Boeing 737

infobox Aircraft
subtemplate=Infobox Boeing Aircraft
name = Boeing 737

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caption = Air Berlin Boeing 737-700 in a hybrid Boeing and Air Berlin livery.
type = Airliner
national origin = United States
manufacturer = Boeing Commercial Airplanes
designer =
first flight = 9 April 1967
introduction = 10 February 1968 with Lufthansa
retired =
status = Active
primary user = Southwest Airlines
more users = Continental Airlines
Ryanair
Alaska Airlines
produced = 1968 - Present
number built =5,844 as of August 2008
unit cost =737-100 US$32 million [Bowers 1989, p. 495.]
737 NG US$50-85 million (2008) [http://www.boeing.com/commercial/prices/ Boeing Commercial Airplanes prices] , Boeing. Retrieved: 29 May 2008.] Karp, Aaron. [http://www.atwonline.com/news/story.html?storyID=9337 "Boeing boosts aircraft prices 5.5% on rising cost of labor, materials"] , "Air Transport World", 26 June 2007. Retrieved: 13 April 2008.]
variants with their own articles = Boeing T-43 Boeing 737 Classic Boeing 737 Next Generation

The Boeing 737 is a short to medium range, single aisle, narrow body jet airliner. Originally developed as a shorter, lower cost twin engine airliner derived from Boeing's 707 and 727, the 737 has nine variants, from the early -100 to the most recent and largest, the -900. Series -600 through -900 are still being produced.

First envisioned in 1964, the 737 entered service in 1968. Forty years later it has become the most ordered and produced commercial passenger jet in the world. It is Boeing's last surviving narrow-body airliner currently in production, sometimes serving markets previously filled by 707, 727, 757, DC-9 and MD-80/90 airliners. The 737 has been continuously manufactured by Boeing since 1967 with over 8,000 ordered and over 5,800 delivered as of 2008. [http://active.boeing.com/commercial/orders/displaystandardreport.cfm?cboCurrentModel=737&optReportType=AllModels&cboAllModel=737&ViewReportF=View+Report 737 Model Orders and Deliveries data] , Boeing, August 2008.] There are over 1,250 737s airborne at any given time, with one departing or landing somewhere every five seconds on average.

Development

Origins

Boeing had been studying short-haul jet aircraft designs and wanted to produce another aircraft to supplement the 727 on short and thin routes. "Transport News: Boeing Plans Jet." "The New York Times", 17 July 1964. Retrieved: 26 February 2008.] Preliminary design work began on 11 May 1964, [Endres 2001, p. 122.] and Boeing's intense market research yielded plans for a 50 to 60 passenger plane for routes 50 to 1,000 mi (80 to 1,609 km) long. [Sharpe and Shaw 2001, p. 12.] Lufthansa became the launch customer on 19 February 1965,Sharpe and Shaw 2001, p. 13.] with an order of 21 aircraft, worth $67 million"German Airline Buys 21 Boeing Short-Range Jets." "The Washington Post", 20 February 1965. Retrieved: 26 February 2008.] (1965, $190.28 million in 2008), after the airline reportedly received assurances from Boeing that the 737 project would not be cancelled. Consultation with Lufthansa over the previous winter resulted in an increase in capacity to 100 seats.

On 5 April 1965, Boeing announced an order by United Airlines for 40 737s. United wanted a slightly larger airplane than the original design; therefore, Boeing stretched the fuselage an extra 91 cm (36 in) ahead of, and 102 cm (40 in) behind the wing.Sharpe and Shaw 2001, p. 17.] The longer version was designated 737-200, with the original short body aircraft becoming the 737-100. [Redding 1997, p. 182.]

Detailed design work continued on both variants at the same time. Boeing was far behind its competitors when the 737 was launched, as rival aircraft BAC 1-11, Douglas DC-9, and Fokker F28 were already into flight certification. To expedite development, Boeing reused 60% of the structure and systems of the existing 727, most notably the fuselage cross section. This fuselage permitted six-abreast seating compared to the rival 1-11 and DC-9's five-abreast layout, but the widened cross-section and short fuselage complicated the aerodynamics of the aft-mounted engines common with airliners of the time. As a result, engineers decided to mount the nacelles directly to the underside of the wings. The placement of this weight below the center of the aircraft also reduced stresses on the airframe, which allowed for a lighter wing, [Sharpe and Shaw 2001, p. 18.] and kept the aircraft low to the ground for easy ramp operations.Sutter 2006, pp. 76–78.] The engine chosen was the Pratt & Whitney JT8D-1 low-bypass ratio turbofan engine. [Shaw 1999, p. 6.] With the wing-mounted engines, Boeing decided to mount the elevator on the fuselage rather than the T-tail style of the Boeing 727.

