What action should be taken first when a hand brake will not release?

When a hand brake will not release, the appropriate first action is to apply the air brakes in emergency. This step is crucial because it immediately ensures the safety of the train and its operation. Applying the air brakes will help to stop the train safely and prevent any potential movement or accident while the issue with the hand brake is addressed.

Handling a situation where a hand brake fails requires prioritizing safety. The air brakes are a more reliable method to halt the train's motion in an emergency since they are designed to provide effective stopping power. Following this action allows for a controlled response to the malfunction, minimizing risks to the crew and passengers.

After applying the emergency air brakes, further investigations into the hand brake mechanism or notifying maintenance can take place without the immediate risk of the train moving unexpectedly.