Boeing 737-900ER. Photo: Boeing

Boeing (NYSE:BA) reported its first-quarter 2014 earnings results on Wednesday. The bad news is that Boeing's defense, space, and security unit reported a first-quarter total revenue decline of 6% compared to the same time last year. The good news is that Boeing's commercial airplanes unit reported a revenue increase of 19%, and a significant backlog of $374 billion -- again, that's just for commercial airplanes. Here's what else you need to know. 

Bring on the billions
When it comes to defense contractors, Boeing is one of the biggest in the world. However, its defense segment pales in comparison to its commercial airplane unit. For example, Boeing's total backlog at quarter-end was $440 billion, but only $66 billion came from defense. Yes, $66 billion is a significant number -- especially when you consider that the top defense contractor in 2013 by defense profits, Lockheed Martin (NYSE:LMT) reported an order backlog of $79.6 billion as of March 30 -- but it's nowhere near the size of Boeing's commercial airline backlog.

As such, when looking at Boeing's future, the primary thing to watch is Boeing's commercial airplane segment.

Boeing's commercial airplanes unit

Depicted here is a Boeing 737-800 in Air Lease Corporation livery. Photo: Boeing.

In its Q1 report, Boeing's commercial airplanes segment reported over $12.7 billion in revenue, as well as an increase to its operating margin of 0.4 points, bringing it up to 11.8%. However, the thing that's most impressive is Boeing's commercial airplane deliveries. For its first quarter, it delivered 161 planes, which is an increase of 18% compared to the same time last year.

Further, in its first-quarter report, Boeing states; "During the quarter, the 787 program reached a 10 per month production rate and completed preliminary design review on the 787-10. ... In April, the 737 program reached a production rate of 42 per month." Considering the 737 is Boeing's most popular plane when it comes to orders, a production rate of 42 per month is great news.

This is important because while a backlog of $374 billion for commercial airplanes is great, it means little if Boeing can't deliver them. Consequently, Boeing's increase in deliveries is good news for investors.

What to watch going forward
Boeing's first-quarter 2014 earnings report is welcome news for investors. In addition to the increase to deliveries, Boeing raised its core earnings per share guidance for 2014 to between $7.15 and $7.35, up from $7.00-$7.20. Further, overall revenue increased 8% despite a loss in defense revenue, operating cash flow increased to $1.1 billion, and Boeing reported $19 billion in net orders during the quarter. Plus, with a backlog of $440 billion, Boeing's future looks solid. However, investors would do well to continue monitoring Boeing's deliveries. Right now, deliveries are going well, and providing Boeing with significant profits. But, that's not a guarantee that deliveries will continue to go smoothly. So, while there's not cause to worry right now, it's still something investors should keep an eye on.

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.