Fatal crash Arizona

On Saturday, May 10, 2014 10:22:28 AM UTC-7, Dan Marotta wrote:
Let's not forget the time it takes to complete the turn or the distance
covered over the ground.

Without getting into the math, I can comfortably say that, using a 30 deg
bank will take longer to complete the turn and leave you further from the
runway. Likewise, at higher elevation airports your sink speed will be
higher (think true airspeed) so height loss will be greater than at sea
level.

Bruce raised the lateral displacement issue as well. Here is a link to a graphical depiction of the main parameters we've been discussing versus bank angle:

https://drive.google.com/file/d/0Bw1...it?usp=sharing

As to the lateral displacement versus bank angle tradeoff, I have some thoughts:

For the range of bank angles being discussed you are going to end up 400-600 feet (two turn radii) laterally displaced from the centerline (less wind drift - assuming a turn into any crosswind component). Where that puts you will depend A LOT on the airport configuration. If your plan is to land back on a 50-100 foot wide paved runway you will have to turn more than 180 degrees initially then do a reversal to get lined up and the displacement is less of a factor. If you are taking off from the centerline of a 800 foot wide turf runway bordered by 150 foot trees the difference between 400 feet of displacement and 600 feet of displacement matters quite a lot. Have situational awareness and control the airplane - words to live by.

Assuming in most cases the pilot will be trying to get back to a more narrow runway we have the challenge of turning 210-220 degrees on the initial turn and then making a reverse turn to get lined up. The reversal will be when the glider is the lowest so it's probably safe to presume that this turn will be at a lower bank angle (say, 20-30 degrees, perhaps in ground effect). This allows you to avoid performing a cartwheel in front of all your friends. I did this at a high bank angle when I was 11 years old (a story in itself) and can attest that it is not fun.

I'd say the best advice (summarizing the summary) is the following:

- Know ahead of time what your specific plan is for the specific takeoff, not just a general idea - including accounting for crosswinds, obstacles and where you are going to go straight ahead if needed. I have walked fields off the ends of the runways of several problematic airports and it helps a lot - if a field is not an airport it is likely full of surprises.
- Call out the decision height for straight ahead versus 180 while towing out.
- When committing to a 180 make a decisive, controlled and coordinated turn - initially up to 45-55 degrees of bank OR whatever maximum bank angle over 30 degrees you still have rock-solid speed control and coordination. Not being honest with yourself on this point can prove fatal.
- Gradually reduce the bank angle as you approach 180 degrees and continue turning until you can make a smooth turn reversal to the runway centerline.
- Fly the airplane - watch airspeed, coordination, wingtip clearance and obstacles (mine was a fence).
- Try to be aware when a controlled crash is better than the chance you are taking - it can happen quickly.

9B

On Sunday, May 11, 2014 3:01:30 AM UTC+12, wrote:
I went through the spread sheet and I found everything correct except for the calculation of the "enhanced sink rate". The sink rate is not just the unbanked rate multiplied by the load factor!

Ahh . yes .. you are correct. That's right for the descent angle, but then you need to adjust that by the ratio of the airspeeds to get the descent rate.


Some manufactures include a circling polar. Using the circling polar of an asw-24 with a total weight of 750 lbs, the speed and sink a

at 30 deg: 45 kt, 150 ft/min
at 45 deg: 50 kt, 205 ft/min
at 60 deg: 59 kt, 345 ft/min

With the correction of multiplying the sink rate by "speed needed"/"min sink speed" my spreadsheet gets the above numbers (and same turn times and height loss) for a glider with a min sink of 122 fpm at 42 knots.

On Saturday, May 10, 2014 8:25:35 PM UTC-7, Bruce Hoult wrote:

With the correction of multiplying the sink rate by "speed needed"/"min sink speed" my spreadsheet gets the above numbers (and same turn times and height loss) for a glider with a min sink of 122 fpm at 42 knots.

New summary chart with correction: https://drive.google.com/file/d/0Bw1...it?usp=sharing

The new minimum altitude loss bank angle is...drum roll...45 degrees.

If for some reason you are worried about dragging the wingtip the bank angle that keeps the wingtip the highest is 36 degrees, though obviously this only matters as you sink lower and/or encounter obstacles.

The discussion about offset from the runway is unchanged going from 45 to 60 degrees of bank will reduce the runway offset by 80 feet or so - I don't think it's worth the risk to crank it over that far in most situations. The simple observation is that between 30 and 55 degrees the amount of altitude lost doesn't vary much, so do whatever allows you to control the airplane and get to a laudable spot in go shape to land.

9B

On Saturday, May 10, 2014 10:51:36 PM UTC-7, wrote:
On Saturday, May 10, 2014 8:25:35 PM UTC-7, Bruce Hoult wrote:



With the correction of multiplying the sink rate by "speed needed"/"min sink speed" my spreadsheet gets the above numbers (and same turn times and height loss) for a glider with a min sink of 122 fpm at 42 knots.



