Boeing 737 Classic

Boeing 737 Classic 737-300/-400/-500
Lufthansa 737-300, the first 737 Classic model, during climbout after takeoff in 2011
Role	Narrow-body jet airliner and Business jet
National origin	United States
Manufacturer	Boeing Commercial Airplanes
First flight	February 24, 1984
Introduction	November 28, 1984 with USAir
Status	In service
Primary users	Southwest Airlines UTair Alaska Airlines
Produced	1981–2000[1]
Number built	1,988[1]
Developed from	Boeing 737
Developed into	Boeing 737 Next Generation

The Boeing 737 Classic refers to the -300/-400/-500 series of the Boeing 737. It is the second generation derivative of the 737, following the original -100/-200 models that began production in 1966. They are short- to medium-range, narrow-body jet airliners. Produced by Boeing Commercial Airplanes from 1984 to 2000, the 737 Classic includes three variants and can seat between 145 and 188 passengers. Improvements over the previous generation of 737 aircraft included CFM International CFM56 high bypass ratio turbofan engines, upgraded avionics, and increased passenger capacity (in the -300/-400 models).

The first model of the Classic series, the 737–300, entered service in 1984. It was followed by a stretched model, the 737-400, which entered service in 1988, followed by shortened 737-500, the smallest variant in the classic series, in 1990. In total, 1,988 aircraft were delivered. The Classic series was introduced as the 'new generation' of the 737,^[2] but following the introduction of the 737 Next Generation in the mid-1990s, was officially designated as the 737 Classic series.

Development and design

Background

Following the success of the Boeing 737-200 Advanced, Boeing wanted to increase capacity and range, incorporating improvements to upgrade the plane to modern specifications, while also retaining commonality with previous 737 variants. Development began in 1979, and in 1980 preliminary aircraft specifications were released at the Farnborough Airshow.^[3] The new series featured CFM56 turbofan engines, yielding significant gains in fuel economy and a reduction in noise, but also posing an engineering challenge given the low ground clearance of the 737 - a trait of its 707-derived fuselage. 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.^[4]

A 737-300 in operation with Piedmont Airlines, one of the first customers of the aircraft. The aircraft features special markings identifying the model type.

The wing incorporated a number of changes for improved aerodynamics. The wing tip was extended 9 inches (23 cm). The leading-edge slats and trailing-edge flaps were adjusted.^[4] The flight deck was improved with the optional EFIS (Electronic Flight Instrumentation System), and the passenger cabin incorporated improvements similar to those on the Boeing 757.

Model developments

In March 1981, USAir and Southwest Airlines each ordered 10 aircraft of the 737-300 series, with an option for 20 more. That aircraft, the initial model of the 737 Classic series, first flew in February 1984 and entered service in December of that year with Southwest Airlines. A further stretched model, the 737-400, was launched with an order for 25 aircraft with 30 options from Piedmont Airlines in June 1986. That aircraft first flew in February 1988 and entered service later that year with Piedmont Airlines. The final model of the series, the 737-500, was launched with an order for 30 aircraft from Southwest Airlines in May 1987. That aircraft, which was designed as a replacement for the 737-200 and had similar passenger capacity and dimensions as well as the longest range of any member of the 737 Classic family, first flew in June 1989 and entered service with Southwest Airlines in 1990.

Engines

Engine inlet of a CFM56-3 engine on a Boeing 737-400 series showing the non-circular design

Boeing selected the CFM56-3 to exclusively power the 737-300 variant. The 737 wings were closer to the ground than previous applications for the CFM56, necessitating several modifications to the engine. The fan diameter was reduced, which reduced the bypass ratio, and the engine accessory gearbox was moved from the bottom of the engine (the 6 o'clock position) to the 9 o'clock position, giving the engine nacelle its distinctive flat-bottomed shape, which is often nicknamed the "hamster pouch". The overall thrust was also reduced, from 24,000 to 20,000 lbf (107 to 89 kN), mostly due to the reduction in bypass ratio.^[5]

Further developments

Throughout the 1980s, the 737 Classic series attracted large orders from airlines in the United States and Europe, with its order totals exceeding that of preceding 737 models. By far the most successful model was the 737-300, with deliveries totaling 1,113 aircraft (the 737-400 and -500 reached 486 and 389 deliveries, respectively). Major operators included US carriers, small national airlines, and charter carriers. However, by the 1990s, with increased competition from the Airbus A320, Boeing began development of a re-winged and updated 737 model which became the 737 Next Generation. Production of the 737 Classic continued alongside that of the Next Generation for a period of time; the first 737-700 was completed in December 1996; the last 737 Classic was completed in February 2000.

Variants

737-300

British Airways Boeing 737-300

The prototype of the -300 rolled out of the Renton plant on January 17, 1984, and first flew on February 24, 1984.^[6] After it received its flight certification on November 14, 1984, USAir received the first aircraft on November 28.^[1] A very popular aircraft, Boeing received 252 orders for it in 1985, and over 1,000 throughout its production.^[7] The 300 series remained in production until 1999 when the last aircraft was delivered to Air New Zealand on December 17, 1999, registration ZK-NGJ.

