Southwest Airlines jets are seen at Baltimore Washington International Airport in Baltimore, Md. (AP Photo/Charles Dharapak, file) Southwest Airlines jets are seen at Baltimore Washington International Airport. (AP Photo/Charles Dharapak, file)

U.S. air traffic controllers made 41 “high risk” mistakes last year, including seven that could have ended in catastrophe, the Federal Aviation Administration said Thursday.

That error count was listed in an FAA report that said the overall number of reported mistakes by controllers had been vastly under counted for years. Largely through the use of a new electronic monitoring system, the agency determined that there were 4,394 errors made by controllers who handled 132 million flights in fiscal 2012. The FAA said 1,271 of those mistakes were serious enough to warrant thorough review.

That overall number is more than twice the 1,895 mistakes reported the year before and in 2010, and more than three times the 1,271 counted in 2009. Critics have long said that the FAA error statistics were far below the reality, and the FAA acknowledged as much in presenting the fresh data Thursday.

In a briefing by top agency officials, who spoke on the condition that they not be identified by name, the FAA said full deployment of an electronic surveillance by January 2012 and policy changes that encourage controllers to report their own errors lead to the upsurge.

They said that the 41 worst mistakes – including the seven listed as potentially “catastrophic” – fell into five categories which the agency was in the midst of addressing.

The basic role of controllers is to keep planes at a safe distance from on another – in most circumstances, when below cruising altitude, three miles distant or 1,000 feet of altitude apart. When they are allowed to stray too close, the degree of risk varies depending on the circumstances.

The FAA said the five areas in which the 41 high risk controller mistakes were made included:

Turning airplanes for their final runway approach, planes coming too close when landing on parallel runways, maneuvers when planes were told to abort their final approach, guidance of pilots who don’t hold to their designated altitudes and coordination between controllers as they pass responsibility for an airplane from one controller to another.

“Out of 132 million flights handled, 41 gave us reason for concerns and we are working to address those issues,” a senior FAA official said.

He said that “in past years we have reported [mistakes] to the best of our ability.”

The agency’s data collection has been challenged by some within the agency and by members of Congress since a series of high profile incidents appeared to put flyers at risk.

The majority of errors did not put passengers at great risk. But there were enough serious incidents that the National Transportation Safety Board stepped in to investigate.

The NTSB reviewed an incident near National Airport in which an airliner carrying Rep. F. James Sensenbrenner Jr. (R-Wis.) swerved to avoid another jet after the on-board collision avoidance system was activated. The NTSB also reviewed an incident in which a White House plane carrying first lady Michelle Obama and Jill Biden, wife of the vice president, was allowed to stray too close to the turbulence of another plane.

Other cases the NTSB reviewed were more serious: A Boeing 737 nearly hit a helicopter while taking off from Houston; a Boeing 777 skimmed under a small plane on takeoff from San Francisco; a Boeing 737 nearly collided with a Cessna in Burbank, Calif.; an Airbus 319 passed 100 feet above the path of a Boeing 747 taking off in Anchorage; and an Embraer 135 taking off from Chicago took evasive action to avoid an in-bound twin-engine prop plane.

In March, federal investigators challenged the FAA’s contention that most of the increase in controller errors was the result of better data collection. The inspector general for the U.S. Department of Transportation said that “the increase in reported errors was linked, in part, to a rise in actual errors rather than increased reporting.”

The inspector general’s report cited a 95 percent increase in controller errors reported in 2010 at the facility that supervises air traffic into the Washington area’s three major airports: Reagan National, Dulles International and Baltimore-Washington International Marshall. It was the fifth-highest increase from 2009 to 2010 in the nation, outranked only by error increases in Southern California, Central Florida, Houston and Miami.