Are 'Single 180 Turn From Downwind to Final' and 'Stall-spin on Turnfrom Base to Final' mutually exclusive?

On Friday, July 29, 2016 at 7:03:37 PM UTC-4, wrote:
On Wednesday, July 27, 2016 at 7:33:48 PM UTC-4, son_of_flubber wrote:

Having recently tried the 'Single 180 Turn...' and LIKED it,

I would be curious as to why you think you like the single 180 degree turn better than the conventional rectangular pattern.
Care to explain?
UH

My strong preference is for the conventional 'square' pattern. Here is a recap on my sole '180' pattern and a guess about what felt right.

I'm using an .igc file at one second intervals to aid recollection.

My default procedure is to set spoilers to 50% open, then adjust pattern shape to make my aim point. In this case, I encountered lift on downwind, so I opened spoilers before turning to base. We had had a lot of low altitude slack rope on tow and I was anticipating similar on the way down.

I started to turn base early due to my chosen airspeed, my sink rate and a strong crosswind pushing me away from the runway. I realized right away that I had started to turn prematurely, and decided to 'fly base on a 45 diagonal' relative to the runway (instead of 90 degree square) in order to place my 'turn to final' farther from the threshold.

At this point, I had just started to bank for the turn to base, so my bank angle was not steep yet, and for no deliberate reason, I held the bank angle steady as I tried to read where the glide slope was going to intersect the ground and how the crosswind was affecting the flight path. The crosswind reduced my rate of turn.

I have a tendency/preference to hold control inputs steady and evaluate the result.

Referring to the flight path recorded in the .igc file I see that when I completed 90 degrees of turn, I opted to increase the bank to make the additional 90 degrees of turn. From to the .igc, I completed the turn 300 feet above my touchdown point. (Given the slot cut in the forest that we fly through on final, and the possibility of sink, this height is just about right..)

I flew two connected shallow 90 degree turns, not a true 180 constant bank turn from downwind to final (that's harder I expect). I assume that there is some similarity. I liked that it seemed rather easy to judge the intersection of the glide slope with the ground. My compensation for crosswind was gradual because my heading changed gradually. It seemed easy to keep my chosen airspeed rock steady (2X stall speed). It seemed easy to align final with the runway. Because everything was smooth, gradual and consistent, it was easy to evaluate how things were going and make small adjustments as needed.

I did not set out to fly a '180 turn pattern'. It happened. I accidentally deviated from my training and 'best practices'. I'm reporting and not advocating. I'm looking for perspective.

On Saturday, July 30, 2016 at 12:51:25 AM UTC-4, son_of_flubber wrote:
My default procedure is to set spoilers to 50% open, then adjust pattern shape to make my aim point.

I'd like to hear some well experienced CFIGs weigh in on that statement. Email fine if you don't want to feed the frenzy here.

best,
Evan Ludeman (rookie CFI)

At 12:50 30 July 2016, Tango Eight wrote:
On Saturday, July 30, 2016 at 12:51:25 AM UTC-4,
son_of_flubber wrote:
My default procedure is to set spoilers to 50% open, then
adjust pattern
shape to make my aim point.

I'd like to hear some well experienced CFIGs weigh in on that
statement.
Email fine if you don't want to feed the frenzy here.

best,
Evan Ludeman (rookie CFI)


I took my CFIG check with an FAA examiner as an 18 year old back
in 1969. On the second flight, the examiner had me cover up the
altimeter at about 1500' overhead the airport, and then told me to
do continuous circles until it was time to roll out and land. I did it,
and made my spot landing too. He told me it would be good
practice for judging an off-field landing where I didn't know the
terrain elevation.

