AvGeekery for beginners: How to tell Boeing 737s apart

Jan 7, 2021

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The Boeing 737 is the original workhorse of aviation. Since its release in 1967, Boeing has made more than 11,000 units.

It is the most popular commercial aircraft of all time. Boeing says that on average in 2019, over 2,000 Boeing 737 aeroplanes were in the air at any given time, and one 737 took off or landed every 2 seconds. Amazing really.

But, how can you tell them all apart? And for that matter, with the Airbus A320 family now sporting blended winglets, how can you differentiate between it and the Boeing 737?

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United 737 and other aeroplanes at LAX Airport 2019. (Photo by Alberto Riva/TPG)

The 737 versus the A320

An Alaska Airlines Boeing 737. (Image courtesy of Alaska Airlines)

The Boeing 737 is similar to the Airbus A320 family of aircraft. Indeed, the A320 was developed as a response to the utter domination of the Boeing 737 in the marketplace.

First, the Boeing 737 has a pointier nose than the Airbus A320. It just looks…angrier. The flight deck windows feature that Boeing touch—a “V” shape. The A320 has a notched upper on the aft cockpit window. Finally, the Boeing 737 vertical stabiliser—that fin at the back of the plane—has a triangular shape where it attaches to the fuselage; the A320 family do not.

Related: Why I prefer an Airbus A320 to a Boeing 737

NEW YORK – AUGUST 24 : A Boeing 737-990 (ER) operated by Alaska Airlines takes off from JFK Airport on August 24, 2019 in the Queens borough of New York City. (Photo by Bruce Bennett/Getty Images)

The Variants

This Lufthansa Airlines Boeing 737-100, seen here on February 26, 1968, was later sold to China. (Photo by © Museum of Flight/CORBIS/Corbis via Getty Images)

The Boeing 737 is a large family with several variants over the years.

  • The 100 and 200 series are the original variants; none of which are flying passengers in the U.S.
  • The Classics: 737-300, 737-400, 737-500; none of which are flying passengers in the U.S.
  • The NG: 737-600, 737-700/-700ER, 737-800 and 737-900/-900ER. Most of these are flying today.
  • The MAX: 737 MAX 7, 737 MAX 8, 737 MAX 8200, 737 MAX 9 and 737 MAX 10.

In each generation, the differences amount to stretch or shrunk variations. For example, WestJet still flies the Boeing 737-600, which is similar in size to the Airbus A318. Southwest is the largest operator of Boeing 737-700s in the world; it also operates Boeing 737-800s. (Spot them with blended winglets.)

A WestJet Airlines Boeing 737 is seen at New York LaGuardia Airport on Sept. 7, 2016. (Photo by Robert Alexander/Getty Images)

The Wingtips

A Delta Airlines Boeing 737-700 takes off from Atlanta. (Photo by Alberto Riva/The Points Guy)

A Boeing 737 will typically have either blended wingtips, split scimitar winglets or the special winglets that are found on the MAX. The split scimitar is an add-on to a blended winglet—literally bolted on to the bottom of the wing tip.

“Basically, the newer the 737, the more stylish are the winglets,” writes Chris Brady, who runs the Boeing 737 Technical Guide, has flown all manner of Classics, NG and the A320. “The 737 Classics, built until 1999, don’t have winglets, although a few have been retrofitted with them.”

“The first 737NGs weren’t built with winglets either as they were only certified in 2000 and for a while were optional. Split scimitar winglets came into service in 2014 and the MAX has a very angular winglet, not curved.”

A Southwest Boeing 737-700 takes off from the Atlanta airport (Photo by Alberto Riva/The Points Guy)

The Engine

Alaska Airlines 737-900ER at SFO. (Photo by Clint Henderson/The Points Guy)

The Boeing 737 has a unique feature starting with the Classic models: the engine nacelle is not perfectly round, but has a flat bottom and is seemingly very close to the ground. If it looks like hamster, well, that’s the nickname it gained. With the NG, Boeing needed to move the engine forward on the aircraft and needed an engine nacelle with a flat bottom so as to maximize ground clearance. Inside the engine, parts were moved around to the side from the bottom, and precious inches of clearance were gained. In addition, from the side you’ll notice the Boeing 737 engines are shifted far forward of the wing.

The Boeing 737 MAX aircraft sport engines that have chevron nacelles, just like the Dreamliner. That, plus its sharp wingtips, makes it easy to spot in the Boeing parking lot.

(Photo by Stephen Brashear/Getty Images)

The Emergency Exits

As the Boeing 737-NG aircraft are each stretch or shrunk models of the main version, the Boeing 737-700, the emergency exits are a tell tale difference between the aircraft. This makes sense; as the plane is stretched out and more seats are added, more emergency exits are required. The 700 has one emergency exit door over the wing, the 800 and 900 each have two. And because the 900 is the longest of them all, it has an additional emergency exit just behind the wing on each side.

737 Eastern Airlines taking off Miami. (Photo by Alberto Riva/TPG)

Its Nickname: FLUF

Frankfurt Airport FRA / EDDF Picture: CN-ROD Royal Air Maroc Boeing 737-7B6(WL) – cn 33062 / 1883 (Photo by Patrick Becker/ullstein bild via Getty Images)

Perhaps the best part about the Boeing 737? Its nickname is FLUF, which stands for “Fat Little Ugly F*cker”, a name given to it by pilots. And that’s not all; Brady has documented a variety of Boeing 737 nicknames.

We love it just the same.

Boeing 737-100, 200
  • Fat, Little and Ugly and mostly in museums
  • No scheduled passengers operators in the U.S.
  • No winglets
Boeing 737-300,400,500
  • No winglets
  • You’re not likely to spot the in the wild but freight versions fly in the U.S.
Boeing 737NG (600,700,800,900)
  • Easy to confuse with the Airbus A320 family of aircraft, its main competitor.
  • The 600 is Fat, Little and Ugly and mostly retired, flown by WestJet with no winglets.
  • Typically features blended or split scimitar winglets on later models.
  • The 700 has one emergency exit door over the wing, the 800 and 900 have two. The 900 has an additional emergency exit just behind the wing on each side.
  • More likely than not:
    • If its a Southwest livery, it’s a Boeing 737-700
    • If it’s American or United, its a Boeing 737-800
    • If its Delta, it’s a Boeing 737-900
Boeing 737 MAX
  • Distinct, long and sharply-angled winglets.
  • Chevron nacelles like the Dreamliner.

The 737 Max

A Boeing 737 MAX airliner piloted by Federal Aviation Administration (FAA) Administrator Steve Dickson lands following an evaluation flight at Boeing Field the in Seattle, Washington, on September 30, 2020. (Photo by Jason Redmond / AFP) (Photo by JASON REDMOND/AFP via Getty Images)

As we’ve been reporting the 737 MAX just returned to service after two deadly accidents grounded the aircraft for nearly two years. American Airlines flew paying passengers on a flight from Miami to New York on Dec. 29, 2020.

Two MAX jets crashed – Lion Air 737 MAX 9 in late 2018 and an Ethiopian Airlines 737 MAX 8 in March 2019. 346 people died in the crashes blamed, in part, on flight control systems software issues.

737 MAX jets at Renton, Washington Boeing assembly line. (Photo by Scott Mayerowitz/The Points Guy)

Hopefully, the relaunch of MAX service means the long successful career of the 737 family can resume again without issue.

Additional reporting by Clint Henderson.

Featured image of a Delta Airlines Boeing 737-700 taking off from Atlanta by Alberto Riva/The Points Guy. 

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