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Boeing 737

The Boeing 737 is the most popular twin jet airliner in the world. More than 10,000 aircraft have been built spread over four generations of the 737. The aircraft is quite a generic overall appearance: low mounted swept wings with two engines under the wings and horizontal stabilisers attached to the rear fuselage. All have the somewhat pointed nose of the early Boeing jets, the 707, 727 and 737, including the V shaped bottom edge of the cockpit side windows. Early versions also have two eyebrow windows on each side, which may be painted over. Also common to all versions is the all two wheel gear, of which the nose gear has large gear doors and the main gear has no covers for the wheels at all.

The nose of the Boeing 737, still with eyebrow windows, used until the 737NG. Also note the V shape of the bottom of the cockpit side windows and large nose gear doors.

No Boeing 737 has main gear doors. The wheels become flush with the fuselage when retracted. Hence they have streamline covers on the rims.

Different versions

To differentiate between the four generations of Boeing 737 variants you have to look at

  • the length of the fuselage
  • the shape of the engine nacelles
  • the wing span outside the flaps
  • the shape of the tailcone
  • the height of the vertical stabiliser
  • the shape of the dorsal fin
  • the number and location of cabin doors and emergency exits
  • the shape of the main gear

Boeing 737-100

Of the first version of Boeing 737, the 737-100, only thirty were produced, mainly for Luft­hansa. Characteristic for both the 737-100 and 737-200 are the long, slim engine nacelles, extending behind the wing trailing edge. These have clamshell thrust reversers. Also notable is the absence of a triangular dorsal fin compared to later versions.

The Boeing 737-100 is quite difficult to distinguish from the 737-200, but appears to be oddly short.

Original Boeing 737s, 100 and 200 series, have long nacelles with a single exhaust and clamshell thrust reversers at the rear.

Boeing 737-200, -200 Advanced, -200C & -200QC

It is quite difficult to distinguish the 737-200 from the 737-100, because basically it is only the length of the fuselage that is different: the 200 is about 1.5 m longer than the 100 series.

The Boeing 737-200 Advanced is externally nearly the same as the original 200, as the changes are longer nacelle/wing fairings, an improvement to the flap system, more powerfull engines and a greater fuel capacity.

Nineteen 737-200s were ordered by the US Air Force for training navigators. It has far fewer cabin windows than standard 737-200s. They are designated T-43A. Six were later converted to executive transports, under the designation CT-43A. One T-43A was converted to a radar test bed aircraft, as NT-43A.

The 737-200C and -200QC are respectively the Convertible and Quick Change variants of the basic 200 series. Both have a large cargo door on the left side, in front of the wing. Some­times the cargo door is not clearly visible, but you can also recognise the version by the two cabin windows close together, at the end of the door.

Confusion possible with

Airbus A320 family

a320

Apart from more subtle differences the A320 family has - compared to the 737 family - a less pointed nose, different cockpit windows without the typical V shape, a smaller dorsal fin, fully enclosing main landing gear doors and smaller nose landing gear doors when the gear is extended.

Dassault Mercure

mercure

The 737 can best be distinguished from the Dassault Mercure by its engines nacelles and cockpit windows. The Mercure has long nacelles with a conical plug in the exhaust. The last cockpit window has a triangle shape; there is just one eyebrow window.

Airbus A220

cs300

Formerly known as the Bombardier CSeries the Airbus A220 has the same basic configuration as the Boeing 737. The A220 has four cockpit windows, a flat tail cone, oval cabin windows and canted winglets as main recognition points.

The Boeing 737-200 is longer than the 737-100, but still has one overwing emergency exit.

The T-43A navigation trainer, based on the 737-200, has far fewer cabin windows than the regular version.

The Boeing 737-200C has many cabin windows but also a large cargo door. Note the closer spaced cabin windows at the right edge of the door, marked by the arrow.

Boeing 737-300

The Boeing 737-300 is the first of the second generation, now called 'classic' family, with the 737-100/200 being the 'orginal' series. The difference compared to the original 737s is easy: the engine nacelles are shorter, and have a larger diameter and separate fan exhaust. Quite characteristic is the flattened bottom of the nacelle. Moreover, the vertical stabiliser now has a triangular dorsal fin.

