Boeing 737-500

The 737-500 was the final model of the 737 Classic series and the smallest. Boeing offered it, due to customer demand, as a modern and direct replacement for the 737-200: it brought the improvements of the Classic series to an aircraft meant to make longer routes with fewer passengers more economical than with the 737-300. Southwest Airlines launched it in May 1987 with an initial order.

Although shorter than the -300 and -400, its fuselage was 1 ft 7 in (48 cm) longer than the 737-200's, accommodating up to 140 passengers, and it had the longest range of the whole Classic family. Customers could choose between a glass cockpit and the older mechanical instrument layout. The CFM56-3 engines gave it a 25% increase in fuel efficiency over the -200's Pratt & Whitney engines. As on the rest of the series, they sat ahead of the wing with their accessories moved to the sides of the pod, the solution Boeing and CFM International devised to fit a large-diameter engine under such a low wing, which gave the intake its flat-bottomed "hamster pouch" shape. It also shared the extended wingtip with adjusted slats and flaps, the tail with a dorsal fin and the Speed Trim System introduced on the Classics.

It first flew on June 30, 1989. A single prototype flew 375 hours for the certification process, and on February 28, 1990 Southwest Airlines received the first production aircraft. In all, 389 were delivered, against 1,113 of the -300 and 486 of the -400; the last one was delivered to All Nippon Airways on July 21, 1999. Like the -300, it could be retrofitted with Aviation Partners Boeing winglets.

The -500 found loyal customers on the second-hand market. Several Russian airlines, including Smartavia, Rossiya Airlines, S7 Airlines, Sky Express, Transaero, Utair and Yamal Airlines, bought used examples to replace ageing Soviet-built aircraft or expand their fleets, and Aerolíneas Argentinas replaced its 737-200s with second-hand -500s. It also served as a state aircraft: in 1997 it became the presidential aircraft of Chile, and in July 2014 the Argentine government announced the purchase of a 737-500 for its official fleet.

In the Next Generation family it was replaced by the 737-600, which unlike the -500 was a slow seller: only 69 were delivered. The -500's retirement was also faster than that of the other Classics. By 2012 retirement of the -300s and -500s had reached 40%, and because of their smaller size -500s were being retired after 21 years of use, compared with 24 years for the -300; and while some -300s were slated for freighter conversion, there was no demand for a -500 freighter. In July 2019, 134 were still in commercial service. On September 5, 2016 Southwest Airlines, its launch customer, flew its last 737-500 revenue flight: Flight 377 from El Paso to Dallas.

On safety, the available figures are those of the Classic series as a whole: 64 hull losses and 1,298 fatalities as of January 2021, and a hull loss rate of 0.71 per million departures over the period 1959–2017 according to Boeing, against 0.17 for the Next Generation and 1.75 for the original 737.