Thursday, February 4, 2010

Unconventional Thoughts on Aircraft Maximum Gross Weight Limitations

Every aircraft has a maximum gross weight limitation established as part of the certification process. I owned a 1974 Cessna Skylane I purchased new for more than 30 years.  It had a maximum gross weight limitation of 2,950 pounds.  Although I made more than one attempt to discover the reason its maximum gross weight was 2,950 pounds by contacting Cessna in Wichita, I was never successful in finding the reason for the establishment of the number - 2,950 pounds...

After doing some research on the issue, I discovered there are different factors which the manufacturer uses to establish the maximum gross weight.  They include structural strength limitations, as well as performance limitations in the form of stall speed criteria.  Another criteria used is minimum climb performance gradients.  Although I was never able to determine which of these were the reason for the 2,950 pound limitation for my Cessna 182, I strongly suspect the reason for the number chosen was the balked landing minimum climb gradient requirement for certification.

In discussions I have had with many, many pilots on this issue of the reason for the choice of the number of 2,950 pounds, none could offer me an answer.  They would mostly guess the structural strength issue as the reason. I did not agree with them in that I felt based upon the 3,000 hours I flew in it, the balked landing go around minimum climb gradient was the reason. This caused me to reach the conclusion that there may be times when it is safer to take off in excess of maximum gross weight if the excess weight is in the form of fuel. (The best substitute for brains is gas and the only time you have too much fuel is when you are on fire.) A little extra fuel offers additional options for each of our flights should we encounter unexpected head winds or bad weather at our destination.

The Federal Aviation Administration will actually approve flights in excess of maximum gross weight by 10% for ferry flights and some normal operations in Alaska. The highest gross weight take off I ever made in my 182 was ???? pounds.
What experiences have you had deliberately flying in excess of maximum gross weight? What are your thoughts on this issue?  Please post them on this blog.

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