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This relates to the accident on 26th April, 2002 reported by NTSB as
DEN02GA039: synopsis http://www.ntsb.gov/NTSB/brief.asp?e...10X00654&key=1 , full report http://www.ntsb.gov/NTSB/brief2.asp?...GA039& akey=1 . I am not surprised that the widow wishes to sue; there are some features of this accident which seem hard to excuse, but she is after the wrong people. A./ THE AREAS WHICH SHOULD BE LOOKED AT INCLUDE THE FOLLOWING: !./ Why did the tug only release the tow rope after it had broken? Was this because the friction on an unmodified Schweitzer prevented release under heavy load? 2./ Why did the glider only release the tow rope after it had broken? Was this also because the hook fitted to the glider would not release under heavy load? 3./ There is no mention in the NTSB report of the tug Schweitzer towing hook being modified. The difficulty of releasing under load from an unmodified hook is by now well known, and suitable modifications are also now common knowledge. 4./ Why did the glider get too high behind the tug? Did the glider with the towing hook in use have positive longitudinal stability when on aerotow? If not, was this a factor? If it was not stable, could another hook have been fitted and used which would have given positive stability on tow? 5./ Was the experience, currency and training of the instructor adequate? This is a question to be answered by those who trained, supervised and authorised the instructor, not by the actual instructor. The question applies both to the training given to the instructor as a solo pilot; and how the instructor was coached, in particular as to how to teach aerotowing. B./ OBSERVATIONS. a./ COMMENTS ON THE ACCIDENT. Comments on the accident by Chris Rollings (who was recently for one year Chief Flying Instructor at Mile High Gliding, Boulder Colorado) may be found at: http://www.glidingmagazine.com/ListF...Dtl.asp?id=327 . Note particularly what he says about the Schweitzer hook. Note also the difference between a K13 on the nose hook, a K13 on the winch hook and a K8 on the winch hook. The accident at the USAF Academy sounds like the case described by Rollings of the K13 on a nose hook, but with a tug hook which would not release under load. b./ STABILITY AND RISK. On the question of stability on tow, and on the question of risk generally, Chris Rollings posted to R.A.S. (on 07 January 2004 07:57 to the thread CG hook on aero tows??), I copy his posting below: "Under JAR 22 (Glider Certification Rules), a glider is required to have positive (or at least neutral) longitudinal stability. Put simply, if you move the nose up (or down) a bit and then leave it alone, it should tend to move back towards where it started from, or at least stay where it is, not continue to pitch further up (or down). "It is quite possible (easy in most cases) to learn to handle a glider that does not have this stability, but it requires CONSTANT vigilance on the part of the pilot. A failure in concentration of only one or two seconds can result in a massive divergence of the flight path with catastrophic consequences. "Following the flight tests referred to earlier in this thread, conducted by Verdun Luck, Brian Spreckley and myself in 1978 and 1982, it became obvious to me that many gliders did not meet this requirement for positive pitch stability when being aerotowed on a C of G release. "My suggestion, at the time, was to change JAR 22 so as to make it explicit that the requirement for positive pitch stability applied when the glider was being aerotowed as well as in free flight (the only practical way I could see to achieve this in most cases was with a release well forward of the C of G, but I felt that other ways of achieving the desired result should be acceptable if they could be found). "The change over to requiring nose hooks is happening very gradually because of the gliding movement's resistance to change, particularly any change that costs money. The result of this is that changes in airworthiness requirements are often not made retroactive. Pre-existing aircraft with what are now seen to be unacceptable characteristics are 'Grandfathered in', rather than face the hassle of making them comply. "An argument, which has appeared often through this thread, is that an individual or a club has done so many aerotows, or operated for so many years, towing on C of G hooks without accident, so there is clearly no problem. "Let's look at the numbers. I will use the UK as an example, since I have a fairly accurate knowledge of the statistics there, but the principals are the same for any of the World's gliding nations. UK gliding fatalities average about four per year, if it goes down to one or two everyone involved in safety promotion starts to feel pleased, if it goes up to six or seven there is concern that there is a problem growing and 'something needs to be done'. The more sensible people, of course, look at a five or ten year moving average rather than being overly influenced by one year's results. There are around (OK probably just under) one hundred gliding operations in the UK; if each one 'only' had a fatal aerotowing accident once every twenty-five years, that would produce four such fatalities a year Nationally and make EVERY year a problem year, with the average number of fatalities double the present level. Central Government would doubtless step in with some very heavy handed legislation. "My point? That the fact that you, or