WASHINGTON, D.C. – The National Transportation Safety Board has opened an investigation into an air traffic control incident on Monday in which the airplane carrying First Lady Michelle Obama aborted a landing attempt at Andrews Air Force Base after an air traffic controller had sequenced it too close to another military plane.

At about 5 pm ET on April 18, the military version of a B-737 that Mrs. Obama was traveling in was directed to abort its landing attempt after the required minimum separation between it and a C-17 military aircraft that was landing ahead of it was compromised.

The incident involved Federal Aviation Administration air traffic controllers at the Potomac TRACON facility in Virginia and at the Andrews tower in Maryland.