Flight Lesson: Slow Acceleration

It was June 1965. My buddy Carly and I had earned our private pilot certificates and flown the additional hours required to check out in the flying club Cessna 172. We were eager to stretch our wings in this bigger airplane, with its beautiful four-seat interior and 145-horsepower, six-cylinder Continental engine. It seemed a major step up from the Aeronca Champ and Tri-Champ we had been flying.

After we each had received an hour of dual instruction in the 172 as part of the checkout, our instructor asked if we wanted to sit in the back seats as he flew with another student in the airplane. It was a gorgeous day at old Tamiami Airport and neither of us could think of anything that would beat spending another hour in the airplane.

It was a warm day. The airplane had full fuel. None of us was a lightweight. Start-up was normal and the pretakeoff checks went OK, but observing from the right rear seat I was not certain the student had gotten the key switch back to the “both” mags position at the end of the magneto check during runup. But the flight instructor seemed happy.

After the student advanced the power and commenced the takeoff roll I thought to myself, Hmm, this seems like slower than normal acceleration. I didn’t say anything because, after all, there was an experienced instructor in the right front seat and I was just a beginner. Runway 14 was about 4,000 feet long, as I recall, with an expanse of grass off the end. After about 1,000 feet of takeoff roll, the instructor sensed something was not right and applied full carb heat to combat what he thought was carburetor icing. The engine lost more horsepower.

“Try turning the other mag on,” I said loudly. The instructor instantly reached over to turn the key to the Both position. The engine reaction was instantaneous and positive. He then turned off the carb heat, and we lifted off at near normal airspeed about 200 feet before the end of the runway.

After landing we talked over the pretakeoff checks and the takeoff. We agreed that the best mag check process is to take the key switch from Both to Left in one continuous motion (two clicks left), check the left mag and then back to Both followed by one click left to check the right mag—and then back to Both. The student had checked the right mag first and then the left mag and had inadvertently only come back to the right one click, leaving us on the right mag instead of both.

I asked the instructor why he had applied full carb heat on a hot summer day at wide open throttle. He replied that it was possible to get carburetor ice regardless of outside air temperature. When I asked why he had allowed the takeoff attempt to continue rather than abort he said he thought we could “just make it.”

There are a couple of lessons here. Do not continue a takeoff if things do not seem right. Stop the takeoff attempt and figure things out on the ground. Second, never sit quietly in an airplane when you sense something is not right, even if you do not have as much experience as the people flying. I also learned that the back seat would not become one of my favorite places to sit.