When it comes to Minimum Equipment Lists (MELs), compliance isn’t just about legal sign-offs, it’s about protecting safety, operational efficiency, and your company’s reputation. Whether you operate under Part 135, hold a Part 91 LOA, or manage a multi-aircraft fleet, understanding common MEL pitfalls is critical to avoiding FAA scrutiny, trip disruptions, and lost revenue.
Below, we break down recurring issues seen with pilots, managers, and maintenance teams, along with practical, regulation-based solutions to keep your operation safe, compliant, and running smoothly.
Just because the MEL says an item is deferrable doesn’t mean you should accept the aircraft. For example:
Modern aircraft have deeply linked systems. A radar altimeter may feed your EGPWS, which ties into the auto throttle and weight-on-wheels sensors. MELs might allow you to defer each system individually, but not together. Knowing your aircraft’s system relationships is essential to making safe deferral decisions.
One often neglected aspect of deferring items is forgetting to adjust the aircraft equipment suffix on the Flight Plan. Dispatchers and Pilots should understand the applicable suffix to each aircraft. For example, deferring an autopilot removes RVSM capability, meaning the “W” suffix in Block 10 of the ICAO flight plan must be removed. Failing to make that change could cause ATC confusion or regulatory issues.
Pilots must ensure all maintenance discrepancies are properly documented, closed, and deferred in accordance with company approved procedures. This is especially important at outstations that are unfamiliar with your operation.
Adding a new airplane to your D085 without an MEL is not just risky, it’s a red flag about your safety culture. As discussed in the Sky Safety pilot hiring guide, an absent MEL often signals operational shortcuts. Aircraft will break, and usually at the worst possible moment. Without an MEL, the choice becomes losing a $40,000 trip or pressuring a crew to fly an un-airworthy airplane, and that’s a choice no compliant operator should face.
Some insurers and safety accreditation programs require operators to have an MEL. Not having one could impact coverage and market credibility.
A few single-engine taxi cycles can offset the cost of producing a compliant MEL. Without it, you may be forced to ground an aircraft unnecessarily, costing far more than the investment in the manual itself. You cannot afford to operate without one.
Independent mechanics often follow the book with little personal interpretation, but because they work on multiple aircraft types, they may lack deep type-specific MEL knowledge.
If a pilot calls about an issue, the first question should be: “Did you write that up?” The FAA has been cracking down on this apathy, and for good reason. A common problem is pilots see that an item is deferrable, assume that it carries no safety risk to fly with it inoperative, and fail to create a maintenance discrepancy write-up. The mechanics are the last line of defense to stop these behaviors. One infamous Piaggio operator lost its certificate largely due to improper maintenance documentation.
MELs are a two-purpose document. First is to keep the operation going and getting the airplane fixed. Second is to monitor trend and gather data. SOP changes and pilot training are also affected by this practice. It’s a mx document and an SMS tool built in one. This second aspect is often forgotten by mechanics, even by departments with CASS (continuing analysis and surveillance system). CASS is a type of tracking and trend monitoring that helps fix issues before they become more serious. It is this type of planning ahead and monitoring that allows a Mx department to excel at their job, and not hinder the operation because an airplane broke down in a way that was totally predictable and preventable. Moral of the story is, enforce your write ups and gather that data!
Mechanics unfamiliar with an operator’s FAA-approved procedures may sign off a deferral incorrectly; with the wrong placard, logbook entry, or inconsistent digital record. Every detail, from placard wording to maintenance tracking software, must align with approved company procedures to maintain compliance integrity.