your club, may have been operating in a certain way for 25 years without a fatal accident, does not mean that the practices are at an acceptable level of risk viewed nationally, simply that they are not actually suicidal. "Aerotowing on a C of G hook is something you can 'get away with', given a high level of concentration, reasonable skill and the absence of bad luck. However it carries a significantly higher risk of a nasty accident (often fatal for the blameless tow-pilot), with the only real gain being the saving of the (relatively) small cost of fitting a forward release. In my opinion it should be something that is only done rarely, in case of real need, not something that anyone accepts as the 'normal' way to launch to save the cost of fitting the proper equipment. "I am a staunch defender of anyone's right to risk his or her own life in pursuit of any goal they hold dear (including saving money). In launching on a C of G hook you are risking the tow-pilots life more than your own, and this I will not defend." c./ INSTRUCTOR TRAINING AND EXPERIENCE. From the NTSB report, "The instructor aboard N7538, a cadet third class, said she had made about 100 glider flights, each flight averaging about 15 minutes." If this means what it says, the instructor had a total gliding flight experience of about 100 flights and about 25 hours. This presumably includes dual instruction as pupil, solo flying, coaching to become an instructor, and experience as an instructor. I do not know what is normal in the U.S.A., either in the U.S.A.F. or in civilian life, for an instructor teaching aerotow launching; but this is vastly less than enough by U.K. standards. The minimum requirements for U.K. civilian gliding instructors are set out in "Laws and Rules for Glider Pilots" first revision to 14th edition, July 2004 published by the British Gliding association at http://www.gliding.co.uk/bgainfo/doc...tion14rev1.pdf . Instructor Ratings and Endorsements are covered on pages 41 to 45, Instruction and Passenger Carrying is covered on pages 19 and 20. The requirements for a BGA Basic Instructor Rating include "Silver badge" and "Minimum of 50 hours P1 on gliders". Basic instructors are only allowed to teach the first upper air lessons, collision avoidance, effects of controls etc.; they are not allowed (or trained) to teach launching or landing. The BGA Assistant Instructor Rating requirements include "Silver badge" and "Minimum of 75 hours P1 on gliders, including 100 launches". Before training to be an Assistant instructor, it is first necessary to become a Basic instructor (see 15.8, p.44). These are minimums, many clubs require much more experience. d./ PUPIL TRAINING AND EXPERIENCE. From the NTSB report, "The student pilot aboard N7538 said that this was his second glider flight." So, on his second glider flight ever the pupil was unable to maintain station behind the tug. No surprise there then! There is nothing in the NTSB report to suggest that the accident was the fault of the pupil in anyway whatever. It is the instructor who is supposed to prevent things going disastrously wrong, that is what an instructor (and the coaching of instructors) is for. e./ AEROTOW LAUNCH TRAINING. From the NTSB report, "She decided to hold their position and raised the nose about 1-3 degrees to reduce airspeed and make it easier for the tow plane to get back in position." This is extraordinary. Aerotowing is (among other things) an exercise in formation flying. It is for the glider to formate on the tug, not the other way around! Where did the instructor get this idea, was she trained to think like this? If not, why was this not picked up in her training, either as a pilot or as an instructor? The UK methods of instruction are covered in the BGA Instructors' Manual (Second edition) available by mail and internet order from the BGA (but not available to read online) http://www.gliding.co.uk click on "B.G.A. Shop" then on "Manuals, Logbooks & handbooks" then on "Instructors' Handbook", anyone may buy it. Aerotowing is covered in section 4, chapter 17. I now give some quotes. From the introduction (in full): "Many aerotow trained pilots look back on their training and remember how difficult it was to learn to aerotow. Some will admit to having been so discouraged that they almost gave up. This is usually the result of introducing aero-towing too early. "If a trainee cannot fly the glider in a reasonably straight and coordinated line in free flight, they won't be able to handle an aerotow. Ability to fly in a decent straight line suggests that the trainee can detect and correct for small changes in the bank angle - this is a must. Attempting aero-towing too early (say after a set number of flights) will reduce a trainee's confidence and probably prolong the training to solo. This is certainly not 'giving value for money'. Post-solo pilots with wire launch experience only, generally find learning to aerotow much easier, and progress more rapidly. However, if tug upset accidents are to be avoided (see page 17-8), you need to be thorough with these pilots as well. "The trainee should not attempt the take-off and early part of the launch until he can maintain position successfully during the later part of the tow. Even experienced solo pilots converting to aerotow should follow this sequence, though they might be given the complete aerotow briefing in one session. "The demonstrations and the trainee's early attempts shouldn't begin until the tow reaches a height