What is an important safety measure before starting the engines?

Installing wheel chocks is a critical safety measure before starting the engines because it ensures that the aircraft remains stationary and prevents any unintended movement. This precaution is necessary to protect ground personnel and equipment, as well as the aircraft itself. Properly securing the aircraft with wheel chocks helps to ensure that safety protocols are followed and reduces the risk of accidents during engine start-up.

Other safety measures like stopping all ground operations or checking weather conditions are important for overall safety but do not specifically address the immediate risk of the aircraft moving unexpectedly during engine start. Completing a pre-flight checklist is also vital, but it encompasses a wider range of checks beyond just securing the aircraft; thus, it may not directly prevent movement during the critical moments before engine start. Installing wheel chocks is a focused, immediate action that directly enhances safety in that specific context.