WASHINGTON -- The nation’s regional airlines are having trouble hiring enough pilots, the government says, suggesting one reason may be that they simply don’t pay enough.

A pool of qualified pilots is available, but it’s unclear whether they are willing to work for low entry-level wages, the Government Accountability Office said in a report released Friday.

One key economic indicator supports the emergence of a shortage, something regional airlines have complained of and point to as a reason for limiting service to some small communities. But two other indicators suggest the opposite is true, GAO said. Also, two studies reviewed by the GAO "point to the large number of qualified pilots that exist, but may be working abroad, in the military or in another occupation, as evidence that there is adequate supply," the report said.

The U.S. airline industry will need to hire 1,900 to 4,500 new pilots annually over the next 10 years due to an expected surge in retirements of pilots reaching age 65 and increased demand for air travel, the report said.

Eleven out of 12 regional airlines failed to meet their hiring targets for entry-level pilots last year, the report said. However, no major airlines were experiencing problems finding pilots.

Regional carriers account for about half of all domestic airline flights. One big concern is that communities served only by regional airlines will see their service reduce or eliminated. Five regional airlines told GAO they are already limiting service because of a pilot shortage.

Major airlines generally pay significantly higher salaries than regional carriers and frequently hire pilots from regionals. The average starting salary for first officers, also called co-pilots, at regional airlines is $22,400 a year, according to the Air Line Pilots Association.

Earlier this month, Wyoming-based Great Lakes Airlines ended service in a handful of small towns, citing a dearth of qualified pilots. The pilots association says Great Lakes pays newly hired first officers $16,500 a year.

"Data indicate that a large pool of qualified pilots exists relative to the projected demand, but whether such pilots are willing or available to work at wages being offered is unknown," the report said. And, the size of the pilot pool has remained steady since 2000, the report said.

There are currently 66,000 pilots working for U.S. airlines, but there are 109,465 currently active pilots with a first-class medical certificate who are licensed to fly airline passengers, the report said. An additional 100,000-plus pilots with commercial licenses might at some point choose to pursue an airline career, the report said

The unemployment rate for professional pilots is very low, only 2.7 percent. That would normally indicate a shortage, but that may not be the case, GAO said. Average professional pilot salaries went down 9.5 percent from 2000 to 2012, while the number of pilots employed went up 12 percent. Both trends are inconsistent with a shortage, the report said.