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.

Two planes had to perform "go-arounds" to avoid a military helicopter on Thursday at Ronald Reagan Washington National Airport, the site of a harrowing midair plane crash in January.