Title: Boeing 737 Content:  The Boeing 737 is a twin narrow-body airliner built by Boeing. At first, Boeing was making it to be a shorter, cheaper airliner than its 707 and 727. However, the 737 has become a family of many different models. The number of passengers it can carry ranges from 85 to 215. The 737 is the only narrow-body airliner that Boeing is making. The only types of 737 that Boeing is still making are the -700, -800 and -900ER. A version of the 737 with larger engines, the 737 MAX, came into service in 2017 but was grounded between 2019 and 2021 as unsafe. Boeing began designing the 737 in 1964. The very first 737-100 flew in 1967. It was first used by an airline in February 1968.Kingsley-Jones, Max. "6,000 and counting for Boeing’s popular little twinjet." Flight International, Reed Business Information, April 22, 2009. Retrieved: April 22, 2009."The Boeing 737-100/200." Airliners.net, Demand Media, Inc. Retrieved: April 22, 2009. The 737-200 started being used in April 1968. The -200 was basically just a longer version of the 737-100. In the 1980s Boeing made the -300, -400, and -500 models. Boeing called these models the Boeing 737 Classic series. The 737 Classics could carry more passengers, and they had new engines: CFM56 turbofans. The 737 Classic planes also had some improvements made to the wings. In the 1990s, Boeing brought out the 737 Next Generation. The 737 Next Generation planes also had redesigned wings, a better cockpit and a new cabin. The 737 Next Generation is made up of the -600, -700, -800, and -900ER models. These models go from to in length. The 737 is the best-selling jet airliner in history. Boeing has never stopped making 737s since 1967. 7,283 aircraft have been delivered, and the 737 still has 2,759 orders that have not been delivered yet ."737 Model Orders and Deliveries data." Boeing, June 2011. Retrieved: July 25, 2011. Boeing 737s are built at the Boeing Renton Factory in Renton, Washington. The 737's main rival is the Airbus A320 family."Airbus A320 Aircraft Facts, Dates and History." Flightlevel350.com. Retrieved: May 12, 2010. On average, 1,250 737s are in the air at any time and two land or leave somewhere every five seconds. "The 737 Story: Little Wonder." flightglobal.com. Retrieved: January 7, 2008. ==Development== ===Background=== Boeing was looking at designs for aircraft which flew short distances. Boeing wanted to make another aircraft to replace the 727 on short flights."Transport News: Boeing Plans Jet." The New York Times, July 17, 1964. Retrieved: February 26, 2008. It began designing the 737 on May 11, 1964.Endres 2001, p. 122. Boeing did a lot of research and found that airlines wanted an airliner which could hold 50 to 60 passengers. This airliner would also be able to fly routes long.Sharpe and Shaw 2001, p. 12. Lufthansa was the first airline to order a Boeing 737 on February 19, 1965.Sharpe and Shaw 2001, p. 13. They ordered 21 aircraft, worth $67 million"German Airline Buys 21 Boeing Short-Range Jets." The Washington Post, February 20, 1965. Retrieved: February 26, 2008. (1965, $190.28 million in 2008). After Boeing spoke to Lufthansa in winter 1964, they made the 737 bigger so that it could hold 100 passengers. On April 5, 1965, Boeing announced that United Airlines had ordered 40 737s. United wanted a plane which was a bit bigger than the 737-100. Boeing made a different type of 737 for United, which was longer. This other plane was called the 737-200. Boeing changed the name of the original 737 to the 737-100.Redding 1997, p. 182. ===Making and testing of the 737=== The first 737s were made near Boeing Field (now officially called King County International Airport) because the factory in Renton was too busy building the 707 and 727. After 271 aircraft were made at Boeing Field, Boeing moved the 737s to Renton. This was in 1970.Wallace, J. "Boeing delivers its 5,000th 737." Seattle Post-Intelligencer, February 13, 2006. Retrieved June 7, 2011.Gates, Dominic. "Successor to Boeing 737 likely to be built in state." Seattle Times, 30 December 2005. Retrieved: February 10, 2008. The first Boeing 737-100 prototype was ready in 1966. It made its first flight on April 9, 1967."Original 737 Comes Home to Celebrate 30th Anniversary." The Boeing Company press release, May 2, 1997. Retrieved: April 12, 2008. On December 15, 1967 the Federal Aviation Administration said that