Which supply line evolution is most commonly used by the first arriving engine company at a fire scene?

The forward hose lay is the most commonly used supply line evolution by the first arriving engine company at a fire scene due to its efficiency and practical application in combating fires. In this method, the hose is extended from the engine toward the fire scene, allowing firefighters to quickly establish a water supply and begin the attack on the fire.

This technique is especially advantageous when the engine arrives at the scene and needs to establish a reliable water source while ensuring that it can get close enough to the fire to effectively deploy the line. It allows for rapid deployment, which is crucial in emergency situations where time is of the essence.

In addition, the forward hose lay typically facilitates better visibility and maneuverability for firefighters on the scene, as they can advance towards the fire while simultaneously laying out the necessary hose. This ensures that the firefighting efforts are coordinated and effective, making it a standard practice in fire response.

The other options, such as the reverse hose lay or split lay, although useful in specific scenarios, are less typical for initial responses when immediate water supply is critical, or when responding quickly to the fire's initial stages.