Aircraft Weight Fundamentals and Operational Use

This article provides an overview of the primary aircraft weight definitions, their calculation methods, and operational applications.

Aircraft weight management plays a central role in commercial aviation. While often automated or predefined within airline systems, these values are critical to flight safety, structural integrity, and performance planning.

Operational Weight Definitions

Basic Weight (BW)

The manufacturer-defined weight of the aircraft upon factory release. This includes the aircraft structure and standard flight equipment. Any operator-specific installations (e.g., galleys, extra seats, antennas) are excluded.

Dry Operating Weight (DOW)

Calculated by adding the following elements to the Basic Weight:

• Flight crew and cabin crew

• Crew baggage

• Standard catering items

• Potable water and technical equipment

DOW values may vary depending on the number of assigned crew and type of service (domestic or international). On the load sheet, crew information is indicated as a numerical pair (e.g., 2/4, representing two cockpit and four cabin crew), along with a pantry code specifying the route type. In the case of additional equipment, manual adjustments are applied based on predefined weight indexes.

Operating Weight (OW)

The sum of DOW and take-off fuel. Represents the aircraft’s ready-for-departure configuration without payload (passengers or cargo). Taxi fuel is not included in this value.

Take-Off Weight (TOW)

The sum of OW and the total traffic load (passenger and cargo weight). Represents the aircraft’s gross weight at brake release. Taxi fuel remains excluded.

Zero Fuel Weight (ZFW)

The total weight of the aircraft without fuel. Calculated by adding the total traffic load to the DOW. Important for assessing wing loading and structural limits.

Landing Weight (LAW)

The expected aircraft weight at touchdown. Determined by subtracting trip fuel from the TOW.

Maximum Weight Limits

Each operational weight has a maximum allowable value, defined by aircraft structural and performance limits. These limits must not be exceeded during planning or execution of flight operations. Common abbreviations include:

• MZFW: Maximum Zero Fuel Weight

• MTOW: Maximum Take-Off Weight

• MLW: Maximum Landing Weight

Exceeding these thresholds may result in structural damage or compromised aircraft performance.

Structural Weight Limits

Maximum Taxi Weight (MTW)

Represents the maximum weight permitted during ground taxiing without overloading the aircraft's landing gear or struts. Includes taxi fuel. Distinct from MTOW, which is the limit at take-off roll initiation.

Maximum In-flight Weight

Derived from engine thrust and aerodynamic lift capacity. Reflects the theoretical upper weight limit the aircraft structure can sustain while airborne.

Conclusion

Accurate calculation and application of aircraft weights are essential for safe, efficient, and regulation-compliant flight operations. Although operational software handles many aspects automatically, understanding the definitions and limits provides valuable context for load planning, performance evaluation, and abnormal situations.