the -100 was allowed to fly with passengers.Sharpe and Shaw 2001, p. 20. They gave it the Type Certificate A16WE."Type Certificate Data Sheet A16WE." faa.gov. Retrieved: September 3, 2010. Lufthansa got its first 737 on December 28, 1967. On February 10, 1968, Lufthansa became the first non-American airline to fly a new Boeing aircraft. It was the only large airline which bought the 737-100. Only 30 -100s were ever made.Sharpe and Shaw 2001, p. 120. The 737-200 first flew on August 8, 1967. The FAA allowed it to fly with passengers on December 21, 1967.Endres 2001, p. 124. The first flight it made for United Airlines was on April 28, 1968. It flew from Chicago to Grand Rapids, Michigan. Airlines liked the 737-200 much more than the 737-100. ===737-200 Advanced=== A "thrust reverser" is a part of the engine of a plane. It changes the flow of air through the engine so that it ends up trying to push the plane backwards instead of forwards. The first thrust reversers on the 737 were not very good. They were said to lift the aircraft off the runway when they were used. This meant that the wheels were not being pushed down onto the ground very much, which made the brakes less useful. In 1968, Boeing improved the thrust reverser."Powerplant - Reverse Thrust." b737.org.uk. Retrieved: November 1, 2011. This improvement was put onto all aircraft after March 1969. Aircraft which were made before the improvement could have it installed. Boeing also improved the flaps. This improvement allowed the flaps to be used more during takeoffs and landing. All these changes meant that the 737 could hold more cargo and fly further. In May 1971, after the 135th aircraft was built, all of these improvements, as well as better engines and more fuel, were put into the 737-200. This gave it 15% more payload and range than the first 737-200s.Redding 1997, p. 183. This type of 737-200 became known as the 737-200 Advanced. In 1970, Boeing only got 37 orders for 737s. Since Boeing were running out of money, they thought about stopping making 737s and selling the design to Japanese companies. Boeing cancelled the Boeing Supersonic Transport and started making less Boeing 747s. By doing this, Boeing kept enough money to keep the 737 project going.Sharpe and Shaw 2001, p. 21. In 1988, Boeing stopped making 737-200s. 1,114 aircraft were made and the last one was delivered to Xiamen Airlines on August 8, 1988.Sharpe and Shaw 2001, p. 23."737 Family." Boeing.com, January 5, 2008. Retrieved: April 12, 2008. ===737 Classic=== In 1979, Boeing started working on a large improvement for the 737. Boeing wanted to allow the aircraft to hold more passengers and travel further. It also wanted to make improvements to make the aircraft more modern. However, it also wanted to keep it similar to the older 737s. In 1980, information on this new type of 737 (called the 737-300) was given at the Farnborough Airshow.Endres 2001, p. 126. thumb|left|The first type of Boeing 737 Classic was this 737-300 of Lufthansa The CFM56-3B-1 engine was chosen to be the engine for this new 737 type. This engine burned much less fuel and was much less noisy. However, it was also difficult to fit these engines to the aircraft. This was because the 737's wings were not very high above the ground, and the CFM56 had a bigger diameter than the original engines. Boeing and CFM solved the problem by putting the engine slightly ahead of the wing, instead of right under it. They also moved some parts of the engine, which would normally go on the bottom, to the sides. This made the engine look a bit like a hamster pouch,Brady, Chris. "History & Development of the Boeing 737 - Classics." The Boeing 737 Information Site, 1999. Retrieved: September 5, 2010.Endres 2001, p. 128. because the engine is not shaped like a circle. The plane could now carry 149 passengers, because the fuselage of the plane was made bigger. Many changes were made to the wings. The tip of the wing was made longer by . The wingspan was also made bigger. The flaps on the wings were changed. The flight deck (cockpit) was improved with electronic displays. However, airlines could choose not to have these in their planes. The main cabin (where the passengers sit) was also made better. It looked similar to the cabin of a Boeing 757.Shaw 1999, p. 10. The prototype of the 737-300 first flew on 24 February 1984. Its pilot was Jim McRoberts. In June 