Federal aviation officials are investigating an air-safety incident involving President Trump's Marine One helicopter in Washington, D.C.Why it matters: The incident comes as regulators work to improve safety in increasingly congested U.S. airspace, particularly around D.C.Zoom in: The Wall Street Journal first reported that the helicopter was carrying Trump on Tuesday when it flew too close to a commercial airliner departing from Ronald Reagan Washington National Airport.NTSB confirmed in a statement to Axios that it is "investigating a reported loss of separation event" between the two aircraft.Representatives for the FAA and White House did not immediately respond to Axios' Wednesday evening request for comment.Editor's note: This is a breaking news story. Please check back for updates.