Which specific fuel-related incident requires immediate notification of authorities?

A significant oil spill necessitates immediate notification of authorities because it poses a substantial risk to the environment and public safety. Such incidents can lead to widespread contamination of land and water resources, harming wildlife and ecosystems. Additionally, significant spills can create hazardous conditions for individuals nearby or complicate the operation of emergency services. Prompt reporting enables quick response measures to mitigate damage, ensure proper cleanup, and manage any potential health risks. In contrast, minor leaks and routine operations typically do not present the same urgent risk levels, whereas tank calibration errors, while potentially serious, do not immediately threaten safety or the environment in the way a significant spill does.