Stall/spin and ground reference maneuvers

On Wednesday, March 5, 2014 7:35:51 AM UTC-6, John Carlyle wrote:

Would you do a circling approach if you were going into a difficult strip, too? Say, a narrow cornfield surrounded by trees. I ask because the Navy pilots I know who fly gliders have reverted to the non-circling approach.

Depends. If low, yes - I'll fly whatever pattern I can to land safely. If I have more time and want to look over the landing area more, then I might fly a higher, longer pattern to give more time to pick the best place to land. Also need to be able to fly bigger patterns when sequencing behind other gliders, so all the skills need to be maintained.

I think it's important to be able to fly a "de-stabilized" (non-constant airspeed) approach in gliders, so that energy can be maintained until late in the approach, and used or gotten rid of as required. Also should be able to fly an approach from just about anywhere around the intended point of landing. Always flying the same pattern into the same airfield pretty much guarantees that your first landout will be exciting! Power pilots are taught to fly "stabilized approaches" because that is how you land a big airplane.. Totally unnecessary in small planes, and IMO downright dangerous in gliders.

As far as watching the ASI, after reaching the TLAR point where I want to start the turn, I look just to the inside (11 or 1 o'clock) when initiating the turn, monitor the ASI for trend (glider is trimmed slightly fast), monitor the yawstring, then check how the turn is progressing, then back to ASI - yawstring - turn, etc until time to roll out. If it's a busy runway I might roll out momentarily to check the extended final, then roll back into the turn - those would be pretty aggressive rolls with lots of speed.

Kirk

Kirk,

Thank for writing that - very interesting that you mix approach types.

I'm not too clear about your comment "always flying the same pattern into the same airfield pretty much guarantees that your first landout will be exciting". I always use a downwind-base-final pattern, I've logged 10 landouts in farmers fields, and except for having to dodge an electric wire fence once they were low or no drama events (although some of the retrieves were interesting).

Your "de-stabilized" (non-constant airspeed) approach comment was also interesting. I tend to keep high until on final, just to keep my options open, but my speed stays pretty much constant. Being high has helped me on several occasions to delay a bit (once a person behind me with no radio landed under me, another time someone drove onto the field). Do I understand correctly that you tend to keep your energy in speed rather than altitude?

-John, Q3

On Wednesday, March 5, 2014 11:30:30 AM UTC-5, kirk.stant wrote:
On Wednesday, March 5, 2014 7:35:51 AM UTC-6, John Carlyle wrote:

Would you do a circling approach if you were going into a difficult strip, too? Say, a narrow cornfield surrounded by trees. I ask because the Navy pilots I know who fly gliders have reverted to the non-circling approach.

Depends. If low, yes - I'll fly whatever pattern I can to land safely. If I have more time and want to look over the landing area more, then I might fly a higher, longer pattern to give more time to pick the best place to land. Also need to be able to fly bigger patterns when sequencing behind other gliders, so all the skills need to be maintained.

I think it's important to be able to fly a "de-stabilized" (non-constant airspeed) approach in gliders, so that energy can be maintained until late in the approach, and used or gotten rid of as required. Also should be able to fly an approach from just about anywhere around the intended point of landing. Always flying the same pattern into the same airfield pretty much guarantees that your first landout will be exciting! Power pilots are taught to fly "stabilized approaches" because that is how you land a big airplane. Totally unnecessary in small planes, and IMO downright dangerous in gliders.

As far as watching the ASI, after reaching the TLAR point where I want to start the turn, I look just to the inside (11 or 1 o'clock) when initiating the turn, monitor the ASI for trend (glider is trimmed slightly fast), monitor the yawstring, then check how the turn is progressing, then back to ASI - yawstring - turn, etc until time to roll out. If it's a busy runway I might roll out momentarily to check the extended final, then roll back into the turn - those would be pretty aggressive rolls with lots of speed.

