The Jan. 29 collision over the Potomac River in Washington, DC — which preliminary reports have blamed on the military Black Hawk flying too high — was the deadliest US air disaster since 2001, and caused officials to change the flight path of helicopters near the airport.

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

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.