What defines an undue delay in the context of minimum fuel?

In the context of minimum fuel, an undue delay is defined primarily by its impact on safety. When an aircraft declares minimum fuel, it indicates that its fuel reserves are low, and any significant delay could hinder its ability to reach a safe landing at the intended destination or an alternate airport. Therefore, if a delay threatens to compromise safety, it is considered undue, regardless of the exact duration.

While the other options hint at factors that may contribute to the perception of a delay, they do not accurately capture the reason behind the designation of "undue." A delay exceeding a specific time limit, like ten minutes, could vary based on the circumstances, and is not universally applicable to all situations involving minimum fuel. Likewise, any delay longer than planned is subjective and does not inherently imply a safety risk. Although delays caused by air traffic control can create issues, they are not solely what defines an undue delay—rather, the focus is on how these delays might affect the aircraft's safety and landing capability.