A 2016 bus crash near Laredo, Texas that killed nine people was caused by the driver’s fatigue and diabetes complications, according to an investigation by the National Transportation Safety Board (NTSB).

How it happened

The May 14 incident occurred at approximately 11:24 a.m., central daylight time, when a 49-passenger motorcoach, operated by OGA Charters LLC of San Juan, Texas, entered a horizontal curve to the right, but drifted from its lane to the left. The driver steered to the right and applied the brakes, which resulted in the vehicle’s loss of control, so that it slid and yawed clockwise. The motorcoach departed the right - or east - side of the highway and, after entering the earthen right-of-way, overturned onto its left side.

Nine passengers died, 36 passengers sustained injuries ranging from minor to serious. The motorcoach driver and trip coordinator were treated for minor injuries. The injury severity for five passengers could not be determined.

Blurred vision, sleep deficit

The NTSB determined that the probable cause of the Laredo, Texas, crash was the driver’s failure to maintain the motorcoach fully within the northbound travel lane, due to a combination of fatigue from an acute sleep deficit and blurred distance vision due to hyperglycemia resulting from poorly controlled diabetes; then, as the motorcoach drifted left from the travel lane, the driver abruptly steered to the right and braked, causing the vehicle to leave the highway and roll over.

Contributing to the driver’s inability to regain control of the motorcoach was the low friction value of the wet pavement and the inoperable antilock braking system. Contributing to the severity of the passenger injuries was the failure of the left side passenger windows to keep passengers within the motorcoach.

The safety issues

The investigation focused on the following safety issues: inadequate federal oversight and guidance for commercial drivers with diabetes treated without insulin; inaccurate and incomplete highway maintenance recordkeeping by the Texas Department of Transportation (TxDOT); need for improved training for TxDOT maintenance workers; need for increased motorcoach crashworthiness through improvements to window glazing and retention; driver fatigue resulting from poor safety management by OGA Charters and inadequate federal safety ratings for passenger motor carriers with repetitive safety violations in the area of driver performance. As a result of this investigation, the National Transportation Safety Board (NTSB) makes new safety recommendations to Federal Motor Carrier Safety Administration (FMCSA) and TxDOT. The NTSB also reiterates two recommendations to the FMCSA and one recommendation to the National Highway Traffic Safety Administration.