According to the NTSB, Amtrak 188, the train that crashed in Philadelphia on May 12, 2015 killing eight people and injuring 200, most likely ran off the rails because the engineer was distracted by radio transmissions relating to a nearby commuter train which had been hit by a thrown rock. The rock had shattered the train’s windshield and the engineer on that train was requesting medical assistance. In interviews with investigators, Bostian said he the rock-throwing incident left him concerned about the engineer and the possibility of people on the track. He also mentioned being “slightly” concerned for his own safety, if the rock thrower would then aim at his train. The NTSB investigation concluded that Engineer Brandon Bostian was apparently so focused on the rock-throwing incident that he lost track of where he was in his route and accelerated full-throttle to 106 mph as he went into a sharp curve with a 50 mph limit. NTSB investigators said they believe Bostian was accelerating because he thought he had already passed the sharp curve. After the curve is a straightaway where the speed limit is 110 mph.

Early in the investigation, the NTSB focused on whether the Amtrak train had also been hit with a thrown rock or other projectile minutes before the crash, but investigators confirmed that Amtrak 188 had not been hit by any projectiles. NTSB authorities also ruled out cellphone use by Bostian, as well as use of drugs or alcohol.

Additionally, the NTSB blamed the incident on delays in installing Positive Train Control (“PTC”), equipment that automatically slows trains that are going over the speed limit. Had PTC been in use along the stretch of track, “we would not be here today,” said Ted Turpin, an NTSB investigator. “Unless PTC is implemented soon,” NTSB chairman Christopher Hart warned, “I’m very concerned that we’re going to be back in this room again, hearing investigators detail how technology that we have recommended for more than 45 years could have prevented yet another fatal rail accident.”

In addition to other recommendations, the NTSB recommended training for railroad crew members on multitasking and the use of new equipment and procedures to help engineers keep track of their location in spots where PTC has not yet been installed. In a statement, Amtrak said it has “taken full responsibility for and deeply regrets the tragic derailment” and will carefully review the NTSB findings and recommendations and quickly adopt them where appropriate. Amtrak noted that PTC is already in place on most of its portion of the Northeast Corridor and that it has also installed inward-facing video cameras on locomotives.

I spoke with Law360 about the NTSB’s findings. The article, entitled “Amtrak Philly Crash Probe May Yield Slow Safety Fixes” can be viewed here (subscription required).