Boeing (BOE, Chicago O'Hare) is hoping to complete the certification of its smallest B737 MAX Family variant, the B737-7, and commence deliveries of the aircraft this year. However, the largest variant, the B737-10, will not deliver before 2023, two years behind the original schedule.

"This schedule reflects several factors, including an updated assessment of global certification requirements informed by continued discussions with regulators and resulting in a management decision to make modifications to the aircraft’s design," the manufacturer said in its annual report.

Having completed the recertification of the B737-8 and B737-9 - the two MAX variants that were in service before type's grounding in March 2019 - Boeing has now turned to certifying variants which have yet to secure regulatory approval.

The B737-7 was announced in 2011 and flew for the first time in March 2018. As such, it was close to certification when the family was grounded globally. The ch-aviation fleets advanced module shows that Boeing currently has 79 firm orders for the type (including four B737-7(BBJ)s) with Southwest Airlines (WN, Dallas Love Field) as the largest customer with 30 aircraft due.

In turn, the -10 was announced in 2017 in response to Airbus's success with the A321-200N and was originally due to start delivering in 2021. Boeing has firm orders for 467 B737-10s, including 128 from United Airlines (UA, Chicago O'Hare) and 106 from VietJetAir (VJ, Hanoi).

The third, as-yet-uncertificated, variant of the B737 MAX is the B737-8-200, a modified high-density B737-8 aimed at the low-cost segment. It is in the final stages of certification and due for initial delivery to Ryanair Holdings later this quarter.