Originally, 737-300s were delivered without winglets. They can however be equipped afterwards with tall blended winglets from the wingtip up. Sometimes these are referred to as 737-300SP.

The 737-300 was the first member of the second generation, and the middle one regarding length. It has one emergency exit.

The original wing tip of a 737-300. Note the relatively short span outside the trailing edge flaps compared with the 737NG.

Boeing 737-300s can be retrofitted with blended winglets. These tall winglets only point up from the wing tips.

The second generation 737s have the flattest bottom of the engine nacelles of all 737 variants.

Boeing 737-300F

Several companies offer cargo conversions of 737-300, after which they are known as 737-300F or 737-300BDSF, depending on the company that performed the conversion, Pemco or IAI Bedek. In both cases a large cargo door is installed in the left front fuselage and cabin windows are replaced by metal plugs.

A Classic Boeing 737 without cabin windows but with a single overwing emergency exit, so this is a 737-300F or 737-300BDSF.

Boeing 737-300QC

The Quick Change (QC) version of the 737-300 has a large cargo door, but retains the cabin windows.

The Boeing 737-300QC has a large cargo door but also many cabin windows.

Boeing 737-400

The Boeing 737-400 is the longest of 'classic' family, with a fuselage stretched about 3.5 m compared to the 737-300. To accommodate the larger number of passengers, the number of overwing exits is two on each side compared to one for the 737-300 and -500.  For the rest the 737-400 is the externally the same as the 737-300, except that they cannot have winglets.

The Boeing 737-400 is longer than the 737-300 and has two overwing emergency exits.

Boeing 737-400SF

This is the cargo version of the Boeing 737-400, converted from passenger aircraft. The cabin windows have been replaced by metal plugs. The 737-400SF is still recognisable by the two overwing emergency exits on each side.

The Boeing 737-400SF without cabin windows, except for the ones in the two overwing emergency exits.

Boeing 737-500

After the 737-400 Boeing developed the shorter 737-500, as a more direct replacement for the original 737-200. It has about the same dimensions as that aircraft, but of course has the characteristics of a 'classic' 737. Like the 737-300 it has one overwing exit on each side. It is only the length that helps you identify a -500, so count the cabin windows if you are in doubt. Like the 300 series the 737-500s can be equiped with blended winglets, after which they may be called 737-500SP.

The Boeing 737-500 is 2.4 m shorter than the 737-300, which is visible to the trained eye.

Boeing 737-600

The 737-600 is the smallest of the 'Next Generation' (NG) family, the third generationof the Boeing 737. It is comparable to the 737-500 in length, but has the properties of the rest of the NG series. What is most apparant is the larger vertical stabiliser of the NG, on the -600 in particular. Further­more the NG series have an increased wing span compared to the Classic 737s. This concerns the part outside the trailing edge flaps. You can see it well when you see a Classic and a Next Gene­ration from the front, side-by-side. Compare the detail photos of the 737-300 above and the Next Gene­­ration one below and you will see what we mean. Other differences with regard to the second generation are the slightly less flattened engine cowlings.

No 737-600s have been fitted with winglets, unlike longer members of the Next Generation 737s.

The Boeing 737-600 appears as long as the 737-500, but clearly has a larger vertical stabiliser.

Wingtip of the 737NG and 737MAX series, with a longer part outside the trailing edge flaps compared to the 737 classic.

The tail cone of 737-100/200, 737 Classic and 737 Next Generation series is the same, but different from the MAX's.

The engine nacelles of 737 Next Generation are slightly more rounded than those of the Classic series, but still have a flattened bottom.

Boeing 737-700, -700ER & Boeing Business Jet (BBJ1)

The first 'Next Generation' (NG) family was the 737-700. It is comparable to the 737-300 in length, but has the properties of the rest of the NG series: a larger vertical stabiliser, an increased wing span and the slightly less flattened engine cowlings. Because of the relative dimensions of the vertical tail compared to the fuselage length, the 737-700 is most often confused with the 737-500.
Most 737-700s have been fitted with blended winglets, but there are still a few without winglets.

