A note on glossary terms: over the years there has been a proliferation of aircraft weight and balance terms. This is the result of many factors, such as the Federal Aviation Administration (FAA) certification regulation under which an aircraft was constructed; the FAA regulation under which the aircraft is being operated; manufacturer standardization agreements or a combination of these and others. Examples of such terms are empty weight, licensed empty weight, basic empty weight, operational empty weight, etc.

Many of these terms may have similar meanings or sound similar. Pilots and aircraft mechanics must ensure they understand the terminology and are applying the correct values based on the procedure and situation dictating the calculations undertaken.

Occasionally, the acronym “GAMA” follows the glossary term. This indicates that it is part of the standardized format adopted by the General Aviation Manufacturers Association in 1976, known as GAMA Specification No. 1. These aircraft are usually manufactured under Title 14 of the Code of Federal Regulations (14 CFR) part 23 and differ from aircraft manufactured under the earlier certification rule Civil Air Regulation (CAR) part 3 for weight and balance purposes in the condition under which empty weight was established.

Aircraft certificated under 14 CFR parts 23, 25, 27, and 29 establish their certificated empty weight as required in the appropriate section of these regulations, which states that the empty weight and corresponding center of gravity (CG) must be determined by weighing the aircraft with:

In contrast, aircraft certificated under the older CARs established certificated empty weight under similar conditions as the newer aircraft, with the important exception that the aircraft weight did not include full oil, only undrainable oil. Mechanics and repair stations should consult the appropriate certification rule when reestablishing empty weight.

14 CFR part 121. The Federal regulations governing domestic, flag, and supplemental operations.

14 CFR part 135. The Federal regulations governing commuter and on-demand operations.

Adverse loaded CG check. A weight and balance check to determine that no condition of legal loading of an aircraft can move the CG outside of its allowable limits.

Aircraft specifications. Documentation containing the pertinent specifications for aircraft certificated under the CARs.

Airplane Flight Manual (AFM). An FAA-approved document, prepared by the holder of a type certificate for an aircraft, that specifies the operating limitations and contains the required markings and placards and other information applicable to the regulations under which the aircraft was certificated.

Approved type certificate. A certificate of approval issued by the FAA for the design of an aircraft, engine, or propeller.

Arm. (GAMA) The horizontal distance from the reference datum to the CG of an item. The algebraic sign is plus (+) if measured aft of the datum or to the right side of the center line when considering a lateral calculation. The algebraic sign is minus (–) if measured forward of the datum or the left side of the center line when considering a lateral calculation.

Balanced laterally. Being balanced in such a way that the aircraft wings tend to remain level.

Ballast. A weight installed or carried in an aircraft to move the center of gravity to a location within its allowable limits.

Permanent ballast (fixed ballast). A weight permanently installed in an aircraft to bring its CG into allowable limits. Permanent ballast is part of the aircraft empty weight.

Temporary ballast. Weights that can be carried in a cargo compartment of an aircraft to move the location of CG for a specific flight condition. Temporary ballast must be removed when the aircraft is weighed.

Basic empty weight. (GAMA) Standard empty weight plus optional equipment.

Basic operating index. The moment of the airplane at its basic operating weight divided by the appropriate reduction factor.

Basic operating weight (BOW). The empty weight of the aircraft plus the weight of the required crew, their baggage, and other standard items, such as meals and potable water.