1986, Boeing said that it was working on the 737-400.Redding 1997, p. 185. The 737-400 made the fuselage even bigger (by ). This change meant that the -400 could carry 170 passengers.Shaw 1999, p. 7. The 737-400's first flight was on February 19, 1988. The first airline to use it was Piedmont Airlines. thumb|A Transaero 737-400 being flown Boeing made a 737-500 because its customers wanted one. It was a replacement of the 737-200. The -500 is longer than the 737-200. Up to 132 passengers can travel on the 737-500. Cockpits with electronic displays could be installed on the -500, but airlines could choose the use the older cockpit if they wanted.Shaw 1999, p. 14. The 737-500 was first ordered by Southwest Airlines in 1987. Southwest Airlines ordered 20 aircraft.Shaw 1999, p. 40. The 737-500 flew for the first time on June 30, 1989. On February 28, 1990, Southwest Airlines got their first delivery.Endres 2001, p. 129. After the Boeing 737 Next Generation planes were brought into service, Boeing named the 737-300/-400/-500s the 737 Classic series. ===737 Next Generation=== In 1991, Boeing started working on an updated group of 737s. They did this so they could have a plane to rival the Airbus A320.Endres 2001, p. 132. Boeing said that the 737 Next Generation (NG) program had begun on November 17, 1991.Shaw 1999, p. 8. The -600, -700, -800, and -900 models are all part of the 737 Next Generation program. The 737 was changed so much by the 737NG program that it is almost like a new aircraft. However, some important parts of the plane were kept similar to the older 737s. The wing was changed again. Many different changes were made. An example of one is a bigger wingspan (made bigger by ). Since the wings were made bigger, 30% more fuel could fit in the plane. CFM56-7B engines were used, which were newer, quieter and burned less fuel.Endres 2001, p. 133. The improvements to the wing, engine and fuel mean that the 737NG can travel 900 nautical miles further. This means it can travel over in total, which means that the 737NG can travel between different continents. Winglets can be added to most 737NG models. The flight deck was given modern electronics (called avionics). The main cabin was also improved. The first NG to be built was a 737-700. It was finished on December 8, 1995. This aircraft was 2,843rd 737 built. It first flew on February 9, 1997. The prototype 737-800 was finished on June 30, 1997 and first flew on July 31, 1997. The smallest of the 737NGs, the -600, is the same size as the -500. It was the last NG to be launched (it was launched in December 1997). It first flew on January 22, 1998. The FAA certified it on August 18, 1998.Shaw 1999, pp. 14–15. A Boeing delivered the 5,000th 737 to Southwest Airlines on February 13, 2006. The 6,000th 737 was delivered to Norwegian Air Shuttle in April 2009. The Airbus A320 family has sold more planes than the 737NG over the past ten years."Airbus A320 Family passes the 5,000th order mark." Airbus. Retrieved: September 3, 2010."Airbus 320 Aircraft History, Information, Pictures and Facts." aviationexplorer.com.. Retrieved: September 3, 2010."Airbus orders and deliveries." Airbus. Retrieved: September 3, 2010. However, this total includes sales for the A321 and A318. The A321 has been the rival of Boeing's 757 and the A318 has been the rival of the 717. The Next Generation series helped make sure the 737 stayed the bestselling"Boeing 737: Das meistverkaufte Flugzeug der Welt" (in German). Rhein-Zeitung, January 3, 2004. via Agence France-Presse. Retrieved: May 12, 2010.Robertson, David. "Boeing gets ready for all-new 737." The Times, March 12, 2007. Retrieved: April 22, 2010. Anderson and Eberhardt 2009, p. 61. airliner family since it first flew.O’Sullivan, Matt. "Boeing shelves plans for 737 replacement." The Sydney Morning Herald, January 2, 2009. Retrieved: April 22, 2010. Quote: Boeing will stick with the 737, the world's most widely flown aircraft."Boeing airliner deliveries rise 11%." Chicago Tribune, January 4, 2008. Retrieved: April 22, 2010.Layne, Rachel. "Bombardier’s Win May Prod Airbus, Boeing to Upgrade Engines." BusinessWeek, February 26, 2010. Retrieved: April 22, 2010.Rahn, Kim. "B737: Best-Selling Aircraft in the World." Korea Times. Retrieved: April 22, 2010."Boeing 737 Aircraft Profile." Flight Global. Retrieved: April 22, 2010. Quote: the best selling commercial airliner