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Boeing 737

United States · Early Jet (1946–1969)

Boeing 737 — Fixed Wing
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The Boeing 737 is the most commercially successful jet airliner in aviation history — a single-aisle, twin-engine narrow-body that has been continuously produced since 1967, sold over 12,400 airframes across nine major variants, and become the dominant short-haul jet of the global airline industry. Originally conceived in 1964 as a 60–85 seat twinjet to fit between the larger Boeing 727 trijet and the smaller turboprop competition, the 737 has grown into a 230-seat single-aisle workhorse over six decades of incremental upgrades — making it both Boeing's most profitable product and, after the 2018–2019 MAX crisis, the most scrutinised commercial aircraft in service.

The 737 family is structured into four generations. The 737 Original (737-100 and 737-200, 1968–1988) introduced Pratt & Whitney JT8D low-bypass turbofans and the distinctive low-slung engine pylons that became the family's signature. The Boeing 737 Classic (737-300/400/500, 1984–2000) introduced CFM56-3 high-bypass turbofans — flattened on the bottom to maintain ground clearance under the original short landing gear — and stretched fuselages. The Boeing 737 Next Generation (737-600/700/800/900, 1997–2019) added a substantially redesigned wing, glass cockpit, and CFM56-7B engines. Finally, the Boeing 737 MAX (737-7/8/9/10, 2017–present) introduced LEAP-1B turbofans, split-tip winglets, and aggressively repositioned engines that contributed to the 2018–2019 MCAS-related crashes that grounded the type for 20 months.

The original 737-200 entered service in 1968 with United Airlines on its inaugural Chicago–Cleveland route. By the early 1990s the 737 Classic had become Boeing's principal narrow-body, and Southwest Airlines' all-737 fleet model proved that point-to-point low-cost operations on standardised single-aisle aircraft could profitably serve markets the major carriers had abandoned to bus and car travel. The 737 Next Generation extended that model globally — Ryanair, easyJet, and dozens of other low-cost carriers built airline industries around its operating economics — while the legacy carriers also operated mixed fleets dominated by the 737 alongside the A320. Total deliveries through the end of 2025 stand at 12,486 airframes, making the 737 by orders of magnitude the most-produced jet airliner in history.

The 737 MAX programme has been bittersweet. Designed in response to the A320neo's economic threat, the MAX entered service in 2017 and accumulated more than 5,000 firm orders before the 29 October 2018 Lion Air Flight 610 crash and 10 March 2019 Ethiopian Airlines Flight 302 crash — both attributed to the MCAS automated flight-control system responding to a single faulty angle-of-attack sensor — grounded the type globally on 13 March 2019. The grounding lasted 20 months. After hardware and software fixes, FAA recertification (November 2020), and pilot retraining, the MAX returned to service. By 2026 over 1,300 MAX airframes are flying with no loss of confidence, but Boeing's reputation, certification authority independence, and the 737's eventual replacement timeline have all been permanently affected. The MAX 10, the largest variant at 230 seats, entered service in 2024; a clean-sheet 737 successor (the rumoured "Future Small Airplane") is not expected before the late 2030s.

For Kids — a shorter, friendlier version

The Boeing 737 is the most popular jet airliner ever made. Airlines have ordered more than 12,400 of them. That is more than any other jet plane in history. Boeing has been building the 737 since 1967, and they are still making them today.

The first 737 was designed to carry 60 to 85 passengers on short trips. It was smaller than the bigger Boeing 727. Over the years, engineers kept improving the design. The newest versions can carry up to 230 passengers.

The 737 has gone through four main groups of designs. The first group started flying in 1968. The second group added more powerful engines. The third group, called the Next Generation, came out in 1997. Each new group was better than the one before it.

The 737 is longer than a city bus and holds many more people. Its engines hang low under the wings because the plane sits close to the ground. This is one of the most recognizable things about the 737.

Today, the 737 flies for airlines all around the world. It is the backbone of short-haul air travel. Millions of passengers fly on 737s every single year.

