Airship

An airship (飛行船) is a lighter-than-air craft that uses buoyant gasses to float in the air. Due to their passive flotation abilities, an airship can possess a greater range and fuel efficiency than airplanes, such as a flying boat.

Airships vary in their design, but most appear to possess a rigid frame due to the ribbing that can be seen through the envelope, and the envelope themselves do not deflate once the airship has landed.

Prior to the year 850, airships were only in possession of nations outside of Paradis Island, due to its century-long isolation from the rest of the world. However, by 854 the Survey Corps have obtained their own airship, which they use to extract troops from the raid on Liberio.

History
In the year 817, Marley was operating at least one airship. This airship was followed by Grisha and Faye Yeager out of the internment zone to its hangar, where they would get punished by Marleyan officers of the PSA for trespassing. After his physical punishment, Grisha was allowed to continue watching the craft with the officer.

Sometime later on Paradis Island, Armin Arlert's parents attempted to escape the Walls using a hot air balloon (which due to being unpowered is technically not an airship). Unfortunately, the Military Police caught wind of their attempt, and they were promptly killed, leaving Armin an orphan.

Marley arc
In the closing stages of the Marley Mid-East War, the Marleyans employ an airship to survey the battlefield and prepare an attack on the enemy position, floating high above Fort Slava. Along with the captive Eldians, who are to be transformed into Titan fodder, Reiner Braun and Zeke Yeager are preparing to jump and assault the fort. After the armored train has been disabled, the Eldians are parachuted down from the airship's hold. While in mid-air they are transformed by Zeke into Titans, and employed as both a kinetic bombardment and living weapon as some survive the landing and start wreaking havoc on the fort's defenders. Reiner follows them down to take out the remaining anti-Titan artillery, and is soon followed by Zeke. The airborne operation succeeds in taking the fort and annihilating the Mid-East Allied Navy, but Reiner is left grievously wounded.

Trivia

 * Due to their designs incorporating a rigid, supportive frame, most of the airships seen would be classified as zeppelins.