What is indicated by the term "mandatory" concerning the use of checklists?

The term "mandatory" concerning the use of checklists indicates that it is necessary to use checklists for safe operations. This underscores the critical role that checklists play in aviation safety. They are designed to ensure that pilots adhere to a systematic process, reducing the likelihood of errors during key phases of flight, such as takeoff, landing, and during abnormal situations.

When checklists are termed "mandatory," it stresses that the adherence to these lists is not merely a suggestion but an essential practice for ensuring all necessary actions are completed and that nothing is overlooked. This aspect is key to adhering to standard operating procedures and maintaining safety throughout the flight.

Therefore, the importance of using checklists cannot be understated, as they help establish consistency, provide a double-check system, and ultimately contribute to the overall safety and reliability of flight operations.