During a penalty brake application, how should independent brake cylinder pressure be controlled?

During a penalty brake application, independent brake cylinder pressure should be controlled by moving the handle into the application zone and actuating it. This method directly engages the independent brakes and allows for precise control over braking force. Specifically, when the handle is moved into the application zone, it communicates to the braking system the need for increased braking power, thus raising the brake cylinder pressure effectively and allowing for a more decisive response to control train speed or stop.

The other options do not provide the same level of direct control over the braking system. Adjusting the handbrake on each car is more of a manual and less immediate method, and may not be practical during a critical braking situation. Maintaining the power throttle position does not influence brake cylinder pressure; instead, it relates to the train's propulsion. Requesting assistance from the crew may be necessary in certain situations, but it does not actively manage the braking process at that moment. Understanding the direct control afforded by the independent brake application is crucial for effective train handling during emergency or penalty situations.