/IR sams) a faster aircraft will be able to remain lower and still out of effective range despite being slower than the missile's max speed.

Yes and no, a lock-on within the visual range of the seeker is not going to give an aircraft too much time to outrun it, aircraft at low altitudes aren't going to be able to go supersonic very well anyhow, even if it's a fighter.

Also modern MANPADs have sustained supersonic speed which is why they are only good for 4-5KM, but within that they'll splash you at max speed. A SA-18 traveling at 800M/S+ has only a range of 5000M so there isn't any "coasting" this isn't a movie they fly for 5-6 seconds and either hit something or drop like a rock.