Fatal crash Arizona

On Tuesday, May 6, 2014 6:20:44 PM UTC-7, Bill D wrote:
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.

The discussion seems to focus exclusively on the decision height for a turn around. I think that is only one factor in making this decision. As reported by Bob T there was heavy sinking air on the departure end of the runway. Returning to the airport would have required transiting thru this air a 2nd time, which strikes me as inadvisable without much more altitude than Knauff had.

The other issue is that a tow rope break requires immediate lowering of the nose. This is done routinely at altitude, but at low altitude this means pointing the glider's nose uncomfortably down at the ground while executing a steep banked turn. If the ground is rising, as it is at Sampley, the picture seen by the pilot is even more disturbing. All that it takes is a momentary hesitation in this reflex and the outcome can be fatal.

As an aside, I once did a wind mill start in my DG400 below 1000' (over a runway). This maneuver requires achieving in excess of 90 kt airspeed. Because the engine & prop act like dive brakes, you feel like you are standing on your rudder pedals when you do this close to the ground. I got to this airspeed and the prop still didn't rotate. This meant that I had to steepen the descent even more. All of my instincts said no, but my brain said yes, which is what I did. The engine started, but I decided that this maneuver really needs to be started at a higher altitude.

On Thursday, May 8, 2014 6:39:06 PM UTC-6, 2G wrote:

The other issue is that a tow rope break requires immediate lowering of the nose.

Why would anyone lower the nose? The glider is presumably at aero tow speed - 65 - 70 knots which is way above the pattern speed. A better plan is to use the excess airspeed to maintain height while turning until airspeed drops to pattern speed.


This is done routinely at altitude, but at low altitude this means pointing the glider's nose uncomfortably down at the ground while executing a steep banked turn. If the ground is rising, as it is at Sampley, the picture seen by the pilot is even more disturbing. All that it takes is a momentary hesitation in this reflex and the outcome can be fatal.

The nose is not "uncomfortably down". The turn back is a normal turn.



As an aside, I once did a wind mill start in my DG400 below 1000' (over a runway). This maneuver requires achieving in excess of 90 kt airspeed. Because the engine & prop act like dive brakes, you feel like you are standing on your rudder pedals when you do this close to the ground. I got to this airspeed and the prop still didn't rotate. This meant that I had to steepen the descent even more. All of my instincts said no, but my brain said yes, which is what I did. The engine started, but I decided that this maneuver really needs to be started at a higher altitude.

Aha! You're really a motor glider pilot, not an aero tow pilot which explains your misconceptions.

On Thursday, May 8, 2014 8:55:27 PM UTC-4, Bill D wrote:

Why would anyone lower the nose? The glider is presumably at aero tow speed - 65 - 70 knots which is way above the pattern speed.

Perhaps I have a fundamental misunderstanding...
but I thought that the AofA at 65 knots on aerotow is steeper than the AofA at 65 knots in free flight. So if you don't reduce the AofA (aka drop the nose) after the rope breaks, the glider will slow down. If you start the turn before reducing the AofA, you may find yourself going too slow for the turn.

It is true that you can use the speed coming off aerotow or PTOT to gain a bit of altitude, but that just means lowering the nose gradually as you bleed off the speed. In both cases the AofA needs to be adjusted to match the desired free flight speed.

I thought that we practiced this 'gain altitude and slowly drop the nose' every time we release from aerotow?

On Thursday, May 8, 2014 7:43:42 PM UTC-6, son_of_flubber wrote:
On Thursday, May 8, 2014 8:55:27 PM UTC-4, Bill D wrote:



Why would anyone lower the nose? The glider is presumably at aero tow speed - 65 - 70 knots which is way above the pattern speed.



