We didn’t finish all of the FARs we needed to cover from last week, so we started with the rest of those. Nothing especially interesting.
The rest of the class was about airplane performance and weight/balance. These things are very important to know and calculate before every flight. Takeoff and landing performance is especially important. Factors include airplane weight, wind speed and direction, air temperature, humidity, airport altitude, and engine power. The airplane manual includes multiple charts to help calculate required runway lengths for takeoff and landing under a given environment. It’s possible to fly in to an airport in the cool, crisp morning air with no problems, and not be able to fly out of it in the hot, humid, afternoon air because the plane just can’t lift off soon enough in the thinner air.
Weight and balance are also important. The more an airplane weighs, the faster it must go to fly. That means it needs more runway to takeoff and more runway to land. Each airplane (not each model, but every individual airplane) is weighed with all of its installed equipment to establish a starting point for that airplane’s weight. Everything else you add to it (fuel, pilot, passengers, luggage, etc.) must be considered when calculating the weight to make sure it’s below the specified limits. Not only is it illegal to fly an overloaded airplane, it’s dangerous.
Even more dangerous, however, is an unbalanced airplane. Each plane has a range of acceptable center of gravity. As with the weight, the center of gravity for each plane is given as a starting point. The weight and location of everything you add (fuel, pilot, passengers, luggage, etc.) must be used to calculate the new center of gravity and make sure that it’s within limits and will remain within limits throughout the flight. There are charts for each plane that help with these calculations.
An unbalanced plane can become uncontrollable. Even if you get it off the ground, you won’t likely go far before you crash. We were told a story about a corporate plane where the bigwig passengers insisted on sitting in the far back of the plane to play cards, even though the pilot told them to sit up front knowing the plane would be unbalanced otherwise. The flight ended shortly after takeoff as a lesson on when you should quit your job before you take no for an answer.