Fatal crash Arizona

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.

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

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.

On Tuesday, May 6, 2014 2:41:23 PM UTC-6, Don Johnstone wrote:

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.

If you should check out in the USA, you'll be required to demonstrate competence in this maneuver. Every pre-solo student is required to do so and more than a half century of safety records do not suggest a problem. In fact, even with low performance gliders, there's quite a large safety margin. The most likely outcome is a pilot will find the glider uncomfortably high for a downwind landing requiring full spoilers and a slip.

The logic is simple - it's better to have pilots trained for the option. No one says a pilot is required to turn back or that 200' is always adequate to do so. What is illogical is to suggest a pilot be required to crash in unlandable terrain when a safe option exists to land on the departure runway.

At 22:22 06 May 2014, Bill D wrote:
On Tuesday, May 6, 2014 2:41:23 PM UTC-6, Don Johnstone wrote:

Frankly I would be horrified to be required to conduct a turn back at
=20
200ft, I would suggest that this is one of those occasions where the
dang=
er
=20
of practice is to great to justify.

If you should check out in the USA, you'll be required to demonstrate
compe=
tence in this maneuver. Every pre-solo student is required to do so and
mo=
re than a half century of safety records do not suggest a problem. In
fact=
, even with low performance gliders, there's quite a large safety margin.
T=
he most likely outcome is a pilot will find the glider uncomfortably high
f=
or a downwind landing requiring full spoilers and a slip.

The logic is simple - it's better to have pilots trained for the option.
N=
o one says a pilot is required to turn back or that 200' is always
adequate=
to do so. What is illogical is to suggest a pilot be required to crash
in=
unlandable terrain when a safe option exists to land on the departure
runw=
ay.

What are you trying to save? The pilot or the aircraft? The priority should
be survival of the soft bit, that is you and me.
As an instructor with nearly 50 years experience I know that when I
initiate an emergency procedure I do so allowing a margin to ensure my
survival if it does not work out, I have been bold but never certifiable.
Most living instructors have the same survival instinct. That is why I have
lived long enough to do 10,000 launches, and of course landings. It has
already been hinted that the practice you describe involves modifying what
you normally do, in my view that probably makes it pretty useless and not
real preparation for the event. If you did carry out the training in
exactly the same way as the possible real event you might find that the
results were very different, not to mention painful. I will stick with my
300ft thank you, I know it works. Low turns, below that height may have
been acceptable in old wooden gliders, the minimum height in T31 and T21
gliders was 150ft, but for modern glass gliders it is just far too low, you
only have to look at the accident statistics to see that low final turns
figure to a large degree in accidents so why plan for it?
I repeat a controlled descent with wings level is far more likely to have a
better result than hitting the ground in a turn or even worse spinning in
trying to avoid it.

PS Despite all that there have been times when I have initiated a practice
emergency and very quickly wished I had not, no plan survives first
contact.

On Tuesday, May 6, 2014 4:56:44 PM UTC-7, Don Johnstone wrote:
At 22:22 06 May 2014, Bill D wrote:

On Tuesday, May 6, 2014 2:41:23 PM UTC-6, Don Johnstone wrote:



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

=20

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

dang=

er

=20

of practice is to great to justify.



If you should check out in the USA, you'll be required to demonstrate

compe=

tence in this maneuver. Every pre-solo student is required to do so and

mo=

re than a half century of safety records do not suggest a problem. In

fact=

, even with low performance gliders, there's quite a large safety margin..

T=

he most likely outcome is a pilot will find the glider uncomfortably high

f=

or a downwind landing requiring full spoilers and a slip.



The logic is simple - it's better to have pilots trained for the option.

N=

o one says a pilot is required to turn back or that 200' is always

adequate=

to do so. What is illogical is to suggest a pilot be required to crash

in=

unlandable terrain when a safe option exists to land on the departure

runw=

ay.



What are you trying to save? The pilot or the aircraft? The priority should

be survival of the soft bit, that is you and me.

