Boeing 737-400

Updated: October 2026 – Long tube, short wing, two exits over the wing: anyone who stood in Hanover, Palma or the Canary Islands in the 1990s very likely had the Boeing 737-400 in front of the lens. It was the largest version of the 737 Classic and popular with leisure airlines because it could carry up to 188 people on a medium-haul route. Here you learn why Boeing stretched the -300 once more, what role the -400 played in European charter traffic, what the Kegworth accident changed and where you find it today as a freighter or a combi memory.

What is the Boeing 737-400?

The 737-400 is a twinjet narrowbody for short and medium routes and the stretched member of the 737 Classic. Typical seating was about 147 to 168, up to 188 in dense charter layouts. Like its siblings, it is powered by two CFM56-3 engines from CFM International, and the range is about 3,800 kilometers – enough for routes from Germany to the Mediterranean and, depending on load, as far as the Canary Islands.

The Classic generation also includes the 737-300 and the shorter 737-500. Before it came the 737-100 and 737-200 with slim JT8D engines, and after it the Next Generation. You get the overview of all generations in the article How to tell the Boeing 737 Original, Classic, NG and MAX apart, and more about the manufacturer on the Boeing page.

Development: even more seats on the Classic fuselage

In the mid-1980s, the 737-300 was doing very well, but there was a gap between it and the much larger 757-200. Many airlines were looking for a successor to the aging 727-200 but wanted to stay with the family whose pilots, spare parts and maintenance they already knew. So in 1985, Boeing started work on a stretched 737.

The solution was comparatively simple: the -300 fuselage received additional sections ahead of and behind the wing and so grew by about three meters. More passengers meant more weight, so Boeing strengthened the wing spar and raised the maximum takeoff weight. Because the longer tail can touch the ground more easily on rotation, Boeing also mounted a tail skid under the rear fuselage. The larger cabin required two overwing exits per side – still the quickest recognition feature today.

Boeing left the wingspan itself practically unchanged. That is why the -400 looks slightly out of proportion in profile: a long fuselage on a rather short wing. That sets it apart at first glance from the Next Generation, which got a completely new, much larger wing.

The powerplant also stayed with the proven. The -400 uses variants of the CFM56-3 with the typical flat-bottomed inlets, mounted ahead of the wing on short pylons. Why the engines look like this is explained in the article How to recognize engines; for the heavier -400, the higher-thrust versions of the engine were available.

First flight, launch customer and production

In June 1986, the US airline Piedmont Airlines gave the go-ahead with an order for 25 aircraft and 30 options. The first -400 rolled out of the hangar on January 26, 1988 and made its first flight on February 19, 1988. In fall 1988, it entered scheduled service with Piedmont. This refers to the historic Piedmont, which was absorbed into USAir shortly afterward – not today’s regional subsidiary, which is distinguished on the Piedmont Airlines page. The -400 later also flew in the network of US Airways.

By the end of production, 486 aircraft had been built. The last two went to ČSA Czech Airlines on February 28, 2000 – they were also the very last 737 Classics Boeing delivered. Its successor in the Next Generation became the 737-800, which entered service from 1998 and, with its new wing, flies much farther.

An important operator in North America was Alaska Airlines, which used 40 aircraft in total from 1992. In March 2018, the airline’s last passenger -400s flew – making Alaska the last major airline with the 737 Classic in regular scheduled service.

Kegworth: the accident that changed rules

Only a few months after entering service, the -400 went through its darkest hour. On January 8, 1989, an almost new aircraft of British Midland, registration G-OBME, was en route from London Heathrow to Belfast. A fan blade broke in the left engine. However, the crew shut down the intact right engine, wanted to divert to East Midlands – and shortly before the runway, the damaged left engine failed as well. The aircraft hit the embankment of the M1 motorway near Kegworth. 47 of the 126 people on board lost their lives, 79 survived.

The investigation led to numerous safety recommendations. The remaining 737-400s were temporarily grounded at the time and their engines modified, because the blades had gone into vibration at high power. New or heavily revised engines must since be tested under realistic flight conditions, and the analysis of the injuries fed into a revised brace position for passengers. The crash site lies only a few kilometers from today’s Aeropark East Midlands; more about the airport is on the East Midlands Airport page.

The -400 in European leisure flying

In Europe, the 737-400 was above all a vacation aircraft. Charter and leisure airlines usually sell their capacity in fixed blocks to tour operators, and every additional seat on the way to Mallorca or Antalya pushes down the cost per passenger. That is exactly what the -400 was built for: many seats, medium-haul range and technology that maintenance shops already knew from the -300. How charter and scheduled traffic differ is explained in the article Charter flights and scheduled flights.

