WASHINGTON (AP) -- It's not clear why a plane was allowed to take off as President Donald Trump's helicopter was approaching Ronald Reagan Washington National Airport on Tuesday afternoon in an apparent violation of safety procedures put in place after last year's midair collision near the busy airport. The airspace near the White House and Reagan is heavily congested with military and commercial aircraft. The airplane that took off Tuesday was climbing above Marine One as the helicopter approached, so the two aircraft were not on a collision course. The White House emphasized that Trump was never in danger. "Washington National Tower did not delay the helicopter crew, ask them to hold, or otherwise alter their flight profile."