The National Transportation Safety Board is preparing to issue its final findings on a midair collision between a U.S. Army Black Hawk helicopter and an American Airlines passenger jet that killed 67 people near Washington, D.C., nearly one year ago.

The NTSB will hold its concluding public meeting Tuesday, where investigators are expected to announce the probable cause of the crash and release a series of safety recommendations aimed at preventing similar disasters.

NTSB Chair Jennifer Homendy said the investigation has already made clear that the tragedy was not the result of a single failure.

“These are complex investigations, and it’s not just one thing,” Homendy told CBS News. “It ends up that it’s numerous failures in the system that led to a tragedy.”

Homendy added that the scope of the investigation was unusually broad and will result in an extensive final report.

“I can tell you now we are going to have a lot of findings, more than I have ever seen on an investigation that I’ve been part of, and a pretty lengthy list of recommendations that must be implemented following our issuance of the final report,” she said.

The collision occurred near Ronald Reagan Washington National Airport when an Army Black Hawk helicopter carrying three soldiers struck an American Airlines aircraft transporting 60 passengers and four crew members. Both aircraft crashed into the Potomac River. The incident remains the deadliest aviation disaster in the United States since November 2001.

Last month, the U.S. government acknowledged partial responsibility for the crash in a court filing, stating that the helicopter crew failed to establish and maintain proper visual separation from the passenger jet.

Investigators are expected to address air traffic control procedures, military flight coordination, cockpit communication, and systemic safety gaps during Tuesday’s meeting. Any recommendations issued by the NTSB are not legally binding, but historically have played a significant role in shaping aviation safety standards.

The board’s final report is anticipated to influence future military and civilian aviation operations around high traffic airports nationwide.