Washington | Staffing shortfalls and crowded airspace have emerged as possible safety issues at Washington’s airport after a passenger plane and an army helicopter collided midair, killing 67 people in America’s worst aviation disaster in more than two decades.

The air traffic control tower at Reagan National Airport was understaffed when the American Airlines plane and Blackhawk helicopter crashed and plummeted into the Potomac River on Wednesday (Thursday AEDT), according to an initial government report into the accident.