What is the purpose of MEL and CDL in flight operations?

• A. They determine flight speed
• B. They specify cleaning schedules
• C. They allow operation with inoperative equipment or configuration deviations within defined limits to maintain safety
• D. They govern maintenance scheduling

Answer: (C)

MEL and CDL are tools that define how a flight can operate safely when certain equipment is inoperative or when the aircraft’s configuration isn’t standard. They establish which items may be deferred or which configuration deviations are permitted, and they lay out the conditions, procedures, and any minimum crew actions required to maintain safety.

Why this is the best match: The purpose of these lists is to keep the aircraft flying within safety limits when things aren’t perfect. The MEL specifies which inoperative equipment can be tolerated for a flight, with specific limits and required actions. The CDL covers approved configuration deviations, indicating what non-standard configurations are allowed and what checks or procedures must be followed. Together, they enable a flight to depart and operate safely even with certain deficiencies, rather than forcing immediate repairs or grounding.

They don’t set flight speed, cleaning schedules, or general maintenance timelines, so those options aren’t what MEL and CDL are used for.