Perhaps I have a fundamental misunderstanding...

but I thought that the AofA at 65 knots on aerotow is steeper than the AofA at 65 knots in free flight.
---------------
I think you are confusing pitch attitude with angle of attack. In unaccelerated flight, for a given weight and airspeed, the AOA will always be the same whether you are being towed or not.
------------
So if you don't reduce the AofA (aka drop the nose) after the rope breaks, the glider will slow down.
------------
Yes it will slow down if the pitch attitude isn't reduced. However, lowering the nose to establish a normal glide at pattern speed will actually see an increase in AOA due to the lower speed - you're just changing the flight path from a climb to a glide at a slower speed.
--------------
If you start the turn before reducing the AofA, you may find yourself going too slow for the turn.
--------------
What you are saying is if the pilot attempts a turn while continuing the nose-up climb after a rope break, the glider will slow down. Of course it will but in most cases this is desirable since the tow speed was well above pattern speed. Just don't continue the slowdown below pattern speed. The AOA is more closely related to airspeed than pitch attitude.



It is true that you can use the speed coming off aerotow or PTOT to gain a bit of altitude, but that just means lowering the nose gradually as you bleed off the speed. In both cases the AofA needs to be adjusted to match the desired free flight speed. I thought that we practiced this 'gain altitude and slowly drop the nose' every time we release from aerotow?

Yes, this technique is correct but the glider is just transitioning from being towed to a normal glide. The AOA will actually increase as the glider slows down.

Discussions like this highlights why gliders should have an AOA indicator in addition to and ASI.

On Thursday, May 8, 2014 9:43:42 PM UTC-4, son_of_flubber wrote:
On Thursday, May 8, 2014 8:55:27 PM UTC-4, Bill D wrote:



Why would anyone lower the nose? The glider is presumably at aero tow speed - 65 - 70 knots which is way above the pattern speed.



Perhaps I have a fundamental misunderstanding...

but I thought that the AofA at 65 knots on aerotow is steeper than the AofA at 65 knots in free flight. So if you don't reduce the AofA (aka drop the nose) after the rope breaks, the glider will slow down. If you start the turn before reducing the AofA, you may find yourself going too slow for the turn.



It is true that you can use the speed coming off aerotow or PTOT to gain a bit of altitude, but that just means lowering the nose gradually as you bleed off the speed. In both cases the AofA needs to be adjusted to match the desired free flight speed.



I thought that we practiced this 'gain altitude and slowly drop the nose' every time we release from aerotow?

You have a few things wrong.
First- angle of attack is related to the geometry of the glider and airflow over it. On tow the attitude of the glider is slightly nose up relative to the ground compared to the attitude it would have at the same angle of attack in a gliding configuration.
Second- "Every time" implies that we handle all releases the same. In normal flight we will transition from tow attitude and speed to gliding attitude and the associated speed. If in lift, that likely means slowing to thermalling speed. If not in lift we would be going to the appropriate speed to fly.
Third- There is no reason to try to gain altitude in PTT as the amount of gain accomplished by going from tow speed to pattern/approach speed is likely to be quite small. The correct action is to lower the nose slightly to establish a gliding attitude and speed appropriate for the conditions. In many cases, tow speed is about right for the return to the runway.
Also note that "every time" we turn right on release because that is standard. There is a 50% chance that, due to wind velocity and direction(including shear that may be present), terrain considerations, and position, that the correct action is to turn left.
These considerations are why we MUST have an emergency response plan in mind on every launch. There is no time to figure it out- you must execute the plan you have in your head already.
And forget all the mumbo jumbo calculations espoused in this thread.
UH

On Thursday, May 8, 2014 5:55:27 PM UTC-7, Bill D wrote:
On Thursday, May 8, 2014 6:39:06 PM UTC-6, 2G wrote:



The other issue is that a tow rope break requires immediate lowering of the nose.



Why would anyone lower the nose? The glider is presumably at aero tow speed - 65 - 70 knots which is way above the pattern speed. A better plan is to use the excess airspeed to maintain height while turning until airspeed drops to pattern speed.





This is done routinely at altitude, but at low altitude this means pointing the glider's nose uncomfortably down at the ground while executing a steep banked turn. If the ground is rising, as it is at Sampley, the picture seen by the pilot is even more disturbing. All that it takes is a momentary hesitation in this reflex and the outcome can be fatal.



The nose is not "uncomfortably down". The turn back is a normal turn.







