Especially on a clear night, beside an airport and the military helicopter would have been trained on heightened awareness around DC approach paths. Very suspicious
Discussion
This is either going to be pilot error, or a communications systems failure in the minutes prior to the crash. The helicopter was warned about the jet 30 seconds before the impact, but never responded to the tower. That could be a communications failure, potentially leaving the helicopter pilot without crucial information, or it could indicate some other mechanical problem that was occupying the pilot's attention right before the crash. There's a number of plausible scenarios, so we really have to wait for the investigation to reveal the cause.