and position from which landing back on the airfield poses no problem. Good airmanship requires the trainee and the instructor to be aware of the circuit and landing options available during every moment of the tow. Then, if there is a launch failure, or you have to release unexpectedly, there will be less thinking to do. In the tow's early stages this reduction in workload can be critical. "The briefing and flying exercises are divided into three sections: * positioning behind the tug, slack in the rope and releasing * ground operations, ground run, take-off and initial climb * launch failures, tug upsets and emergency signals." From "Tug Upset Accidents" p. 17-6 (extracts): "These are serious, and have caused the deaths of a number of tug pilots. If the glider is allowed to climb rapidly behind the tug, it can very quickly become impossible to prevent it accelerating upwards in a slingshot action (rather like a winch launch), and tipping the tug over into a vertical dive. Once this has happened only height can save the tug pilot from disaster. Downward displacement of the glider to a position below the slipstream is quite acceptable, but upward displacements are much more critical. "The glider pilot must release immediately if: * the glider is going high and the tendency cannot be controlled, or * the pilot loses sight of the tug. "Factors which can combine to create a tug-upset accident a * a light pilot flying close to the minimum cockpit weight * an inexperienced pilot - particularly wire launch pilots with little recent aerotow experience * glider with a belly or CG hook * short rope * turbulent conditions." From "Advice to Instructors" p. 17.9 (extracts): "Aerotowing should not be taught before the trainee is capable of reasonably well coordinated straight and turning flight. Because most early trainees find the workload in this exercise very high, it is best to allow them to fly only the last 500' to 1,000' of the tow. Progressively increase the workload by lowering the height at which they take over control. Don't allow them to attempt the take-off and first 500' until they can keep station without assistance or frequent prompting on the upper part of the tow. As a rule, if trainees get out of position below about 400', take over rather than try to prompt them back." From "Common Difficulties" p. 17-10 (extracts); "Tends to rise above tug soon after take-off. Explain that (at least) until the tug climbs away, the combination is still accelerating, so the glider will rise unless it is prevented from doing so. The strength of this tendency will depend, to a large extent, on the trim setting at the time." C./ CONCLUSIONS. This post is already too long, I plan to complete this in another post. W.J. (Bill) Dean (U.K.). Remove "ic" to reply. "Stewart Kissel" wrote in message ... http://www.thedenverchannel.com/news...52/detail.html |
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It was interesting to read the "student's " response that 'the tow plane
did not rise up to take the slack out of the rope', apparently not briefed on doing the tow, and what to expect. Fred |
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![]() "Fred Blair" wrote in message nk.net... It was interesting to read the "student's " response that 'the tow plane did not rise up to take the slack out of the rope', apparently not briefed on doing the tow, and what to expect. Fred There is some evidence that the tow was not going as planned and that the pilot may have been stricken. Sad and unfortunate series of events. Frank |
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F.L. Whiteley wrote:
"Fred Blair" wrote in message nk.net... It was interesting to read the "student's " response that 'the tow plane did not rise up to take the slack out of the rope', apparently not briefed on doing the tow, and what to expect. Fred There is some evidence that the tow was not going as planned and that the pilot may have been stricken. Sad and unfortunate series of events. Frank This is a quote lifted from the coroner's contribution to the NTSB report. "the likelihood is high that he did suffer some sort of cardiac event which, while not immediately fatal, did so incapacitate him that he was unable to control the plane or to even use his radio to alert anyone." Shawn |
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"W.J. \(Bill\) Dean \(U.K.\)." wrote
"My point? That the fact that you, or your club, may have been operating in a certain way for 25 years without a fatal accident, does not mean that the practices are at an acceptable level of risk viewed nationally, simply that they are not actually suicidal. There is another way to consider this. Not all training programs are the same, and result in the same skill level. It is entirely possible that some pilots are simply more skilled and can handle a cg hook just fine, while others are not and can not except under ideal conditions. "Aerotowing on a C of G hook is something you can 'get away with', given a high level of concentration, reasonable skill and the absence of bad luck. Or maybe just reasonable skill - and what constitutes reasonable skill is another matter. I have yet to fly a certified glider that is anywhere near as demanding in handling as the most docile of powered trainers. My glider is equipped only with a CG hook, mounted off center at that, and I don't find flying it on tow to be particularly demanding or unforgiving. It was a bit of a surprise the first time (my first