When responding to a Brake Pipe rupture, what is the first step?

In the context of responding to a Brake Pipe rupture, the initial step is to ensure that the deadman valve is not operated. This is critical because the deadman valve is a safety feature designed to apply the brakes in the event that the engineer becomes incapacitated. If the deadman valve is activated, it can result in the train being brought to a stop abruptly, which may not be necessary or safe given the situation.

Ensuring that the deadman valve is not operated allows the engineer to maintain control over the train's braking system while assessing the situation. This control is essential for making informed decisions about the next steps to take, such as whether to activate emergency brakes or make adjustments to the braking system.

The other options, while relevant in different contexts, do not prioritize the critical need for maintaining control of the train. Checking for activated emergency brake valves or moving the valve into a FULLSERVICE position are important steps, but they come after confirming that the deadman valve is properly managed to prevent unintended consequences during the emergency situation. Turning off the blowers may also be a consideration, but it does not address the immediate concern of the deadman valve in the context of a brake pipe rupture.