Rectangular traffic patterns on uncontrolled civilian airports are
probably the safest (because other pilots know where to look to find
you), and give you as a pilot the chance to clear for others
blundering into your space before you make each turn. It is also
easier to teach because you can set altitudes to hit at certain check
points along the way. It makes for a cookie cutter pattern that will
keep a student safe as long as they set it up properly. The problem
with soaring is that Murphy always rears his head, and glider pilots
get presented with non cookie cutter situations to deal with. That's
where learning "judgement" comes into play. If the student winds
up caught downwind with sink, will the judgement be there to
realize they don't have the altitude to do the cookie cutter pattern
any more? I have personally witnessed 2 occasions where the
person flew the "correct" ground track, but wound up in the trees
short of the runway because they started the pattern too low.
Judgement is not an easy thing to teach, but it is vital to learn.
Pilots need to be able to recognize things and circumstances have
changed, and be able to adapt to those changes on a running basis.
If that means doing a tight 180 degree turn to intercept the desired
final glide path prior to touchdown at the desired point, the pilot
has to be able to adapt to that. If it means flying a mirror image
traffic pattern from the other side of the airport because that's all
that altitude and energy will allow any more, they have to have the
judgement to realize that's what is required to get on the ground
safely. That is the hard part to teach...... You have to be able to fly
and chew gum at the same time. Some pilots get so locked in on
one thing that they don't see the real danger coming from another
approaching issue...

Overhead 360 degree traffic patterns were lots of fun to fly in the
military, and are a great way to safely recover a bunch of aircraft in
a very short period of time. Doing the Space Shuttle like SFO
(Simulated Flame Out) approaches from 8000' overhead at 215
knots in an F-16 were a blast. All of these are generally done in a
controlled traffic environment where you (for the most part) don't
have to worry about someone blundering into your way once you
have clearance. These patterns also have their place and time.

For civilian glider operations on uncontrolled airfields, the standard
rectangular patterns that everyone expects to see (and clear for)
are the way to go, with the caveat that one has to get the glider on
the ground safely. If circumstances dictate doing something other
than the standard robotic pattern in order to get on the ground in
one piece, then judgement has to come into play, and things will
need to be modified as necessary to yield a positive final outcome.

RO

On Saturday, July 30, 2016 at 8:50:08 AM UTC-4, Tango Eight wrote:
On Saturday, July 30, 2016 at 12:51:25 AM UTC-4, son_of_flubber wrote:
My default procedure is to set spoilers to 50% open, then adjust pattern shape to make my aim point.

I'd like to hear some well experienced CFIGs weigh in on that statement. Email fine if you don't want to feed the frenzy here.

best,
Evan Ludeman (rookie CFI)

This sounds like someone experimenting to try to find a better way than the proven rectangular pattern that works well for most every flight. Obviously adjustments need to be mad periodically.
Maybe we need a thread on do it yourself brain surgery.
I hope low time folks don't take this stuff to heart.
UH

On Saturday, July 30, 2016 at 8:50:08 AM UTC-4, Tango Eight wrote:
On Saturday, July 30, 2016 at 12:51:25 AM UTC-4, son_of_flubber wrote:
My default procedure is to set spoilers to 50% open, then adjust pattern shape to make my aim point.

I'd like to hear some well experienced CFIGs weigh in on that statement.

What I left unsaid, because I thought it was understood, is that the pilot will first adjust the spoilers moderately, and then if necessary, change the heading of the base leg.

You want a CFIG to weigh in?

To quote Tom Knauff from 'Preventing Launching and Landing Accidents' page 27

"After the turn onto the base leg, the pilot has two plans of action in case the apparent final approach glide angle appears too steep or too shallow. If the slope appears too steep, the pilot uses a plan of action to open the dive brakes and angle away to extend the glide path to lose some altitude.. If the glide angle appears too shallow, the pilot will immediately close the dive brakes and turn towards the landing area." Copyright 2004 Knauff and Grove

A schematic figure that shows a non-rectangular pattern follows immediately in the text.

On page 26 "The dive brakes of a typical modern glider will allow the glider to descend anywhere from 5:1 to a very conservative 20:1. The pilot should never be very close to either of these extremes." Copyright 2004 Knauff and Grove

Based on this and other things written by Tom, I conclude that aiming to keep the spoilers near 50% effectiveness gives the pilot the most flexibility (either way) to compensate for things that don't go according to plan. That's my default (goal) as previously noted.

So changing the heading on base leg (non-square pattern) is a Knauff-recommended means to recover from an incorrectly timed turn to base. That said, almost all of my patterns are square, my turns are steep, and my spoilers stay open to about 50% until I touch down.

