Boeing 737 MAX 9

ICAO type code: B39M · Boeing · narrowbody airliner

737 MAX 9 at a glance

First flight

2017

Length

138 ft 4 in (42.2 m)

Wingspan

117 ft 10 in (35.9 m)

Engines

2 × CFM LEAP-1B turbofans

Seats

178–220

Cruise speed

~453 kt (521 mph) / Mach 0.79

Service ceiling

41,000 ft

Range

~3,300 nmi

How to recognize the 737 MAX 9

The MAX 9 combines the long fuselage of the 737-900ER with the new engines and wingtips of the MAX family. It looks long and slim, with noticeably fat engines under a wing that seems small for the body.

• Engines: big LEAP-1B nacelles with a round intake and sawtooth chevrons around the rear edge. They sit forward of and slightly higher than older 737 engines.
• Wingtips: the MAX split-tip winglet, with a tall upper blade and a short lower blade.
• Mid-cabin exit: behind the wing there is either an extra exit door or, on lower-density cabins like United's and Alaska's, a sealed "door plug" that looks like a door outline with a window but no handle.
• Tail: the sharper, extended MAX tail cone and a retractable tail skid for rotation.
• Stance: slightly nose-high when parked because of the taller nose gear.
• Sound: quieter than older 737s, with a smoother, lower-pitched engine note.

At cruise it leaves the usual pair of merging contrails. Length separates it from the MAX 8: about 9 ft more fuselage, most of it visible ahead of the wing.

Where and when you'll see it

United (callsign UAL) and Alaska (ASA) are the two big US operators. United flies MAX 9s across its domestic network and to Latin America, while Alaska uses them up and down the West Coast, to Hawaii and to Mexico. Copa and Aeromexico add more on flights into US gateways like Miami, Houston and Los Angeles.

Typical cruise is FL350 to FL410, with approaches flown at 2,000 to 3,000 ft and roughly 140 to 155 kt on final. On ADS-B it shows type code B39M with a mainline callsign. Over Seattle and Houston it is one of the most common arrivals of the day.

United uses the MAX 9 heavily on routes between its hubs and to sun destinations like Florida, Cancun and Puerto Vallarta, while Alaska runs it on busy West Coast corridors such as Seattle to Los Angeles and San Francisco. Morning and evening departure banks are the best times to look.

Easily confused with

• Boeing 737-900 / 737-900ER: The 737-900ER has the same length but smaller flat-bottomed engines with no chevrons.
• Boeing 737 MAX 8: The MAX 8 is about 9 ft shorter and has no extra exit or plug behind the wing.
• Airbus A321neo: The A321neo sits higher on its gear, has round engines without chevrons and curved sharklets.

Quick facts

• In January 2024 a door plug blew out of an Alaska Airlines MAX 9 shortly after takeoff from Portland, leading the FAA to ground MAX 9s with plugs for inspections.
• The MAX 9's plug exists because the extra exit is only required when airlines install high-density seating.
• Its first flight took place in April 2017 from Renton, Washington, where all 737s are assembled.

737 MAX 9 questions

Cities where it's a regular

Los Angeles · Chicago · San Francisco · Seattle · Denver · Portland · San Jose

Spot one live

Open the live sky tool and look for B39M in the type column, or browse the live map on airplanes.live.