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

Bob W wrote, "actual reality" is
the ultimate arbiter of "what must be done" in every landing pattern.

I'm not saying that everyone should always fly square approach patterns. I'm saying that in glider operations straight legs with well-banked instead of shallow continuous turns are a generally safer way to operate and train.

And that there are well established aerodynamic and human factors to support this as best practice.

On 7/29/2016 1:10 PM, kirk.stant wrote:

Snip...
So, for gliders, all that is really useable is the second half - the
continuous 180 degree turn to final. As others mention, that is not what is
normally taught, and has some limitations that need to be taken into
consideration; the main one is that it has to be done from a low downwind,
and it happens fast.

I don't comprehend why a circle-from-downwind-to-final landing pattern in a
glider "...has to be done from a low downwind, and it happens fast." I
understand it CAN be done that way, but not why it MUST be done that way.

If Joe Glider Pilot is aiming to produce a threshold landing directly from the
180-degree turn, I suppose an overall lower flight path compared to the case
where he seeks to achieve the same "no straight final leg" threshold landing
directly from the base-to final turn would be the case, simply because the
latter/"tangencies-to-the-circle" flight path pattern would be longer due to
the "uncut corners," and hence the "rectangular path" pattern has greater
distance over which spoilers can be modulated. (The preceding scenario assumes
a "normal downwind offset distance;" the closer in the final, the less
additional distance flown, of course.) But if the goal is "simply" to hit a
pre-selected landing spot on a runway, he can also do "the circling thing" to
final, rolling out short-of and "normally above" the runway onto his final
approach path...which is what all of my "circling patterns" sought to achieve.
IOW, my circling-to-final in the HP allowed me to be able to use less bank
angle-per-unit-time (aka lower roll rate/stick forces) to a high, straight,
final approach path; I wasn't trying to emulate Joe Carrier Pilot in any way
beyond borrowing his 180-degree downwind-to-final turn. Likewise, the
microburst-influenced "fully circling pattern" described in another post, in
actuality, by design, resulted in a (very) short straight final.

Tangentially and as noted elsewhere, for whatever reason, I found no
difference in difficulty judging "howzitgoing" with respect to my glider's
status "in the descent cone" whether circling from downwind to final or using
separate, distinct, 90-degree turns to get there...if anything, the circle
seemed "more natural" to me..but then I preferred playing outfield to infield
as a kid! Either way, every pattern's goal: to arrive on a straight final
"somewhere on the high side" of my ship's theoretical descent cone.

Back to my original puzzlement...am I correct in believing "military approved"
circling approaches essentially do NOT include "a straight final" portion,
a-la the "immediately before touchdown" curving flight path understandably
employed by (e.g.) Pitts biplane pilots as a means of retaining over-the-nose
vision for as long as possible until the runway edges appear on either side of
the nose?

And that is why I think it is actually a useful skill to practice: If you
end up low and tight, you should be able to fly a safe 180 (or 270, or 90)
pattern and land out of it - because you don't have the option of going
around!

"Roger that!" on the go-around-impossible bit. (No mulligans in sailplane
landing patterns!) When I blundered into the sport, the concept of being
unable to "re-do a poor pattern" by going around was a
new/completely-foreign/ignorantly-scary concept to my "power-polluted" (in the
reading sense of things) brain. Upon becoming "stick-time/usefully familiar"
with the flight physics of sport sailplanes, the no-go-around reality quickly
mentally-morphed into "entirely normal and not a big deal"...so long as
reasonable and continuing assessment of "minding the approach store" was part
of the piloting package. It was immediately clear to me "an easily repeatable"
landing pattern was the primary tool in minding the store.

And "Roger that!" on being able to safely do (or more accurately, salvage, if
previous inattention/screwups have contributed, sardonic chuckle) low
patterns. Following "licensure," safely expanding one's flight envelope surely
is the name of the aviation game! So - where do I go to practice departures
from controlled flight *in* my landing pattern?

Bob W.

On Wednesday, July 27, 2016 at 7:33:48 PM UTC-4, son_of_flubber wrote:
The 'Single 180 Turn From Downwind to Final' (aka 'military style pattern') and 'Stall-spin on Turn from Base to Final' are both well discussed as independent topics on RAS. But I've not seen anything about how these pieces fit together.

Having recently tried the 'Single 180 Turn...' and LIKED it, I'm wondering if there is any good reason why I should not fly this approach at an uncontrolled airport with mostly glider traffic. What about at a controlled airport with mostly GA power traffic?

And I'm wondering if anyone has ever stall-spinned from a 'Single 180 Turn...' pattern and whether there are subtle 'gotchas' associated with that pattern shape that I should know about.

What is the military's track record wrt 'Stall-spin in the pattern'? Does it happen just as often with the 'Single 180 Turn...'?

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

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)

On 7/29/2016 4:19 PM, BobW wrote:
Back to my original puzzlement...am I correct in believing "military
approved" circling approaches essentially do NOT include "a straight
final" portion, a-la the "immediately before touchdown" curving flight
path understandably employed by (e.g.) Pitts biplane pilots as a means
of retaining over-the-nose vision for as long as possible until the
runway edges appear on either side of the nose?

It's been quite a long time, but as I recall, the roll out on final was
around 1/2 - 3/4 mile from touchdown and that goes pretty quickly in a
jet. The way I currently fly the glider, it's closer to 1/4 mile from
completion of the turn to the touchdown point. I try to make my final
approach about the same flight time (vs. distance). Years of practice
have made this pretty routine.
--
Dan, 5J

As reported in the not very popular booklet, "Preventing Landing Accidents," (another important book very few glider pilots in denial have bothered to read.)

64% of fatal glider accidents occur during the landing phase.

64% !!!

There is no reason for disagreement of a proper landing technique.

Tom Knauff

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