...superiority to level The Fort? (quote by AwesomePossum)

I bet it's got to do something with law holding them back.

Well they aren't currently authorizing their full force to be sent west, which is why the veteran rangers and heavy troopers only show up near the end of the conflict. Maybe their aircraft is being diverted towards other uses, like for transportation of goods, or for whatever is going on in Baja. That is, assuming that they actually have any sort of air force. For all we know, Bear Force One and the destroyed choppers at the Long 15 were among a very small number of vertibirds that they've got. It would explain why Oliver nearly pisses himself if you threaten to send the Boomers west.

Because there'd be no Fallout: New Vegas.

In all seriousness, in-universe, it's probably because they don't want to "waste" something as valuable as a Vertibird unless absolutely necessary. Why risk having one of your rare Vertibirds getting shot down when your ground forces already proved they could hold the dam without them?

Does Legion even have anti-aircraft weapons? Even if they have rocket launchers, which I have never seen a Legion soldier use, that isn't easy to shoot a flying target with. You would need heat seaking missiles or AA guns to pose a threat, not to mention you can perform air raids at night, which also make it harder to defend against.

Hanlon's viewpoint would certainly not be all too uncommon. Bombing the Fort (even with just one or two carriers) would confront the legion with unexpected warfare.

Caesar himself could of course hide in the bunker with his veterans, but the other camps would suffer great losses.

You two, how have I never noticed that y'all have mirrored avatars?

Yeah, the Legion doesn't seem to have anything capable of bringing down aircraft. Hell, we had to go through a whole quest just to build a weapon capable of taking them down in Broken Steel. My guess is that the NCR simply doesn't have the air strength that we think it does. If it does, then they are sorely wasting it somewhere else.

Lack of ammo? I guess Enclave leaving Navarro didn't leave any mininukes or missiles. Are there even instances of NCR soldiers using those? Enclave chopper in the Battle of Hoover Dam also didn't seem to use any. So, maybe even if they had some ammo, they run out of it while ago. After all, it's been long since fall of Navarro. Same goes for NCR and their military campaigns. I don't remember, are Gun Runners creating rockets?

It's normal for retreating armies to destroy the equipment they can't take so it wouldn't fall into hands of enemy. I was even surprised to see any virtibirds at all in NV. Guess they managed to repair few.

Another theory - maybe NCR was planning to use those during final assault on Dam, but they were prevented from doing so by Fiends attacking McCarran.

@The Good Doctor, I unscrupulously copied it, but then evl decided to have his avatar pimped up so mine remains but a lousy shadow of his.

Maybe, but they salvaged Enclave goodies and could get behind the tech, like with the president's vertibird.

It just doesn't make sense to me. Someone should have at least mentioned this issue ingame.

@Kalasanty that could be it. Maybe they don't have the bombs. Could explain Oliver's fear of the Boomers. The situation would certainly teach them a lesson in the future. There would have been debates going on in the west we didn't witness.