To compete with the Gulfstream and Bombardier large cabin jets Boeing mated the fuselage of the 737-700 and the (heavier) wings and landing gear of the 737-800 to create the Boeing Business Jet (BBJ). Externally it is not different from the standard 737-700. After the introduction of the corporate version of the 737-800 the original BBJ became known as BBJ1.

The US Air Force operates the BBJ as the C-40B and C-40C. The main difference between the B and the C model is the communication systems, which are more advanced for the C-40B to allow it to be used as an "office in the sky" for senior military and government leaders. The C-40C is more a basic passenger transport aircraft.

ANA All Nippon Airways was the launch customer for the 737-700ER, where ER stands for Extended Range. Just as the BBJ is has the wings and undercarriage of the 737-800, to allow a higher maximum take-off weight to carry the extra fuel for the longer range. It is externally the same as the standard 737-700.

Originally, Boeing 737-700 were delivered without winglets. Nowadays few are left without.

C-40B Clipper is the designation of the US military variant of the Boeing Business Jet (BBJ1).

Here you see a Boeing 737-700 with blended winglets, that only point up from the wing tips.

Boeing 737-700C

The 737-700C is a version with a large cargo door on the left side. This is what differentiates this version from other 737-700s. It still has many cabin windows. Most 700Cs have been delivered as C-40A Clipper of the US Navy.

The Boeing 737-700C convertible is quite a rare aircraft, as only a handfull commercial versions have been delivered. (photo: Eric Salard/WikiMedia)

Most 737-700Cs are transport aircraft for the US Navy, designated C-40A Clipper by them.

Boeing 737-800 & Boeing Business Jet (BBJ2)

The most popular NG version is the 737-800, built as successor of the 737-400. So it has about the same length as the -400 but a larger vertical stabiliser, wider wingspan and more rounded engine nacelles. Compared to the 737-600 and -700 it has two overwing exits on both sides. Nearly all 737-800 have been fitted with winglets, the blended winglets and split-scimitar winglets.

The BBJ2 is the corporate jetliner version of the 737-800. It is not recognisable from the standard model.

A Boeing 737-800 with blended winglets and two overwing emergency exits.

Boeing 737-800BCF, 737-800BDSF & 737-800SF

Boeing has developed a freighter conversion of the -800. It has a large cargo door in the left side, forward of the wings. The cabin windows have been replaced by metal plugs. The marketing name depends on the holding of the supplemental type certificate, Boeing (BCF-Boeing Converted Freighter), IAI Bedek (BDSF, Bedek Special Freighter) or AEI (SF, for Special Freighter).

Three companies offeer a cargo conversion of the Boeing 737-800. This 737-800BCF is an 'official' Boeing version of the 800 series freighter. (photo: Windmemories/WikiMedia

Boeing 737-900

The Boeing 737-900 is the longest version of the Next Generation family. Compared to the -800 the fuselage is about 3 m longer. It is quite difficult to distinguish from the -800, because the standard -900 has the same door configuration (two main doors and two overwing emergency exits on each side), unlike the -900ER.

The standard Boeing 737-900, with two overwing emergency exits and two regular cabin doors.

Boeing 737-900ER & Boeing Business Jet (BBJ3)

To accommodate a higher number of passen­gers and still comply with regulations for eva­cua­tion the 737-900ER has a third emergency exit on each side, aft of the wing. Its size is in between the overwing exits and the main cabin doors. For the rest the aircraft is the same as the basic 737-900.

The BBJ3 is the corporate jetliner version of the 737-900ER. It is not recognisable from the standard model.

The Boeing 737-900ER has an extra emergency exit visible just behind the wing. Also note the split-scimitar winglets on this specific aircraft.

