On Tuesday, May 6, 2014 4:08:26 PM UTC-6, Mike the Strike wrote:
On Tuesday, May 6, 2014 1:41:23 PM UTC-7, Don Johnstone wrote:

While in no way do I wish to speculate on the cause of this accident or



indeed suggest that my comments in any way address the cause of this



accident.



I feel that comment is needed on some of the things said here. We have a



rule here in the UK, launch failure on aerotow below 300ft a landing should



be made ahead, or slightly to one side. No attempt should be made to turn



back below this height.



The reason is simple, a controlled crash into difficult terrain is likely



to result in a better outcome than an uncontrolled arrival on the airfield.



The important bit to keep intact is the bit you are sitting in, the rest of



the glider does not really matter too much. The best chance of achieving



that is flying to the ground with the wings level. It has only happened to



me once, there was a field ahead but it was full of the Tiger Moth tug that



had landed in the middle. I discovered that there was just enough space for



a Skylark 2 as well. I have no doubt that a turn back would have resulted



in an accident. I was at 250ft agl max.



If there really is nowhere to land ahead you should really ask the



question, "should I be taking a launch".



Frankly I would be horrified to be required to conduct a turn back at



200ft, I would suggest that this is one of those occasions where the danger



of practice is to great to justify.



I have also voiced my concern at this tow termination training. Most times, it is a planned event and the towplane flies a modified pattern to give the trainee the best opportunity of returning to the launch runway. I have done several of these and they are not problematic. They also don't much resemble what happens in the real world when a rope break or disconnect is unplanned.



I have had only one of these in nearly 50 years of gliding. In one of my biannual tests, the instructor reassured me that no low altitude rope breaks would be simulated and then pulled the plug on me at a hair under 200 feet. Being unplanned. my reaction time was much longer - you have to work through the "holy ****, the tow rope's gone" thought process before taking any action. I landed successfully, but not on the departure runway - a story for another day. it did teach me that I didn't want a rope break under 200 feet and preferably not under 500 feet!



I have had several ropes break on the initial acceleration but none in the air. I have had three tugs lose power - two on the take-off run and one during climb-out. From my experience, I am skeptical that rope breaks between take-off and 200 feet are common enough to warrant the attention and training they get here in the USA..



I can also comment on the weather the day of the accident. It was perhaps one of the strongest (and highest) blue days I have seen in Arizona. The atmosphere was stable and dry under a dominant high-pressure system. Thermals were created by heating the air so much it had to rise, but these conditions resulted in very narrow, very strong, often multi-core, thermals surrounded by vicious sink and turbulence. These can be challenging if encountered on tow and can rapidly erode any height margin you have. You can expect to bash your head a few times (and perhaps your shins) on a day like this. Good when you're high, but nasty below pattern altitude.



Mike

Mike,

Turns do not cause stall/spin accidents. In fact, the steeper the turn, the greater the stall margin. That's because elevator authority is progressively used up making the glider turn as the bank gets steeper until the angle of attack can't be raised above stall. Try it. You'll find many gliders will run out of up elevator before they can be stalled at bank angles over 45 degrees.

Low turns don't cause stall spins either - they just insure there will be a permanent record should one occur. Pilots spin gliders unintentionally at higher altitudes too but they don't tell anybody.

Spins happen because the pilot stalled the glider, not because the pilot was turning.

The root cause of stall/spin accidents is pilot incompetence although it may not be their fault. Pilot training in gliders skips over an important area that is well covered in airplane training - its called ground reference maneuvers. If a student is drilled in low turns, it's less likely they will spin in on turns to final.