The FAA has given Boeing the green light to start certification test flights of its long-awaited 737 MAX 10

• The FAA gave Boeing the green light to start certification flight testing of its 737 MAX 10.
• The variant is expected to enter service in 2024 after years of production delays.
• The 737 MAX 10 will rival Airbus' best-selling A321neo praised for its capacity and efficiency.

Boeing is one step closer to certifying its largest MAX variant.

In a memo sent to employees on Wednesday and viewed by Business Insider, the American manufacturer said the Federal Aviation Administration has granted a type inspection authorization for its 737 MAX 10.

This means the FAA's pilots can start certification flight testing, Boeing's senior vice president for development programs, Mike Fleming, 737 program head, Ed Clark, and testing lead, Wayne Tygert, said in the letter.

The 737 MAX 10 is one of Boeing's two MAX variants — the other being the MAX 7 — not yet certified to fly. The MAX 8, MAX 9, and high-density MAX 8200 are currently in service.

"With more than 400 flights and nearly 1,000 flight hours, the 737-10 has performed well in our own rigorous test program," the three executives wrote in the Wednesday memo. "Our entire team has remained focused on this goal, working with diligence and resilience in a dynamic environment."

The news comes after years of production delays due to increased scrutiny after two MAX planes crashed in 2018 and 2019, prompting aviation authorities to implement a worldwide grounding of the type.

The accidents were due to flaws in something called MCAS, which was a MAX-specific system that worked in the background to keep the jet from stalling.

But in both instances, MCAS fed erroneous data to the plane due to faulty angle of attack sensors and triggered a stall alert, forcing the jets to nose dive.

Boeing knew about this fault but did not consider it high-risk at the time, the Seattle Times reported. Both the MAX 8 and 9 were officially ungrounded in November 2020, and Boeing expected its 737 MAX 10 to enter service in 2022.

However, to mitigate risk after the accidents that killed 346 people, regulators required the reengineering of several MAX components — particularly the December 2022 deadline to add a new crew alert system to the cockpit.

Because the requirement did not apply to the already certified MAX models, it would make the MAX 10 flight deck different from the other variants and put off potential buyers who prefer commonality across cockpits as it saves money on pilot training.

Fortunately for Boeing, Congress granted the manufacturer a waiver so long as two specific safety enhancements are installed on every MAX variant starting three years after the MAX 10 is certified.

The 11th-hour success puts the MAX 10 on track to enter service in 2024 without the significant changes to the cockpit. Once in the hands of airlines, it will rival Airbus' narrowbody A321neo, which has won over airlines for its range, capacity, and efficiency.

According to Boeing, the MAX 10 will provide "more capacity and the lowest cost per seat of any single-aisle airplane," making it a particularly attractive alternative to widebody planes on lower demand, long-haul routes.

And despite its problems, hundreds of orders for the jet have been placed by global carriers, including United Airlines, Delta Air Lines, Ryanair, and Air India.