Aeronautical Terms beginning with M

Major Alteration

An alteration not listed in the aircraft, aircraft engine, or propeller specifications, (1) that might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness; or (2) that is not done according to accepted practices or cannot be done by elementary operations.

Maximum Landing Weight

(GAMA) Maximum weight approved for the landing touchdown.

Maximum Permissible Hoist Load

The maximum external load that is permitted for a helicopter to carry. This load is specified in the POH.

Maximum Ramp Weight

(GAMA) Maximum weight approved for ground maneuver. It includes weight of start, taxi, and runup fuel.

Maximum Takeoff Weight

(GAMA) Maximum weight approved for the start of the takeoff run.

Maximum Taxi Weight

Maximum weight approved for ground maneuvers. This is the same as maximum ramp weight.

Maximum Weight

The maximum authorized weight of the aircraft and all of its equipment as specified in the Type Certificate Data Sheets (TCDS) for the aircraft.

Maximum Zero Fuel Weight

The maximum authorized weight of an aircraft without fuel. This is the total weight for a particular flight less the fuel. It includes the aircraft and everything that will be carried on the flight except the weight of the fuel.

METO Horsepower (maximum except takeoff)

The maximum power allowed to be continuously produced by an engine. Takeoff power is usually limited to a given amount of time, such as 1 minute or 5 minutes.

Minimum Fuel

The amount of fuel necessary for one- half hour of operation at the rated maximum-continuous power setting of the engine, which, for weight and balance purposes, is 1/12 gallon per maximum-except-takeoff (METO) horse-power. It is the maximum amount of fuel that could be used in weight and balance computations when low fuel might adversely affect the most critical balance conditions. To determine the weight of the minimum fuel in pounds, divide the METO horsepower by two.

Minor Alteration

An alteration other than a major alteration. This includes alterations that are listed in the aircraft, aircraft engine, or propeller specifications.


A force that causes or tries to cause an object to rotate. It is indicated by the product of the weight of an item multiplied by its arm.


(GAMA) The product of the weight of an item multiplied by its arm. (Moment divided by a constant is used to simplify balance calculations by reducing the number of digits; see reduction factor.)

Moment Index

The moment (weight times arm) divided by a reduction factor such as 100 or 1,000 to make the number smaller and reduce the chance of mathematical errors in computing the center of gravity.

Moment Limits vs Weight Envelope

An enclosed area on a graph of three parameters. The diagonal line representing the moment/100 crosses the horizontal line representing the weight at the vertical line representing the CG location in inches aft of the datum. When the lines cross inside the envelope, the aircraft is loaded within its weight and CG limits.

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