A double-deck aircraft has two decks for passengers; the second deck may be only a partial deck, and may be above or below the main deck. Most commercial aircraft have one passenger deck and one cargo deck for luggage and ULD containers, but only a few have two decks for passengers, typically above a third deck for cargo.
Many early flying boat airliners, such as the Boeing 314 Clipper and Short Sandringham, had two decks. Following World War II the Stratocruiser, a partially double-decked derivative of the B-29 Superfortress, became popular with airlines around the world.
The first full double-deck aircraft was the French Breguet Deux-Ponts, in service from 1953. The first partial double-deck jet airliner was the widebody Boeing 747, in service from 1970, with the top deck smaller than the main deck. Boeing originally designed the distinctive 747 bubble top with air cargo usage in mind. The small top deck permitted the cockpit and a few passengers and nose doors with unobstructed access to the full length of the hold. Most 747s are passenger jets, and a small percentage are cargo jets with nose doors.
The first full double-deck jet airliner is the Airbus A380, which has two passenger decks extending the full length of the fuselage, as well as a full-length lower third deck for cargo. It entered regular service in late-October 2007.
Double-deck flying boatsBoeing 314 ClipperDornier Do-XShort SandringhamShort Empire C-Class and the related G-classSaunders-Roe Princess - did not enter service.Partial second passenger deckAirbus A330 and Airbus A340Optional lower deck lavatories and crew restBoeing 377 StratocruiserLower deck could be configured for lounge areas or additional seatingBoeing 747Partial upper deck lounge areas or seatingOptional upper deck crew rest and galleysBoeing 767Optional lower level crew rest area sleeps sixBoeing 777Optional lower deck lavatories and galleyOptional upper deck crew restJunkers G.38Ilyushin Il-86Lower deck galleyLower deck "self loading luggage storage"Lockheed L-1011 TristarLower deck galleyLower deck lounge (Pacific Southwest Airlines) (LTU International)McDonnell Douglas DC-10Lower deck galleysTupolev Tu-114Lower deck galleys.Lower deck aircrew rest area.Full second passenger deckBreguet 761, 763 and 765Airbus A380Cargo aircraft with a separate passenger deckAntonov An-225Antonov An-124Lockheed C-5 GalaxyBoeing C-97 StratofreighterDouglas C-124 Globemaster IIShort BelfastLockheed R6V ConstitutionBlackburn Beverley - military transport, the main deck could be used for cargo or troopsDouble-deck cargo aircraftAviation Traders CarvairArmstrong Whitworth AW.660 ArgosyBristol FreighterConvair XC-99Douglas C-124 Globemaster IIProposed double-deck passenger aircraftMcDonnell Douglas MD-12Sukhoi KR-860