As an instructor with nearly 50 years experience I know that when I

initiate an emergency procedure I do so allowing a margin to ensure my

survival if it does not work out, I have been bold but never certifiable.

Most living instructors have the same survival instinct. That is why I have

lived long enough to do 10,000 launches, and of course landings. It has

already been hinted that the practice you describe involves modifying what

you normally do, in my view that probably makes it pretty useless and not

real preparation for the event. If you did carry out the training in

exactly the same way as the possible real event you might find that the

results were very different, not to mention painful. I will stick with my

300ft thank you, I know it works. Low turns, below that height may have

been acceptable in old wooden gliders, the minimum height in T31 and T21

gliders was 150ft, but for modern glass gliders it is just far too low, you

only have to look at the accident statistics to see that low final turns

figure to a large degree in accidents so why plan for it?

I repeat a controlled descent with wings level is far more likely to have a

better result than hitting the ground in a turn or even worse spinning in

trying to avoid it.



PS Despite all that there have been times when I have initiated a practice

emergency and very quickly wished I had not, no plan survives first

contact.

I should also add that over the years, I have retrieved various sailplanes that made controlled landings into terrain in Arizona, including mesquite bushes, palo verde trees and ironwood trees. Only one of these aircraft was seriously damaged and all the others have been repaired. No pilot was seriously injured. Level flight into quite evil terrain does appear a much better option than a sharp turn at low altitude, with a significant possibility of stall/spin or uncontrolled ground impact.

Mike

On Tuesday, May 6, 2014 5:56:44 PM UTC-6, Don Johnstone wrote:
At 22:22 06 May 2014, Bill D wrote:

On Tuesday, May 6, 2014 2:41:23 PM UTC-6, Don Johnstone wrote:



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

=20

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

dang=

er

=20

of practice is to great to justify.



If you should check out in the USA, you'll be required to demonstrate

compe=

tence in this maneuver. Every pre-solo student is required to do so and

mo=

re than a half century of safety records do not suggest a problem. In

fact=

, even with low performance gliders, there's quite a large safety margin.

T=

he most likely outcome is a pilot will find the glider uncomfortably high

f=

or a downwind landing requiring full spoilers and a slip.



The logic is simple - it's better to have pilots trained for the option.

N=

o one says a pilot is required to turn back or that 200' is always

adequate=

to do so. What is illogical is to suggest a pilot be required to crash

in=

unlandable terrain when a safe option exists to land on the departure

runw=

ay.



What are you trying to save? The pilot or the aircraft? The priority should

be survival of the soft bit, that is you and me.

As an instructor with nearly 50 years experience I know that when I

initiate an emergency procedure I do so allowing a margin to ensure my

survival if it does not work out, I have been bold but never certifiable.

Most living instructors have the same survival instinct. That is why I have

lived long enough to do 10,000 launches, and of course landings. It has

already been hinted that the practice you describe involves modifying what

you normally do, in my view that probably makes it pretty useless and not

real preparation for the event. If you did carry out the training in

exactly the same way as the possible real event you might find that the

results were very different, not to mention painful. I will stick with my

300ft thank you, I know it works. Low turns, below that height may have

been acceptable in old wooden gliders, the minimum height in T31 and T21

gliders was 150ft, but for modern glass gliders it is just far too low, you

only have to look at the accident statistics to see that low final turns

figure to a large degree in accidents so why plan for it?

I repeat a controlled descent with wings level is far more likely to have a

better result than hitting the ground in a turn or even worse spinning in

trying to avoid it.



PS Despite all that there have been times when I have initiated a practice

emergency and very quickly wished I had not, no plan survives first

contact.

So, you're saying the pilot will be safer if they don't learn to perform the return to runway maneuver when it's safe to do so?

I can assure you that the higher a glider's performance, the safer it is. It's the old, low L/D gliders that can run out of altitude before getting lined up with the runway.

I just practiced 10 simulated PTOTs at my home field using Condor. It gave me a better perspective on my options. I will practice again with different wind directions and speed.

