Boeing (NYSE:BA) ended a miserable year positively, with the return of the 737 MAX fueling an uptick in deliveries and boosting the aerospace giant to its best quarter of 2020.

The company reported 39 military and commercial deliveries in December, 27 of them 737 MAX planes. American Airlines Group took 10 of them and United Airlines Holdings took eight, in the early stages of working through a backlog of more than 400 planes that were assembled during the 20 months in which the 737 MAX was grounded.

A Boeing 737 MAX in flight.

Image source: Boeing.

The 737, including the MAX and other variants, make up more than 75% of Boeing's order book, and the plane's return meant an uptick in deliveries. The company delivered only 118 jets between January and November.

It delivered 59 commercial aircraft in the entire fourth quarter, 37% of the company's 157 plane total for 2020.

The return of the 737 MAX was the highlight, but there were worrisome signs as well. For the second straight month, Boeing delivered no 787 Dreamliners, ending the year with only four 787 deliveries during the fourth quarter. The Dreamliner has been plagued with its own quality issues and has seen demand plummet as airlines scale back international flying due to the pandemic.

By comparison, Airbus delivered 566 aircraft for the year, which was down from a record 863 deliveries in 2019.

Boeing heads into 2021 looking to build on the 737 MAX delivery momentum, while scaling back production of the 787 and other larger, wide-body aircraft. The company hopes to gradually build 737 MAX production to more than 30 per month in early 2022, well short of the 50-plus airframes it had hoped to build monthly prior to the grounding and the pandemic.

The backlog of 737 orders stood at 4,031 at year's end, compared to Airbus' 5,885 orders for the comparable A320 family.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.