The first lady was returning from a television appearance and other events in New York with US Vice President Joe Biden's wife Jill Biden, and was aboard a Boeing 737 -- part of the presidential fleet -- when the error occurred on the plane's final approach to the base, The Washington Post reports.
The Federal Aviation Administration controllers in the tower at Andrews recognised that the massive C-17 and the Obama flight were far too close when the Warrenton controller handed off responsibility for the two aircraft.
They ordered the Obama plane to execute a series of S-turns in an effort to create a safe distance between it and the C-17, federal officials said. But when those manoeuvres failed to achieve the required distance between the two planes. The Andrews controllers realised that the cargo jet would not have time to get off the runway before the presidential plane arrived and they aborted the landing of the Obama plane and ordered it to circle the base, the report said.
"The manager and tower controller at Andrews did several things to try to increase the separation on final approach before ordering a go-around," said a senior FAA manager familiar with the incident, adding that the Warrenton controller exhibited "really bad controller technique."
"Not only did he get them too close, but he also told the Andrews controller that they were farther apart than they were," he said.
When the handoff occurred, the planes were 3.08 miles apart, according to radar, but the Warrenton controller told the Andrews tower that they were four miles apart. Before handing off, the Warrenton controller warned Obama's pilot of potential wake turbulence.
In the Andrews tower, controllers had already identified "a serious loss of separation", but were reluctant to contact the Warrenton facility to point it out, officials said.
The Andrews controllers ordered the S-turns as soon as they assumed responsibility, but the two planes still grew closer. Finally, they ordered the 737 to abort the landing attempt as they feared that the cargo plane could not get off the runway in time for the Obama plane to land, the report said.
The FAA classified Monday's error as an A -- the most serious type. However, another federal official who works with the air traffic control system but is not authorised to speak publicly, said, "In the grand scheme of things, events like this happen fairly frequently. Unfortunately, this one involves a presidential plane."
The number of air traffic controller errors, where planes come too close to each other, has increased dramatically in the past year.
