Meet CAAPVAA
To determine the CAAPVAA power setting, start a power-off glide and listen to the engine. The resulting engine sound is caused by the relative wind turning the propeller, which is turning the engine. Now make a slight power increase so that the engine is turning the propeller. The engine tachometer will probably indicate 1,400 to 1,500 rpm, but don't place too much reliance on the tachometer. Learn to use engine sound.
I always laugh when I hear a student pilot say that he makes better landings in airplane A as compared to airplane B-they are identical models. I have him set power using engine sound in airplane A and then note the tachometer indication, 1,400 rpm, which he normally uses. We do the same thing in airplane B, but that tachometer indicates 1,500 rpm. So, when he flies airplane B and sets 1,400 rpm like he does in airplane A, less power is being developed and a poor landing occurs.
At low power settings, tachometers are not that accurate. Learn to use your sense of hearing-and yes, you can do this while wearing a headset.
To determine the CAAPVAA attitude, set the power as described and stabilize the airplane at the proper final-approach speed with full flaps and landing gear extended. Now look inboard of either wing tip and visualize the wing's chord line. It will be approximately parallel to the Earth's horizon. Now that you know the attitude and power, you can fly the approach in any airplane.
To begin, assume that I'm number one for landing when flying a left downwind leg-carburetor heat on if applicable. When abeam the runway numbers, I select the CAAPVAA pitch attitude and power setting and extend the first increment of flaps. (If I must follow traffic, I delay this action and maintain pattern altitude until I intercept the proper glidepath, but I do extend the first increment of flaps in order to reduce speed somewhat and remain close to the airport.)
I turn onto the base leg when the runway is 45 degrees behind the left wing. I now have several options for controlling my glidepath without changing power: flap extension and base leg orientation-I can widen out my pattern a bit if too high or turn toward the runway if too low.
You must anticipate the need for flap extension; don't wait until you are above the desired glidepath. Extend the next increment of flaps when your approach looks perfect, because in a normal wind gradient, you are about to go above that glidepath.
Approaching the final leg, I have other glidepath-control options: the starting point for the turn to final-a shallower or steeper than normal bank angle will affect vertical speed and ground track-and full flap extension when on final. I try to roll out on the runway's extended left edge, not the extended centerline. This is a good trick because I always overshoot the extended edge and wind up on the extended centerline.
Updrafts and downdrafts-caused by surface heating-and wind gradient are my final considerations for completing the approach using constant power. If properly evaluated, I'll cross the runway threshold and set idle power during the landing flare. If desired, you can adjust for the slight power increase that occurs during the descent-one inch of manifold pressure per 1,000 feet.
The CAAPVAA approach makes me fly smoothly and makes me continually practice forced-landing thinking. An actual forced landing requires only two changes: Idle power, obviously, and a decreased pitch attitude for final-approach airspeed.
You can practice this approach at every opportunity because a flight instructor is not required. If you misjudge one or more of the factors involved and get excessively low or high, you must change pitch and power in order to recapture the proper glidepath. The more you practice, however, the sharper you will get. And I do mean sharp!
Ralph Butcher, a retired United Airlines captain, is the chief flight instructor at a California flight school. He has been flying for 43 years and has 25,000 hours in fixed- and rotary-wing aircraft. Visit his Web site.
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