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 boats
Boeing 314 Clipper
Dornier Do-X
Short Sandringham
Short Empire C-Class and the related G-class
Saunders-Roe Princess - did not enter service.
Partial second passenger deck
Airbus A330 and Airbus A340
Optional lower deck lavatories and crew rest
Boeing 377 Stratocruiser
Lower deck could be configured for lounge areas or additional seating
Boeing 747
Partial upper deck lounge areas or seating
Optional upper deck crew rest and galleys
Boeing 767
Optional lower level crew rest area sleeps six
Boeing 777
Optional lower deck lavatories and galley
Optional upper deck crew rest
Junkers G.38
Ilyushin Il-86
Lower deck galley
Lower deck "self loading luggage storage"
Lockheed L-1011 Tristar
Lower deck galley
Lower deck lounge (Pacific Southwest Airlines) (LTU International)
McDonnell Douglas DC-10
Lower deck galleys
Tupolev Tu-114
Lower deck galleys.
Lower deck aircrew rest area.
Full second passenger deck
Breguet 761, 763 and 765
Airbus A380
Cargo aircraft with a separate passenger deck
Antonov An-225
Antonov An-124
Lockheed C-5 Galaxy
Boeing C-97 Stratofreighter
Douglas C-124 Globemaster II
Short Belfast
Lockheed R6V Constitution
Blackburn Beverley - military transport, the main deck could be used for cargo or troops
Double-deck cargo aircraft
Aviation Traders Carvair
Armstrong Whitworth AW.660 Argosy
Bristol Freighter
Convair XC-99
Douglas C-124 Globemaster II
Proposed double-deck passenger aircraft
McDonnell Douglas MD-12
Sukhoi KR-860