Boeing 737-7 (MAX7) & BBJ MAX7

The smallest member of the fourth generation Boeing 737, the MAX series, is the MAX7, desig­nated 737-7. It is slightly longer than the 737-700, but still significantly shorter than the next member of the family, the MAX8. Still, it has two overwing emergency exits. Therefore the length is the way to recognise the MAX7 from the larger MAX version. For the rest look at the characteristics of the MAX series: nearly round engine nacelles (compared to flattened at the bottom) with serrated fan exhausts, a longer tail cone and revised advanced technology winglets. The winglets are similar to the split-scimitar winglets available on the Next Generation aircraft, but have a but different shape.

The Boeing 737 MAX7 is the smallest member of the MAX series. Being slightly larger than the 737-700 it has two emergency exits over the wings. (copyright Boeing)

The serrated fan exhaust of the 737MAX are another key feature to recognise the MAX family.

The tail cone of the 737MAX series is more pointed than that of the earlier variants. It looks more similar to that of the 787 Dreamliner now.

Although still slightly flat at the bottom, the engine nacelles and air intakes of the 737MAX series are nearly round.

Boeing 737-8 (MAX8) & BBJ MAX8

The 737 MAX8 has the same length as the 737-800, so it is much longer than the 737 MAX7. It differs from the 800 series by the engine nacelles, tailcone and winglets (see description at 737 MAX7 for details about the characteristics of the MAX series). The standad 737-8 has two small emergency exits above the wings, like the 737-7.

The standard Boeing 737-8 (MAX8) has two overwing emergency exits, like the 737-7, but no larger door behind the wings.

Here is a detail photo of the MAX's winglets. Compared to the split-scimitar winglets of the 737NG they have no raked tips.

Boeing 737-8-200 (MAX8-200)

Especially for Ryanair Boeing created a high density vesion of the MAX8, marketed as MAX8-200 (or MAX200), because it can seat up to 200 passenger. It has the same length as the MAX8 and extra (large) emergency exit behind the wing: the standard MAX8 does not have this.

The Boeing 737 MAX8-200 has an additional large emergency exit behind the wings.

Boeing 737-9 (MAX9) & BBJ MAX9

Being the replacement for the 737-900 the 737 MAX9 has (nearly) the same length as its predecessor. The MAX characteristics (see description at 737 MAX7) make it easy to recognise from the 900 and 900ER. Still it may be difficult to distinguish the MAX9 from the MAX8-200 and larger MAX10 because all models have an extra emergency behind the wing and the only apparent difference is the fuselage length.

The Boeing 737-9 (MAX9) looks very similar to the 737-8-200, except that it is longer.

Boeing 737-10 (MAX10)

The 737 MAX10 is only about 1.5m longer than the 737 MAX9, which makes identification tricky, also from the shorter 737 MAX200 because all models have an extra emergency behind the wing. The only way to recognise a MAX10 is its modified, levered landing gear. This means that - when on the ground - the wheels on the main landing gear are slightly aft of the leg, not in the centre of the strut like on other 737 subtypes.

Boeing 737-10 (MAX10) (copyright Boeing)

Zooming in on the landing gear of the Boeing 737-10 you can see different position of the wheel compared to the strut.

E-7 Wedgetail

Boeing developed an airborne early warning & control version based on the 737-700ER frame, which can be recognised by the large bar on top of the fuselage. As this significantly disturbs the airflow, it has two ventral fins.

It was first delivered to Australia, where it was nicknamed "Wedgetail". This name stayed even for other customers; the Royal Air Force calls it Wedgetail AEW1. It is officially designated E-7 or E-7A though.

The E-7A Wedgetail has a large bar antenna on top of the fuselage. To compensate for its disturbance, ventral fins are placed under the rear fuselage.

P-8 Poseidon (Boeing 737-800A)

Boeing builds a maritime surveillance aircraft that is based on the 737-800. The main differences compared to the standard -800 are the raked wingtips and the lack of cabin windows, and of course the mission equipment. The US Navy designates the aircraft as P-8A Poseidon, Boeing as 737-800A. In UK military service the aircraft is known as Poseidon MRA1.

The P-8A Poseidon differs from the standard 737-800 mainly by the raked wingtips, multiple sensors and lack of cabin windows.