Kirk

Always check for that low airplane dragging it in on a long final.
JMF


At 18:08 05 March 2014, John Carlyle wrote:
Kirk,

Thank for writing that - very interesting that you mix approach types.=20

I'm not too clear about your comment "always flying the same pattern into
t=
he same airfield pretty much guarantees that your first landout will be
exc=
iting". I always use a downwind-base-final pattern, I've logged 10
landouts=
in farmers fields, and except for having to dodge an electric wire fence
o=
nce they were low or no drama events (although some of the retrieves were
i=
nteresting).=20

Your "de-stabilized" (non-constant airspeed) approach comment was also
inte=
resting. I tend to keep high until on final, just to keep my options
open,
=
but my speed stays pretty much constant. Being high has helped me on
severa=
l occasions to delay a bit (once a person behind me with no radio landed
un=
der me, another time someone drove onto the field). Do I understand
correct=
ly that you tend to keep your energy in speed rather than altitude?=20

-John, Q3

On Wednesday, March 5, 2014 11:30:30 AM UTC-5, kirk.stant wrote:
On Wednesday, March 5, 2014 7:35:51 AM UTC-6, John Carlyle wrote:
=20
Would you do a circling approach if you were going into a difficult
str=
ip, too? Say, a narrow cornfield surrounded by trees. I ask because the
Nav=
y pilots I know who fly gliders have reverted to the non-circling
approach.=
=20
=20
Depends. If low, yes - I'll fly whatever pattern I can to land safely.
I=
f I have more time and want to look over the landing area more, then I
migh=
t fly a higher, longer pattern to give more time to pick the best place
to
=
land. Also need to be able to fly bigger patterns when sequencing behind
ot=
her gliders, so all the skills need to be maintained.
=20
I think it's important to be able to fly a "de-stabilized"
(non-constant
=
airspeed) approach in gliders, so that energy can be maintained until
late
=
in the approach, and used or gotten rid of as required. Also should be
able=
to fly an approach from just about anywhere around the intended point of
l=
anding. Always flying the same pattern into the same airfield pretty
much
=
guarantees that your first landout will be exciting! Power pilots are
taug=
ht to fly "stabilized approaches" because that is how you land a big
airpla=
ne. Totally unnecessary in small planes, and IMO downright dangerous in
gl=
iders.
=20
As far as watching the ASI, after reaching the TLAR point where I want
to=
start the turn, I look just to the inside (11 or 1 o'clock) when
initiatin=
g the turn, monitor the ASI for trend (glider is trimmed slightly fast),
mo=
nitor the yawstring, then check how the turn is progressing, then back to
A=
SI - yawstring - turn, etc until time to roll out. If it's a busy runway
I=
might roll out momentarily to check the extended final, then roll back
int=
o the turn - those would be pretty aggressive rolls with lots of speed.
=20
Kirk

On Wednesday, March 5, 2014 12:08:55 PM UTC-6, John Carlyle wrote:

Thank for writing that - very interesting that you mix approach types.

My experience is that you can never be sure that you will be able to fly a "textbook" pattern, so better to be comfortable in a variety of situations. It's a matter of getting your glider from where it is to short final to your desired landing area, at a safe speed and altitude for the existing conditions. Patterns are guides - but one can land safely from all sorts of patterns; one can also (as we are proving) crash from "textbook" patterns.


I'm not too clear about your comment "always flying the same pattern into the same airfield pretty much guarantees that your first landout will be exciting". I always use a downwind-base-final pattern, I've logged 10 landouts in farmers fields, and except for having to dodge an electric wire fence once they were low or no drama events (although some of the retrieves were interesting).


If you have the luxury of large fields and plenty of time, then setting up a "standard" pattern is always a good option - but what if you don't have those options? You may find on base that the field you picked is not landable, or the wind changes 180 degrees due to a gust front; you may be following a valley and have to suddenly land in that field on your left; or you may get back to your own field and be in a gaggle of gliders all vying for the same runway at the same time. Most of my landouts have been benign also - but I've also done a couple of final glides into fields that I couldn't see and the pattern consisted of one turn, gear & flaps down, and land. I think you have to be prepared for these kinds of eventualities, and be able to fly your glider safely when low and stressed. That takes planning and practice.


