Stall/spin and ground reference maneuvers

I agree, there are multiple inputs to the pilot. The trick is prioritizing them and not getting distracted. I'm probably not any better at it than you; it's more likely that my instructors taught me somewhat differently.

On downwind I concentrate on airspeed, variometer rate, and traffic scan (I'll note the position of the runway as part of my traffic scan). When the runway disappears I'll wait an appropriate amount of time (judged from how fast I moved down the runway), take a quick look for traffic, runway position and turn roll out reference, and then (and only then) initiate my turn to base. During the 5 seconds I'm turning I'm looking directly forward over the nose, paying attention only to airspeed, yaw string and bank angle. The bank angle I always try to use is 45 degrees, while auxiliary inputs are slipstream noise, one or two glances at the ASI, the appearance of the rollout reference, and the imagined voice of my instructor chanting "airspeed, yaw string" over and over.

On the base leg I again concentrate on airspeed, variometer rate, and traffic scan (again noting the runway position as part of my traffic scan). At the appropriate position (judged from how fast the runway extended centerline is approaching, I initiate my turn to final. During the 5 seconds I'm turning I'm again looking directly forward over the nose, paying attention only to airspeed, yaw string and bank angle. Again the bank angle I always try to use is 45 degrees, while auxiliary inputs are slipstream noise, one or two glances at the ASI, the appearance of the runway, and the imagined voice of my instructor chanting "airspeed, yaw string" over and over.

Until a few months ago when I read about "pivot height" on this board, I had never known that the wing tip direction could reverse direction during a turn depending on your height. I assure you that's not from lack of experience on my part, it's just that I never look at the ground when I'm low and turning.

I also agree with you that the numbers of stall/spin accidents are appalling. As a community we need to try to reduce them. I just don't know if making people aware of peripheral vision changes is the way forward. Isn't it better to get them to focus only on what matters for the few seconds that are needed in a low altitude turn?

-John, Q3

On Tuesday, March 4, 2014 9:54:01 AM UTC-5, wrote:
On Tuesday, March 4, 2014 5:34:09 AM UTC-8, John Carlyle wrote:

Just because you perceive something doesn't mean that you have to pay attention to it. The most important things in a pattern turn (or low altitude thermalling) are perfectly coordinated turns and proper airspeed. Scans for traffic and feeling for lift are fine, but who cares what the ground does?



One does look at the airport when initiating the turn from base to final, but once the turn starts all you need to do for the next 5 seconds is look over the nose for pitch, yaw and bank. The airport will appear when you need it without having to search for it.



Well, it's a human in the loop feedback control system with multiple inputs - visual, inertial and some auditory. If you are making a low turn from base to final you may initiate the turn while looking away from the yaw string and airspeed because the runway is off to the side and you are trying to set a turn rate to put you in-line with the runway on final. At the same time your peripheral vision at this altitude is now subtly telling you that you are over-banked/under-ruddered because you are below the pivotal height where the turning cues of the wing against the background reverse. You aren't used to this peripheral cue and may not be aware of how it affects your overall perception of attitude and coordination and how that feeds back into the control system.

You may be better at it than I am, but I can't just take a snapshot to the side before initiating the turn to final and then look ahead to the yaw string and airspeed without ever looking out to the runway again and expect to end up both pointed at and in-line with the runway heading. I tend to scan back and forth. It only takes a moment of being over-ruddered to generate a spin, particularly if you are at low speed (and an approach into an airport in a mountain valley can make you fly too nose-high if you are not paying proper attention).

Is any of this good and proper airmanship - well no. But that is a little beside the point. The fact is that over the past 20 years 39% of fatal glider accidents and 36% of all glider fatalities have been due to stall/spin. That's 43 dead glider pilots and passengers, or slightly more than two per year. It is the leading cause of death while flying gliders. We must be doing something (or some things) wrong. My thought is if we are all aware that our perception from peripheral vision changes (and which way those changes work) we all may be in a slightly better position to resist the subconscious urge to do the wrong thing at just the wrong time.

9B

I wonder if part of the problem we have in patterns is the patterns themselves. Probably because of a military aviation background, I really (for both power and gliders) prefer the military continuous 180 turn from a lower closer downwind to final to the civilian higher, downwind - turn - base - turn - final approach.

