You will notice that many terran structures have the lift-off command, which grants them flight capabilities. They are bulky, slow, and vulnerable while in the air, but their mobility can be an asset in many situations. You can lift-off the command center, the orbital command, the barracks, the factory, and the starport.
Structures may only land on unobstructed terrain, and they cannot land if a unit, or group of units, are blocking their landing zone (enemy troops or vehicles cannot be crushed). Flight-capable structures have no weapons to fend off attackers, and are easy prey for enemy air units.
Some interesting uses for lift-off:
- Use as Doors – You can place a barracks or a factory on a ramp to block it. When you need to go through your blockade, just lift-off. Read more on the ramp defense page.
- Reuse Command Centers - Don't let your command centers sit idle when minerals and gas run dry in one of your bases. Fly to a fresh resource spot and set up a new mining operation there. Go places, see the map!
- Fly to Avoid Units with no Anti-Air - When your structures are besieged, you can try to lift-off and fly away.
- Easily Expand to Islands - On island maps you can expand quickly by building a command center and flying it to another island. Unlike the zerg or the protoss, the terrans don't need to research and build transport units in these scenarios.
- Run Away and Start Over! - If your base is under heavy fire (or on fire), lift-off might allow you to save some of your important structures, find a new location, and get back on your feet. This is especially useful if you have allies to watch your back while you rebuild.
- Fly up to High Ground - You can build a structure on lower ground and fly it to higher ground for added safety, or to pump out units to attack a nearby enemy base. Some maps have secondary resource nodes on higher ground that are only accessible by air.
- Switch Add-ons - If you wish to shift your production from mass to higher tech, for example, you don't have to destroy your old reactor. Simply lift-off and build a tech lab nearby. You can always swap add-ons to better respond to changing battle conditions.
- Build Add-ons Efficiently - Terrans can use an existing production structure to build an add-on for a production structure that is currently under construction. Once your new structure is completed, lift-off both production structures, switch them, and start building units. [Factory and barracks exchanging Add-ons].
- Spot for Siege Tanks with Flying Structures - Tanks in siege mode have an attack range of 13, but their sight range is only 11. Therefore, in order to maximize their effectiveness, something needs to spot for them. Doing so with units or scans is costly, so why not use a lifted building? Structures are much sturdier, so leading your army with a lifted structure will allow you to hit the enemy’s siege tanks from a distance with your own without taking damage in return. Additionally, this will allow you to siege up the high ground or to maximize defensive potential. Should your structure take a beating, you can just fly it back to your forces, repair it with SCVs, and send it back into the fray.
- Reclaim Abandoned Add-ons - If you find valuable add-ons left behind by a terran ally or enemy, you can potentially fly your structures to that location and land alongside them. This, of course, is a rare occurrence.
- Avoid Weapons of Mass Destruction - If your base is being targeted by a nuke, you can lift-off your structures and flee before impact if you are fast enough. You probably won't escape the blast entirely, but you can get away from ground zero and reduce the amount of damage taken.
- Build Offensively - Fly some barracks and land outside the enemy base, preferrably in a spot that's out of the way of through traffic. Check out this picture here.
- Deny Landing Zones - Try to position units under flying terran structures to prevent them from landing. Check out this picture of a probe blocking the landing zone of a terran barracks. If the enemy is trying to sneak production structures into your base, you can prevent them from making any troops if you manage to pull this off.