The initial assembly of the 737 was adjacent to Boeing Field (now officially called King County International Airport) because the factory in Renton was at capacity building the 707 and 727. After 271 aircraft, production was moved to Renton in late 1970.Wallace, J. [http://seattlepi.nwsource.com/business/259251_boeing13.html "Boeing delivers its 5,000th 737,"] "Seattle Post-Intelligencer", 13 February 2006. Retrieved: 18 December 2007.] [Gates, Dominic. [http://www.forecastinternational.com/notable/seattletimes.pdf "Successor to Boeing 737 likely to be built in state."] "Seattle Times", 30 December 2005. Retrieved: 10 February 2008.] A significant portion of the fuselage assembly is in Wichita, Kansas previously by Boeing but now by Spirit AeroSystems, which purchased some of Boeing's assets in Wichita. [ [http://www.hispanicbusiness.com/news/newsbyid.asp?id=25041&cat=PR+Newswire&more=/pr_newswire/ "Spirit AeroSystems, Inc., Completes First Developmental Section for 787 Dreamliner."] Pr newswire. Retrieved: 23 January 2008.] The fuselage is joined with the wings and landing gear, then moves down the assembly line for the engines, avionics and interiors. After rolling out the aircraft, Boeing tests the systems and engines before its maiden flight to Boeing Field, where it is painted and fine tuned before delivery to the customer. [Shaw 1999, p. 16.]

The first of six -100 prototypes rolled out in December 1966, and made its maiden flight on 9 April 1967 piloted by Brien Wygle and Lew Wallick. [http://www.boeing.com/news/releases/1997/news.release.970502.html "Original 737 Comes Home to Celebrate 30th Anniversary"] , The Boeing Company press release, 2 May 1997. Retrieved: 12 April 2008.] During nearly 1,300 hours of flight testing it was discovered that the aircraft produced excess drag at high speeds, which could buckle the rear wing spar at loads only 34% above normal. The aircraft were modified with reinforcements, but at a cost to the weight and short-field performance. [Sharpe 2001, pp. 19–20.] On 15 December 1967 the Federal Aviation Administration certified the -100 for commercial flight,Sharpe and Shaw 2001, p. 20.] issuing Type Certificate A16WE. [http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/e038ae3ed2dbc2ae86257479004d1e57/$FILE/A16WE.pdf "Type Certificate Data Sheet A16WE"] ] . The 737 was the first aircraft to have, as part of its initial certification, approval for Category II approaches.Redding 1997, p. 183.] Lufthansa received their first aircraft on 28 December 1967 and on 10 February 1968 became the first non-American airline to launch a new Boeing aircraft. Lufthansa was the only significant customer to purchase the 737-100 and only 30 aircraft were ever produced. [Sharpe and Shaw 2001, p. 120.]

The 737-200 had its maiden flight on 8 August 1967. It was certified by the FAA on 21 December 1967, [Endres 2001, p. 124.] and the inaugural flight for United was on 28 April 1968 from Chicago to Grand Rapids, Michigan. The lengthened -200 was widely preferred over the -100 by airlines.

In 1968 an improvement to the thrust reversal system was introduced. The improvement became standard on all aircraft after March 1969, and a retrofit was provided for active aircraft. Boeing fixed the drag issue by introducing new longer nacelle/wing fairings, and improved the airflow over the flaps and slats. The production line also introduced an improvement to the flap system, allowing increased use during takeoff and landing. All these changes gave the aircraft a boost to payload and range, and improved the short-field performance. In May 1971, after aircraft #135, all improvements, including more powerful engines and a greater fuel capacity, were incorporated into the 737-200, giving it a 15% increase in payload and range over the original -200s. This became known as the 737-200 Advanced, which became the production standard in June 1971.

In 1970, Boeing received only 37 orders. Facing financial difficulties, Boeing considered closing the 737 production-line and selling the design to Japanese aviation companies. After the cancellation of the Boeing Supersonic Transport, and the scaling back of 747 production, enough funds were freed up to continue the project. [Sharpe and Shaw 2001, p. 21.] In a bid to increase sales by offering a variety of options, Boeing offered a "737C" (Convertible) model in both -100 and -200 lengths. This model featured a 340 x 221 cm (134 x 87 in) freight door just behind the cockpit, and a strengthened floor with rollers which allowed for palletized cargo. A "737QC" (Quick Change) version with palletized seating allowed for faster configuration changes between cargo and passenger flights. [Sharpe and Shaw 2001, p. 19.] With the improved short-field capabilities of the 737, Boeing offered the option on the -200 of the gravel kit, which enables this aircraft to operate on remote, unpaved runways. [ [http://www.b737.org.uk/unpavedstripkit.htm Unpaved Strip Kit] . www.b737.org.uk Retrieved: 10 February 2008.] [ [http://www.airliners.net/open.file?id=0686303&size=L&width=1024&height=695&sok=&photo_nr=&prev_id=&next_id= Boeing 737-2T2C/Adv aircraft picture] . airliners.net. Retrieved: 10 February 2008.] Until retiring its -200 fleet in 2007, Alaska Airlines used this option for some of its rural operations in Alaska. With the retirement of these aircraft, some airports, such as Red Dog Airport, have upgraded runway facilities from gravel to paved. [ [http://www.dced.state.ak.us/dca/aeis/NWAB/Transportation/NWAB_Transportation_Narrative.htm Northwest Arctic Borough: Transportation] . Retrieved: 21 January 2008.] [ [http://www.world-airport-codes.com/Alaska/red-dog-6237.html|title=www.world-airport-codes.com/Alaska/red-dog-6237.html Red Dog (RDB) Alaska] Retrieved: 12 April 2008.]

In 1988 the initial production run of the -200 model ended after producing 1,114 aircraft. The last one was delivered to Xiamen Airlines on 8 August 1988.Sharpe and Shaw 2001, p. 23.]

