From The Heretic Knowledge Vault
A non-magical means of getting around. Ellis mentions it (with his usual delicacy and tact) as an alternative to Warp gate travel, but Meji points out some of the drawbacks. Some time ago an airship was hijacked and crashed into the Tower of Artifex (whatever that is), causing security in Tsuirakushiti to be tightened to a point that she finds unacceptable, or at least irritating.
Airships are also mentioned here, in which it is implied that they only serve the larger cities. This is an interesting reversal of the real world, where the high-tech things that go WHSHHH and get you from place to place quickly (i.e., airplanes) serve the larger cities, while small towns in the boonies are reached by more mundane mechanical contrivances like buses.
Tsuirakuan General Izayoi indicates to Sarine (who doesn't seem too surprised by the news) that the Tsuirakuans have a fleet of "long-range airships" with which they have explored the far corners of the world, including the Far North where weird stuff is happening involving Senilis. Given that shortly thereafter, Sarine was held up there and threatened with execution for treason and murder, she probably hoped he wasn't exaggerating their capabilities, but as we've learned at the beginning of Chapter 44, the general appears to have been telling it like it is.