in history.Jiang, Steven. "Jetset: 'Tianjin Takes Off'." The Beijinger. Retrieved: April 22, 2010. Quote: A320, the workhorse of many airlines and the second best-selling jetliner family of all time (after Boeing’s venerable B737). ===737 MAX=== Since 2006, Boeing has been thinking about replacing the 737 with a completely new design. This was named the Boeing Y1 by people who worked at Boeing. This re-design would be launched after the Boeing 787 Dreamliner."Boeing firms up 737 replacement studies by appointing team." Flight International, March 3, 2006. Retrieved: April 13, 2008. Boeing did not decide on whether or not to go ahead with this. They said they would decide in 2011.Hamilton, Scott. "737 decision may slip to 2011: Credit Suisse." flightglobal, 2010. Retrieved: June 26, 2010. On July 20, 2011, Boeing said that they were working on a new 737 version, which would have the CFM International LEAP engine. American Airlines said they would order 100 of these aircraft."Boeing and American Airlines Agree on Order for up to 300 Airplanes". Boeing, July 20, 2011. Retrieved: November 1, 2011. On August 30, 2011, Boeing said that a new 737 would definitely be launched. It was called the 737 MAX.Boeing 737 MAX. NewAirplane.com It would also definitely have CFM International LEAP-1B engines."Boeing Launches 737 New Engine Family with Commitments for 496 Airplanes from Five Airlines." boeing.mediaroom.com, August 30, 2011."Boeing officially launches re-engined 737." flightglobal.com, August 30, 2011.Board Approves Re-Engined 737&channel;=comm "Boeing Board Approves Re-Engined 737." Aviation Week, August 30, 2011. The MAX 8 first carried paying passengers in May, 2017. In 2019 two MAX 8 aircraft crashed, killing all aboard and causing aviation authorities to ban commercial operation of the 737 MAX until they are fixed. ==Design== The 737's main landing gear (wheels) go into holes at the bottom of the plane. The wheels do not have a door to close over them. The tires can be seen easily when a 737 is taking off or is flying low-down.Dekkers, Daniel, et al. (Project 2A2H). [home.deds.nl/~hink07/Report.pdf "Analysis Landing Gear 737-500."] Hogeschool van Amsterdam. Aviation Sudies. October 2008. Retrieved: August 20, 2011. 737s do not have fuel dump systems. A fuel dump system is a system which gets rid of any unneeded fuel if the aircraft needs to make an emergency landing while it still has a lot of fuel on board. This is useful because aircraft can only land safely at a certain weight or below. Getting rid of unneeded fuel helps to get to a safe weight for the plane to land. The first 737s were too small to need these systems. Adding a fuel dump system to the bigger 737s would make the plane much heavier. Instead, if the emergency is not very serious, 737s fly around in circles to get rid of fuel. If the emergency is serious, the 737 just needs to land at an unsafe weight. If it has to land at an unsafe weight, the plane needs to be looked at for damage. If there is no damage, the plane can be put back into service."Fuel Dump." Boeing. Retrieved: August 20, 2011.Cheung, Humphrey. "Troubled American Airlines jet lands safely at LAX." tgdaily.com, 2 September 2008. Retrieved: August 20, 2011. ===Engines=== thumb|left|An engine on a 737-800, showing that it is not shaped like a circle. This shape is nicknamed the "hamster pouch". Engines on the 737 Classic series (300, 400, 500) and Next Generation series (600, 700, 800, 900) are not shaped like a circle like most planes. The 737 Classics had CFM56 turbofan engines. These burned much less fuel and made much less noise than the Pratt & Whitney JT8D engines which were used on the -100 and -200. However, because the 737's wings and fuselage are not very high above the ground, it was impossible to get the engines to fit on the wings. Boeing and CFM fixed this problem by putting the engines slightly ahead of the wings instead of putting them right underneath. They also moved some parts of the engines which would normally go at the bottom to the sides. This is what makes the engines non-circular. The gearbox of the engine was moved from the bottom of the engine to the side. The gearbox makes the engine look a bit like a triangle. Since the engine is close to the ground, it is possible that they can be damaged by things lying on the ground. The CFM56-7 engine on the 737 Next Generation burns even