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. All have the somewhat pointed nose of the early Boeing jets, the 707, 727 and 737. This nose helps best in recognising the 737 from similar models.
Within one generation the main difference between subtypes is the length of the fuselage. Then it helps looking at the number and location of (emergency) doors to tell the exact subtype. To differentiate between the four generations 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
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. Also notable is the absence of a ("real") triangular dorsal fin compared to later versions.
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
Apart from more subtle differences the Boeing 737 has - compared to the A320 family - a more pointy nose, different cockpit windows, a smaller dorsal fin and smaller nose landing gear doors when the gear is extended.
The 737 can best be distinguished from the Dassault Mercure by its cockpit windows and engines nacelles.
The Boeing 737-300 is the first of the 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, with a separate fan exhaust. Quite characteristic is the flattened bottom of the nacelle. Moroever, the vertical stabiliser now has a dorsal fin.
However, the differences with the Next Generation family are more subtle. The 737-600/700/800/900 have a larger vertical stabiliser and a larger wing span. The latter is most apparent when you view the aircraft from the front. It concerns the part of the wing outside the trailing edge flaps. Winglets are no good recognition point, because there are classic 737-300s with winglets and NG 737s without. The classics have no 'split-scimitar' winglets though.
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).
It is most difficult to distinguish from a Next Generation 737-800. The -800 has a larger vertical stabiliser and a larger wing span, being the part of the wing outside the trailing edge flaps. This is best visible when you view the aircraft from the front. Winglets could be an additional recognition point, because winglets are not available for the -400 and nearly all 737-800s have them.
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!
Comparing the -500 to the Next Generation 737s is easier, because the smallest member, the 737-600, has a significantly larger vertical stabiliser. This makes it stand out compared to a 737-500. Note that 737-500s can be refitted with blended winglets.
The 737-600 is the smalles of the 'Next Generation' (NG) family. 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, 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 photos of the Southwest 737-300 above and the Luxair 737-700 below and you will see what I mean.
Other differences with regard to the -500 are the slightly less flattened engine cowlings.
No 737-600 have been fitted with winglets.
Boeing 737-700, 700C, -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.
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. All 700Cs have been delivered as C-40A Clipper of the US Navy.
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.
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. It was first delivered to Australia, where it was nicknamed "Wedgetail". This name stayed even for other customers. It is officially designated E-7.
Boeing 737-800, 800BCF, Boeing Business Jet (BBJ2) & P-8 Poseidon
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.
Boeing has developed a freighter conversion of the -800 which is dubbed 737-800BCF. It has a large cargo door in the left side, forward of the wings.
The BBJ2 is the corporate jetliner version of the 737-800. It is not recognisable from the standard model.
Finally 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.
Boeing 737-900, -900ER & Boeing Business Jet (BBJ3)
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 exits on each side), unlike the -900ER.
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.
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. 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.
Boeing 737-8 (MAX8 and MAX200) & BBJ MAX8
The 737 MAX8 has the same length as the 737-800, so it is much longer than the 737 MAX7 and 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).
To distinguish the MAX8 from the MAX200 - which has the same length - look at the existence of an extra (large) emergency exit behind the wing: the MAX8 does not have this.
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 MAX200 and larger MAX10 because all models have an extra emergency behind the wing and the only apparent difference is the fuselage length. The only way to recognise a MAX10 may be its modified, levered landing gear.
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.