Waymo this week released a detailed postmortem examining the events that led to a high-profile service disruption during a citywide blackout in San Francisco earlier this month, shedding new light on how its autonomous vehicle systems respond to urban-scale infrastructure failures. The report, which was originally covered in an article titled “Waymo Released a Revealing Postmortem on Its San Francisco Blackout Meltdown” by Startup News FYI, outlines a series of cascading technical issues that disabled nearly a third of Waymo’s robotaxi fleet during the December 14th power outage.
According to Waymo, the disruption was triggered by a sudden loss of power to several key backend infrastructure nodes the company relies on for real-time mapping, fleet coordination, and vehicle-to-cloud communications. While the self-driving vehicles themselves remained operational on battery backup, a breakdown in server-to-vehicle connectivity created considerable latency in remote guidance and situational updates. In some cases, cars defaulted to conservative safety protocols, pulling over and refusing to continue service until a stable link was reestablished.
The blackout, caused by a region-wide PG&E transformer failure, presented what Waymo referred to as a “difficult but instructive edge case” for its autonomous systems. The vehicles are designed to maintain basic navigational integrity even in the absence of cloud support, but prolonged disconnection exposed weaknesses in edge processing, particularly in downtown environments dense with unstructured human activity. The report describes how several vehicles “entered extended safe-mode loops,” remaining stationary for hours and obstructing traffic in some intersections until human technicians arrived.
While no accidents or injuries were reported, the incident drew criticism from both city officials and civic technology advocates, some of whom called for clearer accountability measures as autonomous vehicles become further embedded into municipal transportation systems. Waymo acknowledged these concerns in its postmortem and outlined specific software and operational changes, including the development of a localized fallback communication protocol and adaptive route rerouting capabilities in the event of cloud failure.
Startup News FYI noted the unusual transparency of the company’s response, including its release of annotated system logs and a high-level decision tree that guided vehicle behavior during the blackout. Analysts have welcomed this level of candor, saying it marks a shift from the often opaque nature of AV industry disclosures.
The company concluded its report by framing the incident as an “accelerant for resilience” and pledged to implement corrective measures by the end of Q1 2026. Despite the temporary eroding of public trust in the system, Waymo appears committed to positioning the blackout not as a setback, but as a necessary inflection point in the rollout of autonomous urban mobility.