less fuel than the engines on the 737 Classics. The Boeing 737 MAX aircraft will have CFM International LEAP-1B engines. These engines are supposed to burn 10-12% less fuel than the CFM56-7B engines on the 737 Next Generation family. ===Flight systems=== The 737's controls are very safe. If the hydraulics or both engines fail, servo tabs will be automatically used. Servo tabs are small hinges which move important parts of an aircraft. The tabs are controlled by the yoke (the thing used to steer the plane). For the 737 Next Generation, a new cockpit with LCD displays was made. These cockpits also have modern avionics (autopilot etc.). Most 737 cockpits have "eyebrow windows". These are smaller windows which are above the main windows. There are two on each side. Eyebrow windows were used on the Boeing 707. They helped the pilot see better when the plane was turning. However, because autopilot, advanced radar etc. exist, they are no longer needed. They were removed from the 737 cockpit in 2004. However, 737s used by the military still have them installed. If the customer likes, Boeing will install eyebrow windows for them. ===Upgrades=== thumb|left|A winglet on a 737 Next Generation Winglets can be fitted to 737s which do not have them already installed. They can also be added when the aircraft is built. The winglets are about tall. They are fitted at the end of the wing and help the engines to burn less fuel because they reduce drag. They also help make less noise on takeoff. Winglets can help a plane burn up to 5% less fuel. the 737 has carbon brakes. These are made by Messier-Bugatti. These new brakes have been allowed by the Federal Aviation Administration. They weigh less than the steel brakes normally fitted to the 737 Next Generation family.Volkmann, Kelsey. "Boeing gets OK for new carbon brakes." St. Louis Business Journal via bizjournals.com. Retrieved: April 22, 2010. If 700 pounds of weight is taken off a Boeing 737-800, it burns 0.5% less fuel.Wilhelm, Steve. "Mindful of rivals, Boeing keeps tinkering with its 737." Puget Sound Business Journal, August 8, 2008. Retrieved: January 21, 2011. ===Main cabin=== How the cabin looks was changed in each different type of 737 (Classic and Next Generation). The cabin design of the 737 Original was changed 737 Classic using designs from the 757. Designs from the Boeing 777 were used to design the cabin for the Next Generation 737. The newest cabin design is called the Sky Interior. It has curved walls. It also has redesigned windows. The Sky Interior has more headroom and LED mood lighting.Kingsley-Jones, Max. "Narrow margins: Airbus and Boeing face pressue with the A-320 and 737." flightglobal.com, October 27, 2009. Retrieved: June 23, 2010."Check Out Boeing's Swanky New High-Tech Interior." businessinsider.com. Retrieved: November 1, 2011. Overhead bins which move have been installed. These bins are similar to the bins on a 777 and Boeing 787 Dreamliner. They have more space for luggage than the other designs. The Sky Interior is also designed to make the cabin less noisy by 2–4 dB. The first 737 with the Sky Interior was delivered to Flydubai in 2010. Malaysia Airlines, TUIFly"Wolkenlos in Seattle – an Bord des neuen Jets von TUIfly." podcastexperten, March 7, 2011. Retrieved: May 12, 2011. and Continental Airlines have also ordered 737s with the Sky Interior."Continental Airlines Is First North American Carrier to Fly With Boeing's New Sky Interior." Continental Airlines, December 29, 2010. Retrieved: March 14, 2011. ==Types of 737s== The 737 are split into three "generations". These are Original, Classic and Next Generation. The "Original" models are the 737-100, 737-200/-200 Advanced. The "Classic" models are the 737-300, 737-400 and 737-500. The "Next Generation" models are the 737-600, 737-700/-700ER, 737-800, and 737-900/-900ER. The fourth generation of 737 is called the 737 MAX. It is still being worked on, but when it is finished, it will be made up of the 737-MAX-7, 737-MAX-8 and 737-MAX-9. The MAX-7 will replace the 737-700, the MAX-8 will replace the 737-800 and the MAX-9 will replace the 737-900 and 739-900ER. ===737 Original=== ====737-100==== The very first 737 model was the 737-100. It was first ordered by Lufthansa in 1965. The -100 was finished on January 17, 1967. It entered service in 1968. The aircraft is the smallest type of 737. Only 30 737-100s were ordered