Boeing 737-600

The 737-600 was born within the 737 Next Generation program, the series with which Boeing responded to the threat posed by the Airbus A320. When United Airlines, a regular Boeing customer, bought the fly-by-wire A320, Boeing began developing an updated series of the 737 in 1991; the company's board of directors authorized the program in November 1993, and it was publicly announced on November 17, 1993. The new generation, made up of the -600, -700, -800 and -900, introduced a redesigned wing with a greater span and a larger area, more fuel, high-bypass-ratio CFM56-7 engines and a flight deck with screen displays; taken together, these changes extended the range of the 737 by 900 nautical miles (1,700 km), to more than 3,000 nautical miles (5,600 km), which was enough to fly from one side of the United States to the other.

The -600 was the smallest member of the family and the successor to the 737-500, with which it shared its size; it was compared with the Airbus A318, and also with the A319. The Scandinavian airline SAS launched it with an order placed in March 1995 (development formally got under way in March 1996). It was the last version of the series to leave the assembly line, in December 1997; it flew for the first time on January 22, 1998, and obtained its certification from the FAA on August 18, 1998. Ten aircraft took part in the flight test campaign: three -600s, four -700s and three -800s. SAS received the first one in September 1998.

Like the rest of the generation, its engines did not have a circular intake: the flattened lower section was needed to house the larger diameter of the CFM56 beneath the low-mounted wing of the 737. One difference specific to the -600 is that it never carried winglets, since they were not offered as an option. WestJet was going to introduce a -600 fitted with winglets, but abandoned the idea in 2006. The aircraft could, however, be equipped with the short-runway package, which was optional on the -600, the -700 and the -800, and which, on runways shorter than 5,000 feet (1,500 m), increased the payload by up to 4,000 pounds on landing and by up to 400 pounds on takeoff on the -600 and the -700.

Commercially, it was a failure. It sold worse than the -500 it replaced, and in total 69 aircraft were ordered and delivered; the last ones went to WestJet in 2006, which had received 13 aircraft by September of that year. It could seat up to 149 passengers, although around 100 seats was the usual layout, and it cost between 50 and 57 million US dollars. With no further orders coming in, it became the first version of the Next Generation to go out of production. Boeing kept it on its price list until August 2012, although its definitive removal from the catalogue is placed in 2016, when the 737-700, which had sold far better, took over the role of the smallest version.

When Boeing renewed the family with the 737 MAX, there was no direct successor to the -600: the MAX 7, the shortest version, is derived from the 737-700 and is even longer than that aircraft. In July 2018 all 69 examples were still in commercial service. Among its incidents is that of an Air Algérie 737-600 registered 7T-VJQ which, on February 4, 2018, while flying from Algiers to Beirut, had to return after 30 minutes when one of its two engines caught fire.