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Boeing 737 Classic

Boeing · Narrowbody / Commercial Aviation · USA · Cold War (1970–1991)

Boeing 737 Classic — Narrowbody / Commercial Aviation
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The Boeing 737 Classic (737-300/400/500) was an American twin-engine short-haul jet airliner — the second-generation 737 family + the foundation of the 737's continuing market dominance. Boeing developed the 737 Classic in 1979-1983 as a re-engined refresh of the original 737 Original (737-100/200); first flight 24 February 1984 (737-300). About 1,988 737 Classics were built between 1984 and 2000 at Boeing Renton. The aircraft serves worldwide commercial + cargo operators through 2026.

The 737-400 used 2 × CFM International CFM56-3 turbofan engines (22,000 lbf each). Maximum speed 893 km/h, range 4,180 km, service ceiling 11,300 m. Capacity: 146-188 passengers depending on configuration. The 737 Classic introduced CFM56 turbofan engines (replacing the original 737 Original's JT8D engines) — notably better fuel economy + lower noise + longer range than the predecessor.

737 Classic service was extensive. Major operators included Southwest Airlines (USA), Lufthansa, KLM, British Airways, Aer Lingus, Air Berlin, Ryanair (foundational fleet during the airline's growth), and ~200 other operators worldwide. The aircraft was the world's most-numerous airliner family in the 1990s before replacement by the 737 Next Generation from 1997 onwards. About 1,200 737 Classics remain in service worldwide in 2026 — many in cargo conversion + secondary-operator service.

For Kids — a shorter, friendlier version

The Boeing 737 Classic is the second generation of the Boeing 737 family — the world's most-built airliner. The 737 Classic series (737-300, 737-400, 737-500) was built between 1984 and 2000. These airplanes were much improved over the original 737 — more efficient engines, bigger cabins, more passengers.

The 737-400 (the biggest Classic) is about 119 feet long — longer than three school buses. Two CFM56 engines under the wings give it modern fuel efficiency. Top speed about 540 mph. Each one carried 145-188 passengers depending on configuration.

About 1,988 Boeing 737 Classics were built. Major operators included Southwest Airlines (huge fleet — Southwest only flies 737s, ever), United Airlines, Continental, Delta, Lufthansa, British Airways, Aer Lingus, easyJet, Ryanair, and dozens more. Almost every airline in the world bought at least a few.

The 737 Classic was replaced by the 737 Next Generation (NG) starting in 1997, then by the 737 MAX in 2017. Some 737 Classics still fly today, mostly as cargo aircraft for FedEx and small airlines. The 737 family — Classic, NG, and MAX — is by far the most-produced airliner in history: over 11,000 built across all generations.

Fun Facts

  • About 1,988 Boeing 737 Classics were built between 1984 and 2000.
  • Three Classic versions: 737-300, 737-400, 737-500.
  • Southwest Airlines only flies 737s — never any other type of airliner.
  • The 737 family — Classic, NG, and MAX — is the most-produced airliner in history.
  • Over 11,000 total 737s have been built across all generations.
  • The 737-400 is about 119 feet long — longer than three school buses.
  • Some 737 Classics still fly today as cargo aircraft for FedEx and small airlines.

Kids’ Questions

Why does Southwest only fly 737s?

Southwest Airlines has decided to only fly one type of airplane — the Boeing 737. There are three big advantages. First, every pilot can fly every airplane in the fleet — no special training for different types. Second, every mechanic knows every airplane — no specialty mechanics for one type. Third, every spare part fits every airplane — no need for different inventories at different airports. This makes Southwest much more efficient than airlines with mixed fleets. The downside: Southwest can only fly routes the 737 is good at — mostly short-to-medium distance flights within the U.S. (no transatlantic, no very long routes).

What was the original Boeing 737?

The original Boeing 737 (the 737-100 and 737-200, also called the "Original" series) flew from 1968 to 2000. About 1,144 were built. They had different (less-efficient) engines and a different cockpit than the Classic series that replaced them. The 737 family then evolved: Classic (1984-2000), Next Generation or NG (1997-2019), and MAX (2017-present). Each generation kept the 737 fuselage shape but added new engines, wings, electronics, and cockpit features. This evolution let Boeing keep building 737s for 60+ years without ever designing a clean-sheet replacement.

Variants

737-300 (basic)
Standard 124-149 passenger variant. About 1,113 built.
737-400 (stretched)
Stretched 146-188 passenger variant. About 486 built.
737-500 (shortened)
Shortened 110-132 passenger variant. About 389 built.

Notable Operators

Worldwide commercial + cargo
~1,200 active 2026 across ~200 operators worldwide. Southwest + Ryanair foundational fleets.

Frequently Asked Questions

How is the 737 Classic different from the Original 737?

The 737 Original (737-100/200, 1968-1988) used Pratt & Whitney JT8D engines. The 737 Classic (737-300/400/500, 1984-2000) re-engined the family with CFM International CFM56 turbofans — quieter + more fuel-efficient + longer range. Same general airframe + cockpit; notably improved economics + environmental performance.

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See Also