Black Hawk helicopter flights begin along U.S. border in Alberta

The deadly mid-air crash in Washington, D.C., Wednesday night is likely the result of unique air traffic patterns in the area and shouldn’t cause wider fears over air safety, says an aviation expert.John Gradek, who teaches aviation management at McGill University, said the Ronald Reagan Washington National Airport has seen rising activity over the years while military aircraft also frequently fly in the area, making it a higher-risk airspace.