On Wednesday, May 7, 2014 1:20:44 PM UTC+12, Bill D wrote:
So, you're saying the pilot will be safer if they don't learn to perform the return to runway maneuver when it's safe to do so?

I can assure you that the higher a glider's performance, the safer it is. It's the old, low L/D gliders that can run out of altitude before getting lined up with the runway.

I agree with you. I'm shaking my head every time I read this thread.

In a modern glass glider (such as the DG1000's I instruct in) with a 40 knot stall speed and being towed at 70 knots you should be able to execute a safe 180º turn with *zero* loss of height.

Just slowing down from 70 knots towing speed to 55 knots gains you 80 ft on top of whatever you already had.[1]

How much height do you lose in a 45º banked turn at 55 knots? Most modern gliders lose no more than 120 fpm at 45 knots in straight and level flight.. A 45º banked turn gives 1.41 Gs (1/cos(45)), which needs sqrt(1.41) = 1.19 times more speed for the same angle of attack and L/D. 45 knots times 1.19 is 53.6 knots. So 55 knots in a 45º turn has a little more margin above stall than 45 knots in straight and level. The sink rate will be 120 * 1.41 = 170 fpm.

Converting to SI and using a=v^2/r, a 45º banked turn at 55 knots (28.3 m/s) has 115.3m radius, or 725m circumference for a full turn. A 180º turn (362m) will take 12.8 seconds. In 12.8 seconds at 170 fpm you'll lose 36 feet.

So the height loss in the turn is only about half the height gained from slowing down from towing speed to circling speed!

It would actually be better to start turning immediately, but these calculations assume you delay (deliberately or not) and climb straight ahead (no pull-up required) for several seconds before starting the turn.

With 18m wingspan in a 45º bank your wingtip is 18m/2*sin(45) = 6.4m or 21 ft below you.

So you theoretically could do this from absolutely zero height, with nearly 20 ft to spare.

I wouldn't want to try it! But from 100ft? No problem at all. IF you start from normal towing speed and reasonably benign weather conditions.

Even if you're releasing from a sick tug that's slowed to 55 knots, you'll be fine from 200 ft.


Another post mentioned that glider pilots make mistakes when flying close to the ground because they are not trained to do so and don't do "ground reference" manoeuvres like power plane pilots do.

Obviously that person lives in very flat ground, because I can assure them that here we're flying close to ridges and peaks a LOT, from almost the first flight, doing 180º turns at the end of ridge lift runs, or circling low over a peak or head of a gully looking for a thermal. We'd very often be only 100-200 ft or so above the terrain while doing so.


[1] handy formula: X knots of kinetic energy is worth (X/5)^2 feet of gravitational potential energy. e.g. 70 knots = (70/5)^2 = 14^2 = 196 ft. 50 knots = (50/5)^2 = 10^2 = 100 ft. Less drag loses of course. You'll never turn speed into quite that much height, and you'll need more height than that to get speed. But the differences are large in a high performance glider at moderate speeds.

At 06:55 07 May 2014, Bruce Hoult wrote:
[1] handy formula: X knots of kinetic energy is worth (X/5)^2 feet of
gravitational potential energy. e.g. 70 knots = (70/5)^2 = 14^2 = 196 ft.
50 knots = (50/5)^2 = 10^2 = 100 ft. Less drag loses of course.
You'll never turn speed into quite that much height, and you'll need more
height than that to get speed. But the differences are large in a high
performance glider at moderate speeds.

...or you could use my rule of thumb: a change of speed of 10 knots IAS
gives
you (or costs you) the number of feet in height of the speed you arrive at.

For example:
70 knots to 60 knots : plus 60 feet
60 knots to 70 knots: minus 60 feet
70 knots to 50 knots (i.e. 70 to 60, then 60 to 50) : (60+50) = plus 110
feet

(N.B. Done without undue delay, and at sea level - more height change at
greater altitudes. Height in feet, IAS in knots, works for a change of
speed of 10 knots. Results
are realistic but approximate.)