WASHINGTON — Regional airlines are having trouble hiring enough pilots, the government says, suggesting one reason may be that they simply don’t pay enough.Qualified pilots are 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 that regional airlines say is limiting service to small communities. But 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 pilots annually over the next 10 years because of an expected surge in retirements and increased demand for air travel, the report said.Eleven of 12 regional airlines failed to meet their hiring targets for entry-level pilots last year, the report said. No major airlines were experiencing problems finding pilots. Regional carriers account for about half of domestic flights and about 20 percent of passenger traffic. One big concern is that communities served only by regional airlines will see service reduced or eliminated. Five regional airlines told the GAO that they are already limiting service because of a pilot shortage. Major airlines generally pay significantly more than regional carriers and often hire pilots from regionals. At regional airlines, the average starting salary for first officers, also called co-pilots, is $22,400 a year, according to the Air Line Pilots Association. This month, Wyoming-based Great Lakes Airlines ended service in a few 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. At the same time, pilot qualifications have been ramped up. Both captains and first officers need at least 1,500 hours of flying experience, with some exceptions. First officers used to need just 250. In a statement, the trade group for regional airlines blamed that rule for the pilot shortage and called on Congress to address it. “Its impact has proven more immediate and significant than analysts predicted,” said Roger Cohen, president of the Regional Airline Association. The new regulations stem from an aviation safety law enacted by Congress more than three years ago after the 2009 crash of a regional airliner near Buffalo, N.Y., blamed on pilot error. All 49 people on board and a man on the ground were killed.