Improved variants

Development began in 1979 for the 737's first major facelift. Boeing wanted to increase capacity and range, incorporating improvements to upgrade the plane to modern specifications, while also retaining commonality with previous 737 variants. In 1980 preliminary aircraft specifications of the variant, dubbed 737-300, were released at the Farnborough Airshow. [Endres 2001, p. 126.]

The CFM56-3B-1 turbofan engine was chosen to power the aircraft, which yielded significant gains in fuel economy and a reduction in noise, but also posed an engineering challenge given the low ground clearance of the 737 and the larger diameter of the engine over the original Pratt and Whitney engines. Boeing and engine supplier CFMI solved the problem by placing the engine ahead of the wing, and by moving engine accessories to the sides of the engine pod, giving the engine a distinctive non-circular air intake.Endres 2001, p. 128.]

The passenger capacity of the aircraft was increased to 149 by extending the fuselage around the wing by 2.87 m (9 ft 5 in). The wing incorporated a number of changes for improved aerodynamics. The wing tip was extended 9 in (23 cm), and the wing span by 1 ft 9 in (53 cm). The leading-edge slats and trailing-edge flaps were adjusted. The flight deck was improved with the optional EFIS (Electronic Flight Instrumentation System), and the passenger cabin incorporated improvements similar to those developed on the Boeing 757.Shaw 1999, p. 10] The prototype -300, the 1,001st 737 built, first flew on 24 February 1984 with pilot Jim McRoberts. It and two production aircraft flew a nine month long certification program. [Shaw 1999, pp. 12–13.]

In June 1986 Boeing announced the development of the 737-400, [Redding 1997, p. 185] which stretched the fuselage a further 10 ft (3.45 m), increasing the passenger load to 170. [Shaw 1999, p. 7.] The -400s first flight was on 19 February 1988 and, after a seven-month/500-hour flight testing run, entered service with Piedmont Airlines that October. [Shaw 1999, p. 14.]

The -500 series was offered, due to customer demand, as a modern and direct replacement of the 737-200. It incorporated the improvements of the 737 Classic series; allowing longer routes with fewer passengers to be more economical than with the 737-300. The fuselage length of the -500 is 1 ft 7 in (47 cm) longer than the 737-200, accommodating up to 132 passengers. Both glass and older style mechanical cockpits arrangements were available.Shaw 1999, p. 14.] Using the CFM56-3 engine also gave a 25% increase in fuel efficiency over the older -200s P&W engines.

The 737-500 was launched in 1987 by Southwest Airlines, with an order for 20 aircraft, [Shaw 1999, p. 40.] and flew for the first time on 30 June 1989. A single prototype flew 375 hours for the certification process, and on 28 February 1990 Southwest Airlines received the first delivery. [Endres 2001, p. 129.] The 737-500 has become a favorite of some Russian airlines, with Aeroflot-Nord, S7 Airlines, and Rossiya Airlines all buying second-hand models of the aircraft to replace aging Soviet-built aircraft.

After the introduction of the -600/700/800 series, the -300/400/500 series was called the 737 Classic series.

The price of jet fuel has skyrocketed in the past five years; airlines devote 40% of the retail price of an air ticket to pay for fuel in 2008, versus 15% in 2000. ["To Save Fuel, Airlines Find No Speck Too Small." "New York Times", 11 June 2008] Consequently, carriers have begun to retire the Classic 737 series to reduce their fleet sizes; replacements consist of more efficient Next Generation 737s or Airbus A320/A319/A318 series aircraft. On June 4, 2008, United Airlines announced it would retire all 94 of its Classic 737 aircraft (64 737-300 and 30 737-500 aircraft), replacing them with Airbus A320 jets taken from its Ted subsidiary, which is being shut down. ["UAL Cuts Could Be Omen." "Wall Street Journal", 5 June 2008, p. B3.] [ [http://www.united.com/press/detail/0,6862,59665,00.html United Airlines Press Release, 22 July 2008] ] ["Airline Shares Gain Despite Losses." "Wall Street Journal", 23 July 2008, p. B3.]

Next Generation

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width1 = 150
caption1 = Early 737 cockpit

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width2 = 150
caption2 = Modern 737-800 cockpitPrompted by the modern Airbus A320, in 1991 Boeing initiated development of an updated series of aircraft. [Endres 2001, p. 132.] After working with potential customers, the 737 Next Generation (NG) program was announced on 17 November 1993.Shaw 1999, p. 8.] The 737NG encompasses the -600, -700, -800 and -900, and is to date the most significant upgrade of the airframe. The performance of the 737NG is essentially that of a new airplane, but important commonality is retained from previous 737 models. The wing was modified, increasing its area by 25% and span by 16 ft (4.88 m), which increased the total fuel capacity by 30%. New, quieter, more fuel-efficient CFM56-7B engines were used. [Endres 2001, p. 133.] All three improvements combined increase the 737's range by 900 nmi, now permitting transcontinental service. A flight test program was operated by 10 aircraft; 3 -600s, 4 -700s, and 3 -800s.

