Tipping the Scales

How Can You Be Sure Your Aircraft Loading is
Safe and Legal?

"Pilots should never become complacent about the weight and balance limitations of an airplane..."

Aircraft manufacturers are not fussy about what method you use to calculate your aircraft's center-of-gravity, except that they expect you to do it right. I sat on the jump seat of an African registered B737-300 the other day and watched the two pilots struggle with their calculations for 15 minutes. The Training Captain finally figured out that the Captain was entering the data incorrectly. That settled they scribbled out their figures on the scrappy looking load sheet and passed it to the cabin attendant. I guess Air Canada is all automated, but what about the rest of us? Is there any reason we can't be automated as well?

It is the responsibility of the pilot to ensure that the aircraft is loaded properly.

Calculating your weight and balance is not really difficult as we were all taught how to do it as student pilots. "Let's see now... there is me... my instructor and fuel. Weight times Arm equals Moment. Place the dot on the chart and there you are. In balance. That was easy."
Now, however, you have your commercial ticket and 7 passengers including the one in the front right seat, and you have removed the rear seat for cargo, and filled your amphib float lockers, and you have three stops enroute, one on land and two on water, and you require VFR fuel.... Humm, where is the chart for that? Not so easy, right?
Well that is still not so tough because how wrong can you go on a 9 passenger aircraft?
One Caravan crashed in the ocean west of Liberia killing all on board. While the pilot was making a desperate Mayday the air traffic controllers heard a strange howling siren in the background. The Cessna representative listened to the tapes and decided it was the high speed warning horn. That horn only comes on when the airspeed exceeds 176 knots which is the maximum structural operating speed of the Caravan.
All 13 people on board including the pilot died on impact. Not to say anything about the 6 goats and 24 chickens. Although the dispatcher had not calculated the weight and balance before take-off he did have a list of the passengers and cargo loaded on board. Besides the 12 passengers, goats, and chickens, there was also 6-80lb bags of cement and 9-50lb bags of rice. The total weight was something like1200lbs over the maximum allowable gross weight.
 It was testimony to the stubbornness of the pilot and the ability of the aircraft to even get airborne with such a load, but when the FCU failed and the engine lost power the pilot could not prevent a deep stall without entering a fatal spiral dive. The Caravan must have hit the ocean at the speed of sound with the trim in the full nose down position. Ironically, the pilot might have saved the situation by employing the emergency power lever, but I imagine when the engine powered down he had his hands full dealing with the severe out of limits situation and forgot to pull out the emergency checklist.
This is an extreme example but there was a recent case where a B1900 was only 100 lbs and 1% out of its weight and balance requirements and the cause of the fatal crash was still blamed on a “heavy takeoff weight and improper weight distribution combined with a malfunctioning elevator.”
An aviation authority said that “airplane weight limits generally have a built-in safety margin, much like the ‘empty’ line on automobile gas tanks.” “You could be 10 percent over the weight limit of an airplane and still fly it.” “But the location of a plane's center of gravity is not as forgiving. The FAA says a pilot may not fly a plane if its center of gravity is beyond its forward or aft limit, because such a plane can be uncontrollable once airborne.” “It's a very black-and-white thing.”
It may be a very black and white to some but often most airlines don’t give the pilots the proper tools to make those calculations. It is easy to print blank aircraft specific load sheets and enter all the calculations in by hand as long as you have the time and there are no last minute changes. Cessna even acknowledges the problem of quick cofg fixes by throwing in a special $2 plastic plotter with each million dollar plus aircraft that they sell. Unfortunately the plotter has a disclaimer on it saying “if the plotter shows a marginal condition developing” then don’t use it. In other words, only use the plotter if the situation is not critical. That is not very helpful.
Some companies have gone through the trouble of printing aircraft specific load sheets with graphic plotters. Follow the lines and you can show whether or not the load is within limits. Again, however, the sheet has to be tallied for every change in load. A last minute passenger means filling out another complete sheet. The other problem is that these sheets need to be certified by the printer or a slight printing error can show an unsafe condition as being within limits. Thus, these sheets need to be printed and certified by specialist companies and are not easily changed. You cannot simply photocopy them if you need more. Photocopying voids the certification.
The weight and balance of your aircraft, however, is based on computations. Thus, the modern way to complete your manifest and load sheet, to calculate your total all up weight, and to determine whether your center-of-gravity is within the moment envelope is to do it on a computer.

That is where The Bush Pilot Company comes in. We have developed a fool proof method to combine all your dispatch requirements into one simple program. The program is aircraft specific and takes into account all the variables you will encounter when operating a Caravan or, given a little more lead time, any other aircraft or helicopter carrying 19 passengers or less.

What does The Bush Pilot Company Weight and Balance Calculator give you?

  • Multiple Aircraft
  • Total Gross Weight
  • Take-off Weight
  • Runway Landing Weight
  • Water Landing Weight
  • Runway payload remaining
  • Water payload remaining
  • Rear Cargo (Zone 6) Limitations
  • Baggage and Cargo Weights (Zone 5 & 6)
  • Float Locker Weight Limitations
  • Minimum Fuel Requirements
  • Route Specific Fuel Requirements
  • Additional Fuel Carried
  • Pilot Specific Weights
  • Printed Passenger Manifest (names and weights and baggage)
  • Printed Load Sheet
  • Printed Graphic Charts
  • Both pounds and kilos

The best part is that the program gives the pilots and dispatchers an easy to comprehend graphic visual representation of both the Center of Gravity Moment Envelope and the Center of Gravity Limits. With this powerful presentation the pilots and dispatchers can quickly see where the loading problem lies and how to fix it quickly.

Using a desktop PC, or a handheld PC Tablet, the pilot can fill out a specific manifest and load sheet for every flight whether he does one or twenty a day.
Moreover you can print out the passenger manifest, print out the graphic charts and store each and every flight in the data base. When you are away from the office you can store each flight in your Tablet and print out the results when you get back to the office. You have the ability to know your center-of-gravity for every flight as long as you are willing to carry around a bathroom scale or have the nerve to ask the singing lady what her real weight is when she says "only 220lbs." In reality every destination could have a calibrated scale that will make your computations easy and straight forward. After all when the chicken runs to the back of the plane and you go out of cofg you know you cut it too damn close.

    To view the graphic interface of our calculator click below and then save the file to your desk-top to run. If you are interested in automating your manifesting and load control contact The Bush Pilot Company for a quote.

Take the Caravan and the Beaver for a test flight today.

Other aircraft available on request.

  • Twin Otter
  • Dash-8 De-Havilland
  • Bell Helicopters
  • S76C+ and C++
  • Citation S11

The attitude indicator will guide you back to The Bush Pilot Company.
Article by John S Goulet

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Last modified on November 13, 2007.
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