A couple of years ago I used to teach “Flight preparation” theory classes to student PPLs in Geneva, which included weight and balance and take-off performance. The weight and balance limits are easy to teach, but exact performance calculations are not easy. Wind and temperature are known at the last moment, and who really weigh all what’s on board to the pound ?
I’m not naive – I know that pilots don’t always make detailed performance calculations and I’ve no problem with that. Taking off from a 4.000 meters (13.000 feet) long runway at sea-level, alone in a Cessna 172 with full fuel, temperature below freezing and 15 knots of headwind is not a problem, no need to check the aircraft manual.
A common problem is that pilots tend to become a bit lazy with time. We easily think “I made it in similar conditions before, I don’t need to re-calculate all of it”. Degree per degree, pound per pound, one slowly reaches the limits of the aircraft. I tried to to teach the students to detect unusual conditions. Flying on particularly hot days, or with one more passenger than usual, or operating at unusual altitudes shall ring a bell.
Check this accident report from AOPA. It’s about a Bonanza crashing few hundred feet after take-off. Shifting winds also play a role in this accident but both weight and balance calculations reveal interesting points. The aircraft was in overweight, and had four persons on board. Because of high temperature the density altitude was 3000 feet higher than the elevation. Quoting the AOPA article: “The pilot stated that he “mentally” performed a weight and balance after topping off the airplane’s fuel tanks. He also said he had previously performed takeoff-over-obstacle calculations for the airport in similar warm-weather conditions.”
One is always smarter after an accident and criticizing from the comfort of my living room is easy… but I’ve one extra remark. The video clearly shows that the landing gear remains extended all the time. This raises the old question: when to retract the landing gear ? As soon as airborne, or when a landing is no longer possible ? The decision depends of the type of take-off, but also of the type of aircraft. I personally don’t like the emergency landing gear extension system of the Bonanza. I would tend to leave the gear down longer on a Bonanza because of it. Could gear retraction have saved the doomed aircraft ? Hard to say.
This accident carries several lessons. Take some time to think about it and let me know what it teaches YOU.
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