The first NG to roll out was a -700, on 8 December 1996. This aircraft, the 2,843rd 737 built, first flew on 9 February 1997 with pilots Mike Hewett and Ken Higgins. The prototype -800 rolled out on 30 June 1997 and first flew on 31 July 1997, again with Hewett and Jim McRoberts. The smallest of the new variants, the -600s, is the same size as the -500. It was the last in this series to launch, in December 1997. First flying 22 January 1998, it was given certification on 18 August 1998. [Shaw 1999, pp. 14–15.]

In 2004, Boeing offered a Short Field Performance package in response to the needs of Gol Transportes Aéreos, which frequently operates from restricted airports. The enhancements improve takeoff and landing performance. The optional package is available for the 737NG models and standard equipment for the 737-900ER.

On 21 August 2006, Sky News alleged that Boeing's Next Generation 737s built from 1994 to 2002 contained defective parts. The report stated that various parts of the airframe produced by Ducommun were found to be defective by Boeing employees but that Boeing refused to take action. Boeing said that the allegations were "without merit". [ [http://www.upi.com/NewsTrack/view.php?StoryID=20060821-113928-7593r "Report alleges faulty parts in jets."] "United Press International", 21 August 2006. Retrieved: 22 August 2006.]

Boeing has already hinted that a "clean sheet" replacement for the 737 (internally dubbed "Boeing Y1") could follow the Boeing 787. [ [http://www.flightglobal.com/articles/2006/03/03/205223/boeing-firms-up-737-replacement-studies-by-appointing.html Boeing firms up 737 replacement studies by appointing team] "Flight International", 3 March 2006. Retrieved 13 April 2008]

Design

Engines on the 737 Classic series (300, 400, 500) and Next-Generation series (600, 700, 800, 900) appear not to have circular inlets, as most aircraft do. The accessory gearbox was moved from the 6 o'clock position under the engine to the 4 o'clock position (forward looking aft). This was done because the 737 sits lower to the ground than most airplanes and the original 737s were designed for small P&W engines, but additional ground clearance was needed for the larger CFM56 engines. This side-mounted gearbox gives the engine a somewhat triangular rounded shape. Boeing and CFM International, the engine manufacturer, claim that the shape actually yields slightly improved performance.Fact|date=May 2007 The necessary nacelle redesign is known in the industry as "hamsterisation", because of the resemblance of the shape to the rodent.Fact|date=April 2008 Because the engine is so close to the ground, 737-300s and later are more prone to engine foreign-object damage (FOD).

737s are not equipped with fuel dump systems. Depending upon the nature of the emergency, 737s either circle to burn off fuel or land overweight. To save weight and reduce cost and complexity the 737 lacks full doors to cover the main landing gear. The main landing gear (under the wings at mid-cabin) rotate into wells in the aircraft's belly, the legs being covered by partial doors, and "brush-like" seals aerodynamically smooth (or "fair") the wheels in the wells. The sides of the tires are exposed to the air in flight. "Hub caps" complete the aerodynamic profile of the wheels. It is forbidden to operate without the caps, because they are linked to the ground speed sensor that interfaces with the anti-skid brake system. When observing a 737 takeoff, or at low altitude, the dark circles of the tires can be plainly seen.

Most 737 cockpits are equipped with "eyebrow windows" positioned above the main glareshield. Eyebrow windows were a feature of the original 707. They allowed for greater visibility in turns, and offered better sky views if navigating by stars. With modern avionics, they became redundant, and many pilots actually placed newspapers or other objects in them to block out sun glare. They were eliminated from the 737 cockpit design in 2004, although they are still installed in military variants and at customer request. These windows are sometimes removed and plugged, usually during maintenance overhauls and can be distinguished by a metal plug which differs from smooth metal which appears in later aircraft that were not originally fitted with the windows.

Blended winglets are available as retrofits and in production on newer 737 aircraft. These winglets stand approximately 8 feet tall and are installed at the wing tips. They help with reduced fuel burn (by reducing vortex drag), reduced engine wear, and less noise on takeoff.

A short-field design package is available for the 737-600, -700 and -800, allowing operators to fly increased payload to and from airports with runways under 5,000 feet. The package consists of sealed leading-edge slats (improved lift), a two-position tail skid (enabling reduced approach speeds) and increased flight spoiler deflection on the ground. These improvements are standard on the 737-900ER. [ [http://www.boeing.com/news/releases/2006/q3/060729a_nr.html "Boeing Delivers First 737 with Enhanced Short Runway Package to GOL."] boeing.com, 31 July 2006. Retrieved: 10 February 2008.]

Variants

The 737 models can be divided into three generations, including nine major variants. The "Original" models consist of the 737-100, 737-200/-200 Advanced. The "Classic" models consist of the 737-300, 737-400, and 737-500. The "Next Generation" variants consist of the 737-600, 737-700/-700ER, 737-800, and 737-900/-900ER. Of these nine variants, many feature additional versions.

737 Original

737-100

The initial model was the 737-100. It was launched by Lufthansa in 1965 and entered service in 1968. The aircraft is the smallest variant of the 737. Only thirty 737-100s were ordered and delivered, and no 737-100s remain in service today. The original Boeing prototype, last operated by NASA, retired more than 30 years after its maiden flight, and is on exhibit in the Museum of Flight in Seattle.