I keep the pattern speed a bit high (say 60 - 65 knots in glass), half spoilers abeam the touchdown aimpoint, about 500' agl, pretty close in to the field, then at the TLAR point, roll into about 30 degrees of bank and turn in. If wide I can steepen up, if tight open out, but the turn is one continuous turn until rollout on final, and then I start transitioning to my final speed and adjusting to where I want to touch down.

Lower and closer in, I find it a lot easier to judge the angles; I HATE long finals!

So the turn is pretty much like any thermalling turn while adjusting the center, without having to roll completely in and out twice with the usual chance to under/over rudder the turn..

Just my 2 cents...

Kirk
66

On Tuesday, March 4, 2014 10:58:56 AM UTC-5, John Carlyle wrote:
I agree, there are multiple inputs to the pilot. The trick is prioritizing them and not getting distracted. I'm probably not any better at it than you; it's more likely that my instructors taught me somewhat differently. On downwind I concentrate on airspeed, variometer rate, and traffic scan (I'll note the position of the runway as part of my traffic scan). When the runway disappears I'll wait an appropriate amount of time (judged from how fast I moved down the runway), take a quick look for traffic, runway position and turn roll out reference, and then (and only then) initiate my turn to base. During the 5 seconds I'm turning I'm looking directly forward over the nose, paying attention only to airspeed, yaw string and bank angle. The bank angle I always try to use is 45 degrees, while auxiliary inputs are slipstream noise, one or two glances at the ASI, the appearance of the rollout reference, and the imagined voice of my instructor chanting "airspeed, yaw string" over and over. On the base leg I again concentrate on airspeed, variometer rate, and traffic scan (again noting the runway position as part of my traffic scan). At the appropriate position (judged from how fast the runway extended centerline is approaching, I initiate my turn to final. During the 5 seconds I'm turning I'm again looking directly forward over the nose, paying attention only to airspeed, yaw string and bank angle. Again the bank angle I always try to use is 45 degrees, while auxiliary inputs are slipstream noise, one or two glances at the ASI, the appearance of the runway, and the imagined voice of my instructor chanting "airspeed, yaw string" over and over. Until a few months ago when I read about "pivot height" on this board, I had never known that the wing tip direction could reverse direction during a turn depending on your height. I assure you that's not from lack of experience on my part, it's just that I never look at the ground when I'm low and turning. I also agree with you that the numbers of stall/spin accidents are appalling. As a community we need to try to reduce them. I just don't know if making people aware of peripheral vision changes is the way forward. Isn't it better to get them to focus only on what matters for the few seconds that are needed in a low altitude turn? -John, Q3 On Tuesday, March 4, 2014 9:54:01 AM UTC-5, wrote: On Tuesday, March 4, 2014 5:34:09 AM UTC-8, John Carlyle wrote: Just because you perceive something doesn't mean that you have to pay attention to it. The most important things in a pattern turn (or low altitude thermalling) are perfectly coordinated turns and proper airspeed. Scans for traffic and feeling for lift are fine, but who cares what the ground does? One does look at the airport when initiating the turn from base to final, but once the turn starts all you need to do for the next 5 seconds is look over the nose for pitch, yaw and bank. The airport will appear when you need it without having to search for it. Well, it's a human in the loop feedback control system with multiple inputs - visual, inertial and some auditory. If you are making a low turn from base to final you may initiate the turn while looking away from the yaw string and airspeed because the runway is off to the side and you are trying to set a turn rate to put you in-line with the runway on final. At the same time your peripheral vision at this altitude is now subtly telling you that you are over-banked/under-ruddered because you are below the pivotal height where the turning cues of the wing against the background reverse. You aren't used to this peripheral cue and may not be aware of how it affects your overall perception of attitude and coordination and how that feeds back into the control system. You may be better at it than I am, but I can't just take a snapshot to the side before initiating the turn to final and then look ahead to the yaw string and airspeed without ever looking out to the runway again and expect to end up both pointed at and in-line with the runway heading. I tend to scan back and forth. It only takes a moment of being over-ruddered to generate a spin, particularly if you are at low speed (and an approach into an airport in a mountain valley can make you fly too nose-high if you are not paying proper attention). Is any of this good and proper airmanship - well no. But that is a little beside the point. The fact is that over the past 20 years 39% of fatal glider accidents and 36% of all glider fatalities have been due to stall/spin. That's 43 dead glider pilots and passengers, or slightly more than two per year. It is the leading cause of death while flying gliders. We must be doing something (or some things) wrong. My thought is if we are all aware that our perception from peripheral vision changes (and which way those changes work) we all may be in a slightly better position to resist the subconscious urge to do the wrong thing at just the wrong time. 9B

I get a bit concerned about the term "concentrate", that implies to me, the exclusion of information. Any time one narrows the focus the opportunity to get and process potentially valuable information is lost. I see many pilots "concentrate" on the runway or touchdown point to the exclusion of other valuable information such as attitude, airspeed, and coordination. Maybe Q3 is using too strong a word for what he does.
UH

Airspeed and coordination - it's only two items, yet so many people lose
track of one or the other or both.