and delivered. No 737-100s are still being used by airlines. The 737-100 prototype is in the Museum of Flight in Seattle. ====737-200==== thumb|A Canadian North Boeing 737-200C The 737-200 is a 737-100 with a larger fuselage. It was created because of an order from United Airlines in 1965. The -200 was finished on June 29, 1967. It entered service in 1968. The 737-200 Advanced is an improved version of the -200. Its first user was All Nippon Airways. It began using the -200 Advanced on May 20, 1971.Bowers 1989, p. 496. The -200 Advanced has many improvements. For example, more powerful engines and more fuel. The 737-200 Advanced can also fly further than the 737-200.Sharpe and Shaw, 2001, p. 41. The last delivery of a 737-200 aircraft was in August 1988 to Xiamen Airlines. This was the 1,095th 737-200 built."About the 737 Family." The Boeing Company. Retrieved: December 20, 2007. Many 737-200s are still used by airlines. thumb|left|A Britannia Airways 737-200 Advanced After 40 years the last 737-200 aircraft in the United States were retired on March 31, 2008. This happened with the last flights of Aloha Airlines. ===737 Classic=== The Boeing 737 Classic is the name of the 737-300/-400/-500. However, they were only called the 737 Classics after the 737 Next Generation (737-600/700/800/900) aircraft were made. Until then, the 737 Classics were called the 'new generation' of the 737.Shaw, 1999, p. 7. The 737 Classics were made from 1984 to 2000. 1,988 aircraft were delivered in that time. As of January 1, 2001, 1,945 are in service.Endres, 2001, p. 129. ====737-300==== The 737-300 was brought into service in 1981. It was used by both US Airways and Southwest Airlines. The 737-300 is the first model of the 737 Classic series. The -300 can usually hold 128 passengers.Fisher, Lawrence M. "Boeing Gets Orders for 63 737-X." The New York Times, November 18, 1993. Retrieved: February 1, 2008. The 737-300 series was made until 1999. The last -300 was delivered to Air New Zealand on 17 December 1999. This was the 1,113th 737-300 made. ====737-400==== The 737-400 brought into service in 1985. It was just a longer version of the 737-300. Piedmont Airlines was the launch customer. They ordered 25 aircraft in 1986. The first 737-400s were brought into service in 1988 with Piedmont. The last -400 was delivered to CSA Czech Airlines. This was the 486th -400 built. The 737-400F was a 737-400 changed into a cargo plane. The -400F was not delivered by Boeing. They were changed into cargo planes by the airlines that owned them. Alaska Airlines was the first airline to change a -400 to a -400F. It could carry 10 pallets of cargo."Alaska Airlines and Horizon Air Aircraft Information."alaskaair.com. Retrieved: June 7, 2011. ====737-500==== The 737-500 was finished 1987. It was brought into service with Southwest Airlines in 1990. The 737-500 is around the same length of the 737-200. It was a modern, complete replacement of the 737-200. The last 737-500 was delivered to All Nippon Airways on July 26, 1999. This was the 389th built. ===737 Next Generation=== In the 1990s, Boeing realized that the Airbus A320 family was a serious threat. Boeing could lose customers because of it. In November 1991, Boeing began the Next Generation program. The Next Generation aircraft would replace the 737 Classics. The 737-600, 737-700 and 737-800 planes were planned."Next Generation 737 Program Milestones." The Boeing Company. Retrieved: January 22, 2008. ====737-600==== The 737-600 replaced the 737-500. It was also supposed to replace the McDonnell Douglas DC-9. The 737-600 was finished in 1995. The first aircraft was delivered to Scandinavian Airlines on September 18, 1998. The 737-600 is the only Boeing 737 still being made that cannot be fitted with winglets."Next-Generation 737 Production Winglets." Boeing. Retrieved: February 10, 2008. The 737-600's rivals are the Airbus A318, Embraer 195 and Sukhoi Superjet 100. The Bombardier CSeries will also be a rival."Bombardier Launches CSeries Jet." This information comes from: Boeing 737 specifications,"Boeing 737 Technical Information." Boeing Commercial Airplanes. Retrieved: September 3, 2010. 737 Airport Planning Report,"Boeing 737 Airplane Characteristics for Airport Planning." Boeing Commercial Airplanes. b737.org.uk site."Boeing 737 Technical Specifications." boeing.com. Retrieved: September 3, 2010. == Related pages ==