Fun Facts

  • More than 12,400 Boeing 737s have been ordered — more than any other jet airliner ever!
  • Boeing has been building the 737 nonstop since 1967, making it one of the longest-running jet programs in history.
  • The 737 is longer than a city bus and can carry up to 230 passengers.
  • The 737's engines are flattened on the bottom so they fit under the plane's short landing gear.
  • The very first 737 was designed to carry as few as 60 passengers on short flights.
  • The 737 started as a smaller companion to the bigger Boeing 727, which had three engines.
  • Some airlines, like Southwest, use only the 737 — every single plane in their fleet is a 737!

Kids’ Questions

How many Boeing 737s have been built?

More than 12,400 Boeing 737s have been ordered since 1967. That makes it the most produced jet airliner in history. No other jet plane has ever been ordered that many times!

Why do the 737's engines look different from other planes?

The 737 sits close to the ground, so its engines had to be shaped specially. Engineers flattened the bottom of the engines so they would fit without scraping the runway. That flat shape is one of the easiest ways to spot a 737.

How many people can a Boeing 737 carry?

Early 737s carried about 60 to 85 passengers. The newest versions can carry up to 230 passengers. The plane grew bigger and better over more than 60 years of improvements.

What are the four main versions of the Boeing 737?

The four groups are called the Original, the Classic, the Next Generation, and the MAX. Each group brought new engines and better designs. The Original started flying in 1968, and the newest MAX versions are still being built today.

Variants

737 Original (737-100 / 737-200)
Initial 1968 production family with Pratt & Whitney JT8D low-bypass turbofans and short-fuselage 100-115 seat configuration. 1,144 built before production ended in 1988; most retired by the late 2000s.
737 Classic (737-300 / -400 / -500)
1984 mid-life redesign with CFM56-3 high-bypass turbofans, glass cockpit option, and stretched fuselages up to 188 seats. Distinctive flat-bottomed engine nacelle accommodates short landing gear. 1,988 built between 1984 and 2000.
737 Next Generation (737-600 / -700 / -800 / -900ER)
1997 substantial redesign with new wing, larger horizontal stabiliser, CFM56-7B engines, full glass cockpit, and 130-220 seat capacity. Most successful narrow-body of its era; over 7,100 airframes delivered between 1997 and 2019.
737 MAX (737-7 / -8 / -9 / -10)
2017 re-engining with CFM LEAP-1B turbofans, repositioned engines, split-scimitar winglets, and 130-230 seat capacity. Grounded 2019-2020 after two fatal MCAS-related crashes; recertified November 2020. The current production family.
Military variants (P-8 Poseidon / E-7 Wedgetail / VC-25)
Maritime patrol (P-8 Poseidon), AEW&C (E-7 Wedgetail), and presidential transport (VC-25, replacing the older 707-based Air Force One) variants based on the 737NG and MAX airframes.

Notable Operators

Southwest Airlines
Largest single 737 operator with 800+ airframes — the world's only major carrier with an all-737 fleet. Pioneered the low-cost, point-to-point model around the 737's standardised operating economics.
Ryanair / easyJet / WizzAir
European ultra-low-cost carriers with 500+ 737 / A320 family airframes between them. Ryanair operates an all-737 fleet of over 600 airframes; easyJet and WizzAir operate the competing A320 family.
United Airlines / American Airlines / Delta Air Lines
U.S. legacy carriers with mixed 737 NG / MAX fleets typically of 200-400 airframes each, paired with A319/A320/A321 fleets at most operators. United's launch order for the original 737 in 1965 made it the type's first operator.
Other major operators
China Southern Airlines (200+), Air China, Turkish Airlines, IndiGo (in transition to A320neo), Lion Air, Gol, AeroMéxico, Norwegian, and approximately 200 other airlines worldwide. The 737 is the most widely operated airliner in history.

Frequently Asked Questions

Why is the Boeing 737 the most-produced airliner ever?

