first the issue of air unit elevation is somehting that always comes to mind when you see two helicopters with guns that are completely capable of killing each other simply state at each other and do nothing. the other thing is the case where close air support units like the venom can so easily engage fighters like the stormriders.
it always felt akward to me, and even though for balance or visual reasons it could prove difficult to create i believe that air units should have low altitude and high altitude.
low altitude should be reserved for helicopters and close air support fighters that are using their guns, rocket pods, ect. in low altitude the helicopters are also vulnerable to infantry, most machinegun fire and- tanks. tanks is tricky, because tanks are usually meant to be pray for helicopters. but i believe that if a player wishes to force his tanks to fire at helicopters with low probablity of hitting them would be cool. this would also cause helicopter domination that you see so often slightly be nerfed by the very simple reason that they are considered low altitude aircraft. even if infantry shouldn't be effective against helicopters (or at least attack helicopters and heavy transport), it would at least be belivable that they will fire at helicopters.
and of course helicopters this way, or STOVs if we wish so, would no longer ignore each other should most of their weapons be anti ground weapons. they will now engage, and this also can create a more interesting dynamic with early to mid game helicopter harassment. once fighters come in, they can engage helicopters, but helicopters would not or have a very hard time to engage of they could.
i think one way to make fighters that come out of airfields to be more useful in finishing of the job they are left to do is to have guns with limited power for strafing runs. all in all i even believe the physicallity, the way dogfights happen, fighter on fighter, fighter on helicopter. those should all be much closer to reality. missiles should only lock on from behind, and frontal encounters will only be autocannon fire exchanges.
speaking of the way aircraft control, aircrafts should do more interesting maneouvers simply by what angle you click to mouse from their position, should you click behind them some will create a split S maneouver, others will do a loop above and break to half split S. with this control level you could make your aircraft dogfight in a very natural way simply by which direction you click the mouse dictating the script at how sharp their turns will be. flares and countermeasures could be active or passive, depending on faction and functionality implementation.
aircrafts also brought me to the tought of at least two very distinct types of stealth in see in RTS, or simply anywhere in gaming- high tech stealth and low tech stealth. Generals however is slightly different, so we will go to three different types of stealth: air stealth, camoflague and jammer. at least in the logic of generals, which is somewhat based on that of reality, aircrafts are stealthy because they can avoid radar, and ground units enjoy stealth because of in the case of GLA- camoflague for Infantry and some vehicles. and in the case of some mechanised vehicles, maybe the USA drone and the chinese listening post- jammer devices.
if you split those three to three levels of stealth, you can get really interesting mechanics. now i know that one might think that splitting stealth into three categories is detectors overload, but i believe that stealth is an important aspect of modern, or for Generals 2 sake- future combat. this would make certain tactics work, and certain tactics not work depending on the detector composition, or detector types. it would make sense to have at least one support unit that can detect all types of stealth, but for most purposes, most if not all units should be able to detect at least one type.
for example jammer devices like say, a specialised Gatling tank that is hidden from view of aircraft locking devices. would be hidden from aircrafts, but it will be visible for tanks. tanks in 2030 will obviously all use thermal sights and will catch the gatling tanks easily. pretty neat huh? considering tanks are never thought to be a detection of unit of any kind, just bruce force...
camoflague for example is a cool way for GLA to stop USA (or would it be EU) radar scan spam... i worked for millitary intelligence in the IDF, and the very thing camoflague is meant to bluff would be radar. however camoflague would be cought off guard simply by having infantry inspect the area. for better inspection range, send your own camoflagued EU snipers. camoflague is great against vehicles, because it bluffs their thermal or regular vision, and camoflague is the way you use say... RPG troopers to ambush tanks, send in any sharp observer units and it's all toast for GLA.
air units and their stealth should be detected obviously by radar (even though stealth is radar re... well get in that "Generals logic" and bear with me). this would be the most straightforward and should come from the most familiar stealth detectors from RTS, ground defenses, maybe that uber WTFBBQ support unit that people neglect, you get the point. stealth air should also be most visibly detected by scout fighters- those for example, the ones that have a hard time finding ground jammered and zero chance of finding ground camoflague, yep- those.
i could think of many different ways three types of stealth could work with each other, against each other and have different stealth properties that work in different situations and different proximities. but i think you guys get the picture, one definition of "stealth" for the entire game just isn't enough, as well as one definition for flight ceiling.