What does "plane tied down during start-up" imply in operational procedures?

The concept of "plane tied down during start-up" primarily addresses the need to secure the aircraft to prevent any unintended movement when starting the engines. This procedure is crucial for safety, as engines can create significant forces upon startup that could lead to the aircraft rolling or sliding on the ground if not properly secured. Tying down the aircraft ensures that it remains stationary, protecting both personnel in the vicinity and the aircraft itself from potential damage or accidents during this critical phase of operation.

While there are standard practices for securing aircraft in various weather conditions and specific protocols for engine operation, the particular emphasis on tying down during the start-up phase directly relates to ensuring the aircraft's immobility. This safety measure is essential in maintaining a controlled environment, especially when many crew members may be present around the aircraft during engine start.