The engineer of Amtrak Train 188 was distracted by radio communication just before the train derailed in Philadelphia last May, killing eight people, investigators with the National Transportation Safety Board said Tuesday.

Investigators believe Brandon Bostian was distracted by reports that a nearby SEPTA train had been struck by debris. Bostian was concerned there were SEPTA workers on the track near the disabled train and worried for the safety of the SEPTA train and its passengers, the NTSB said during a meeting just days after the one-year anniversary of the May 12 crash. Investigators say Bostian, who was highly regarded by his coworkers and had no past blemishes on his safety record, lost "situational awareness," causing him to believe he was at a different curve in the track.

Shortly after passing the disabled SEPTA train that had reported the debris and traveling around a curve, the Amtrak train was going 65 miles per hour, the NTSB reported. Bostian then applied full throttle and held it at its high position for about 40 seconds, increasing the train's speed to 106 miles per hour, investigators found. "Given that the maximum authorized speed was 80 miles per hour, this maneuver was not an appropriate action at this location. However, this maneuver would have been appropriate after the curve just past the derailment site," the NTSB said during the presentation.

The darkness likely contributed to Bostian's confusion about where he was. Investigators say Bostian had no medical issues that caused a lapse in consciousness. Extensive toxicology testing also came up negative. Bostian was not using his cell phone in the moments leading up to the derailment, the NTSB has said. Officials there have analyzed his cell phone calls, texts and data usage from tower records and information from the train's WiFi system.

Authorities believe the crash would have been prevented by Positive Train Control technology, which is now in place along the Northeast Corridor. Positive Train Control controls train speed via GPS, wireless radio and other technology.

The NTSB says if Positive Train Control was in place on the night of the crash, it would have stopped the train altogether if the engineer had not responded to its commands to reduce the train's speed.

The Crash and Investigation The derailment happened shortly before 9:30 p.m. in the Frankford Junction section of the city. In addition to the eight deaths, 200 people were injured when the train sped off the tracks and crashed on its side.