The 737 entered the airline market in 1968 just as short-haul jet travel was becoming mainstream, faced limited single-aisle competition (the Douglas DC-9 was its only rival until the A320 launched in 1988), and benefited from Boeing's continuous incremental upgrades — Original to Classic to NG to MAX — that kept it economically competitive across six decades. Southwest Airlines' single-type fleet model, then replicated by Ryanair, easyJet, WizzAir, and dozens of other LCCs globally, drove enormous demand for the type. Total deliveries reached 12,486 airframes by end-2025, more than double the next most-produced airliner (A320 family at ~12,500). (Boeing 737 MAX programme)

What was the 737 MAX MCAS crisis?

The Maneuvering Characteristics Augmentation System (MCAS) was a flight-control software addition introduced on the 737 MAX to compensate for the aircraft's tendency to pitch up at high angles of attack — caused by the larger LEAP-1B engines being mounted further forward and higher than on previous 737 variants. MCAS automatically commanded nose-down trim if it detected high AOA. On Lion Air Flight 610 (29 October 2018) and Ethiopian Airlines Flight 302 (10 March 2019), faulty single-channel AOA sensors triggered MCAS to repeatedly push the nose down, overpowering pilot input and crashing both aircraft (346 fatalities total). FAA grounded the worldwide 737 MAX fleet on 13 March 2019. The grounding lasted 20 months until November 2020, after MCAS hardware redundancy, pilot training, and stringent recertification.

Why does the 737 have flat-bottom engine nacelles?

The 737's short landing gear was designed in 1964 around the JT8D engine, which sat far above the wing. When Boeing introduced CFM56-3 high-bypass turbofans on the 737 Classic in 1984, the larger engine wouldn't fit under the wing without raising the landing gear (an enormous cost). Instead Boeing flattened the bottom of the engine nacelle, shifted the gearbox accessories to the side, and brought the intake to a slightly oval cross-section. The flat-bottom nacelle remained on the NG and is one of the family's most distinctive visual features — and a contributing factor to the MAX engine repositioning that triggered MCAS.

How does the 737 compare to the Airbus A320?

Direct competitors in the same market segment with broadly similar economics. The A320 is approximately 16 inches wider in the cabin, allowing 18-inch seats vs the 737's 17-inch standard, and uses fly-by-wire flight controls (the 737 retains conventional cables). The A320 family also has a unified cockpit philosophy with later Airbus widebodies easing pilot retraining. The 737 has slightly better fuel economy on short missions and lower trip costs in some configurations. Airline preference largely tracks legacy fleet decisions — Southwest, Ryanair, and Alaska are 737-only; easyJet, WizzAir, JetBlue (US), and IndiGo are A320-only; United, American, Delta, and Air Canada operate both.

Will the 737 ever be replaced?

Eventually, but not soon. Boeing has explored a clean-sheet narrow-body replacement (variously called the New Mid-Market Airplane, FSA, or 797) since 2017, but the 2018-2019 MAX crisis, the Covid-19 demand collapse, and Boeing's broader certification, supplier, and labour issues pushed any clean-sheet timeline well into the 2030s. The 737 MAX is expected to remain in production through at least 2035, with a replacement entering service in the late 2030s or early 2040s. Airbus is in a similar holding pattern with the A320neo family.

What's the difference between the 737 MAX 8 and MAX 10?

Length, capacity, and landing gear. The MAX 8 is 39.5 m long with up to 178 seats; the MAX 10 is 43.8 m long with up to 230 seats. The MAX 10 also has a stretched main landing gear that telescopes during rotation to give clearance — required because the longer fuselage would otherwise strike the runway during normal takeoff rotation. The MAX 10 is roughly the same length as the original Boeing 757-200 and competes directly with the larger A321neo / A321XLR. It entered service with United Airlines in 2024.

What's the difference between the 737 NG and MAX?

Engines, winglets, and avionics. The MAX uses CFM LEAP-1B turbofans (~14% better fuel economy than the NG's CFM56-7B), split-scimitar winglets (vs the NG's blended winglets), and an upgraded cockpit display suite with larger PFD/MFDs. Aerodynamically the engines are larger, mounted further forward and higher than on the NG — which created the high-AOA pitch-up tendency that MCAS was designed (badly, as it turned out) to compensate for. The MAX is also slightly heavier, slightly faster, and approximately 6-8 dB quieter than the NG.

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