Michelle Obama's plane aborts landing after getting too close to cargo jet

While there apparently was little risk to Mrs. Obama, the episode puts the FAA back into the spotlight as officials struggle to calm public jitters about flying that have been raised by nine suspensions of air traffic controllers and supervisors around the country in recent weeks, including five for sleeping on the job.

The first disclosed case of a controller falling asleep on duty occurred March 23 at Washington's Reagan National airport, not far from Andrews. The most recent was this week when a controller at a regional radar facility near Cleveland was suspended for watching a movie on a DVD player when he was supposed to be monitoring air traffic. The head of the U.S. air traffic system resigned last week.

This latest incident occurred at about 5 p.m. (2100 GMT) on Monday when a Boeing 737 belonging to the Air National Guard, one of several guard planes used by the White House, came within about three miles (five kilometres) of a massive C-17 as the planes were approaching Andrews to land, according to the FAA and Maj. Michelle Lai, a spokeswoman for Andrews.

The FAA requires a minimum separation of five miles (eight kilometres) between two planes when the plane in the lead is as large as the 200-ton cargo jet, in order to avoid dangerous wake turbulence that can severely affect the trailing aircraft.

The FAA is investigating the incident as a possible error by controllers at a regional radar facility in Warrenton, Virginia, that handles approaches and departures for several airports, including Andrews, where the president's aircraft, Air Force One, is maintained.