Boeing · Narrowbody · In Production
Boeing 737 MAX 9
Robbie Klinkenberg — CC BY-SA 4.0
The Boeing 737 MAX 9 is a stretched, single-aisle narrow-body airliner powered by two CFM International LEAP-1B turbofan engines. Developed as the direct successor to the 737-900ER, it forms the upper-middle capacity tier of Boeing's fourth-generation 737 family, bridging the gap between the high-volume MAX 8 and the larger MAX 10.
Designed primarily for mainline network carriers and dense leisure routes, the aircraft offers competitive range and lower operating costs per seat-mile compared to its predecessors. However, its market trajectory has been shaped by intense competition with the Airbus A321neo and intensive regulatory scrutiny following industry-wide grounding events across the MAX product line.
By The Numbers
The Boeing 737 MAX family, which encompasses the stretched MAX 9 variant, continues to scale production as part of Boeing's wider single-aisle output targeting higher monthly assembly rates. Across the entire 737 MAX program, cumulative deliveries have surpassed 2,390 aircraft out of thousands of total firm orders, backed by a substantial multi-year backlog numbering over 4,800 jets.
The Boeing 737 MAX 9 is operated most heavily in North and South America and parts of the Middle East. Key high-volume operators flying the variant include United Airlines and Alaska Airlines in the United States, alongside international carriers such as Aeroméxico and flydubai, which utilize the high-capacity narrowbody across core domestic and regional international networks.
Manufacturing
Where It's Built
Final assembly of the Boeing 737 MAX 9 takes place primarily at Boeing's Renton factory in Washington state, with additional assembly operations located at the Everett facility. Major structural components and subassemblies are outsourced to specialized global tier-one suppliers: Spirit AeroSystems in Wichita, Kansas, manufactures the primary fuselage structure, which is transported by rail to final assembly. Wings and associated high-lift systems are largely built in-house by Boeing using advanced composite technology and local fabrication resources, while specialized control surfaces and structural fairings are sourced from an extensive international supply chain. Propulsion is provided by CFM International via the LEAP-1B engine program. Avionics suites, flight management systems, and display hardware are predominantly supplied by Rockwell Collins (now part of RTX Corporation) and Honeywell Aerospace.
Regarding program economics, a precise, standalone public development cost specifically isolated to the 737 MAX 9 variant has not been formally or transparently itemized by Boeing. Financial analysts and industry estimates historically placed the broader 737 MAX family's initial airframe development expenditure between $2.5 billion and $4.0 billion—significantly lower than an all-new clean-sheet design—though subsequent engineering redesigns, quality remediation programs, and regulatory compliance updates have escalated total enterprise program costs substantially past initial projections.
Notable Operators
Watch
Boeing 737 MAX 9 In Action
Takeoff from Seattle (SEA) - Alaska Airlines Boeing 737 MAX 9 (N971AK) | June 12, 2025
Boeing 737 MAX Advanced Technology winglet design unveiled
Safety Record
Notable Safety History
The Boeing 737 MAX 9 has been subject to official regulatory intervention and investigations regarding structural design integrity. On January 5, 2024, an in-flight structural failure occurred involving an unused mid-cabin exit door plug on an Alaska Airlines flight, leading to an uncontrolled decompression. The National Transportation Safety Board (NTSB) and the Federal Aviation Administration (FAA) initiated formal safety investigations into the incident.
Investigators discovered that four retention bolts intended to secure the mid-cabin door plug were omitted during assembly at the Renton factory. In response to the investigation findings, the FAA issued an Emergency Airworthiness Directive (EAD) mandating immediate inspections of all 737 MAX 9 aircraft equipped with the specific door plug configuration prior to further flight, alongside mandatory engineering and quality control procedural revisions for future manufacturing verification.
Covers officially investigated accidents only, per aviation safety authorities (NTSB, FAA, EASA, AAIB or equivalent).
Sources & Further Reading