Great, thought-provoking, thread, with excellent points-n-perspectives all
around. And though I doubt what's below will add anything not already noted,
repetition is often useful in learning...

I flew gliders (only) for more than a decade before learning of "pivotal
altitude" (from an article in "Soaring" magazine as I recall). By then,
reading had also alerted me to a whole bunch of other not-then-experienced
optical illusions and "altered visual perspectives" pilots could encounter.
Meanwhile, I'd been flying successfully enough I'd not yet (or to-date) come
even vaguely close to an unexpected departure from controlled flight in the
landing pattern, despite "the usual number" of off-field landings by then.

Yet by the time I became aware of "pivotal altitude" I knew of dead pilots -
soaring and otherwise - who evidently HAD experienced unexpected departures
from controlled flight in landing patterns (mostly at airports), including
some with gobs more time than I. My conclusion? Clearly, failure to pay
attention to and control airspeed and coordination (neither being more
important than the other, IMO) - as noted above - could easily be my last mistake.

The $64,000 question is: How can a person "become immune" from making the
mistake(s) in the landing pattern that lead to NOT always being able to
effectively monitor/control airspeed & coordination in the pattern?

IMO, education is good. (Duh!) And given the complex differences among humans,
the idea of making students aware of all known possible distractions (visual
and otherwise) in landing patterns is probably a good instructional thing, and
- clearly - conveying in practical terms the "look and feel" of pivotal
altitude cannot be done in a sailplane. So if you're one of the lucky ones who
can always monitor and effectively control airspeed and coordination in your
landing patterns, then probably no need for power-plane exposure to pivotal
altitude. But for anyone uncertain of their capabilities...maybe it'd be a
great idea to go get some personal exposure with a power instructor you're
certain is knowledgeable of - and confident about their ability to safely
teach - the concept. For I suspect not all instructors ARE safely qualified to
expose students to the pivotal altitude concept. (I hope I'm wrong, but when
it's my life at stake, I tend to be conservative! :-) )

Bob W.

How about "concentrate by prioritizing tasks and not getting distracted while not developing tunnel vision"? grin I do get your point, and it's valuable.

-John, Q3

On Tuesday, March 4, 2014 12:00:44 PM UTC-5, wrote:
I get a bit concerned about the term "concentrate", that implies to me, the exclusion of information. Any time one narrows the focus the opportunity to get and process potentially valuable information is lost. I see many pilots "concentrate" on the runway or touchdown point to the exclusion of other valuable information such as attitude, airspeed, and coordination. Maybe Q3 is using too strong a word for what he does.

UH

On 3/4/2014 9:54 AM, kirk.stant wrote:
I wonder if part of the problem we have in patterns is the patterns
themselves. Probably because of a military aviation background, I really
(for both power and gliders) prefer the military continuous 180 turn from a
lower closer downwind to final to the civilian higher, downwind - turn -
base - turn - final approach.

I keep the pattern speed a bit high (say 60 - 65 knots in glass), half
spoilers abeam the touchdown aimpoint, about 500' agl, pretty close in to
the field, then at the TLAR point, roll into about 30 degrees of bank and
turn in. If wide I can steepen up, if tight open out, but the turn is one
continuous turn until rollout on final, and then I start transitioning to
my final speed and adjusting to where I want to touch down.

Lower and closer in, I find it a lot easier to judge the angles; I HATE
long finals!

So the turn is pretty much like any thermalling turn while adjusting the
center, without having to roll completely in and out twice with the usual
chance to under/over rudder the turn..

Just my 2 cents...

Kirk 66

FWIW...

Way back when I had about 200 total hours, all glider, I flew an HP-14 from a
busy municipal airport with 3 closely-spaced parallel runways. SOP traffic
separation had gliders flying a 4-sided pattern entered from midfield, the
downwind, base and final legs being inside the same-turning-direction power
pattern, which normally used the southernmost E-W runway.

