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FAQ's

Can I copy the graph?

No, for two reason’s.  First, the American Aeronautics graph is copyrighted material.  Copying the plotter or graph is the equivalent of copying computer software.  Second, and most important, copying the graph alters the scale and renders the calculation inaccurate. You can copy a ruler and measure it to see the change.  Only graphs produced by American Aeronautics are guaranteed to be of the correct scale.

How does the American Aeronautics calculator work?

The American Aeronautics calculator uses the “vector method” of mathematics.  The vector method simply converts numbers into lines that can be drawn on a graph using a special ruler called a plotter.  If you can draw a line with a ruler, you can do the most difficult aircraft weight and balance calculation in about 20 seconds.  

How Accurate is the American Aeronautics weight and balance calculator?

The American Aeronautics weight and balance calculator is extremely accurate.  The plotter and graph system is accurate to the width of a pencil or pen line drawn over eight inches.  Well under 1% error. Just as a chain is only as strong as its weakest link, a calculation is only as accurate as its weakest data.  Taking into consideration normal error introduced from such things as aircraft weighing, passenger weight determination, and fuel gauges, the best accuracy, even if everything is done right, is 2% error.  This is a much larger error than the approximately ¼ % introduced by the American Aeronautics system.

Does American Aeronautics have a calculator for my aircraft?

We do weight and balance calculators for all aircraft.  If you have a Piper Cub or a Boeing 747 we have a system for you.  We even have calculators for many aircraft with custom modifications such as Beryl D’Shannon and Osborne tip tanks for Beechcraft.  Even if you have an extremely new or unusual modification, we can design a system for you.

Where do I start my calculation?

For most light aircraft the starting point on the graph is the aircraft basic empty weight (BEW) and center of gravity (C.G.).  The weight and balance document indicating your current BEW is required to be in the aircraft and must be amended anytime there is an equipment change (i.e., GPS, Wx radar, etc.) or the aircraft has been weighed.  As a convenience item, American Aeronautics can print this point on the graph for you.

Is the weight and balance calculator approved by the FAA?

When American Aeronautics went into business in 1981, the FAA in Washington at the Office of Flight Standards was approached for approval of our system.  After a little discussion it was determined that our vector template (nomograph) system fell into the same category as electronic computers, hand held calculators, E-6B flight computers, and Jeppesen navigation plotters.  They are simply calculators, and have never been issued an STC or needed to be “approved by the FAA”.

Is the weight and balance calculator approved by the FAA for use by Air Carriers?

It is up to each individual Flight Standards District Office (FSDO) to determine if the weight and balance control calculation system being used by a 121, 125, or 135 operator is valid and accurate.  If the Principal Maintenance Inspector (PMI) or Principal Operations Inspector (POI) feels that they cannot adequately determine the validity of a system, they are supposed to “bump” it up to the regional engineering office for examination.  American Aeronautics has been approved by every FSDO in the U.S. at least once, most many times.

Does it matter what order I calculate my weight and balance?

The weight and balance will have the same end result no matter which order the calculation is done.  However, it is recommended that all fuel calculations be done last to insure that the aircraft is within its maximum zero fuel weight limitation if it has one.  Also, it is much easier to determine landing weight and cg if fuel is done last.  Just back down the fuel line to the landing fuel quantity and you have your landing weight and cg.

What’s the difference between Max. Takeoff Gross Wt. & Max. Allowable Takeoff Gross Wt.?

Many pilots typically consider the maximum takeoff gross weight to mean the maximum certificated takeoff weight.  For instance, the typical Learjet 35 has a max. certificated takeoff weight of 18,300 lbs.  Maximum Allowable Takeoff Weight, however, is limited by the most restrictive of the following requirements:


• Maximum Certificated Takeoff Weight
• Maximum Takeoff Weight to meet minimum single-engine climb gradients and not exceed brake energy limits (Climb or Brake Energy Limited)
• Maximum Takeoff Weight for runway length available
• Maximum Takeoff Weight for obstacle clearance

What’s the difference between Max. Landing Wt. & Max. Allowable Landing Wt.?


  The same applies for landing weight as does for takeoff weight.  The limiting factors are:


• Maximum Certificated Landing Weight
• Maximum Landing Weight (approach climb or brake energy limited)
• Maximum Landing Weight for the runway length available

What is a Load Manifest? SUBPART B - Flight Operations FAR § 135.63 Recordkeeping requirements.

It is important to note that Subpart B of the FAA part 135 regulations states:
§ 135.63  Recordkeeping requirements.
(a)     …
(b)     …

(c)     For multiengine aircraft, each certificate holder is responsible for the preparation and accuracy of a load manifest in duplicate containing information concerning the loading of the aircraft.  The manifest must be prepared before each takeoff and must include—


(1)     The number of passengers;
(2)     The total weight of the loaded aircraft;
(3)     The maximum allowable takeoff weight for that flight;
(4)     The center of gravity limits
(5)     The center of gravity of the loaded aircraft, except the actual center of gravity need not be computed if the aircraft is loaded according to a loading schedule or other approved method that ensures that the center of gravity of the loaded aircraft is within approved limits.  In those cases, an entry shall be made on the manifest indicating that the center of gravity is within limits according to a loading schedule or other approved method;
(6)     The registration of the aircraft or flight number;
(7)     The origin and destination; and
(8)     Identification of crewmembers and their crew position assignments.


(d)     The pilot in command of the aircraft for which a load manifest must be prepared shall carry a copy of the completed load manifest in the aircraft to the destination.  The certificate holder shall keep copies of completed load manifest for at least 30 days at its principal operations base, or at another location used by it and approved by the Administrator.