Waymo announced a recall of 3,791 robotaxis on May 12, 2026, following an incident where an unoccupied autonomous vehicle drove into floodwater and was swept into Salado Creek in San Antonio, Texas. The recall affects both fifth- and sixth-generation Waymo models due to a software issue that could allow vehicles to drive onto flooded roads, with a fix currently in development.
Unoccupied Vehicle Swept Into Creek During April Incident
On April 20, 2026, a Waymo autonomous vehicle entered a flooded section of roadway with a 40 miles per hour speed limit in San Antonio. The vehicle proceeded into the floodwater at reduced speed and was ultimately swept into Salado Creek, requiring recovery days later. No passengers were on board and no injuries were reported, but the incident triggered an investigation by the National Highway Traffic Safety Administration.
According to NHTSA, the Automated Driving System software may allow vehicles to slow and then drive into standing water on higher speed roadways. The software failed to properly assess the flood hazard and prevent the vehicle from entering dangerous conditions that could lead to loss of vehicle control.
Software Fix in Development for 3,791 Vehicles
The recall encompasses 3,791 robotaxis across Waymo's fifth- and sixth-generation vehicle platforms. The company is developing a software fix to address the vulnerability in flood detection and avoidance systems. The NHTSA filing noted the issue could result in loss of vehicle control when vehicles enter standing water, highlighting the critical nature of the software flaw.
Despite the recall, Waymo announced plans for expansion into more Houston neighborhoods, indicating the company continues operations while addressing the safety issue. This dual approach reflects the company's confidence that the software update will adequately resolve the identified hazard.
Edge Case Detection Challenges for Autonomous Vehicles
The incident highlights ongoing challenges in edge case detection for autonomous vehicles, particularly in handling unusual weather conditions and environmental hazards that may not be well-represented in training data. Flooded roadways present unique challenges for sensor systems and decision-making algorithms, as water depth and flow velocity are difficult to assess remotely.
The story generated significant discussion on Hacker News, receiving 152 points and 145 comments, indicating substantial community interest in autonomous vehicle safety issues. The incident adds to the growing body of real-world scenarios that autonomous vehicle developers must account for as they expand operations into diverse geographic and climatic conditions.
Key Takeaways
- Waymo recalled 3,791 robotaxis on May 12, 2026, after a vehicle drove into floodwater and was swept into Salado Creek in San Antonio on April 20, 2026
- The unoccupied vehicle entered standing water at reduced speed on a 40 mph roadway, with no passengers on board and no injuries reported
- NHTSA identified a software flaw in the Automated Driving System that fails to properly assess flood hazards, potentially causing loss of vehicle control
- Both fifth- and sixth-generation Waymo models are affected, with a software fix currently in development
- Waymo continues expansion plans into Houston neighborhoods while addressing the safety issue, and the incident generated 152 points and 145 comments on Hacker News