Schreder's original HP-14 design wasn't noted for being a rapid roller. While
it WAS possible to fly a rectangular pattern in it inside the power pattern,
doing so required serious (both arms essentially required) stick effort to
achieve max aileron deflection on the final-to-base and base-to-final turns,
to the point I found doing so a mental distraction...and thus less than
"ideally safe."

I found "a circling approach" (a la the U.S. Navy) from downwind to final
considerably easier - and a no-brainer, as Kirk suggests above - to implement.
A circling approach quickly became my standard procedure in that ship at that
airport.

When people asked, I told 'em why. Few asked.

Bob W.

I'm looking at aim point and clearing final for that Cessna on a straight-in
who didn't use his radio... No need to look at the ground - I know it's
still there.


"John Carlyle" wrote in message
...
Who looks down the wing at the ground when they turn? In pattern turns I'm
looking straight over the glare shield, focused on airspeed (pitch), yaw
string, and bank angle.

-John, Q3


On Monday, March 3, 2014 10:54:39 PM UTC-5, Bill D wrote:
The argument which says one should avoid low turns ignores the fact that
every glider flight ends with at least one turn at or below 300' AGL.
Unless a pilot is well trained for low turns this is a recipe for a
stall/spin accident. I respectively suggest a better alternative is to
find a CFI willing to provide GRM training in a touring motorglider or
slow LSA and get really good at it.

I know someone who flies the pattern as you describe; he had flown F-4's onto carriers. My instructor told me he felt it was safer to separate tasks in the pattern rather than combine them. So I do it his way...

-John, Q3

On Tuesday, March 4, 2014 11:54:37 AM UTC-5, kirk.stant wrote:
I wonder if part of the problem we have in patterns is the patterns themselves. Probably because of a military aviation background, I really (for both power and gliders) prefer the military continuous 180 turn from a lower closer downwind to final to the civilian higher, downwind - turn - base - turn - final approach.

I keep the pattern speed a bit high (say 60 - 65 knots in glass), half spoilers abeam the touchdown aimpoint, about 500' agl, pretty close in to the field, then at the TLAR point, roll into about 30 degrees of bank and turn in. If wide I can steepen up, if tight open out, but the turn is one continuous turn until rollout on final, and then I start transitioning to my final speed and adjusting to where I want to touch down.

Lower and closer in, I find it a lot easier to judge the angles; I HATE long finals!

So the turn is pretty much like any thermalling turn while adjusting the center, without having to roll completely in and out twice with the usual chance to under/over rudder the turn..

Just my 2 cents...

Kirk
66

I fly my pattern just like Kirk, though a little higher and faster at the
start. I begin my descending final turn when abeam the touchdown point and
roll out on final at about 200 ft and over the numbers. I do this both in
my LAK and in the tow planes.

I did it this way in the Air Force and when I flew a King Air for
FlightSafety. The only exception was in the B-727. Gotta be gentle for the
pax.

"kirk.stant" wrote in message
...
I wonder if part of the problem we have in patterns is the patterns
themselves. Probably because of a military aviation background, I really
(for both power and gliders) prefer the military continuous 180 turn from a
lower closer downwind to final to the civilian higher, downwind - turn -
base - turn - final approach.

I keep the pattern speed a bit high (say 60 - 65 knots in glass), half
spoilers abeam the touchdown aimpoint, about 500' agl, pretty close in to
the field, then at the TLAR point, roll into about 30 degrees of bank and
turn in. If wide I can steepen up, if tight open out, but the turn is one
continuous turn until rollout on final, and then I start transitioning to my
final speed and adjusting to where I want to touch down.

Lower and closer in, I find it a lot easier to judge the angles; I HATE long
finals!

So the turn is pretty much like any thermalling turn while adjusting the
center, without having to roll completely in and out twice with the usual
chance to under/over rudder the turn..

Just my 2 cents...

Kirk
66

Why are pilots so committed to the idea that they can reliably judge airspeed by looking at the sight picture over the nose? What if the runway tilts up and it is surrounded by hills and trees?

The only time that I bet my life on the sight picture is when I'm on a steep final, I'm holding the air brake at a constant setting, and I'm sure that the glide angle and the touchdown point are stable and unchanging.