LOS ANGELES — The rate of close calls between aircraft on the ground approached record highs in recent years around America, according to a government report released yesterday.

The findings come despite much-touted efforts by the Federal Aviation Administration and airports to ensure that pilots and air traffic controllers follow federal rules that permit only one plane at a time on or near a runway.

Los Angeles International Airport has been plagued by a series of close calls over the past 18 months, including one August 16 in which two commercial jetliners carrying a total of 296 people came within 37 feet of each other. Nationwide, the GAO found that runway safety gains achieved earlier this decade had been eroded by overworked controllers, a jump in flights to levels prior to September 11, 2001, and a lack of leadership by the FAA.

The report, requested by the House Committee on Transportation and Infrastructure, is the harshest indictment in years of the FAA’s progress in addressing incidents in which aircraft violate safety zones around runways. The agency began a much-publicized effort in 2000 to curb close calls, which are considered the most serious threat to domestic aviation. Although GAO researchers applauded such FAA initiatives as enhancing lighting and signs on airfields, providing additional training for pilots and controllers and developing new radar systems, they found that the rate of runway safety violations in 2007 has been nearly as high as its peak in 2001.

Even more concerning, researchers found the rate of the most serious close calls remained relatively steady from 2002 through 2006, suggesting “a high risk of a catastrophic runway collision occurring in the United States.”

In a statement responding to the report, the FAA said it had exceeded its goal for reducing the most serious close calls in 2007.