What is a MEL? (Minimum Equipment List)

A Minimum Equipment List (MEL) is a legal binding document authorised by the airline which allows a list of inoperative equipment in an aircraft to be still flight operable.

A MEL is enforced on the ground, anything that malfunctions in flight will be handled by the companies' Quick Reference Handbook (QRH).

If even one problem, such as the APU went inoperable, without a MEL, the aircraft can be grounded. However, based on the operator's MEL, if certain conditions exist, the aircraft may be still operable. Vice versa, if a mechanic or pilot finds an equipment inoperable, if severe enough, it may lead to a ground stop for that aircraft.

Below is a section from a MEL and the explanation of each section:

Aircraft Information

Lists the aircraft, the revision number, date, and page number of the MEL

System Section

List the system, the sequence number, and the ID of the equipment

Repair Category

The days to be repaired is the amount of days the day AFTER discovery.

Number Installed

Number installed in the aircraft

Number Required For Dispatch

The minimum amount of equipment for that system to be required for that aircraft.

Remarks and Exceptions

Any remarks and limits placed on the aircraft if there are any missing or inoperable equipment. For example, if the APU is inoperative, however the number required is 0, we look at the remarks.

The remark states that the aircraft can be operable if:

• APU is deactived
• Intake door is visually verified to be CLOSED
• Both IDG is operative

There are other limitations that can be placed on the aircraft such as altitude, temperature, and speed restrictions.