You as pilot are responsible for the safe loading of your airplane and must ensure that it is not overloaded. The performance of an airplane is influenced by its weight and overloading it will cause serious problems. The take-off run necessary to become airborne will be longer. In some cases, the required take-off run may be greater than the available runway. The angle of climb and the rate of climb will be reduced. Maximum ceiling will be lowered and range shortened. Landing speed will be higher and the landing roll longer. In addition, the additional weight may cause structural stresses during manoeuvres and turbulence that could lead to damage.
The total gross weight authorized for any particular type of airplane must therefore never be exceeded. A pilot must be capable of estimating the proper ratio of fuel, oil and payload permissible for a flight of any given duration. The weight limitations of some general aviation airplanes do not allow for all seats to be filled, for the baggage compartment to be filled to capacity and for a full load of fuel as well. It is necessary, in this case, to choose between passengers, baggage and full fuel tanks.
The distribution of weight is also of vital importance since the position of the centre of gravity affects the stability of the airplane. In loading an airplane, the C.G. must be within the permissible range and remain so during the flight to ensure the stability and manoeuvrability of the airplane during flight.
Airplane manufacturers publish weight and balance limits for their airplanes. This information can be found in two sources:
1. The Aircraft Weight and Balance Report.
2. The Airplane Flight Manual.
The information in the Airplane Flight Manual is general for the particular model of airplane.
The information in the Aircraft Weight and Balance Report is particular to a specific airplane. The airplane with all equipment installed is weighed and the C.G. limits calculated and this information is tabulated on the report that accompanies the airplane
logbooks. If alterations or modifications are made or additional equipment added to the airplane, the weight and balance must be recalculated and a new report prepared.
Various terms are used in the discussion of the weight of an airplane. They are as follows:
Standard Weight Empty. The weight of the airframe and engine with all standard equipment installed. It also includes the unusable fuel and oil.
Optional or Extra Equipment: Any and ail additional instruments, radio equipment, etc. installed but not included as standard equipment, the weight of which is added to the standard weight empty to get the basic empty weight. It also includes fixed ballast, full engine coolant, hydraulic and de-icing fluid.
Basic Weight Empty: The weight of the airplane with all optional equipment included. In most modern airplanes, the manufacturer includes full oil in the basic empty weight.
Useful load (or Disposable load): The difference between gross take-off weight and basic weight empty. It is, in other words, all the load which is removable, which is not permanently part of the airplane. It includes the usable fuel, the pilot, crew, passengers, baggage, freight, etc.
Payload: The load available as passengers, baggage, freight, etc. after the weight of pilot, crew, usable fuel have been deducted from the useful load.
Operational Weight Empty: The basic empty weight of the airplane plus the weight of the pilot. It excludes payload and usable fuel.
Usable Fuel: Fuel available for flight planning.
Unusable Fuel: Fuel remaining in the tanks after a runout test has been completed in accordance with government regulations.
Operational Gross Weight: The weight of the airplane loaded for take-off. It includes the basic weight empty plus the useful load.
Maximum Gross Weight. The maximum permissible weight of the airplane.
Maximum Take-Off Weight: The maximum weight approved for the start of the take-off run.
Maximum Ramp Weight: The maximum weight approved for ground manoeuvring. It includes the weight of fuel used for start, taxi and run up.