It's not a record you want to brag about: Los Angeles International Airport and two others nearby have the worst runway safety records recently among the nation's busiest airports, a review of federal aviation data shows.

Federal officials are most concerned by the situation at bustling LAX, where commercial jets have come perilously close to crashing at least twice since 1999, the first year of data reviewed by The Associated Press.

The problem persists because, despite millions spent to reduce violations known as runway incursions, LAX's airfield has built-in flaws: It's too tightly packed and arriving aircraft must cross runways used for takeoffs.

Runway incursions occur when a plane or vehicle on the ground gets too close to a plane that is landing or taking off.

LAX, the nation's fourth-busiest airport in terms of flights, has two sets of parallel runways. Planes land on the outer runways and, while taxiing to their gates, cross the inner runways, which are used for takeoffs.

Southern California has long been the nation's runway incursion epicenter. Among the country's 25 busiest commercial airports, John Wayne Airport in Orange County, Long Beach Airport and LAX ranked one, two and three in runway incursion rates — measured by incidents per 100,000 flights — since 1999. The three airports also topped the list for the total number of incidents, regardless of size.

Nationwide, the number of incursions has dropped about 20 percent from its 2001 peak. Airports in Boston, Philadelphia and Newark had unusually high numbers of incursions in fiscal year 2005; those in Denver, San Francisco and New York's La Guardia had none, according to federal records.

Incursions spiked at 407 in fiscal 2001, FAA reports show, before dropping to 326 in fiscal 2004. Boston's Logan International bucked the trend in spectacular fashion by recording 15 incursions in the 2005 fiscal year, which ended Sept. 30, after experiencing just four from 2002 through 2004.

Still, federal attention has focused on LAX because the incursion rate has remained consistently high — even though officials say interim fixes have reduced the severity of the incidents, if not the number.

"I don't feel there's an enormous safety problem there right now (but) the numbers do concern us," said Dave Kurner, the Federal Aviation Administration's regional runway safety program manager.

Spokeswomen at Long Beach and John Wayne airports said most runway incursions at their facilities involved small, private planes. LAX, however, mostly serves commercial aircraft, giving it the greatest potential for a catastrophic accident.

Aviation officials call the geographic clustering a coincidence.

"There's no common theme or thread, nothing unique to Southern California," said FAA spokesman Donn Walker.

The worst aviation accident in history occurred on a runway in 1977, when two jumbo jets collided at the airport in Tenerife in the Canary Islands, killing 582 people. At LAX, 35 people died in 1991 when an air traffic controller cleared a jet to land on the same runway where she had positioned a commuter plane for takeoff.

Now, after years of planning, LAX plans a permanent fix: a $250 million airfield renovation that officials say should eliminate most of the violations.

LAX has seen between six and 10 incursions annually since 1999, though FAA officials caution those numbers can be misleading. None of LAX's eight incursions in 2005 posed an imminent collision risk, Walker said.

That wasn't always the case, though. In November 1999, the pilot of a departing United Airlines Boeing 757 pulled up early to avoid barreling into an Aeromexico MD80 that had mistakenly taxied into its path.

In an August 2004 incident that chillingly echoed the 1991 crash, the pilot of an arriving Asiana Boeing 747 swooped about 200 feet over a Southwest jetliner that an air traffic controller had positioned on the runway where the jumbo jet had been cleared to land.

Looking down from the LAX control tower, the potential for problems is obvious as a succession of arriving jets nose up to a stop line before reaching the inner runway as other planes roar down it.

"I always equate it to the same act of faith as pulling up to a traffic signal and you've got a green light and you see somebody pulling up in the other direction," said Mike Foote, the air traffic controllers union representative at LAX. In other words, you assume — and hope — they'll stop.

Authorities have tried to address LAX's problem by installing new technology in the control tower, and placing "hot spot" warning signs on the LAX charts pilots use. Additionally, LAX has spent $8 million on better airfield signs, lighting and markings, said spokesman Paul Haney. And, next year, the airport is scheduled to get a new ground radar system that will give air traffic controllers precise information about the locations of planes on the airfield.

A major airfield rejiggering should also give air traffic controllers greater control over the planes they guide. The project faces environmental lawsuits, but the airport hopes to settle those and begin construction early next year.