Wide-body aircraft
[5] The largest wide-body aircraft are over 6 m (20 ft) wide, and can accommodate up to eleven passengers abreast in high-density configurations.
By comparison, a typical narrow-body aircraft has a diameter of 3 to 4 m (10 to 13 ft), with a single aisle,[1][6] and seats between two and six people abreast.
[7] Wide-body aircraft were originally designed for a combination of efficiency and passenger comfort and to increase the amount of cargo space.
[8] However, airlines quickly gave in to economic factors, and reduced the extra passenger space in order to insert more seats and increase revenue and profits.
[11] Following the success of the Boeing 707 and Douglas DC-8 in the late 1950s and early 1960s, airlines began seeking larger aircraft to meet the rising global demand for air travel.
Engineers were faced with many challenges as airlines demanded more passenger seats per aircraft, longer ranges and lower operating costs.
Engineers realized having two decks created difficulties in meeting emergency evacuation regulations with the technology available at that time.
As a result, airline manufacturers opted for a wider fuselage rather than a taller one (the 747, and eventually the McDonnell Douglas DC-10 and Lockheed L-1011 TriStar).
By adding a second aisle, the wider aircraft could accommodate as many as 10 seats across, but could also be easily converted to a freighter and carry two eight-by-eight freight pallets abreast.
In the "jumbo" category, the capacity of the Boeing 747 was not surpassed until October 2007, when the Airbus A380 entered commercial service with the nickname "Superjumbo".
[citation needed] The increased reliability of modern jet engines also allows aircraft to meet the ETOPS certification standard, which calculates reasonable safety margins for flights across oceans.
Complete GE90 engines can only be ferried by outsize cargo aircraft such as the Antonov An-124, presenting logistics problems if a 777 is stranded in a place due to emergency diversions without the proper spare parts.
The 560 tonnes (1,230,000 lb) maximum takeoff weight of the Airbus A380 would not have been possible without the engine technology developed for the Boeing 777 such as contra-rotating spools.
Due to current economic pressures on the airline industry, high seating densities in the economy class cabin are likely to continue.
[34] In some of the largest single-deck wide-body aircraft, such as the Boeing 777, the extra space above the cabin is used for crew rest areas and galley storage.
In some countries, such as the United States, it is a requirement to suffix the aircraft's call sign with the word heavy (or super) when communicating with air traffic control in certain areas.
