During 2018, Boeing (BA -1.38%) and Airbus (EADSY 0.23%) faced a difficult backdrop for winning new commercial aircraft orders due to trade tensions, slowing growth in China, and long order backlogs. Nevertheless, it looks like the past year was another solid one for both aircraft manufacturers.

However, one thing appears to have changed in 2018. Between 2013 and 2017, Airbus captured more aircraft orders than its American rival in each and every year. By contrast, based on the data currently available -- final order totals will be published in a week or two -- Boeing appears to have snapped Airbus' five-year winning streak.

The standings as of November

As of the end of November, Boeing had booked 690 net firm orders in 2018. This gave it a big lead over Airbus, which had captured 380 net firm orders.

Based on these results for the first 11 months of the year, Boeing was in good position to achieve a book-to-bill ratio of at least 1.0 -- meaning that new orders would at least match the number of aircraft deliveries for the full year. (Boeing probably delivered between 810 and 815 commercial jets in 2018.) By contrast, Airbus needed a huge December performance to match its planned full-year delivery total of approximately 800 aircraft.

A Boeing 737 MAX 9 flying over clouds

Boeing probably was able to at least match its production with new orders in 2018. Image source: Boeing.

Additionally, Boeing achieved a more diverse mix of orders in the first 11 months of 2018. Higher-value widebody aircraft accounted for approximately 28% of its net firm orders through November, compared to just 21% for Airbus.

Boeing looks to seal the deal

On Dec. 21, Boeing announced two noteworthy aircraft orders. Nigeria-based airline start-up Green Africa Airways ordered 50 737 MAX 8s and Saudi Arabia's flyadeal committed to buy 30 737 MAXs. That said, it isn't clear that either deal has been finalized yet. Based on language in the two press releases, it appears more likely that the order from Green Africa Airways became official before the end of 2018.

It's likely that there were other orders finalized last month, particularly from the large pool of commitments signed back in July at the Farnborough Airshow. Smaller deals often don't merit press releases. Moreover, it's pretty common for aircraft buyers not to want their orders publicized right away. (For example, in the first 11 months of 2018, Airbus booked 69 orders from "undisclosed" buyers and Boeing attributed 123 orders to "Unidentified Customer(s)".) Trade tensions have made many buyers even more eager to remain anonymous.

Considering that December tends to be the busiest month of the year in terms of aircraft orders, there's a good chance that Boeing was able to book the 120 to 125 net orders it needed to match its expected full-year production.

Airbus probably can't pull off another upset

In 2017, Airbus was in even worse shape at the end of November -- both in absolute terms and relative to Boeing. However, the European aerospace giant posted a record monthly order haul in December of that year. This included a record-setting order for 430 A320neo-family aircraft from U.S. airline investment firm Indigo Partners. Airbus' huge December 2017 performance helped it surge past Boeing to end the year with more than 1,100 net firm orders.

It's extremely unlikely that Airbus pulled off a repeat of this achievement last month. It only publicly announced one aircraft order during December: a deal with aircraft leasing company Avolon for 75 A320neos and 25 A321neos.

There will probably be some smaller deals and orders from unidentified customers included in Airbus' December 2018 order total. Still, the vast majority of the orders that Airbus booked in December 2017 were announced in a series of press releases during the month.

Airbus would need to book more than 300 additional net orders in December (aside from the Avolon deal) to match its 2018 production. It would also need at least that many orders to beat Boeing for a sixth consecutive year. That's probably too much to ask. Barring a huge surprise, it looks like Boeing finally surpassed Airbus in terms of annual aircraft orders in 2018.

Check out the latest Boeing earnings call transcript.