737-200

The 737-200 is a 737-100 with an extended fuselage. It was launched by United Airlines in 1965 and entered service in 1968. The 737-200 Advanced is an improved version of the -200, introduced by All Nippon Airways on 20 May 1971. [Bowers 1989, p. 496.] The aircraft has improved aerodynamics, automatic wheel brakes, more powerful engines, more fuel capacity and longer range than the -200. [Sharpe and Shaw, 2001, p. 41.] Boeing also provided the 737-200C (Convertible), that allowed conversion between passenger and cargo use and the 737-200QC (Quick Change), facilitating rapid conversion between roles. The last delivery of a -200 series aircraft was in August 1988. [http://www.boeing.com/commercial/737family/background.html "About the 737 Family."] The Boeing Company. Retrieved: 20 December 2007.] A large number of 737-200s are still in service, mostly with "second tier" airlines and those of developing nations. They are being phased out because of poor fuel efficiency, high noise emissions (despite the vast majority having had their JT8Ds fitted with hush kits) and escalating maintenance costs. This plane was able to operate ongravel runways after a gravelkit was installed; this was done in Alaska.

Nineteen 737-200s were converted to be used to train aircraft navigators for the U.S. Air Force, designated T-43. Some were modified into CT-43s which are used to transport passengers and one was modified as the NT-43A Radar Test Bed. The first one was delivered on 31 July 1973 and the last on 19 July 1974. The Indonesian Air Force ordered three modified 737-200s, designated Boeing 737-2x9 Surveiller. They were used as Maritime reconnaissance (MPA)/transport aircraft, fitted with SLAMMAR (Side-looking Multi-mission Airborne Radar). The aircraft were delivered between May 1982 and October 1983. [Bowers 1889, pp. 498–499.]

After 40 years, the final 737-200 aircraft in the United States flying scheduled passenger service were phased out on 31 March 2008 with the last flights of Aloha Airlines (Aloha continues to fly its interisland cargo flights). The aircraft had been eliminated from regular service in the continental United States in 2006, when Delta Air Lines withdrew the type.Fact|date=April 2008

737 Classic

The new 737 Classic series featured CFM56 turbofan engines, which yielded significant gains in fuel economy and a reduction in noise, but also posed an engineering challenge given the low ground clearance of the 737. Boeing and engine supplier CFMI solved the problem by placing the engine ahead of (rather than below) the wing, and by moving engine accessories to the sides (rather than the bottom) of the engine pod, giving the 737 a distinctive non-circular air intake.Endres 2001, p. 128.] The wing incorporated a number of changes for improved aerodynamics.

737-300

The 737-300 was launched in 1981 by both USAir and Southwest Airlines becoming the first model of the 737 Classic series. The aircraft has a typical capacity of 128 passengers in a two class configuation (137 seats in a one class coach seating configuration). [ [http://query.nytimes.com/gst/fullpage.html?res=9F0CE4DD163BF93BA25752C1A965958260 "Boeing Gets Orders for 63 737-X."] , "New York Times". Retrieved: 1 February 2008.] The 300 series remained in production until 1999 when the last aircraft was delivered to Air New Zealand on 17 December 1999.

Various modifications have been made to aircraft previously in service. The 737-300 can be retrofitted with Aviation Partners Boeing winglets. The 737-300 retrofitted with winglets is designated the -300SP (special performance). Used passenger -300 aircraft have also been converted to freighter versions. The Lockheed Martin CATBird is a modified 737-300 with the nose of a Lockheed F-35 Lightning II, a pair of canards, and (inside) an F-35 cockpit; to be used to flight test the F-35's complete avionics suite.

737-400

The 737-400 was stretched beyond the 737-300, primarily to accommodate charter airlines. Piedmont Airlines and Pace Airlines were the launch customers. The -400 was launched in 1985 and entered service in 1988 with Piedmont. The last delivery of the -400 occurred on 25 February 2000 to CSA Czech Airlines.

The 737-400F was not a model delivered by Boeing but a converted 737-400 to an all cargo aircraft. Alaska Airlines was the first to convert one of its 400s from regular service to an aircraft with the ability to handle 10 pallets. [ [http://www.alaskaair.com/as/www2/company/fleet/fleet.asp "Alaska Airlines and Horizon Air Aircraft Information."] ] The airline has also converted five more into fixed combi aircraft for half passenger and freight. These 737-400 Combi aircraft are now in service.

737-500

The 737-500 was launched in 1987 by Southwest Airlines and entered service in 1990. The fuselage length of the 737-500 is similar to the 737-200 while incorporating the improvements of the 737 Classic series. It offered a modern and direct replacement of the 737-200, while also allowing longer routes with fewer passengers to be more economical than with the 737-300. The last -500 was delivered to All Nippon Airlines on 26 July 1999.

The 737-500 has become a favorite of some Russian airlines, with Aeroflot-Nord, S7 Airlines, and Rossiya Airlines all buying second-hand models of the aircraft to replace aging Soviet-built aircraft.

737 Next Generation

In November 1993, Boeing's board of directors authorized the Next Generation program to replace the 737 Classic series. The -600, -700, and -800 series were planned. [ [http://www.boeing.com/commercial/737family/pf/pf_ng_milestones.html "Next Generation 737 Program Milestones."] The Boeing Company. Retrieved: 22 January 2008.] By the early 1990s, it became clear that the new Airbus A320 was a serious threat to Boeing's market share, as Airbus won previously loyal 737 customers such as Lufthansa. After engineering trade studies and discussions with major 737 customers, Boeing proceeded to launch the 737 Next Generation series.

