An amphibious or amphibian aircraft is an aircraft that can land on either land or water. This has the obvious advantage of flexibility, but incurs great penalties as well: The aircraft will have to handle the extra drag, and weight, of the hull-shaped fuselage, or the floats (see seaplane), and the associated hardware, plus the weight of the landing gear (which normally is retractable, or, on smaller aircraft, semi-retractable). This leads in turn to the use of bigger, more powerful, engine(s) than comparable land aircraft, which in turn escalates weights and/or reduces range.

The amphibian aircraft have their uses, not least as transport aircraft in remote areas, where there are few airstrips, but plenty of lakes and rivers. And they are more versatile than normal seaplanes and flying boats, as they can be flown to a big airport, or airfield, to get service, or just to be able to land, or take-off, when a storm makes the waves too big to handle.

By necessity, amphibian aircraft are heavyer, more complex and more expensive to buy and run than comparable landplanes , but they are very versatile. And yet, on the whole, cheaper to buy and operate, and simpler, than the helicopters that compete for the same types of jobs, if not quite as versatile. Amphibious aircraft have longer range than a comparable helicopter, as an aircraft's wing is more effective than a helicopter's lifting rotor. The main weakness of amphibians compared to seaplanes and landplanes is less performance, because of their increased weight. This means that e.g. an amphibian (of a type Cessna 206) would carry less passengers or goods, and have a decreased range compared to a seaplane (Cessna 206) - which in turn underperform to a pure landplane of the same model (Cessna 206).

Almost no flying boats are manufactured today, but numerous land aircraft are each year converted to amphibious seaplane configuration by exchanging their fixed landing gear for amphibious floats. A handful of manufacturers around the world still produce amphibian aircraft (flying boats with retractable landing gear), but their numbers are dwindling. One example is the Lake Aircraft.

See also:

• Beriev

• List of flying boats and seaplanes
• Seaplane
• Flying boat