Boeing Co. said Thursday orders for its commercial jets fell 11 percent in August, as weaker demand for air travel forces airlines to scale back plans to buy new planes.

The Chicago-based airplane maker also said deliveries tumbled 22 percent compared with the same month last year. Still, Boeing says it remains on track to deliver a projected 480 to 485 planes this year, up from 375 in 2008.

Boeing has struggled with lower demand amid the economic slowdown, which has hurt its airline customers. It also has grappled with costly production problems related to its new 787, a lightweight plane built for fuel efficiency.

Repeated delays have put the 787 more than two years behind schedule. Boeing says it plans to conduct the first test flight of the plane by year's end and book a $2.5 billion charge for three of the test planes, which lack commercial value.

Days after announcing the latest 787 schedule, Boeing said on Monday that Scott Carson was stepping down as head of its commercial airplane division and would be succeeded by Jim Albaugh, the head of its defense business.

According to figures posted online Thursday, Boeing delivered 28 planes last month, down from 36 during the same month last year. Boeing, which receives payments when planes are delivered, has gotten a number of deferral requests and some cancellations from customers.

The deliveries consisted largely of single-aisle 737s, Boeing's best-selling model, as well as a smaller number of 777s.

The company received 32 orders in August. That's down from 36 in August of 2008.

Despite weaker demand for Boeing's commercial jets, the company has a record backlog of orders and operates a defense business that accounts for about half its overall revenue.

The 787 is by far Boeing's best-selling new plane to date. The company has garnered 850 orders, including 73 cancellations so far this year.