Hapag-Lloyd Flug from Hanover is the airline you associate most strongly with the -400 in Germany. From 1988, the company replaced its older fleet with A310s as well as 737-400s and -500s – the smaller Boeings also because they suited regional airports well. The first -400 arrived in 1989, by 1993 there were already eleven in the fleet, and at the peak there were 16 aircraft with 167 seats each. They flew from many German airports to destinations on the Mediterranean and in the Canary Islands. From 1998, the 737-800 gradually took over, and in 2004 the last -400 left the fleet. You can read more about the airline and its transition to TUIfly at Hapag-Lloyd Flug.

Air Berlin also had the -400 in its fleet in the 1990s alongside other 737 Classics, before the airline switched to the Next Generation and Airbus. The look back at the history of Air Berlin puts those years in context.

Operator	Role of the 737-400	Note
Piedmont Airlines	Launch customer, scheduled service from fall 1988	historic airline, later part of USAir
Hapag-Lloyd Flug	Leisure and charter flying from 1989	up to 16 aircraft, last one handed back in 2004
British Midland	Scheduled service in the UK	Kegworth accident 1989
Alaska Airlines	Scheduled, combi and cargo	Combis until 2017, passenger -400 until 2018
ČSA Czech Airlines	Scheduled service	last delivery in February 2000

If you want to go spotting at vacation airports today, you will find almost only the Airbus A320 family and the 737 NG or MAX there. You can see how the picture has changed in the guides to plane spotting in Mallorca and plane spotting in the Canary Islands.

Combi and freighter: the second life

When the passenger airlines gave up their -400s from the 2000s on, many airframes were still technically fit. Their size is ideal for express and mail traffic on short and medium routes, so a conversion paid off. The freighter versions go by designations such as 737-400SF (Special Freighter) or 737-400BDSF (Bedek Special Freighter) – you find details on the page for the 737-300SF and -400SF.

Alaska Airlines played a special role. It was the first to convert a -400 into a freighter with room for ten pallets and in 2006 and 2007 also turned five aircraft into combis: cargo traveled in the front part of the cabin, and up to 72 passengers sat in the back. That way, the airline supplied communities in Alaska without a road connection with people and goods in a single flight. In October 2017, the combis retired, and converted 737-700 freighters took over their tasks.

In Europe, the -400 today flies mainly on behalf of the express services. The Spanish Swiftair has several 737-400SFs in its fleet, some of which fly for DHL. A Swiftair aircraft crashed in November 2024 on approach to Vilnius, and one crew member was killed. ASL Airlines Ireland also operates a 737-400SF. How the big parcel networks work, you can read under Express integrators DHL, FedEx and UPS.

In the long run, larger conversion freighters like the 737-800BCF are replacing the Classic freighters. How to identify freighters in general is explained in the article How to recognize cargo aircraft.

How to recognize a 737-400

In the field, three steps are usually enough to place a -400 reliably.

How to check such features systematically is explained in the introduction Recognizing aircraft types for beginners.

Common mix-ups and how to rule them out

The trickiest mix-up is with the 737-800. Both have two overwing exits and flattened engine inlets, but the -800 is longer still and carries a much larger wing with a span of over 34 meters, usually with winglets. Next to the -800, the -400 looks short-winged and stretched out. Also watch the tail: the NG tapers more sharply, the Classic more bluntly.

Where to see the 737-400 today

In European passenger traffic, the -400 has practically disappeared. Your best chances are at cargo and express hubs, above all at night and at the edges of the day. In Germany, the observation deck at Leipzig/Halle Airport, the big DHL hub, is worth a visit – more about the airport on the Leipzig/Halle Airport page. In Belgium, the spotting place at Liège Airport is a good address for older narrowbody freighters, and in the UK the Aeropark East Midlands.

Whether a -400 is in circulation at the moment depends on the schedule and on substitute aircraft. An alert for the type saves you a lot of waiting. You can find more tips for hunting rarities in Spotting rare aircraft.

Photo tips for the 737-400

Which focal length is good for what is explained in Lenses and focal length for plane spotting, and how to plan the light in advance is covered in Planning the sun position for your photo spot.

Conclusion

The 737-400 was Boeing’s answer to packed leisure flights and the farewell to the 727: a stretched Classic fuselage with up to 188 seats, two overwing exits and a tail skid. In Germany, Hapag-Lloyd above all defined it; worldwide 486 were built before the 737-800 took over. The Kegworth accident made aviation safer, and as a freighter and combi, the -400 proved how versatile a medium-haul airframe can be. Today it is a rarity that you can still catch at express hubs with a bit of planning.