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 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.

A Virginia-based helicopter unit will pause flights pending the outcome of an internal inquiry, an Army spokeswoman said.