Tuesday, June 05, 2007

Just because you can doesn't mean you should

I observed and was told of some very questionable practices regarding how some people teach and practice launching and soaring. While some of these pilots and instructors may be highly skilled, the practices they are teaching may not be appropriate for students and low-time pilots and can get their students into dangerous situations. I spoke with one person who is a long-time power pilot but a short-time glider pilot... I don't know if he has his PPG rating or is still a student. He told me stories which go along with what I observed and were very disturbing.

1. Immediate Pull-Up From my instructors and from some nationally known instructors who spoke at the recent BITS seminar, I learned that in a ground launch it is safer to gain some altitude (at least 150'-200') before beginning the steep part of the climb. I observed some experienced pilots beginning their 40-degree climb as little as 10-20 feet from the ground, as soon as they get any airspeed. They seemed to think this was the best way, and that we were wasting time and cable by climbing gently before pulling up. The problem with this practice is that if you have a loss of winch power, a cable break, or any other anomaly that requires you to abort the launch, you may find yourself at a steep pitch angle relative to the ground and needing to nose over quickly to execute a landing. I realize that in most cases you would have sufficient airspeed into the relative wind to avoid stalling, but that speed will decay very quickly because you are climbing. You need to nose over very quickly to regain safe flying speed (by using gravity to accelerate) and then round out and land straight ahead. If this occurs at low altitude or if you do not recognize the power loss immediately, you could find yourself stalled or at least mushing and have insufficient altitude to execute the pitch-over. If this occurs at 200' or higher, pushing over to regain flying speed and then landing straight ahead is a non-event.

I did not observe any incidents or problems personally. All rope breaks or power losses I saw occurred at safe altitudes. But the pilot I spoke with said he had personally had what he called a "six-G landing," what many would call a "pancake" - landing hard straight down either still rounding out or perhaps stalled. Here's how he related it to me. In one launch, he experienced a loss of winch power but the winch recovered promptly and he continued the launch. In the very next launch, he experienced another loss of power, and he figured the winch paused again, but this time he was fooled: it was an actual rope break. He waited for a few seconds, expecting the winch power to recover, then finally realized it wasn't going to and nosed over. Problem was, this occurred at about 100' AGL. He lost at least 25' while waiting, another 25' or so while nosing over, and barely had enough altitude to round out to his "six-G" landing. It did not seem to occur to him that the low altitude pitch-up is what made this dangerous. More altitude would have given him time to recover. A rope break at low altitude is not a problem if the pitch angle is still low.

2. Low-altitude Thermalling This pilot and others spoke admiringly of an instructor's ability to find a thermal and save a flight, from as low as 100'-150' AGL. They spoke of him being on final approach, hitting a thermal and flying away. Where I learned to soar, and where I have rented sailplanes, that would be unthinkable. Our rule is "no thermalling in the pattern - period". The standard lower limit, where one must commit to landing, is 1000' AGL. At another gliderport I visited, the limit was 1200'. Once you enter the pattern, that's it! Now, I realize we're talking about winch launching, and a 1000' limit would really limit your ability to find ANY thermal, when you're only achieving 1500' or so from the launch. So I personally would be comfortable lowering the commit level to about 800', especially if there are many alternative landing sites on the airfield. But 150' ?!?!?!? I did see a launch abort at about 400' due to a rope break, and the instructor took over and caught a thermal right over the launch zone, and the student got to go on a soaring flight. But it's another questionable thing to teach a student. Here's why:

That same pilot mentioned above tried to pull off his instructor's trick: he flew through a thermal off the approach end of the runway, about 150' AGL, and decided to try to work it rather than continue his landing (I don't know if he was on base or final leg). Only problem was, the thermal gave him lift for about a half of a circle, then turned to sink... and now he was pointed AWAY from his runway. He could not make it back, crashed the glider into the wash off the end of the runway, and destroyed the nose. The pilot was unhurt.

The problem with this whole set of circumstances is that this pilot thinks he SHOULD be able to do these things, because he sees an instructor do them. So he's had two "hard landings" and he only has 15 hours of glider time logged!

The FAA's Aviation Instructor's Handbook has this to say:
The safety practices emphasized by instructors have a long lasting effect on students. Generally, students consider their instructor to be a model of perfection whose habits they attempt to imitate, whether consciously or unconsciously. The instructor's advocacy and description of safety practices mean little to a student if the instructor does not demonstrate them consistently.

The flight instructor must not only teach students to know their own and their equipment's limitations, but must also teach them to be guided by those limitations.

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