WASHINGTON (Bloomberg) — The US government extended the hourly flight restrictions at New York’s LaGuardia Airport, a victory for the largest airlines there.The limit of 75 flights each hour will stay in place indefinitely instead of expiring on January 1, the Federal Aviation Administration said. The curbs were put in place in 2001 to end a congestion surge the previous year when LaGuardia accounted for 25 percent of US air delays.

“Severe congestion-related delays will occur both at LaGuardia and other airports” without the extension, FAA Administrator Marion Blakey said in the order yesterday in Washington.

The status quo protects the dominance of carriers such as AMR Corp.’s American Airlines, which flew 5.2 million passengers at LaGuardia in the year ended in October. That was twice as many as the nearest rival, according to LaGuardia’s web site.

Half of LaGuardia’s traffic came from American, Delta Air Lines Inc., US Airways Group Inc., UAL Corp.’s United Airlines and Northwest Airlines Corp.

The Air Carrier Association, which represents small airlines serving LaGuardia, said the FAA’s decision ensures fares will rise faster than in other markets with more low-cost competitors.

“We are not happy,” said Ed Faberman, executive director of the Washington-based group. “Not only does it limit competition, but it significantly fortifies the legacy carriers.”

The association represents AirTran Holdings Inc., Frontier Airlines Holdings Inc., Spirit Airlines Inc. and Sun Country Airlines Inc. AirTran, Spirit and Frontier together flew 8 percent of LaGuardia passengers. Sun Country doesn’t serve the airport.

“The final order allows scheduling certainty while FAA, Congress and stakeholders consider a long-term solution,” said Katherine Andrus, the Air Transport Association’s assistant general counsel, in a statement.

The association is the Washington trade group for major carriers including American, United and Delta.

The FAA proposed a long-term solution in August. Under that plan, the agency would distribute LaGuardia takeoff and landing slots to carriers based on their historical use.

Awarding Slots

Slots would expire between 2010 and 2019 and be renewable for 10-year terms. After that, the agency wants to award slots through some market-based mechanism, such as an auction. Congress would need to approve a switch to an auction-type system.

The FAA’s 75-flight-an-hour cap will remain in place until the August regulation is completed. The agency has set no timeline for finishing the rule. The cap will be in effect from 6 a.m. to 10 p.m. Monday through Friday and from noon to 10 p.m. on Sunday, according to the rule.

LaGuardia’s problem is that airline demand exceeds the airport’s capacity. As the closest airport to Manhattan, LaGuardia draws business travellers willing to pay top-tier fares to fly on short notice. LaGuardia is limited in its ability to expand because it borders on Bowering and Flushing bays.

The US government has capped capacity at the airport to address congestion since 1968. Delays surged in 2000 because Congress let some airlines exceed the ceiling in an effort to promote competition and service to small communities. The FAA in 2001 cut about half of the 300 added flights.

About 65 percent of LaGuardia flights arrived on time in 2006 through October, the second-worst performance among major US airports, according to the Bureau of Transportation Statistics. Only Liberty airport in Newark, New Jersey, was worse, at 64 percent.

Faberman’s group of small carriers wants the FAA to redistribute 10 percent of LaGuardia takeoff and landings from slot-rich carriers to those with limited service at the airport to promote competition.

The Air Transport Association group of large carriers told the FAA it should reject that approach. The group told the FAA last month that LaGuardia remains “extremely competitive.”