When are flag spots considered non-complying?

Flag spots are considered non-complying when one or more flat spots are 2 ½ inches long. This standard is typically set to ensure that any irregularities in the wheel profile do not compromise the safety and performance of the equipment. Flat spots that exceed this length indicate significant wear or damage, which could lead to issues such as unstable operation or increased risk of derailment during service.

In the context of the other options, while shorter flat spots or specific distances between them may not necessarily affect compliance, a flat spot of 2 ½ inches or longer directly indicates a more severe defect. Understanding these thresholds is crucial for maintenance and safety protocols in equipment handling.