If the braking system fails, what should you expect regarding the parking brake?

In the event of a braking system failure, the expectation is that the parking brake will not function. This stems from the design and purpose of the parking brake, which is typically a separate system that relies on a different mechanism than the primary braking system.

Many aircraft are equipped with a parking brake that may leverage hydraulic pressure or mechanical linkages that could also be compromised during a failure of the main braking system. Furthermore, factors such as the way the aircraft is designed and maintained can impact the reliability of the parking brake during such an event.

In situations where the primary brakes fail, reliance on the parking brake for stopping the aircraft may not be safe or effective, as it may not provide adequate stopping power. Thus, it is critical for pilots to understand that in the event of a complete braking failure, the parking brake is not a dependable solution for halting the aircraft safely.