How is a "major brake failure" defined?

A "major brake failure" is defined as a severe issue rendering brakes ineffective. This definition is critical for safety in locomotive operations, as effective brakes are essential for controlling the speed and stopping distance of a train. When brakes are ineffective, it poses a significant danger to the train crew, passengers, cargo, and surrounding infrastructure.

This kind of failure typically indicates that the braking system is compromised to the extent that it cannot perform its intended function, which can include issues such as complete hydraulic failure or significant mechanical breakdowns. Understanding this definition helps train personnel prioritize maintenance and safety checks, ensuring that any signs of brake performance issues are addressed promptly to prevent accidents.

In contrast, other answer choices describe conditions that may not imply an immediate and critical risk. For example, a minor issue with the braking system, a malfunction that requires immediate repair, or a temporary loss of braking power may not completely disable the brakes, but a major brake failure indicates an urgent and life-threatening situation that must be dealt with swiftly.