If my pattern speed needs to be higher to deal with wind and turbulence, I'll delay opening the spoilers, and if conditions are intimidating, I might turn to base a bit early, so that I have more reserve to deal with the possibility of extraordinary sink, and if it turns out to be just ordinary sink, I'll add a little more spoiler on final to get down.

In the last 30 days, I've flown glider on 13 days, and because I think safe and optimal landing is utterly important and merits practice, I've landed 21 times, (and as often as possible in utter crap conditions in order to stay proficient). So if you think I'm a mad anarchist pilot trying to tear down the status quo, then I've communicated poorly and/or you're projecting something that isn't there.

On Saturday, July 30, 2016 at 11:33:26 PM UTC-4, son_of_flubber wrote:
On Saturday, July 30, 2016 at 8:50:08 AM UTC-4, Tango Eight wrote:
On Saturday, July 30, 2016 at 12:51:25 AM UTC-4, son_of_flubber wrote:
My default procedure is to set spoilers to 50% open, then adjust pattern shape to make my aim point.

I'd like to hear some well experienced CFIGs weigh in on that statement..

What I left unsaid, because I thought it was understood, is that the pilot will first adjust the spoilers moderately, and then if necessary, change the heading of the base leg.

You want a CFIG to weigh in?

To quote Tom Knauff from 'Preventing Launching and Landing Accidents' page 27

"After the turn onto the base leg, the pilot has two plans of action in case the apparent final approach glide angle appears too steep or too shallow. If the slope appears too steep, the pilot uses a plan of action to open the dive brakes and angle away to extend the glide path to lose some altitude. If the glide angle appears too shallow, the pilot will immediately close the dive brakes and turn towards the landing area." Copyright 2004 Knauff and Grove

A schematic figure that shows a non-rectangular pattern follows immediately in the text.

On page 26 "The dive brakes of a typical modern glider will allow the glider to descend anywhere from 5:1 to a very conservative 20:1. The pilot should never be very close to either of these extremes." Copyright 2004 Knauff and Grove

Based on this and other things written by Tom, I conclude that aiming to keep the spoilers near 50% effectiveness gives the pilot the most flexibility (either way) to compensate for things that don't go according to plan. That's my default (goal) as previously noted.

So changing the heading on base leg (non-square pattern) is a Knauff-recommended means to recover from an incorrectly timed turn to base. That said, almost all of my patterns are square, my turns are steep, and my spoilers stay open to about 50% until I touch down.

If my pattern speed needs to be higher to deal with wind and turbulence, I'll delay opening the spoilers, and if conditions are intimidating, I might turn to base a bit early, so that I have more reserve to deal with the possibility of extraordinary sink, and if it turns out to be just ordinary sink, I'll add a little more spoiler on final to get down.

In the last 30 days, I've flown glider on 13 days, and because I think safe and optimal landing is utterly important and merits practice, I've landed 21 times, (and as often as possible in utter crap conditions in order to stay proficient). So if you think I'm a mad anarchist pilot trying to tear down the status quo, then I've communicated poorly and/or you're projecting something that isn't there.

No, I'm not projecting anything. I just wanted to see if the very experienced guys had a different take on your story than I did.

FWIW, putting the *priority* on maintaining spoilers half open, and adjusting the pattern to keep it that way struck me as profoundly odd. In fact I'd rate it right up there with the advice in Joy of Soaring about how to fly the final approach**: it's precisely backwards. Sure, you can make it work. That doesn't make it a best practice.

The normal procedure for correcting glide slope is to use more or less spoiler to capture the desired glide slope for the pattern being flown. Adjustments to the pattern are sometimes necessary or desirable, and the ability to make these adjustments when needed is essential skill for any glider pilot. The passages you've quoted from Tom's books are fine as far as they go, I simply think you've misunderstood the application. Generally, one can make corrections for all but the grossest of errors with spoilers alone. In the case of a really big error (or rotor, or big wind shear or whatever), then you add the pattern variations as Tom describes.

**The Joy of Soaring approach to final approach was this: aim with the nose (in pitch), control airspeed with spoilers.

best,
Evan