July 1, 2004
By Barry Schiff
Retired airline captain Barry Schiff has logged more than 26,000 hours in 275 types of aircraft.
I recently read a letter from an instrument flight instructor to the editor of an aviation publication that really got my attention. In it, the CFII said that he approved of using only rudder to make small heading changes while tracking a localizer during instrument approaches.
This got my attention for two reasons. First, it is a sloppy, unprofessional technique and is not the way an airplane should be flown. Second, the letter reminded me that I, too, once approved and recommended such a technique in an article that I wrote many years ago. I was wrong.
The writer said that he had never had a passenger complain about the use of such skidding turns in more than 25,000 hours of airline flying. My response to this is that I never had anyone complain about a lousy landing either, but that does not mean that I have not made some of my passengers wince during occasional arrivals that probably registered on the Richter scale. Passengers typically do not complain about such things even when they do make them uncomfortable.
Whether passengers complain or not should not be the point. They can feel skidding turns no matter how small (especially when seated in the back of the airplane), and airplanes should be flown so that passengers perceive as little aircraft motion and behavior as possible.
If you think about it, most pilots are perfectly capable of making such small heading corrections and demonstrate this during every visual approach. Can you keep the airplane aligned with the runway centerline during a straight-in approach? You probably do it easily and without thinking about it even when the crosswind component changes during descent. If a pilot can make a 1- or 2-degree heading correction in the conventional manner during visual flight, he should be able to do it just as well during instrument flight. After all, the airplane does not know whether it is in a cloud and behaves the same irrespective of ceiling and visibility.
When coupled to the localizer, autopilots make incredibly precise approaches using banked turns, not skidding turns. Flight director indications result in the same. (The only difference between an autopilot and a flight director is that autopilots command servos to move the flight controls; flight directors command pilots to do the same thing using human muscles.)
Furthermore, a pilot who makes small skidding turns to keep the localizer centered can develop a habit that leads to making larger heading changes in the same way. If 2-degree heading changes can be made this way, why not 5- or 10-degree changes? Using the rudder to turn seems to me to be a concession by the pilot that he does not have the finesse to do it properly. This is perhaps the result of a tendency to overshoot during small heading changes, something easily corrected with practice. Either that or the pilot is lazy.
Speaking of letters, some years ago I received one from a reader who was highly critical of using the best-angle-of-climb speed (V X) after liftoff. He claimed that an accident is likely to be the result of an engine failure that occurs once the aircraft is stabilized in such a relatively steep climb even when there is sufficient runway ahead upon which to otherwise make a safe landing.
The reason for this, he claimed, was that there is not enough time for the aircraft to accelerate and gain the airspeed needed to arrest the high sink rate that develops when the pilot lowers the nose to achieve normal glide speed, which, of course, is what pilots are taught to do immediately following an engine failure.
I never knew what to do about this letter because I could neither confirm nor reject the author's claim. A few weeks ago, however, I decided to see if the claim had merit.
Using a moderately loaded Cessna 172, I lifted off from a very long runway and stabilized in a climb at V X (59 knots), 14 knots below the best-rate-of-climb airspeed (V Y). At an arbitrarily chosen altitude of 300 feet agl, I retarded the throttle and waited a few seconds, the time that the FAA says it takes for a pilot to react to an engine failure. I then lowered the nose abruptly to stop the airspeed bleed and accelerate from what was then about 50 KIAS to the best-glide speed of 65 knots.
Whoa, Nelly! The runway began rushing toward me at an unexpectedly dramatic rate. Nor did I have enough airspeed to arrest the alarming sink rate in time to make a safe landing without risking an accelerated stall. The safest and only option was to apply full power and extricate myself and the aircraft from harm's way. Such an option obviously would not have been available had the engine really failed. I concluded that such a flight most likely would have ended with bent metal.
I later tried the same thing at altitude and encountered similar results. A major difference was that I could not perceive rapidly rising terrain through the windshield; the imperative need to recover was not as obvious.
These experiments convinced me that climbing at V X presents an unanticipated hazard that is not widely recognized and should be at least kept in mind when climbing at V X, looming obstacles or not.
Visit the author's Web site ( www.barryschiff.com).
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