# How does a small charter operator determine where the centre of gravity is for a given flight?

I was reading an account of the 2001 crash of a charter aircraft carrying the singer Aaliyah and her companions.

Within it there's a summary of the investigation by the NTSB which includes the text 'the maximum allowed gross weight of the aircraft was "substantially exceeded" and that the center of gravity was positioned beyond its rear limit'. (similar material here) .

How should the pilots of small charter aircraft go about establishing where the centre-of-gravity is for a given load of passengers and their luggage ? For airliners there are loading specialists and significant information about the weight of the luggage but how do charters of the type involved in this accident establish what's being carried and how the affects the centre-of-gravity ? Is this something pilots are trained in ? Is each piece of luggage weighed ?

• – mins
Sep 3, 2021 at 8:21
• Complete non-sequitor: there is a post-apocalyptic novel, written by Peter Heller, titled "The Dog Stars". The protagonist has to fly is '56 Cessna to a remote location in a canyon and take off again. There is almost an entire chapter on how he calculates his CoG to figure out if he can take off again. the description is complete with the tables and graphs he uses. It was fascinating to me. Sep 3, 2021 at 15:22

For every aircraft, a weight and balance form is provided in that aircraft's flight manual and pilot operations handbook (POH). It provides a method for determining the aircraft's weight and position of center-of-gravity. It is often represented as a some sort of graph where the person making the calculations can rather quickly establish the results.

The load-sheet can be prepared by an operations office, ground handling agent or the pilot, but it should always be present in the cockpit and verified by the pilot before commencement of flight.

To determine the overall mass of passengers and cargo, it is often unfeasible to weigh everybody and every piece of cargo, so often standard masses are used. They are average "close enough" values to be used in calculations. If it is obvious to the crew that standard masses are not applicable for a given flight, a different method should be used - like weighing.

The above method may sound rather inaccurate, which it is. Payload makes only about 10-20% of total aircraft weight, so even gross errors in determining mass of passengers and bags usually does not compromise safety.

Usually the reason behind these kind of accidents is poor safety culture within the airline where load-sheets are not prepared at all or they do not even try to represent actual conditions. It is easy to slip in this kind of behavior if the passenger load is always the same like it could be in a chartered business jet with only a few seats. Then comes the day when the plane is full and bags are heavy. In smaller aircraft the cargo hold is usually in the tail, sometimes in the nose. If it is stacked with heavy bags you are most likely outside approved operational envelope.

Also there are several known cases where VIP passengers have put pilots in tough situation and demand that their gear is loaded even if it is obvious that aircraft is overweight. This can be reinforced by the bosses who want to keep their high-paying, high-profile customers happy.

• When I was bush flying on floats we used stripes painted on the floats that marked the water line at gross wt/aft cg. "Load lines". You'd be picking up a load at a remote lake and you could only guess at the weights - maybe I'm over, maybe I'm not. The load lines did the job as long as the water wasn't too choppy. I was mildly overweight frequently, but when it got to where the load was obvious, in extreme cases I had to use tricks like faking a takeoff attempt to get the customer to agree to offloading gear without complaining to the boss. My boss would back me up in the end though. Sep 3, 2021 at 13:46
• The sad part, @JohnK, is that you had to trick people into saving their own lives (and yours). Sheeple can be so stupid... Sep 3, 2021 at 15:51
• Biggest problem was predecessor pilots the customer knew in the past who would haul anything. "Well, Rusty would carry loads like that all the time". Biggest overload I took was when the lodge owner begged me to take his Indian fishing guide back with me because he seemed to have a tooth abscess. He was a little guy so I was probably less than150lbs over, in a C-185. As long as the CG is ok, and the lake is long, it's not dangerous, just illegal, and for the right reasons you bend the rules a bit. Bush flying is a live-by-your-wits profession, and decision making is often shades of grey. Sep 3, 2021 at 16:59
• Thanks ! Interesting answer. Sep 4, 2021 at 1:23
• Might be worth reflecting that the determination by the investigating agency must also be based on estimates, as much of the baggage and cargo will have been destroyed and redistributed in the crash and any ensuing fire. I get that crash reconstruction can do pretty amazing things but many materials in baggage will simply not survive a fire and can only be guessed at.
– CCTO
Sep 7, 2021 at 13:39