Monday, October 1, 2007
Exploring 20 aviation myths
Right up front I should post a very clear caveat: Myths within any technological field almost always have a grain of, if not truth, at least enough fact that they have some ardent supporters who swear by them. (They “know” it’s true and can prove it because a friend of an uncle knew someone who had it happen to a cousin.)" />
Myth 12 Power-off landings shock cool engines.
Busted! This is somewhat controversial. Larger general aviation engines may have a problem with power-off shock cooling in approach, but these are usually airplanes most people don’t land power-off anyway. The amount of time an airplane spends cooling off during a power-off approach is short and the temperature lost is small. Long, power-off descents from altitude, however, can do some serious shock cooling.
Myth 13 GPS is all that’s needed for cross-country flying.
Busted! From a practical point of view, you’d be placing your entire enchilada in the hands of the GPS and, should it fail (dead batteries, meteor hits one of the satellites, etc.), you’re in deep guano. So a map, compass and course line should always accompany the GPS. None of them have batteries to run down.
Myth 14 Ice only occurs in clouds.
Wrong (although usually right). Ice is found wherever moisture and freezing temperatures occur. Usually that moisture is visible as haze or cloud mist, but it’s not always clearly visible. Moisture can be hanging in the mist just under an overcast and, if it’s in a supercooled condition and you fly your chilly airplane through it, you’ll pick up ice almost instantaneously.
Myth 15 Stall-spin accidents always start with a nose-high attitude.
Totally wrong and then some! A stall only requires that the critical angle of attack be exceeded, and that can happen going straight up or straight down under certain conditions. On many airplanes, in a normal, flaps-down approach, it’s quite easy to exceed the critical angle with the nose below the horizon. This is especially true at full flaps. If you have the ball well off-center at the same time, you not only stall, but can also possibly spin. Both mistakes are totally avoidable with basic flying techniques: Monitor the nose attitude/airspeed and keep the ball in the center.
Myth 16 Running up your engine on the ground once a month prevents rust.
Busted! Under normal conditions, it’s nearly impossible to get an engine hot enough on the ground to cook the moisture out of the oil and drive it out of the breather. You usually can’t pull high enough power settings on the ground long enough to get the temps up to true operating temperature, especially on cool days. Generally, it takes at least two laps around the pattern to get the temps high enough to even begin to clean out the engine. Yet another excuse to go flying: “But honey, if I don’t go flying, the engine will rust.”
Myth 17 On takeoff, it’s safer to leave it on the ground until fast, and then rotate off.
Busted! This is wrong, if for no other reason, because the definition of “fast” is nebulous and it means the pilot is deciding when the conditions are right for the airplane to fly, rather than letting it make the decision. Plus, it’s ugly aviating. Pick the small wheel (whichever end it’s on) off the ground, and hold a slight positive angle of attack throughout the takeoff run and the airplane will leave the ground when the conditions are good for both a clean liftoff and a positive rate of climb. It compensates for everything from weight to density altitude.
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