An Army helicopter flying in the D.C. airspace Thursday forced two commercial passenger jets inbound to Ronald Reagan Washington National Airport to perform go-around maneuvers — roughly three months after the airport was the site of the nation's worst aviation fatality in more than two decades.

Two jets were on final approach when a military Black Hawk strayed into their path, just months after a similar accident. What went wrong this time?

The National Transportation Safety Board is now investigating the aborted landings of two commercial flights approaching Reagan National Airport on Thursday as a U.S. Army Black Hawk helicopter was approaching the Pentagon nearby.