According to the National Transportation Safety Board (NTSB), both the cockpit voice recorder and flight data recorder are now on their way to a specialized lab.

These devices could provide a second-by-second account of what went wrong before the plane, operated by PSA Airlines as American Airlines Flight 5342, hit a U.S. Army Black Hawk helicopter. As “Cockpit Voice and Flight Data Recorders Found as New Details Emerge About Washington, DC Plane Crash” continues to dominate headlines, we’re learning that air traffic control operations were “not normal” that night—a single controller apparently had to juggle both helicopter and fixed-wing traffic.

It seems the controller was forced to split their attention between pilots flying low along the Potomac and commercial jets arriving on the runway. Such a setup can be risky because different frequencies are used for helicopters versus airplanes—meaning the pilots might not hear each other’s communications. Although the Federal Aviation Administration insists no protocols were technically violated, the day’s staffing levels were a third below what’s considered ideal. Some say it was a recipe for disaster.