Investigators have uncovered several factors that contributed to the collision of a U.S. Army helicopter and a passenger airplane near Washington, D.C., last January, killing 67 people in the deadliest U.S. air disaster since 2001.
The National Transportation Safety Board discussed the investigation's findings on Tuesday, including testimony about numerous near-crashes in the years before the fatal collision, as well as missed opportunities for the the Federal Aviation Administration to address risks. Thursday marks the first anniversary of the crash.
The FAA is making permanent changes it imposed after the crash. The rules say helicopters and planes can't share the same airspace around Reagan National Airport, prohibit air traffic controllers from relying on visual separation and require all military aircraft to broadcast their locations.
Here's a timeline of events related to the crash:
Jan. 29
Around 8:15 p.m., American Airlines Flight 5342, with 64 people aboard, begins its initial descent into Reagan National Airport.
At 8:43, from the airport's tower, a controller asks the plane's pilots to switch from landing on Runway 1 to Runway 33. A nearby Army Black Hawk helicopter, referred to by air traffic control as PAT25, is flying south over the river. The skies are clear.
As the helicopter approaches the airport, the cockpit voice recorder captures the pilot saying it is flying at 300 feet (91 meters) and the instructor pilot says it is at 400 feet (122 meters). The discrepancy isn't explained and the helicopter continues to descend. The helicopter route's allowed altitude decreases the closer the aircraft gets to the airport, capping at 200 feet (61 meters).