The National Transportation Safety Board investigation into last year's Amtrak derailment in Philadelphia has concluded that the train's engineer was distracted by radio transmissions before the crash, a federal official briefed on the findings told NPR.
A second source told NPR an official said only that the engineer was distracted, but did not specify radio transmissions.
The crash on May 12, 2015, killed eight people and injured scores of others when the train, going 106 miles per hours in a 50 mile per hour zone, jumped the tracks. The train was traveling from Washington, D.C., to New York.
As NPR's David Schaper reported last week, the yearlong investigation has yielded some answers so far:
"Investigators have ruled out brake, track, engine, and signal failures as potential causes and are focusing on human error. The train's engineer, 32-year old Brandon Bostian, could not explain why he kept accelerating, telling investigators he cannot remember the final moments before the crash. Drug and alcohol testing came back negative and investigators determined he hadn't been using his cell phone.
"Regardless of why the train was going too fast, the nation's top railroad official says "this accident was preventable."
The NTSB is set to publicly report the findings at a public meeting Tuesday.