What action must crew members take immediately when a NON-PASSENGER train experiences an emergency application of the brakes?

When a NON-PASSENGER train experiences an emergency application of the brakes, it is crucial for crew members to protect adjacent tracks to ensure the safety of all trains operating in the vicinity. This action is necessary because an emergency application suggests there may be a potential hazard or blockage on or near the tracks, which could pose a risk to other trains. By transmitting a warning via radio, crew members can alert other personnel and train operators about the situation, allowing them to take necessary precautions to prevent accidents.

Additionally, while notifying the Dispatcher and restricting movements are important actions, they occur after the immediate protection of the area has been established. Investigating the cause of the emergency application is also a vital step but should only follow after proper safety measures are in place to protect others from potential threats. The priority in such situations is to ensure the safety of not only the crew and passengers but also to safeguard adjacent rail operations.