I still think the A-10 has an important role to play in protecting our troops on the ground.
And I think it's still trying to find a mission. The mission it was designed for is gone. It's the F-111 of Attack Fighters.
The AC 130 is a slow cumbersome beast which can be easily hit with modern air defense system.
Top speed of a slick A-10 439mph. When you load him for bear, you are going to be lucky to get much over 250mph. His load is a huge drag. Loaded like that, his radius range will be just over 130miles radius. You want him to do cas, unload him add more gas, and you might get him out to 200 mile radius with a 1 hour loiter time. The A-10 replaced the A-1E which had about the same loadout (2 less weapons points), was slightly slower but could fly 1000 miles with a decent weapons load and still have a decent loiter time.
Now we move on to the AC-130J. This is the Model USAF is accepting now and has a few in service. Top Speed 416 mph loaded. Range 3000 miles loaded. The older ACs could only muster 300mph so they were about equal to the A-10 there (give or take). But the J has cannons and guided munitions and can stand off if it wishes. Plus, it can sit at 20,000 feet and hit that truck, running person or level that half acre cement warehouse to the ground. All while being out of reach to the smaller surface to air weapons.
Both are more than a little susceptible to the larger radar and heat guided ones. But not of the shoulder fire variety. You have to use mark one eyeballs to find your target. If you can't see it you don't know where to point your tracker at. It could be a friendly, you know and that missile is the only one you have with you at the time. I mean, it also could be big wood pecker. But the A-10 has some traits that helps to minimize the damage from manpads. (for another discussion) But if you are getting him by a manpad in your AC you are totally F***king up and you hope it does hit one of your engines because hitting your ammo makes a huge fireball in the sky. Hitting one of your engines just means a long and slow flight home to change your shorts.
Both operates with the idea that you have established air superiority and taken out the longer ranged radar guided missile sites. Until you do, neither bird can really be safe. Up until then, it's the F-18E and F-15E for fighters and the heavy bombers jobs using stand offs. The AC just keeps you a little more honest in this regard.
While yes I know they have countermeasures it would sure as hell be a lot more expensive to replace than the A-10.
While both craft can take off and land on a shitty landing strip the A-10's can be spread out in areas of need while we dont have enough AC-130's to do the same. While I love the AC-130's we havent used them against an enemy with advanced air defenses.
Of course if we have air superiority that lessens the risk greatly,for both aircraft.
Actually, the AC-130J needs a pretty good runway. It's not a trash hauler. He's heavy, real heavy. (and he's my brother....sorry, couldn't help myself). The point here is, if you do get air superiority and neurtalize the SAMS both can operate pretty much with impunity as long as you stay above ground fire capability.
Let's look at your forward mobility of the A-10 versus orbiting AC-130s. The A-10 is good for maybe one or two strikes and then he has to get home for refueling. His range is crap. The A-1E did a much better job but just cost a lot more to operate. (And the A-1E has 2 Mig kills. ) The AC is good for right around 10 hours whether he's in orbit or slagging a small city. By the time the A-10 gets off the ground, the AC has already done the mission and went back to his orbiting station. And yes, the mission for the AC costs a lot more than the mission for the A-10 but you get what you paid for.
The point here is, the A-10 was probably never needed since it's mission never came about. They had to create a mission for it. So they stole a mission from the one Aircraft that was specifically created for CAS and that was the AC-130 that spent it's own time being used in created mission doing the only really mission the A-10 would have been good at, transporation removal service . In reality, CAS isn't on single Aircraft. It's many. When a crew goes down, EVERONE in the area becomes CAS. During 1970, the first to get there were usually the F-4s or F-8s. When the A-7s shown up, the Fs left. Then the A1-E came and the A-7s left low on fuel and out of ordinance. The A1s had the weapons load and staying power to make the enemy put their heads down. Then the UH and AH s showed for the the actual rescue mission, it stirred up a hornets nest and the A1s went back to work. While I can see the A-10 being part of this chain, I just can't see it being an important part of it.
