It may or may not be obvious to the traveller yet, but zeppelins, or air ships, are the premier form of air transport in IB. Combining and perfecting several mid-xix century designs, retired German military officer Count Ferdinand von Zeppelin invented the first truly successful airship. Improved by many designers over the next 30 years, notably by Brasilian Santos Duval and American Tom Baldwin, the zeppelin has proven itself time and again to be the most sensible answer to the question of mass transport. Coming into their own during the Second Great War, especially the Atlantic Air War, their use as aerial battleships is long past, but for passenger transport, heavy lifting and tactical military and civilian use - they can not be beaten by any other aircraft.
In the late 1930s it appeared as if aeroplanes might offer an alternative to airships for long-distance passenger transport, but the Dornburg Disaster laid this notion to rest, at least until the present day.
Newer airships are often made of carbon polymer rings and struts; and titanium plays a part as well, as it is stronger and lighter than steel and aluminium. They tend to run on solar generated / assisted electric power; and the motors are movable so that even large ships can be manouvered into the mooring tower without hundreds of men dragging on ropes. Motors can be tilted up and down to create extra lift or to secure the ship to the ground lest it blow away in a side wind. They come in a variety of shapes including dual cigars and flat bottomed affairs that hold hovercraftlike fans. The hulls are made of strong, light materials like kevlar and mylar. Many ships are capable of speeds in excess of 100mph.
Modern ships come in various sizes. Of course, there are huge behemoths, maybe half a mile long, that lift, carry and place vast pieces of equipment weighing more than a thousand tonnes (powerplant turbines and tunnelers for example) or smaller air and land craft (especially handy for military applications and other government agencies like the Imperial Aid, which is a rescue mission organisation that operates a couple huge airships that contain various sorts of rescue vehicles, food and water stores, a hospital and emergency supplies); large ships carry mail, passengers and goods. Smaller ships act as ferries between islands and the mainland in many places; and as overland pleasure transport in many places. Local tourist boards and pleasure cruise firms use smaller ships to view the land from above.
There are also semirigid ships - airships that have a rigid keel, but not a rigid body (sort of like a blimp with a rigid keel). Less ship weight means greater lift for a smaller size and helium envelope. An economical alternative, though not as safe ultimately as a rigid hull.
Modern passenger airships use helium filled cells; while military and many commercial craft use varying formulations of helium and hydrogen. Modern hulls are fire resistant - practically fireproof when compared to the doped canvas in use in the early days! - which reduces the danger of high hydrogen content in the gas envelopes.
In the World English of Ill Bethisad, the word aeroport is reserved for military airstrips where aeroplanes can land and take off. The aerodrome is where one goes to catch an airship. The world's first airline was called DELAG, Deutsche Luftschifffahrts-Aktiengesellschaft; in the modern period, BOAC and Lufthansa are chief players in the air transport game. Smaller airlines, like Bovair, Continental Air and Panaero, are expanding from regional to worldwide service.