Analysis: Blaming sleep apnea for California crash appears questionable

The National Transportation Safety Board issued a news release on Monday, Oct. 31, announcing it had determined sleep apnea played a role in a 2016 fatality crash involving a tractor-trailer and a motor coach that occurred near Palm Springs, Calif.

Soon after, publications like The Hill posted such headlines as “Undiagnosed sleep apnea a factor in deadly California bus crash.” It’s the type of headline that gets a reader’s attention and fits in nicely with an agenda that has several lawmakers calling for a mandate requiring truck drivers to undergo a sleep study.

However, a review of the NTSB investigation revealed that there was much more to this crash, and the investigators’ claims that the truck driver suffered from undiagnosed sleep apnea appear to be based on assumption alone.

According to the NTSB, a motor coach ran into the rear of a stopped tractor-trailer at 5:16 a.m. Oct. 23, 2016, in the westbound lanes of Interstate 10 outside Palm Springs. The crash resulted in the death of the bus driver and 12 of his passengers. The truck driver and 30 passengers were injured.

The truck and other traffic had been stopped on the highway by police for utility work. When traffic resumed, the truck did not move. The motor coach struck the rear of the truck two minutes later, intruding about 13 feet into the trailer and pushing the combination 71 feet forward.

The NTSB determined the probable cause of the crash was Caltrans’ inadequate transportation management plan. This resulted in a hazardous situation in which law enforcement did not detect the truck’s lack of movement following the traffic break and did not provide any advance warning to the bus driver of the potential for stopped traffic ahead. The board also determined the truck driver did not resume driving after the traffic stoppage because he “most likely” fell asleep because of fatigue, they claim, related to his undiagnosed moderate-to-severe obstructive sleep apnea.

However, the synopsis of the NTSB report indicates that claims saying the truck driver suffered from undiagnosed sleep apnea appear to be based on the driver’s weight and not actual testing.

“Based on the evidence that the truck driver did not move his vehicle for more than two minutes after the traffic break ended and his reported belief that the break had lasted about four times its actual length, he was most likely asleep at the time of the crash, due to fatigue that, given his extremely high level of obesity, probably resulted from undiagnosed and untreated moderate-to-severe obstructive sleep apnea,” the report said.

Attempts to reach someone at the NTSB regarding the investigation and whether or not the truck driver has ever been diagnosed with sleep apnea were unsuccessful Wednesday.

While the release included the words “sleep apnea” in the headline, the synopsis of the investigation detailed several other factors involved in the crash.

The NTSB cited a failed traffic management plan as being a contributing factor.

“In its process for approving permits for temporary traffic breaks, the California Department of Transportation did not require the law enforcement use advance warning devices when conducting the breaks,” the report said. “Such devices could have adjusted the bus driver’s expectations regarding potential traffic stoppage. Moreover, had additional law enforcement vehicles been used to conduct the break, the officers could have monitored the movement of the westbound traffic after the break ended and possibly realized that the stopped truck did not resume operation; they could have then alerted the diver to rejoin traffic.”

The report also said the truck driver had violated hours-of-service regulations for several days prior to the crash and that the bus driver had slept four hours or less in the day-and-a-half leading up to the crash. However, the NTSB news release didn’t mention the hours-of-service violation or the bus driver’s lack of sleep as being contributing factors to their potential fatigue. Instead, the news release referenced the truck driver’s undiagnosed sleep apnea and the bus driver’s untreated diabetes.

Sleep apnea, specifically, has been a hot topic in the trucking industry. Recently, Sen. Cory Booker, D-N.J., introduced a bill that would force the U.S. Department of Transportation to push through a final rule to require testing of sleep apnea for truck drivers and railroad workers.

In March 2016, the FMCSA and Federal Railroad Administration released an advance notice of proposed rulemaking to gather information to determine if a sleep apnea testing mandate was necessary. The FMCSA released a report in July that said the agency “has determined there is not enough information available to support moving forward with a rulemaking action, and so the rulemaking will be withdrawn.” The withdrawal was made official in August.

Proponents of Booker’s bill cited NTSB statistics that sleep apnea had been listed as the probable cause in 10 highway and rail crashes in the past 17 years. Only two of those 10 crashes – one in 2000 and one in 2009 – involved a heavy-duty truck. The addition of the California crash would increase the total of heavy-duty fatality truck crashes blamed on sleep apnea to three over a span of nearly 20 years.

Forcing a mandate based on an extremely limited number of crashes is concerning. Knowing it’s questionable to call sleep apnea the culprit in at least one of the three crashes increases those concerns.

The NTSB’s final report on the California crash is expected to be released in the next several days.