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ASI Safety Spotlight

Why borrow trouble?

Working on possible decisions before something bad can happen

Aeronautical decision making isn’t interesting when all factors point the same way. Do you take off uphill into the wind or downhill with the tailwind? Helping students work through these choices teaches them to think like pilots.

In April 2008, a Cessna 150 crashed shortly after takeoff. The CFI suffered minor injuries and his student, the airplane’s new owner, escaped unhurt. The CFI told investigators that they’d planned to make a test flight around the pattern. Winds were from 300 degrees at 10 knots gusting to 15, so they decided to use Runway 29, 2,600 feet of turf.

The instructor configured the airplane for a short-field takeoff, held the brakes, and opened the throttle. The engine only reached 2,050 rpm and acceleration was sluggish, which the CFI blamed on the tall grass. The Cessna lifted off at 55 mph, but even in ground effect, it wouldn’t accelerate further. With rising terrain and trees ahead, the CFI tried to bank left. When a gust lifted the right wing, the 150 stalled, spun left, and hit nose-first.

The result was “structural damage to the fuselage and both wings." Investigators found carbon fouling on both plugs in cylinder number two. The magnetos’ connections to the plugs were reversed—the left mag to cylinders one and three’s top plugs and two and four’s bottom plugs rather than vice versa—and the left mag’s E-gap (efficiency gap) and breaker-point gaps were double their specified values.

What might this CFI have wished he’d done differently?

Runway selection comes to mind. Alignment with the wind is nice, but isn’t everything. The other runway was 4,670 feet of asphalt, plenty of room to accelerate and stop again with no extra drag to disguise a poorly running engine. The gusts would have been just within the 150’s 12-knot demonstrated crosswind component. With the airplane’s condition uncertain, why add the challenge of an obstructed soft-field takeoff?

Taking off without verifying full power could also be questioned. Even if the POH standard of 2,500 static rpm was obtained with a new engine, 2,050 seems low. Given any choice, the air is almost never where you’d prefer to investigate a possible engine problem. Those are lessons this student probably remembers—although maybe not the ones his instructor tried to teach.

ASI Staff
David Jack Kenny
David Jack Kenny is a freelance aviation writer.

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