WASHINGTON — The last thing Amtrak engineer Brian Bostian remembered from before May’s fatal crash in Philadelphia was pushing the throttle to pick up speed and then braking as he felt the train going too fast into a sharp curve, according to a transcript of his interview with investigators.

Officials left open the possibility of human error as they released documents Monday that showed no problems with the train, tracks, or signals.

When he realized the train was about to derail, Bostian recalled, he held the controls tightly and thought, ‘‘Well, this is it, I’m going over.’’

The transcript was among more than 160 documents released by the National Transportation Safety Board. They don’t come to any conclusions on the cause of the crash. Among the most illuminating are transcripts of two interviews Bostian had with investigators, one immediately after the May 12 crash, which killed eight people and injured nearly 200, and one in November.

A data recorder showed the train reached 106 miles per hour. Then the emergency brake was activated, and the speed fell to 102 as the train entered one of the sharpest curves in Amtrak’s Northeast Corridor. The train derailed. The speed limit for the curve is 50 miles per hour. The limit for the stretch of track prior to the curve is 70; on a portion prior to that it is 80.

‘‘Once I pushed the throttle forward in an attempt to bring the train up to 80 miles an hour, I don’t have any other memories until after the train was already in the curve,’’ Bostian said in the November interview.

An NTSB official described Bostian as ‘‘extremely cooperative’’ with investigators.

Bostian said he had a dim memory of what happened.

‘‘The only word — I hesitate to use the word dreamlike because it sounds like I was asleep and I don’t believe that I was asleep at all.’’ Instead, Bostian said, he had a ‘‘very foggy memory’’ of what went on. ‘‘I remember feeling my body lurch to the right, toward the right side of the engine,’’ he said. “I remember feeling as though I was going too fast around a curve. In response to that feeling, I put the train brake on.’’

Bostian provided his cellphone to investigators, who say there’s no indication he was using it while operating the train.

The train’s assistant conductor said that before the crash he heard Bostian say on his radio that the train had been hit by something. Trains in the Northeast Corridor are frequent targets of rock-throwing vandals. Other trains in the vicinity reported being hit by rocks that evening.

Bostian has been suspended without pay since the crash, for speeding.

The investigators’ draft report is expected about May 12, the anniversary of the crash.