June 2009 Issue

Performance Planning

Even in a basic single, weight, weather and wind can have a wide-ranging impact on performance. Use these simple tips and you’ll know before you go.

Every year, takeoffs and landings account for over half the pilot-related accidents, according to the AOPA Air Safety Foundation. While poor technique accounts for some of them, many accidents could have been prevented if the pilot had consulted available documentation to determine the airplane’s performance. But before any of that can happen, we need to ensure we know how to evaluate current conditions. To assist students in determining performance data, I have them use a takeoff and landing data card on which is all the information a pilot should need to evaluate takeoff and landing performance. The card is also useful for instructors who are in the position of flying multiple aircraft models or versions. As an example, in a recent period I flew four different versions of Cessna 172s (one with the airspeed in MPH, another in knots, a third with the 180-HP STC and still different V-speeds; the fourth was a Thielert diesel conversion—you get the idea). Keeping the numbers straight for these and other different airplanes can be a challenge without a reference card. Let’s look at what’s important to evaluate, and how to go about assembling your own data card. The first item is to evaluate weight and balance, factors directly affecting any aircraft’s performance. That an overloaded airplane’s performance will decrease as its fuel consumption increases should not be news to any pilot. Too, one loaded outside its center of gravity (CG) range will handle differently, and will likely be dangerously unstable. In either case, the plane will not perform in a predictable manner and the pilot is in uncharted, dangerous waters. Step one is to get the aircraft’s empty weight and moment. This sounds simple and straightforward, but I have seen incorrect aircraft weight sheets in logbooks. When I went back and checked the maintenance logs, I found a difference of over 200 pounds. Airplanes of the same make and model do not weigh the same. Don’t forget basic empty weight consists of the aircraft, unusable fuel and oil.

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