What is the correct first step when starting an aerial apparatus?

Answer: B — Disconnect all auxiliary electrical and air sources

The correct first step when starting an aerial apparatus involves ensuring that all auxiliary electrical and air sources are disconnected. This is crucial for several reasons. First, disconnecting auxiliary systems helps to prevent accidental engagement of equipment or systems that could pose safety risks. For example, if an aerial ladder or other apparatus components were to activate accidentally while the vehicle is being started, it could lead to injuries or equipment damage. Second, this step helps ensure that the aerial apparatus operates safely and efficiently. By disconnecting any auxiliary sources, operators can focus solely on the operation of the main vehicle systems without the potential complications introduced by additional power or air supply systems. This practice is fundamental to conducting a safe operation and is a standard procedure in fire apparatus usage, emphasizing safety and operational readiness before any further steps, such as starting the engine or turning on batteries, are undertaken.