What document should you consult when a piece of equipment on your aircraft malfunctions while in flight?

When dealing with a malfunction of equipment during flight, the most appropriate document to consult is the Quick Reference Handbook (QRH). The QRH is designed specifically for use in-flight and provides pilots with critical information on how to handle abnormal situations and emergencies. It contains procedures for dealing with various system malfunctions and outlines the necessary checklists and operational steps to ensure safety while responding to the issue.

The QRH is formatted for easy reference under high-stress conditions, aiding pilots in making quick and effective decisions based on the situation at hand. This immediate access to procedural guidance helps decrease the cognitive load during emergencies, allowing for a systematic approach to troubleshooting or mitigating any issues with the aircraft systems.

In contrast, other documents such as the Minimum Equipment List (MEL), Configurations Deviation List (CDL), and Aircraft Flight Manual (AFM) serve different purposes. The MEL is generally used for deferring items that can be inoperative and still allow the aircraft to be airworthy. The CDL addresses specific equipment that can be inoperative without affecting flight safety but is more focused on operating limitations rather than operating procedures. The AFM, while containing a wealth of operational information including performance data and normal operating procedures, is not structured for quick reference like