Enter The Next Generation

Having established the Boeing 737 as the world leader in its class by some considerable margin, Boeing didn't rest on its laurels, but began work on an even more modern version. Studies began in the early 1990s under the name 737X and looked at ways to increase cpacity up to as many as 200 passengers.

Gradually the new concept was refined, with the help of some 30 possible operators of the type, the Boeing Board authorised the marketing of the 737 Next Generation (NG) family, as it had been dubbed, on June 29, 1993. Although the basic design remained unchanged, the aircraft featured new wings, new engines, state-of-the-art cockpit technology and updated avionics.

Rervised Designation System

Wheras the three variants of the 'Classic' series were numbered in order of appearance, the four variants of the Next Generation series are numbered in ascending order of size. This means the 'New Generation' aircraft do not correspond completly with those of the 'Classic' series, and the four variants are thus the 737-600 (originally known as the 737-500X) that superseeds the 737-500, the 737-700 that replaces the 737-300, the 737-800 (originally 737-400X Stretch) that is successor to the 737-400, and the 737-900 that is directly equivalent to no 'Classic' series but which, as a stretched development of the 737-800 gives Boeing a type to compete more direct against Airbus' A321. However due to limitations in the 737-900's emergency exit layout, the type is not certified to carry more than 189 passengers, the same as the max passenger number of the B737-800. Rumours have been that Boeing is looking into a B737-900X with additional or altered emergency exit layout to accomodate upto 200 passengers.

Southwest Airlines immediatly showed an interest for the new Boeing product, and ordered 63 -700s with options for a further 63. Production go-ahead was given on November 17, 1993, followed by Maersk Air of Denmark, placing an order for six -700s with six on option. Boeing launched the -800 at the 1994 Farnborough show, with Hapag-Lloyd acting as launch customer - deliveries were to commence in early 1998. In March 1995, Scandinavian Airlines System (SAS) finally enabled Boeing to launch the -600 with an order for 35 -600s. The fourth and final variant of the NG family is the -900 which was launched on November 10, 1997, with an intial order for ten aircraft from Alaska Airlines. The -900 features an increase in length to 42.11m (138ft2in) giving room for up to 189 seats in an all-economy layout.

A Real Performer

While critics of Boeing have stressed the point that the 737 family is based at a 1960 design and is heavily antiqated in regards to the Airbus A320 line which took life in the mid-eigthies, the NG family have been a resounding success story for Boeing. Pilots love the aircraft as the new wings and more powerful engines gives the aircraft an impressive climb-rate as well as a higher cruise-speed. This has led some critics to state that Boeing builds aircraft for pilots, while Airbus builds them for the airline manager. In some ways this may be true, but the NG with it's sales success of nearly 2,000 aircraft ordered may prove this wrong.

Powering the 737NG series is the Snecma-General Electric CFM56-7. The powerplant is based on the same CFM56 turbofan as used on the later variants of the 'Classic' series, but in this instance the CFM65-7 (originally CFM56-3XS) unit that combines the core of the CFM56-5 with the improved low-pressure compressor of the CFM56-3 and a fan with a diameter of 1.55m (4ft11in). The CFM56-7 is derated from its nominal thrust for improved engine reliability, lower fuel consumption and reduced emissions, and its noise level on the ground is trimmed by the use of a new diffuser duct. Further decreases in ground-level noise are derived from the introduction of a cooling vent silencer on the APU installation, a new fan and duct for the ECS (Environmental Control System), and a new cooling fan for the electrical and electronic systems.

Ranges from 2,481km (1,542miles) with the CFM56-7B18 powered -600 to 6,037km (3,751miles) with the CFM56-7B27 powered -800 are now possible. The introduction of the latest advanced technology wings provided a cruise speed range of between Mach 0.785 - 0.82, and a maximum altitude of 41,000ft (12,500m). This aerodynamic efficiency helps to produce a 30% fuel saving compared to older models. The wing is a pivotal element of the NG design since it affords 25% more wing area, double slotted inboard and outboard flaps, a bigger aileron and new curved spoilers. An increase in chord, plus redesigned fuel tanks provide 30% additional fuel capacity and with the recent addition of new winglet technology on the -800, performance has been increased even further. The winglets are 2.4m (8ft) tall and help reduce fuel consumption by as much 3,8% and increase payload range by as much as 125nm. They also increase performance in hot-and-high locations.