Double-deck aircraft

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 a few have two decks for passengers, typically above or below 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 Latécoère 521/522 Martin M-130 Latécoère 631 Sud-Est SE.200 Amphitrite 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 Caproni Ca.48/58 Extra seats on top of the passenger cabin. 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.