New summary chart with correction: https://drive.google.com/file/d/0Bw1...it?usp=sharing



The new minimum altitude loss bank angle is...drum roll...45 degrees.



If for some reason you are worried about dragging the wingtip the bank angle that keeps the wingtip the highest is 36 degrees, though obviously this only matters as you sink lower and/or encounter obstacles.



The discussion about offset from the runway is unchanged going from 45 to 60 degrees of bank will reduce the runway offset by 80 feet or so - I don't think it's worth the risk to crank it over that far in most situations. The simple observation is that between 30 and 55 degrees the amount of altitude lost doesn't vary much, so do whatever allows you to control the airplane and get to a laudable spot in go shape to land.



9B

....get to a landable spot in good shape to land.

At 11:24 10 May 2014, Jim White wrote:
At 07:20 10 May 2014, Chris Rollings wrote:
All completely correct but there is one even bigger problem, most pilots
when making a low level turn off a launch failure or to modify a
circuit/pattern that has got too low, tend to be looking for/at the
place
they intend to land with little or no attention to spare for the ASI,
attitude or slip/skid indicator, that's why these events are so
productive
of stall/spin accidents. Training needs to emphasise, GLANCE AT THE ASI
EVERY 2 - 3 SECONDS IN THESE CIRCUMSTANCES. Attitude is un unreliable
indicator very near the ground, even the smallest undulations in the
terrain can give a false impression and just being low can make the
attitude look more nose down than it is.


Surely best practice is simply to keep the speed on until you have got it
all sorted. Certainly in modern slippery gliders. Too much speed is much
safer than too little and costs very little in height through a turn.

Isn't this what you taught us Chris?


Certainly a bit faster than optimum costs very little but you still need to
GLANCE AT THE ASI
EVERY 2 - 3 SECONDS IN THESE CIRCUMSTANCES to check what speed you are
doing.

Lots of playing with numbers but I think Chris'
airspeed checking is the most important; a well sealed modern sailplane
gives no clue to the airspeed from the
air noise. Furthermore you may be in turbulence/ wind
shear situation.
Apologies if this was said before.
John F.

At 11:01 11 May 2014, Chris Rollings wrote:
At 11:24 10 May 2014, Jim White wrote:
At 07:20 10 May 2014, Chris Rollings wrote:
All completely correct but there is one even bigger problem, most
pilots
when making a low level turn off a launch failure or to modify a
circuit/pattern that has got too low, tend to be looking for/at th
place
they intend to land with little or no attention to spare for the ASI,
attitude or slip/skid indicator, that's why these events are so
productive
of stall/spin accidents. Training needs to emphasise, GLANCE AT THE
ASI
EVERY 2 - 3 SECONDS IN THESE CIRCUMSTANCES. Attitude is un unreliable
indicator very near the ground, even the smallest undulations in the
terrain can give a false impression and just being low can make the
attitude look more nose down than it is.


Surely best practice is simply to keep the speed on until you have got
it
all sorted. Certainly in modern slippery gliders. Too much speed is much
safer than too little and costs very little in height through a turn.

Isn't this what you taught us Chris?


Certainly a bit faster than optimum costs very little but you still need
t
GLANCE AT THE ASI
EVERY 2 - 3 SECONDS IN THESE CIRCUMSTANCES to check what speed you ar
doing.

On Sunday, May 11, 2014 5:01:08 AM UTC-6, Chris Rollings wrote:
At 11:24 10 May 2014, Jim White wrote:

At 07:20 10 May 2014, Chris Rollings wrote:

All completely correct but there is one even bigger problem, most pilots

when making a low level turn off a launch failure or to modify a

circuit/pattern that has got too low, tend to be looking for/at the

place

they intend to land with little or no attention to spare for the ASI,

attitude or slip/skid indicator, that's why these events are so

productive

of stall/spin accidents. Training needs to emphasise, GLANCE AT THE ASI

EVERY 2 - 3 SECONDS IN THESE CIRCUMSTANCES. Attitude is un unreliable

indicator very near the ground, even the smallest undulations in the

terrain can give a false impression and just being low can make the

attitude look more nose down than it is.





Surely best practice is simply to keep the speed on until you have got it

all sorted. Certainly in modern slippery gliders. Too much speed is much

safer than too little and costs very little in height through a turn.



Isn't this what you taught us Chris?





Certainly a bit faster than optimum costs very little but you still need to

GLANCE AT THE ASI

EVERY 2 - 3 SECONDS IN THESE CIRCUMSTANCES to check what speed you are

doing.

Being constantly aware of one's airspeed is nothing more than basic airmanship. Why and where would this not be the case?