New features included:
* Improved CFM56-7 turbofan engine, 7% more fuel efficient than the CFM56-3
* Intercontinental range of over 3,000 nautical miles (5,556 km). [ [http://www.boeing.com/commercial/737family/pf/pf_ng_back.html "737 Family, Comprehensive Background."] ]
* Increased fuel capacity and higher Maximum Takeoff Weight (MTOW)
* Six-screen LCD glass cockpit with modern avionics, retaining crew commonality with previous generation 737
* Passenger cabin improvements similar to those on the Boeing 777, featuring more curved surfaces and larger overhead bins than previous generation 737s. The Next Generation 737 interior was also adopted on the Boeing 757-300.
* New airfoil section, increased wing span, area, and chord
* Winglets on most models
* Redesigned vertical stabilizer
* (As of July 2008) Carbon brakes manufactured by Messier-Bugatti. These new brakes, now certified by the Federal Aviation Administration, weigh 550-700 lbs (250-320 kg) less than the steel brakes normally fitted to the Next-Gen 737s (weight savings depend on whether standard or high-capacity brakes are fitted). [ [http://www.boeing.com/news/releases/2008/q3/080804c_nr.html Boeing Press Release, 4 August 2008.] Retrieved: 5 August 2008.] A weight reduction of 700 pounds on a Boeing 737-800 results in 0.5% reduction in fuel burn. [ [http://orlando.bizjournals.com/orlando/business_travel/story/biz/714.html Mindful of rivals, Boeing keeps tinkering with its 737, Orlando Business Journal, August 11, 2008] Retrieved August 24, 2008]

Boeing delivered the 5,000th 737 to Southwest Airlines on 13 February 2006.

737-600

The 737-600 is the direct replacement of the 737-500, was also intended for sale to succeed DC-9s. The 737-600 was launched by Scandinavian Airlines System in 1995 with the first aircraft delivered on 18 September 1998. The -600 is the only Boeing 737 still in production that does not include winglets as an option. [ [http://www.boeing.com/commercial/737family/winglets/index.html "Next-Generation 737 Production Winglets"] , Boeing. Retrieved: 10 February 2008.]

The 737-600 competes with the A318, Embraer 195, and Bombardier's upcoming Cseries jet. [ [http://www.nytimes.com/reuters/business/business-airshow-bombardier.html "Bombardier Launches CSeries Jet"] , "New York Times", 13 July 2008] .] [ [http://www.kansascity.com/382/story/703285.html "Bombardier rejects KC, will build plant in Canada"] , "Kansas City Star", 13 July 2008.] A total of 69 -600s have been delivered with no further unfilled orders as of 2008.

737-700

The 737-700 was the first of Next Generation series when launch customer Southwest Airlines ordered the variant in November 1993. The variant was based on the 737-300 and entered service in 1998. [http://www.airliners.net/info/stats.main?id=95 Boeing 737-600/700] , airliners.net. Retrieved: 4 February 2008.] It replaced the 737-300 in Boeing's lineup, and its direct competitor is the A319. It typically seats 132 passengers in a two class cabin or 149 in all economy configuration.

The 737-700C is a convertible version where the seats can be removed from the plane to carry cargo. There is a large door on the left side of the aircraft. The US Navy was the launch customer for the 737-700C. [ [http://www.defenselink.mil/releases/release.aspx?releaseid=2647 "U.S. Naval Reserve Gets First Look at Newest Class of Aircraft."] , DefenseLink (U.S. Department of Defense). Retrieved: 21 January 2008.]

Boeing launched the 737-700ER on 31 January 2006. [ [http://www.boeing.com/news/releases/2006/q1/060131a_nr.html "Boeing Launches Longest-Range 737 with ANA."] ] All Nippon Airways is the launch customer, with the first one delivered on 16 February 2007. The 737-700ER is a mainline passenger version of the BBJ1 and 737-700IGW. It combines the 737-700 fuselage with the wings and landing gear of a 737-800. It will offer a range of 5,510 nautical miles (10,205 kilometers), with seating for 126 passengers in a 2-class configuration. A competitor to this model would be the A319LR. The 700ER has the second longest range for a 737 after the BBJ2.

At the end of July 2008, Delta Air Lines took delivery of the first of 10 -700 model aircraft fitted with Messier-Bugatti's carbon brakes. [ [http://www.boeing.com/news/releases/2008/q3/080804c_nr.html Boeing Press Release, 4 August 2008.] Retrieved: 4 August 2008.]

All Nippon Airways, Japan’s second-biggest carrier, is to pioneer the model in Asia with a daily service between Tokyo and Mumbai. ANA’s service, believed to be the first all-business class route connecting to a developing country, was to start in September 2007 and use a Boeing 737-700ER outfitted with 36 seats and an extra fuel tank. [ [http://www.ana.co.jp/eng/aboutana/press/2006/070125.html Press release] ]

The C-40A Clipper is a 737-700C used by the U.S. Navy as a replacement for the C-9B Skytrain II. The C-40B and C-40C are used by the US Air Force for transport of Generals and other senior leaders. The Boeing 737 AEW&C is a 737-700IGW roughly similar to the 737-700ER. This is an Airborne Early Warning and Control (AEW&C) version of the 737NG. Australia is the first customer (as Project Wedgetail), followed by Turkey and South Korea.

