Which command is used to stop the airstart procedure?

The command to stop the airstart procedure is to deactivate the airstart unit. This action is crucial because deactivating the airstart unit halts the flow of air that is being used to start the engine. The airstart system is designed to push compressed air into the engine to assist in starting it. When the airstart procedure is no longer necessary or needs to be stopped for any reason—such as ensuring safety protocols are followed or the engine has successfully started—deactivating the unit is the appropriate step.

Properly managing these commands is vital in ramp operations to maintain efficiency and safety. While other seemingly relevant commands might involve closing doors or dealing with emergency situations like an engine fire, they do not directly pertain to halting the airstart procedure. These commands serve different functions and should be executed in their respective contexts.