A long-running dispute over pensions at United Airlines will end with small raises for some retirees.

The federal agency that took over United's pensions in 2005 during its bankruptcy said Wednesday that 8,247 United retirees — about 18 percent of pensioners — will get small raises of 1 percent or less.

United retirees have long claimed that the federal Pension Benefit Guaranty Corp. under-valued the $7.3 billion in assets it got from United when it walked away from its pension plans. The agency now says it under-valued the pension assets by less than 1 percent, or $58 million.

United's pension had some 2,000 different assets when the PBGC took it over, including swaps and options, limited partnerships, as well as the more common stocks and bonds, PBGC spokesman Marc Hopkins said. The limited partnerships were the hardest to value correctly, he said.

Most United retirees are not getting raises because they were already receiving their full pension. But some workers — especially pilots — were forced to take smaller pensions than they expected. So their payouts will rise. Pilots are getting an additional $33.68 per month on average, the PBGC said.

Raises for ground workers will average 21 cents per month, and they'll average 10 cents per month for flight attendants. Management and administrative workers are getting an average increase of 91 cents per month, the agency said.

The raises account for previous under-payments as well as interest, the agency said.

"Unfortunately, PBGC let the people of United Airlines down, but we're determined to put things right," PBGC Director Josh Gotbaum said in a written statement.

United emerged from bankruptcy and in 2010 merged with Continental. It's now run by United Continental Holdings Inc.

United Continental shares rose 13 cents to $18.18 in afternoon trading.