As an aside, I once did a wind mill start in my DG400 below 1000' (over a runway). This maneuver requires achieving in excess of 90 kt airspeed. Because the engine & prop act like dive brakes, you feel like you are standing on your rudder pedals when you do this close to the ground. I got to this airspeed and the prop still didn't rotate. This meant that I had to steepen the descent even more. All of my instincts said no, but my brain said yes, which is what I did. The engine started, but I decided that this maneuver really needs to be started at a higher altitude.



Aha! You're really a motor glider pilot, not an aero tow pilot which explains your misconceptions.

PLEASE stop with the sanctimonious crap! I have done hundreds of aerotows. You need to lower the nose because you are in a climb attitude and need to transition to a glide attitude. On your next tow note where the horizon is on the canopy and compare it to where it is after release at the same airspeed.

Tom

On Sunday, June 15, 2014 6:09:22 PM UTC+12, 2G wrote:
PLEASE stop with the sanctimonious crap! I have done hundreds of aerotows.. You need to lower the nose because you are in a climb attitude and need to transition to a glide attitude. On your next tow note where the horizon is on the canopy and compare it to where it is after release at the same airspeed.

While the nose ends up lower, you don't lower the nose. The decrease in airspeed does that for you, and the movement of the stick is rearward, to prevent the nose falling through into a dive and again attaining the aerotow airspeed.

Whether or not positive action is required to maintain airspeed
depends on the trim; this will be different for nose and belly hooks. A
belly hook on some ( older ) gliders requires
nose down trim to balance the rope force.
JMF


At 11:31 15 June 2014, Bruce Hoult wrote:
On Sunday, June 15, 2014 6:09:22 PM UTC+12, 2G wrote:
PLEASE stop with the sanctimonious crap! I have done hundreds of
aerotows=
.. You need to lower the nose because you are in a climb attitude and
need
t=
o transition to a glide attitude. On your next tow note where the horizon
i=
s on the canopy and compare it to where it is after release at the same
air=
speed.

While the nose ends up lower, you don't lower the nose. The decrease in
air=
speed does that for you, and the movement of the stick is rearward, to
prev=
ent the nose falling through into a dive and again attaining the aerotow
ai=
rspeed.

On Monday, June 16, 2014 12:21:16 AM UTC+12, firsys wrote:
Whether or not positive action is required to maintain airspeed
depends on the trim; this will be different for nose and belly hooks. A
belly hook on some ( older ) gliders requires
nose down trim to balance the rope force.

Yes, I have 60 or 70 hours PIC from aerotow (and a few flights on a winch) in an original model Janus, with only a belly hook. To be honest the only time it is really noticeable on aerotow is if you have slack rope and it comes tight with a jerk. It pays to be ready with forward stick, or even anticipate it.

But in any case, the removal of that nose-up force at tow release makes it even more certain that you'll be moving the stick rearwards after release.

That model is far more of a handfull on the winch, as the hook is really too far forward for good winching. It takes a lot of up elevator to keep the climb steep enough. The all moving tailplane means that it's easily possible to over do it and stall the elevator. And if you get a premature release then you're sitting there nose up with the stick most of the way back. *Definitely* need a positive check forward to neutral stick in that situation!

At 11:31 15 June 2014, Bruce Hoult wrote:
On Sunday, June 15, 2014 6:09:22 PM UTC+12, 2G wrote:
PLEASE stop with the sanctimonious crap! I have done hundreds of
aerotows=
.. You need to lower the nose because you are in a climb attitude and
need
t=
o transition to a glide attitude. On your next tow note where the horizon
i=
s on the canopy and compare it to where it is after release at the same
air=
speed.

While the nose ends up lower, you don't lower the nose. The decrease in
air=
speed does that for you, and the movement of the stick is rearward, to
prev=
ent the nose falling through into a dive and again attaining the aerotow
ai=
rspeed.

The expression you are looking for is "select the approach attitude". That
should be the case after ALL launch failures. With the correct attitude
selected the speed will eventually decay or increase to the correct value.
By selecting the approach attitude you will ensure that the speed is less
likely to reduce below the desired value in any turn. Of course if the
failure occurs at height it may be that normal glide attitude is more
appropriate and this can be selected at the appropriate time but the
initial selection should always be approach attitude.
KISS