737-800

The 737-800 is a stretched version of the 737-700, and replaces the 737-400. It also filled the gap left by Boeing's discontinuation of the McDonnell Douglas MD-80 and MD-90 after Boeing's merger with McDonnell Douglas. The -800 was launched by Hapag-Lloyd Flug (now TUIfly) in 1994 and entered service in 1998. The 737-800 seats 162 passengers in a two class layout, or 189 in one class, and competes with the A320. For many airlines in the U.S., the 737-800 replaced aging Boeing 727-200 trijets and McDonnell Douglas MD-80 and MD-90 series aircraft.

The P-8 Poseidon is a 737-800ERX ("Extended Range") that, on 14 June 2004, Boeing's Integrated Defense Systems division beat Lockheed Martin in the contest to replace the P-3 Orion maritime patrol aircraft. Eventual orders may exceed 100 from the US Navy. The P-8 is unique in that it has 767-400ER-style raked wingtips, instead of the blended winglets available on other 737NG variants.

737-900

Boeing later introduced the 737-900, the longest variant to date. Because the -900 retains the same exit configuration of the -800, seating capacity is limited to 177 seats in two classes, or 189 in a single-class layout. The 737-900 also retains the MTOW and fuel capacity of the -800, trading range for payload. These shortcomings until recently prevented the 737-900 from effectively competing with the Airbus A321.

Alaska Airlines launched the 737-900 in 1997 and accepted delivery on 15 May 2001. There are no announced orders that have not been delivered yet. A total of 52 aircraft have been delivered.

The 737-900ER, which was called the 737-900X prior to launch, is the newest addition and the largest variant of the Boeing 737 line and was introduced to meet the range and passenger capacity of the discontinued 757-200 and to directly compete with the Airbus A321.

An additional pair of exit doors and a flat rear pressure bulkhead increase seating capacity to 180 passengers in a 2-class configuration or 215 passengers in a single-class layout. Additional fuel capacity and standard winglets improve range to that of other 737NG variants.

The first 737-900ER was rolled out of the Renton, Washington factory on 8 August 2006 for its launch customer, Lion Air. Lion Air received this aircraft on 27 April 2007 in a special dual paint scheme combining the Lion Air lion on the vertical stabilizer and the Boeing livery colors on the fuselage.

Boeing Business Jet

Plans for a business jet version of the 737 are not new. In the late 1980s, Boeing marketed the Boeing 77-33 jet, a business jet version of the 737-300. [Endres 2001.] The name was short-lived. After the introduction of the next generation series, Boeing introduced the Boeing Business Jet (BBJ) series. The BBJ1 was similar in dimensions to the 737-700 but had additional features, including stronger wings and landing gear from the 737-800, and has increased range (through the use of extra fuel tanks) over the other 737 models. The first BBJ rolled out on 11 August 1998 and flew for the first time on 4 September. [http://cdn-www.airliners.net/info/stats.main?id=108 The Boeing 737-700/800 BBJ/BBJ2] . www.airliners.net. Retrieved: 3 February 2008.]

On 11 October 1999 Boeing launched the BBJ2. Based on the 737-800, it is 5.84 m (19 ft 2 in) longer than the BBJ, with 25% more cabin space and twice the baggage space, but has slightly reduced range. It is also fitted with auxiliary belly fuel tanks and winglets. The first BBJ2 was delivered on 28 February 2001.

Boeing's BBJ3 is based on the 737-900ER. The BBJ3 has 1,120 square feet of floor space, 35% more interior space and 89% more luggage space than the BBJ2. It has an auxiliary fuel system, giving it a range of up to 4,725 nautical miles, and a Head-up display. Boeing completed the first example in August, 2008. This aircraft's cabin is pressurized to a simulated 6,500 foot altitude. [ [http://www.boeing.com/news/releases/2008/q3/080814b_nr.html Boeing Press Release, August 14, 2008] ]

Operators

The 737 is operated by more than 500 airlines, flying to 1,200 destinations in 190 countries. With over 8,000 aircraft ordered, over 5,000 delivered, and over 4,500 still in service, at any given time there are over 1,250 airborne worldwide. On average, somewhere in the world, a 737 takes off or lands every five seconds. Since entering service in 1968, the 737 has carried over 12 billion passengers over 120 billion km (65 billion nm), and has accumulated more than 296 million hours in the air. The 737 represents more than 25% of the worldwide fleet of large commercial jet airliners. [http://www.flightglobal.com/articles/2006/02/07/204505/the-737-story-little-wonder.html flightglobal.com "The 737 Story: Little Wonder"] . Retrieved: 7 January 2008.] [http://www.boeing.com/commercial/737family/pf/pf_facts.html "737 Facts"] . Boeing. Retrieved: 30 October 2006.]

