How do you know that the parking brake is set?

• A. An ON light illuminates on the EMER/PRKG BRAKE light
• B. A green gauge shows PARK on the flight deck
• C. The brake pedal becomes firm
• D. The landing gear indicator shows PARK

Answer: (A)

When the parking brake is set, a dedicated warning light comes ON—the EMER/PRKG BRAKE indicator. This specific light is built to give an immediate, unambiguous cue that the parking brake is applied, regardless of what else is happening in the hydraulic system or how the pedals feel. It’s the most reliable indicator because it’s intentionally designed to signal brake status directly.

Relying on a green gauge showing PARK isn’t as dependable because that type of readout isn’t a universal or standardized signal for parking brake status across different aircraft. The landing gear indicator showing PARK doesn't reflect brake status at all—it tells you about gear position, not whether the brakes are engaged. A brake pedal feeling firm can occur for various reasons and isn’t a consistent indicator of the parking brake state, so it’s not a reliable cue on its own.