In December 2008, Southwest Airlines selected Boeing to retrofit the 737-300 with a new set of instruments, hardware and software, to improve commonality with the 737-700, as well as to support the Required Navigation Performance initiative, but that order was later cancelled and the retrofits never took place.^[8]

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 737-300 has been replaced by the 737-700 in the Boeing 737 Next Generation family.

737-400

Qantas 737-400

The 737-400 design was launched in 1985 to fill the gap between the 737-300 and the 757-200, and competed with the Airbus A320 and McDonnell Douglas MD-80. It stretched the 737-300 another 10 ft (3.45 m) to carry up to 188 passengers.^[9] It included a tail bumper to prevent tailscrapes during take-off (an early issue with the 757), and a strengthened wing spar.^[10] The prototype rolled out on January 26, 1988, and flew for the first time on February 19, 1988.

The aircraft entered service on September 15, 1988, with launch customer Piedmont Airlines (25 aircraft ordered).^[1]

The 737-400F was not a model delivered by Boeing, but a 737-400 converted to freighter. The Boeing 737-400 never included winglets as an option, just like the Boeing 737-600. Alaska Airlines was the first to convert one of their 400s from regular service to an aircraft with the ability to handle ten pallets.^[11] 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.^[12]

The 737-400 was replaced by the 737-800 in the Boeing 737 Next Generation family.

737-500

Southwest Airlines 737-500

The -500 series was offered, due to customer demand, as a modern and direct replacement of the 737-200, incorporating the improvements of the 737 Classic series in a model that allowed 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 140 passengers.^[9] Both glass and older style mechanical cockpits arrangements were available.^[13] Using the CFM56-3 engine also gave a 25% increase in fuel efficiency over the older -200s P&W engines.^[13]

The 737-500 was launched in 1987, by Southwest Airlines, with an order for 20 aircraft,^[14] and flew for the first time on June 30, 1989.^[13] A single prototype flew 375 hours for the certification process,^[13] and on February 28, 1990 Southwest Airlines received the first delivery.^[1] The 737-500 has become a favorite of some Russian airlines, with Nordavia, Rossiya Airlines, S7 Airlines, Sky Express, Transaero, UTair and Yamal Airlines all buying second-hand models of the aircraft to replace aging Soviet-built aircraft and/or expand their fleets. Aerolíneas Argentinas replaced its 737-200s with second-hand 737-500s. The 737-500 is now replaced by the 737-600 in the Boeing 737 Next Generation family. However, unlike the 737-500, the 737-600 has been a slow seller for Boeing since its introduction, with only 69 aircraft delivered.

As the retirement of all 737 Classic models has accelerated, with retirement of 300s and -500s climbing 40% in 2012, the 737-500 has fared worse because of its smaller size. Aircraft older than 21 years old are being retired (vs. at least 24 years old for the 737-300). While a few 737-300s are slated for freighter conversion, there is no demand at all for a -500 freighter conversion. On September 5, 2016, Southwest Airlines flew their last 737-500 revenue flight, flight 377 from El Paso to Dallas.^[15]

Operators

Cockpit of a 737-300

All-economy cabin interior of a 737-300

Civilian

As of July 2015, 934 Boeing 737 Classic aircraft were in commercial service. This includes 483 -300s, 259 -400s, and 192 -500s.^[16]

Military

Many countries operate the 737 passenger and cargo variants in government or military applications.

• Brazil, Chile, Colombia, India (Indian Air Force), Indonesia, Kuwait, Mexico, Niger, Peru, Philippines (Philippine Air Force), South Korea, Republic of China on Taiwan (ROC's Air Force One), Thailand (Royal Thai Air Force), United Arab Emirates, Venezuela.
• 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.

Deliveries

• Source: Boeing^[17]

Aircraft on display

• N759BA, an ex-China Southern Airlines 737-300 formerly registered B-2921, is on display at the Pima Air & Space Museum in Tucson, Arizona.^[18][19]
• N300SW, Southwest Airlines' first 737-300 delivered in November 1984, is displayed at the Frontiers of Flight Museum at Love Field in Dallas, Texas.^[20]

Accidents and incidents

As of August 2016, 55 hull losses of Boeing 737 Classic series aircraft have occurred, with a total of 1,174 fatalities.^[21][22][23] An analysis by Boeing on commercial jet airplane accidents in the period 1959–2013 showed that the classic series had a hull loss rate of 0.54 per million departures versus 0.27 for the Next Generation series and 1.75 for the original series.^[24]

Specifications

Transaero 737-400 at takeoff

ICAO Aircraft Type Designators

See also

• Boeing 737 rudder issues

Related development

• Boeing 737
• Boeing 737 MAX
• Boeing 737 Next Generation
• Boeing T-43

Aircraft of comparable role, configuration and era

• Airbus A320 family
• McDonnell Douglas MD-80
• McDonnell Douglas MD-90
• Tupolev Tu-154
• Yakovlev Yak-42

Related lists

• List of Boeing 737 operators
• List of civil aircraft

References

Notes

Bibliography

External links

Wikimedia Commons has media related to Boeing 737.

• 737 page on Boeing.com
• Celebrating the 5000th 737 on FlightInternational.com
• "737 classic" (PDF). Boeing. 2007.