Civilian

Military

Many countries operate the 737 passenger and cargo variants in government or military applications.
* Australia, Brazil, Chile, Colombia, India (Indian Air Force) , Indonesia, Kuwait, Mexico, Niger, Peru, South Africa, South Korea, Republic of China (ROC's Air Force One), Thailand (Royal Thai Air Force), United Arab Emirates, United States (Air Force, Navy), Venezuela and Malaysia (Malaysian Air Force VIP).
* The People's Liberation Army Air Force (PLAAF) of the People's Republic of China operates a 737-300 (registered B-4052) as an airborne command post.Fact|date=March 2008

Incidents and accidents

As of August 2008, a total of 289 incidents involving 737s had occurred, [ [http://aviation-safety.net/database/dblist.php?Type=103 "Boeing 737 incident occurrences"] , Aviation-Safety.net, 14 September 2008. Retrieved: 14 September 2008.] including 140 hull-loss accidents [ [http://aviation-safety.net/database/type/type.php?type=103 "Boeing 737 Accident summary"] , Aviation-Safety.net, 14 September 2008. Retrieved: 14 September 2008.] resulting in a total of 3,830 fatalities. The 737 has also been in 106 hijackings involving 324 fatalities. [ [http://aviation-safety.net/database/type/type-stat.php?type=103 "Boeing 737 Accident Statistics"] , Aviation-Safety.net, 3 December 2007. Retrieved: 16 February 2008.]

;737-100 and 737-200 variants
* October 29, 2006 - ADC Airlines Flight 53, a 737-200 crashed during a storm shortly after takeoff from Abuja, Nigeria. All but seven of the 104 passengers and crew are reported to have been killed. [ [http://www.cnn.com/2006/WORLD/africa/10/29/nigeria.crash/index.html "Muslim leader among those killed in Nigerian plane crash."] ]
* August 24, 2008 - Iran Aseman Airlines Flight 6895, a 737-200 crashed while attempting emergency landing on return 10 minutes after departure. The airliner was flying from Bishkek, Kyrgyzstan to Tehran. Out of 83 passengers and 7 crew, there were 22 survivors.

See Boeing 737 Classic incidents and Boeing 737 Next Generation incidents for other 737 variants.

pecifications

ee also

aircontent
related=
* Boeing 737 Classic
* Boeing 737 Next Generation
* Boeing T-43
* Boeing Business Jet
* Boeing 737 AEW&C
* C-40 Clipper
* P-8 Poseidon

similar aircraft=
* Airbus A320 family
* Boeing 717
* Bombardier CSeries
* Dassault Mercure
* Embraer 195
* Kawasaki YPX
* McDonnell Douglas DC-9
* McDonnell Douglas MD-80
* McDonnell Douglas MD-90
* MS 21
* Tupolev Tu-154M
* Tupolev Tu-204
* Yakovlev Yak-42D

lists=
* List of airliners
see also=
* Boeing 737 rudder issues

References

Notes

Bibliography

* Bowers, Peter M. "Boeing Aircraft since 1916". Annapolis, Maryland: Naval Institute Press, 1989. ISBN 0-87021-037-8.
* Endres, Günter. "The Illustrated Directory of Modern Commercial Aircraft". Osceola, Wisconsin: MBI Publishing Company, 2001. ISBN 0-7603-1125-0.
* Redding, Robert and Bill Yenne. "Boeing: Planemaker to the World". Berkeley, California: Thunder Bay Press, 1997. ISBN 1-57145-045-9.
* Sharpe, Michael and Robbie Shaw. "Boeing 737-100 and 200". Osceola, Wisconsin: MBI Publishing Company, 2001. ISBN 0-7603-0991-4.
* Shaw, Robbie. "Boeing Jetliners". London, England: Osprey, 1995. ISBN 1-8553-2528-4.
* Shaw, Robbie. "Boeing 737-300 to 800". Osceola, Wisconsin: MBI Publishing Company, 1999. ISBN 0-7603-0699-0.
* Sutter, Joe. "747: Creating the World's First Jumbo Jet and Other Adventures from a Life in Aviation". Washington, DC: Smithsonian Books, 2006. ISBN 0-06-088241-9.

External links

* [http://www.boeing.com/commercial/737family/background.html 737 page on Boeing.com]
* [http://www.b737.org.uk/ Boeing 737 technical guide site]
* [http://www.b737.org.uk/unpavedstripkit.htm About the gravel kit on Boeing 737-200]
* [http://www.aircraft-info.net/aircraft/jet_aircraft/boeing/737-400/ Boeing 737-400 on Aircraft-Info.net]
* [http://www.aviationhistoryonline.com/aircraft/index.php?id=15 Aviation History Online - Boeing 737-100/200] and [http://www.aviationhistoryonline.com/aircraft/index.php?id=25 Boeing 737-300/400/500]
* [http://www.aerospace-technology.com/projects/boeing737_NG/ Aerospace Technology - Boeing 737-600/700/800/900]
* [http://www.flightinternational.com/Articles/2006/01/31/Navigation/252/204410/Celebrating+the+5%2c000th+aircraft+The+Boeing+737+story.html Celebrating the 5000th 737 on FlightInternational.com]
* [http://www.speednews.com/lists/737NG.html Boeing 737NG operator list]
* [http://www.b737mrg.net/ Boeing 737 Management Reference Guide (for 737 airline pilots)]
* [http://www.flydamnit.com/2006/06/30/how-to-start-a-737 How to start a real Boeing 737 Tutorial]
* [http://www.nytimes.com/2008/06/11/business/11air.html?ref=business "To Save Fuel, Airlines Find No Speck Too Small", New York Times, 11 June 2008]