A Black Hawk military helicopter and an American Airlines jet collided near Washington D.C.'s Ronald Reagan National Airport, resulting in the deaths of all 67 people on board. Investigators suspect the helicopter may not have received critical communication to avoid the jet, possibly due to technical issues with its communication systems. The helicopter crew was using night vision goggles, which may have impaired their visibility. The National Transportation Safety Board (NTSB) is examining why the helicopter did not receive all air traffic communications and is considering the crew's visibility and altitude at the time of the crash. The helicopter was operating outside its permitted altitude range when the collision occurred.