What should a driver do if the parking brake button fails to pop out?

Notifying maintenance immediately is the appropriate course of action if the parking brake button fails to pop out. The parking brake is a critical safety feature in a bus, specifically designed to keep the vehicle stationary when it's parked. If this system is not functioning correctly, it poses a significant risk not only to the driver and passengers but also to other road users.

It's important that any malfunction in the braking system is addressed promptly by qualified maintenance personnel, as they can diagnose the problem accurately and ensure that the bus is safe for operation. Other actions, such as continuing to drive, engaging the accelerator, or turning off the air compressor, could exacerbate the issue or lead to unsafe driving conditions. Therefore, notifying maintenance is essential for maintaining safety and compliance with operational standards.