At 15:46 11 May 2014, Bill D wrote:
On Sunday, May 11, 2014 5:01:08 AM UTC-6, Chris Rollings wrote:
At 11:24 10 May 2014, Jim White wrote:

At 07:20 10 May 2014, Chris Rollings wrote:

All completely correct but there is one even bigger problem, most
pilots

when making a low level turn off a launch failure or to modify a

circuit/pattern that has got too low, tend to be looking for/at the

place

they intend to land with little or no attention to spare for the ASI,

attitude or slip/skid indicator, that's why these events are so

productive

of stall/spin accidents. Training needs to emphasise, GLANCE AT THE
ASI

EVERY 2 - 3 SECONDS IN THESE CIRCUMSTANCES. Attitude is un
unreliable

indicator very near the ground, even the smallest undulations in the

terrain can give a false impression and just being low can make the

attitude look more nose down than it is.





Surely best practice is simply to keep the speed on until you have got
it

all sorted. Certainly in modern slippery gliders. Too much speed is
much

safer than too little and costs very little in height through a turn.



Isn't this what you taught us Chris?





Certainly a bit faster than optimum costs very little but you still
need
to

GLANCE AT THE ASI

EVERY 2 - 3 SECONDS IN THESE CIRCUMSTANCES to check what speed you
are

doing.

Being constantly aware of one's airspeed is nothing more than basic
airmanship. Why and where would this not be the case?

Maybe when you are distracted having been surprised by a launch failure.
It happens, it happened on a check ride I did 2 weeks ago with a pilot who
had not flown for a while. That is why a procedure needs to be formulated
for a moderate level of skill and currency. An experience pilot, current
and on top of his game probably does not need a procedure, he is capable of
formulating and executing his own, he knows his own limitations and the
limitations of his aircraft.
Solly made it up as he went along, procedure dictated that he found a
runway.
The key is knowing what you are going to do before the worst happens.

On Sunday, May 11, 2014 5:40:53 PM UTC-6, Don Johnstone wrote:
At 15:46 11 May 2014, Bill D wrote:

On Sunday, May 11, 2014 5:01:08 AM UTC-6, Chris Rollings wrote:

At 11:24 10 May 2014, Jim White wrote:



At 07:20 10 May 2014, Chris Rollings wrote:



All completely correct but there is one even bigger problem, most

pilots



when making a low level turn off a launch failure or to modify a



circuit/pattern that has got too low, tend to be looking for/at the



place



they intend to land with little or no attention to spare for the ASI,



attitude or slip/skid indicator, that's why these events are so



productive



of stall/spin accidents. Training needs to emphasise, GLANCE AT THE

ASI



EVERY 2 - 3 SECONDS IN THESE CIRCUMSTANCES. Attitude is un

unreliable



indicator very near the ground, even the smallest undulations in the



terrain can give a false impression and just being low can make the



attitude look more nose down than it is.











Surely best practice is simply to keep the speed on until you have got

it



all sorted. Certainly in modern slippery gliders. Too much speed is

much



safer than too little and costs very little in height through a turn.







Isn't this what you taught us Chris?











Certainly a bit faster than optimum costs very little but you still

need

to



GLANCE AT THE ASI



EVERY 2 - 3 SECONDS IN THESE CIRCUMSTANCES to check what speed you

are



doing.



Being constantly aware of one's airspeed is nothing more than basic

airmanship. Why and where would this not be the case?



Maybe when you are distracted having been surprised by a launch failure.

A basic standard of airmanship requires a pilot to expect every launch to fail. One is allowed surprise only when a launch DOES NOT fail. Inattention to airspeed is never acceptable even with a pre-solo student.

I totally agree that pilots should glance at the ASI very frequently on
every approach. When students have trouble keeping a constant
airspeed on approach, I find it helpful to do a demonstration
approach, calling out the airspeed every time I glance at the ASI. Its
about every 2 seconds, as other people have said.

About doing 180 degree turns after a low tow failu I also totally
agree with writers who say the immediate question is 'can I land
straight ahead' and to do that if its possible. Training students to
automatically do a 180 degree turn at 200ft is teaching the wrong
thing. Some damage to the glider should be taught to be acceptable,
since its an emergency situation. Maybe training this at all is a bad
thing, since statistically some solo pilots are going to get it
disastrously wrong attempting it. One could argue that going more-
or-less straight ahead is safer, while attempting a 180 degree turn at
200ft is risking one's life to save the glider from minor damage, or
the club the inconvenience of a retrieve. One could say that a site
where a straight-ahead landing from 200ft will certainly result in
more than minor damage, is a site that should not be used.

I wonder how other countries teach this, and how accident rates
compare. I was taught to glide in the UK, in the 60s, on a winch.
When I could eventually afford aerotows, I was never trained or
practiced a 180 degree turn from 200ft. As I recall, the BGA training
at that time was simply a verbal briefing for a low rope break was to
land more-or-less straight ahead (or at my club, to fly out over the
valley). It was accepted that the glider might be damaged.
Personally, I suspect this verbal briefing to go straight ahead may
produce better severe-accident statistics than the US emphasis on
training low 180 degree turns.