Just off the coast of Washington, D.C., a massive crane now looms over the Potomac River, marking the next phase in the recovery of a tragic collision between a passenger jet and a military helicopter. The incident, which occurred last Wednesday, has left investigators scrambling to uncover what went wrong in this deadly crash.

Teams have started pulling out large chunks of the wreckage from American Airlines Flight 5342, a regional jet that ended up in three pieces, upside-down in the river. The collision with an Army Black Hawk helicopter claimed the lives of all 67 people on board, making it the deadliest U.S. aviation disaster in over two decades.

Divers spent the weekend scouting the underwater debris field to map out how to recover the wreckage. The process is expected to take the rest of the week, with the helicopter’s removal scheduled to follow over the next four days. However, officials caution that the timeline could shift if more human remains are discovered during the operation.

So far, 55 of the 67 victims have been identified. Among them were 28 figure skaters, coaches, and family members connected to the U.S. Figure Skating team, many of whom had just competed in the national championships in Wichita.

Weather could complicate the recovery efforts. While crews are starting under clear skies, the water temperature hovers around a chilly 36 degrees, and forecasts predict rain and sleet by midweek.

Meanwhile, investigators are sifting through new clues. The National Transportation Safety Board (NTSB) revealed that the jet’s flight data recorder showed a slight upward pitch just before the crash. One key question is whether the Black Hawk helicopter was flying above its permitted 200-foot altitude limit along the Potomac’s eastern bank.

The NTSB has retrieved the helicopter’s flight recorder, but details from it remain unknown. A preliminary report is expected in about a month.

Questions about the air traffic control tower’s operations are also under scrutiny. On the night of the crash, a single controller was managing both plane and helicopter traffic, a task typically divided between two people. Whether staffing issues or equipment malfunctions played a role in the collision is yet to be determined.

As recovery teams work to bring closure to the victims’ families, investigators continue to piece together the events that led to this heartbreaking tragedy.