The NTSB said it has booted the rail union from its investigation into the weekend's deadly train derailment for violating confidentiality rules.
The agency made the announcement late Tuesday night, hours after a union representative told CNN that the train engineer apparently "was nodding off and caught himself too late" before the accident.
The train derailment Sunday killed four people and injured 67 others in New York.
In its announcement, the NTSB specifically cited those comments as the violation.
Anthony Bottalico, the union representative, told CNN that engineer William Rockefeller Jr. recognizes his responsibility in the incident.
"I think most people are leaning towards human error," Bottalico said.
Rockefeller's lawyer, Jeffrey Chartier, characterized what happened as "highway hypnosis." He said his client had had a full night's sleep before the crash, and had no disciplinary record.
In a brief conversation with investigators, Rockefeller said that moments before the derailment of the Hudson Line train in the Bronx he was "going along and I'm in a daze. I don't know what happened," according to a law enforcement official familiar with that conversation.
Rockefeller spoke to Metropolitan Transportation Authority and New York Police detectives at the crash site before he was taken to the hospital Sunday.
According to NTSB representatives, results from alcohol breath tests for the train engineer were negative, and the brake and signal systems in the deadly Metro-North accident appeared to be working. Other toxicology results have not yet come back.
Fatigue is a factor being investigated, according to a separate New York law enforcement source. But Rockefeller also told investigators on site that the brakes had failed, as CNN reported previously. Officials noted the train had been able to stop nine times at stations ahead of the crash.
The train was equipped with a "dead man's pedal," designed to stop the train if the engineer becomes incapacitated, said National Transportation Safety Board member Earl Weener. But it was unclear whether that emergency system was activated.
The commuter train that jumped its tracks in the Bronx was barreling into a curve at nearly three times the posted speed when it derailed, killing four passengers, federal safety officials said Monday.
Preliminary data from the event recorders aboard the train clocked it at 82 mph as it approached the 30-mph curve, where the Hudson and Harlem rivers converge, National Transportation Safety Board member Earl Weener told reporters. The data show the engineer cut the throttle and slammed on the brakes, but those moves came "very late in the game," Weener said.
"This is raw data off the event recorders, so it tells us what happened. It doesn't tell us why it happened," Weener said.
Investigators questioned the engineer, William Rockefeller, and the rest of the train crew on Monday. Rockefeller told investigators he applied the brakes, but the train didn't slow down, according to a law enforcement official who was at the scene and is familiar with the investigation.
But while the cause of the derailment has not yet been determined, investigators have seen no indication of brake problems, Weener said.
All seven coaches and the locomotive came off the tracks in the Sunday morning crash on New York's Metro-North Hudson line. In addition to the four dead, at least 67 more were hurt. Three remained in critical condition Monday night, and 16 others were still hospitalized, hospitals told CNN.
The train's recorded speed is not only far faster than the rated speed for the curve where the derailment occurred, it's faster than the 70 mph posted for the section of track that led into the curve, Weener said. The force of the crash ripped apart the rails and a section of the track bed, leaving chunks of concrete strewn about the scene.
David Schanoes, a former deputy chief of field operations for the Metro-North line, said the data is "uncannily similar" to a July rail crash in Spain that left 79 dead.