NEW YORK (AP) — An executive from Boeing Co. said Tuesday the airplane maker continues to have a "very positive outlook on the commercial aerospace market" despite growing economic uncertainty.

Speaking at Deutsche Bank Aviation and Transportation Conference, Boeing's vice president of business development, Nicole Piasecki, said airlines are still buying new aircraft despite renewed fears about a slowdown in the U.S. and Europe. The order growth is being driven mostly by low-cost carriers in emerging markets like China and India.

But many airlines are also focusing more on fuel savings and looking to replace aging fleets with newer, more efficient models.

Delta Air Lines last month confirmed its plan to buy 100 Boeing 737 jets as part of a fleet upgrade, with delivery set for 2013 to 2018. American Airlines in July announced plans to split a massive order between Boeing and rival Airbus. It was the biggest plane order in history: 460 aircraft (260 planes from Airbus and 200 from Boeing) with options to buy 465 more. But the order spelled the end for Boeing's exclusive grip on the airline's fleet.

Piasecki said 20 percent of Chicago-based Boeing's commercial plane demand is for models to replace older gas-guzzlers. This is the segment that should keep "demand strong through uncertainty," she said.

All of the company's commercial airplane segments "are large and growing," she added. Those categories include Boeing's single and twin-aisle planes and its services segment, which performs duties like aircraft maintenance and training. As airlines continue to focus on reducing costs, they are outsourcing more work on their fleets.

Boeing shares rose $1.14, or 1.8 percent, to $63.53 in morning trading Tuesday.