Your "de-stabilized" (non-constant airspeed) approach comment was also interesting. I tend to keep high until on final, just to keep my options open, but my speed stays pretty much constant. Being high has helped me on several occasions to delay a bit (once a person behind me with no radio landed under me, another time someone drove onto the field). Do I understand correctly that you tend to keep your energy in speed rather than altitude?


Energy is the key, high and fast is nice, lower and fast is OK, but slow and low is never good until over the threshold! I see my "hot" pattern speed as a minimum and if it gets a bit high I don't worry about it - final is a fine time to decelerate and get ready to land. Again, it depends on the situation - if there are lots of gliders around trying to land, then playing off altitude and speed is a useful tool to use to get sequenced into the flow - and extra speed on final is good unless you KNOW you have to land short! If there is nothing going on and it's the last landing of the day, then a perfect, constant speed pattern is a fun challenge; but if it's a hectic arrival, I may have to maneuver aggressively to get down; then speed control is more of the "stay fast, stay fast, stay fast..." variety until the immediate problem of where to go is solved. Stall/spins make lousy pattern entries!

Cheers,

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

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

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.

If this is in response to one of my posts, you missed the bit where I said "...auxiliary inputs are slipstream noise, one or two glances at the ASI..."

-John, Q3

On Tuesday, March 4, 2014 1:13:49 PM UTC-5, son_of_flubber wrote:
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?

On Tuesday, March 4, 2014 1:30:34 PM UTC-5, John Carlyle wrote:
If this is in response to one of my posts,

Not particularly your post. Many pilots are committed to the primacy of the sight picture at turn to final.

JC wrote:
you missed the bit where I said "...AUXILIARY (ed. caps) inputs are slipstream noise, one or two glances at the ASI..."


My take is that just before entering the turn to final, slipstream noise and ASI (and yaw string) are PRIMARY reliable inputs, and that point sight picture is an unreliable input that is subject to pilot error and visual illusions.

As I got better over time at using the sight picture to estimate pattern speed, I found myself relying on it more and more. My tendency to discount and neglect the primary reliable inputs made me more dangerous.

On Tuesday, March 4, 2014 5:11:02 PM UTC-7, son_of_flubber wrote:
On Tuesday, March 4, 2014 1:30:34 PM UTC-5, John Carlyle wrote:

If this is in response to one of my posts,



Not particularly your post. Many pilots are committed to the primacy of the sight picture at turn to final.



JC wrote:

you missed the bit where I said "...AUXILIARY (ed. caps) inputs are slipstream noise, one or two glances at the ASI..."





My take is that just before entering the turn to final, slipstream noise and ASI (and yaw string) are PRIMARY reliable inputs, and that point sight picture is an unreliable input that is subject to pilot error and visual illusions.



As I got better over time at using the sight picture to estimate pattern speed, I found myself relying on it more and more. My tendency to discount and neglect the primary reliable inputs made me more dangerous.



At low altitude and certainly in mountainous country, the "sight picture" is unreliable. (If your destination airport is in a deep "V" valley, at which rock or tree do you point the nose?) As other posters noted, at low altitude, the apparent horizon seems high so the nose appears too low even when it right. So what does one watch? The answer is a fast repetitive scan of everything. Keep coming back to the airspeed and yaw string every few seconds to note trends but don't linger there more than a second or two.

One important action is to trim the glider so it will tend to remain at the desired pattern airspeed. Sergio's article in the February Soaring where he describes pushing the stick without effect struck me as perfect description of a mis-trimmed glider. If trimmed correctly, just relaxing pressure on the stick will cause a too-high nose to lower itself - you don't have to push.

In fact, teaching pilots to fly with a relaxed grip instead of a "death-grip" on the stick would probably in itself eliminate many stall/spin accidents. A well trimmed glider simply won't spin itself - it takes gross control inputs to make it spin which is more difficult to do with finger tip pressure.

Another very useful skill is semi-instrument flying - controlling pitch attitude with airspeed alone. (It's the airspeed part of "needle, ball airspeed" partial-panel instrument flying.) This involves watching the airspeed trend. If it's trending lower, the nose is too high and if trending higher, the nose is too low. This is something that can be learned in an airplane while doing ground reference maneuvers.