An Amtrak engineer might have lost track of where he was right before a passenger train derailed, killing eight people and injuring scores of others, federal investigators have found.

In a briefing with reporters Tuesday, investigators with the National Transportation Safety Board said Brandon Bostian might have thought he was past a curve when he accelerated to 106 mph.

As we've reported, Bostian has told investigators he cannot remember what happened during the moments before the crash in Philadelphia. The train was carrying 238 passengers and five crew members and had been headed from Washington, D.C., to New York City.

The Associated Press reports that NTSB investigator Steve Jenner said Bostian was distracted by radio traffic from another commuter train operator who was reporting that a rock had shattered his windshield.

Bostian took the curve in the 50-mph zone at more than twice the speed he should have and the train derailed.

The AP adds:

"Investigators said the derailment would not have happened had the stretch of track been equipped with positive train control, which automatically slows a train that's exceeding the speed limit."If the system had been in place, 'we would not be here today,' said Ted Turpin, an NTSB investigator."Copyright 2016 NPR. To see more, visit