“Air Power rests at the apex of the first triad of victory, for it combines Mobility, Flexibility, and Initiative.”
— Spartan Battle Manual
Doctrine: Air Power is the last of the Doctrine line of technologies. It is a fifth-tier exploration technology that relies on Synthetic Fossil Fuels and Doctrine: Flexibility. As one might expect, it enables the creation of military units with the fixed-wing aircraft chassis, which are called needlejets by default. I always thought that was an evocative name. Anyway, they follow special rules compared to all of the other military units that have appeared thus far in SMAC. It’s worth going into them in detail to understand why this is such an epochal technology.
First off, by default air units have 10 movement points. That means that they move five times faster than rovers and even twice as fast as a loaded cruiser transport. Additionally, air units do not suffer any terrain penalties, as they can just fly straight over anything in the way at one point per square. This, alone, tremendously increases the reach and efficiency of a faction’s military.
Secondly, air units have limited fuel. They must return to a friendly base or airbase terrain improvement every other turn, in addition to costing minerals under their home base’s supply cap. This is in contrast to all other previous units, which can remain in the field indefinitely as long as they get their support minerals. Since an attack costs all the movement for that turn, this generally means, unless they are willing to sacrifice themselves kamikaze-style, a needlejet can only attack every other turn.
Third, air units in the air are immune to attack by all units that do not have the Air Superiority special ability. Air Superiority is enabled by Doctrine: Air Power, which means that if your faction doesn’t get it first, you get to watch all your guys get strafed and then see the jets hang there and taunt you for a turn before they fly home, re-arm, and dice you up again. It’s an intensely frustrating experience.
Fourth, if an air unit is built with the Air Superiority special ability, it reduces the speed of the aircraft by 2 per turn and applies a -50% modifier to attacking ground and sea targets. In exchange, it gets a +100% when attacking air units.
Fifth, when air units fight each other, both sides use their attack values. Unlike artillery, which also do this, they fight to the death. This means that needlejet units almost never have higher than 1 armor, since it greatly increases the cost of the aircraft and almost never comes into play.
So all of these rules together imply that after Doctrine: Air Power, factions build two kinds of aircraft: fighters with Air Superiority and bombers without. The fighters protect against enemy bombers and clear out enemy fighters, while the bombers do their work to destroy enemy land and sea forces. And this third-dimensional battlefield quickly becomes the critical one. The traditional attack forces based on cheap, lightly-armored rovers that had dominated Planet since the second-tier of the technology tree are completely obsoleted by swarms of aircraft. In fact, it is worth noting that even with the fighter penalty, a jet with a decent weapon can easily strafe an unarmored target outside of a base.
So when the Spartan Battle Manual states that air power is the combination of Mobility, Flexibility, and Initiative, the game rules richly support that interpretation. Air power wins on Planet. And it wins in exactly the way that the Spartans claim that it does. Needlejets are way faster than anything else, they can hit anything anywhere out of the blue, and they always get the jump on their targets, in that they get to apply their higher base attack value against their opponents’ lower base defense values.