The Supreme Commander team will always side with fun over realism, which is certainly the case with air combat. So even though the game takes place in the far future where giant robots slug it out on alien planets, air combat itself takes a few pages from the history books. The design team structures air combat more like World War II (with slower planes, pilots that would dogfight, and heavy bombers that had to be escorted) as opposed to modern air warfare (where pilots would push a button to launch a missile miles away from the target, then veer off and zoom away at several times the speed of sound.)
As a result, except aerial combat in Supreme Commander to be just as crazed and intense as the Battle of Britain or the skies over the Normandy invasion.
Numerous aircraft types will be available: Scouts, fighters, bombers, anti-fighters (used for air superiority), torpedo bombers, gunships... There isn't any weapon that the designers are afraid to strap some wings to.
All of these different craft have tradeoffs with regards to how much they cost to build and what kind of weapons they carry. Scouts, for instance, are dirt cheap, super fast, and have virtually no weapons but a great line of sight. Assuming the enemy hasn't ramped up his air defenses, a couple of these can tell you all about his base. Map information and enemy buildings scouts reveal will continue to be displayed in shades of grey long after the plane has been shot down; you can mouse over these areas to see how old the information is.
Anti-fighters are also inexpensive, because their armament is limited. They're fast, maneuverable machines with machineguns as their primary attack. Their job is to sweep the skies clean so you can bring in the big guns. Like the gunships! These massive (and expensive) gun platforms can dish out serious damage with pinpoint accuracy, but you need to protect them from enemy aircraft.
Is your enemy relying on naval power? A whole wing of torpedo bombers are a great way to remove even the monstrous Battleship from the map, if he's not smart enough to protect it with an escort of cruisers.
Next: Bombers and special experimental weapons...
Bombers, meanwhile, are devastating against land targets. Large and slow, they'll line up near a target, swoop in, and unload a stream of enormous bombs. A single bomber will leave a line of explosions up to and over his target. A whole wing of bombers, filling the screen, can cover a base with explosions. They, too, should be protected if you want to use them for more than one bombing run. The best part about bombers is that they have some degree of auto-targeting. You can order them to a region, then allow them to pick their victims -- important factories and power plants, especially if they're already damaged, will be the first to go and you can concentrate your attention elsewhere.
All aircraft have a limited range and ammo. In between attacks they'll have to land at a friendly airbase. And the maps are huge! For this reason, if you want to use airpower, you can't just click on the enemy base far away and wait for victory. You'll want to build a series of airbases moving closer and closer to his territory. Naturally, this is where aircraft carriers come in handy: a mobile airstrip that you can park in his back yard? Hook me up!
It's a sign of the brutality of Supreme Commander that your fighters also have an alternate attack where they kamikaze themselves into enemy structures.
Each of the three factions in Supreme Commander has a few tricks up their sleeves when it comes to air power. The Cybrans specialize in stealth -- most of their aircraft don't have a radar signature, although they'll still show up on your map once your units make visual contact. The Terran forces from Earth use just the opposite approach: they have technology that'll spam tons of false radar signatures. The Aeon faction, which has incorporated alien technology into their arsenal, has actually developed true cloaking technology. This makes their aircraft invisible to both radar and the naked eye ... at least until they start firing.
As with everything else in Supreme Commander, air combat is also taken to the extreme: It's possible to build a flying aircraft carrier. Of course it's ridiculous... but it's cool. And, knowing the Supreme Commander design philosophy, it'll probably look awesome when you blow it up