aerotow with a cg hook was solo, and I believe I had less than 50 flights in gliders at that point) but it only took me a couple of minutes to get the hang of it. Had it been a dual flight, it would have been a total non-event, as this flight should have been. "I am a staunch defender of anyone's right to risk his or her own life in pursuit of any goal they hold dear (including saving money). In launching on a C of G hook you are risking the tow-pilots life more than your own, and this I will not defend." I am a tug pilot. I am comfortable with the risk, and have been on both ends of the rope with a cg hook more than a few times. Will you now tell me I'm deluded? Frankly, I just don't see towing someone with a cg hook to be a big deal. I support the right of any tug pilot to refuse the operation, but I know none who consider it a big deal. That's not to say there are none. From the NTSB report, "The instructor aboard N7538, a cadet third class, said she had made about 100 glider flights, each flight averaging about 15 minutes." If this means what it says, the instructor had a total gliding flight experience of about 100 flights and about 25 hours. This presumably includes dual instruction as pupil, solo flying, coaching to become an instructor, and experience as an instructor. I do not know what is normal in the U.S.A., either in the U.S.A.F. or in civilian life, for an instructor teaching aerotow launching; but this is vastly less than enough by U.K. standards. In the US, it is considered enough. In fact, I believe that was approximately the experience level of the instructor who trained and signed me off for my glider INSTRUCTOR rating. He had additional (extensive) experience in airplanes. This was not necessary. In the US, the requirement for a commercial pilot in a glider is 25 hours of flight time in a glider (including instruction) and 100 flights. The requirements are MUCH less if one already has 200 hours in powered aircraft. After the commercial, there are no additional experience requirements - only a checkride. I suspect that the cadet instructor had significant additional aircraft experience, and I think that should make it OK from a safety standpoint. Certainly I see nothing so special about aerotowing that would make it unsafe for an experienced power pilot with 100 aerotows to teach. I am far more concerned about glider intructors with lots of glider experience who have never been tuggies teaching aerotow. They are the ones who have scared me most as a tuggie. I think many of them truly do not understand where the limits are. If it were up to me, everyone who wanted to teach aerotow would have to spend a few flights up front in the tug while students were learning to fly aerotow in back. The real issue, where safety is concerned (learning to soar is another matter entirely) is not so much low glider time (gliders, after all, are quite similar to and generally easier to fly than airplanes) but low total time. An inexperienced instructor is a hazard. From the NTSB report, "The student pilot aboard N7538 said that this was his second glider flight." So, on his second glider flight ever the pupil was unable to maintain station behind the tug. No surprise there then! Maybe. In my experience, it would have been surprising. Of course I have never actually trained a glider student who did not have powered aircraft experience (this is the norm in the US rather than the exception), which certainly makes a difference. However, I find it nromal to have the student flying on tow and maintaining position on the FIRST flight, and taking off on the second. That's not every student, but it's not rare either. There is nothing in the NTSB report to suggest that the accident was the fault of the pupil in anyway whatever. It is the instructor who is supposed to prevent things going disastrously wrong, that is what an instructor (and the coaching of instructors) is for. Yes of course. There's no question that when a student under instruction mishandles the aircraft, the fault is with the instructor for not correcting unless the student does something really egregious. An instructor who can't correct a student's mishandling of the tow (especially on an early flight) isn't much of an instructor. "If a trainee cannot fly the glider in a reasonably straight and coordinated line in free flight, they won't be able to handle an aerotow. This is of course correct. However, it's a rare power pilot who can't fly the glider in a reasonably straight and coordinated line in free flight. Since, as I have previously mentioned, in the US the glider student without power experience is the exception rather than the norm, this leads to a different perspective on when to introduce aerotow. Aerotow on the first lesson is common in the US for just that reason - and of course if the student is able to maintain position on tow for 1500 ft unassisted, I see no reason not to let him try a takeoff, even if that is his second glider flight. No point holding back and frustrating a capable student. Michael |
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From someone with a little inside knowledge.
Bullwinkle And who would that be Bullwinkle, Rocky the Squirrel? |
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On Thursday, October 28, 2004 at 7:17:10 PM UTC-4, Stewart Kissel wrote:
http://www.thedenverchannel.com/news...52/detail.html Anyone know what the outcome of this lawsuit was? Walt |
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