NTSB: Crew fatigue main reason behind fatal 2014 train crash

Crew fatigue brought on by irregular work schedules and a moderate form of sleep apnea is the primary reason behind a middle-of-the-night train crash that killed two Union Pacific workers and injured two others in northern Arkansas, the National Transportation Safety Board said Tuesday.

The panel also blamed an automatic horn that improperly reset alarms and the railroad industry's slow adoption of a system to stop trains automatically.

The conductor and engineer killed in the crash were likely sleeping in their southbound train as it sped through a stop signal Aug. 17, 2014, and hit a northbound Union Pacific train, the board found.

"This tragedy illustrates...