The National Transportation Safety Board said Tuesday the probable cause of a commuter rail accident that killed four people in New York City last year was the engineer having fallen asleep “due to undiagnosed severe obstructive sleep apnea.”
The engineer’s sleep apnea was made worse by a recent schedule change, which had him starting work at 4 or 5 a.m.
The Dec. 1, 2013 derailment in the Bronx occurred on a curve where the speed limit was 30 miles per hour. The Metro-North train was traveling at 82 mph when it derailed, the NTSB said.
The safety board also said that all four passengers who were killed “were completely or partially ejected from the train through window openings.”
“The engineer had multiple OSA [obstructive sleep apnea] risk factors, including obesity, male gender, snoring, complaints of fatigue, and excessive daytime sleepiness,” the NTSB said.
But “neither his personal medical providers nor his occupational health evaluations by Metro-North” had identified his sleep apnea.
COMMENT: Although we have established that the prevalence of sleep apnea in transport workers is high, it is still unclear how much crash risk is attributable to sleep apnea compared to other factors as short sleep times, scheduling issues etc. We are undertaking studies funded by the NHMRC and the CRC for Alertness, Safety and Productivity to address this important question.