The engineer of Amtrak Train 188 was not talking or texting on his cellphone before the train's deadly derailment at Frankford Junction on May 12, the National Transportation Safety Board said Wednesday.
The finding supported statements by the lawyer for engineer Brandon Bostian that the engineer's cellphone was turned off and stowed in his bag during the trip.
However, NTSB vice chair Tho "Bella" Dinh-Zarr told a Senate committee Wednesday that investigators have not determined whether the engineer was using an app or the phone for other purposes.
There was "no talking, texting, or data usage involved," said Dinh-Zarr. But, she added, "there are 400,000 pieces of data involved in the analysis. Because of the extent of that, things like use of an app or other use of the phone has not been determined. We are working with the records."
"To determine whether the phone was in 'airplane mode' or was powered off, investigators in the NTSB laboratory in Washington have been examining the phone's operating system, which contains more than 400,000 files of metadata," the agency said in its statement Wednesday. "Investigators are obtaining a phone identical to the engineer's phone as an exemplar model and will be running tests to validate the data."
The NTSB's determination heightened the mystery surrounding the cause of the accident: Why was the train traveling more than 100 m.p.h. as it entered the Frankford Junction curve, where the speed limit was 50 m.p.h.?
Eight people were killed and more than 200 injured in the crash.
Bostian, 32, has declined to give a statement to Philadelphia police investigators but told the NTSB that he suffered a concussion and remembers nothing in the seconds leading up to the crash. Investigators said the train's emergency brakes were applied just as the train entered the curve, but Bostian's lawyer, Robert Goggin III, said his client has no recollection of hitting the brakes.
Some engineers have speculated that Bostian may have lost track of his location, mistakenly believing he had already passed the Frankford Junction curve and was clear to open the throttle on the way to New York.
"Everybody at some point in their career has done that," said one engineer, referring to the possibility of losing one's place on a route. He spoke on the condition that he not be identified.
Engineers are required to memorize their routes and the speed limits and other standards, aided by signals in the locomotive cab and on the side of the track.
Speed-limit signs often are not posted.
After the Amtrak 188 derailment, the Federal Railroad Administration ordered Amtrak to post speed-limit signs throughout the Northeast Corridor within 30 days, "with particular emphasis on additional signage at the curve locations" with sharp speed reductions such as Frankford Junction.
The head of the engineers' union told a congressional committee last week that the lack of such signs could prove to be a significant lapse.
"If we eventually learn that, for some reason, the engineer of Amtrak 188 became temporarily confused as to his location, it may be reasonable to conclude that the simple use of speed signs in the approach to the curve, as a reminder, may have prevented this accident," said Dennis Pierce, president of the Brotherhood of Locomotive Engineers and Trainmen.
"That would raise a question whether the decision not to post such signs was a human error that contributed to the accident."
The NTSB said Wednesday that "analysis of the phone records does not indicate that any calls, texts, or data usage occurred during the time the engineer was operating the train."
"Amtrak's records confirm that the engineer did not access the train's WiFi system while he was operating the locomotive," the report said.
The NTSB said the analysis of the engineer's phone records was "more complicated than anticipated because the phone carrier has multiple systems that log different types of phone activity, some of which are based in different time zones.
"Investigators worked with the phone carrier to validate the time-stamps in several sets of records with activity from multiple time zones to correlate them all to the time zone in which the accident occurred," the agency said.
Staff writer Jonathan Tamari contributed to this article.