Clues emerging from the moments before the deadly collision Wednesday night between an Army helicopter and an American Airlines passenger jet suggest that multiple layers of the country’s aviation safety apparatus failed, according to flight recordings, a preliminary internal report from the Federal Aviation Administration, interviews with current and former air traffic controllers and others briefed on the matter.

The helicopter flew outside its approved flight path. The American Airlines pilots most likely did not see the helicopter close by as they made a turn toward the runway. And the air traffic controller, who was juggling two jobs at the same time, was unable to keep the helicopter and the plane separated.

An F.A.A. spokesman said the agency could not comment on the ongoing investigation, which is being led by the National Transportation Safety Board. Crash investigators will spend the next several months reviewing flight data, recordings from inside the cockpits, weather patterns, as well as interviewing controllers and others involved to try to figure out what went wrong.

But the catastrophe already appeared to confirm what pilots, air traffic controllers and safety experts had been warning for years: Growing holes in the aviation system could lead to the kind of crash that left 67 people dead in the Potomac River in Washington.

Even before an official cause is determined, there were signs Wednesday that pilots and air traffic controllers at Reagan National were not operating under optimal conditions.

The duties of handling air traffic control for helicopters and for planes at Reagan National on Wednesday night were combined before the deadly crash. That left only one person to handle both roles, according to a person briefed on the staffing and the report.

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