What happened

The incident occurred at dusk on Interstate 17 near Flagstaff, Arizona, during conditions of severe sun glare, which reduced visibility for drivers and the vision-only FSD system. 

Eyewitness accounts and onboard footage confirm the vehicle failed to slow down for stopped traffic or detect Johna Story, who was assisting at the scene of a prior accident and was wearing a reflective safety vest when she exited her Toyota 4Runner to help direct traffic. 

The Tesla, traveling at highway speed and with its FSD system activated under human supervision, failed to slow down for stopped vehicles and did not detect Story, striking her head-on and causing fatal injuries.

Why it happened

The incident exposed significant limitations in Tesla’s vision-only autonomous driving approach, particularly its inability to handle reduced visibility - such as severe sunlight - effectively. 

Federal investigators are probing whether Tesla’s approach - using vision-only sensors instead of multi-sensor systems (like lidar and radar) - increased risks for collision in variable weather and lighting environments.