Slip to landing on PPG practical test

Mark Grubb wrote:
CV wrote in message ...

Andreas Maurer wrote:

......it's going to
take a runway of *at least* 6.000 ft and a sideslip to *very* low
altitude to be able to land without using the airbrakes.


While it seems a excessive for a private rating, most pilots can train
to safely and repeatedly conduct this maneuver in considerably less
airport than 6000 ft.! I have done it a lot and some of my friends
could do it consistently. Success requires a very high degree of
speed discipline - even in extremely "slipped" attiudes, a very good
understanding of slips and adverse yaw, and a different mindset
regarding pattern altitudes and shapes. One also must slip to very,
very low altitudes - e.g., through the flair. Sounds bad but it is
not really that bad.

Remember that AS-W12 pilots routinely (1000's of flights) slipped a
50:1 glider to a landing in considerably less than this in extreme
conditions including Appalachian ridge days(Schuemann), wild thermal
days in TX (Scott, Greene) and monster wave days in NV (Herold).

I have landed 100's of flights in glass in Tehachapi, CA without drag
devices. These landings were typically over a 30 ft obstacle at
density altitudes 5000 ft, and ALL stopped in less than 2500 feet.
More than 50 if those were in an AS-W12. Other gliders involved:
AS-K21, AS-W20, AS-W17, G-103, G-102, LS-4, and Caproni (not
recommended!).
I must take issue with that Mark. I am a much less experienced pilot than you,
but let's look at this from my perspective. As safety officer at my club I would
exercise my prerogative of referring anyone who wanted to perform slips into
the flare for any reason to the CFI for review of their permission to fly.

A few comments -
1] I know it can be done, and even reasonably safely.
2] I know it is dangerous to do this in anything with long wings, and we have a
sloped undulating runway with long grass near the runway.
3] Given the remote probability of ever experiencing this I think the standard
way of testing here, is better. Student gets to find airbrakes frozen at some
point in the circuit, and needs to demonstrate decision making, and execution.
(but the landing is carried out normally)
4] Show that you can perform slips, and S-turns and low approaches by all means.
5] Decision making is far more important than demonstrating a dangerous manouever.
6] Experience is less indicative of safety than is attitude, ask someone like JJ
where most of the repair jobs come from.

For what it is worth - My glass experience is restricted to the Std Cirrus and
Grob 103 Twin II. The Cirrus slips if you want her to, but turbulence over the
tail and pitch sensitivity make low slips highly undesirable. The Grob is heavy
and predictable, but roll rate is not exactly electrifying at low speed. In both
cases the extra speed you would be carrying for control would negate any
advantage. Since it does not benefit you, I can't see any justification for
doing something dangerous.

Our club's founder - Dieter Henschell learned to fly in the 1940s. His favorite
demonstration to pupils who insisted on too high approaches was to make a normal
approach in the Blanik and then proceed up the 2km runway with the brakes closed
from around 10m height and 100km/h. All the way reciting in his gentle German
accent, look the speed is X and I am still flying.. Look the speed is now x-5
and I am still flying...
Most students got the point in one. And that was with a Blanik. Tried something
similar with my Cirrus - the only way to get her stopped on tar without brakes
is to be dangerously slow over the numbers 2m up and 80km/h. That is 10kt
above stall. Eventually touched down tail first - a gentle full stall landing
indicating around 60km/h nearly 400 m later. Work it out, effective L/D is
probably around 70, and I have to lose 15-20km/h - that is a fair amount of
energy. My wingtip on the ground has less than one metre clearance, from a 2m
height I only have 3m clearance, over a length of 7.5m - do the trigonometry
that is a serious cartwheel type impact at a slip angle of less than 21 degrees.
The Cirrus does not seem to lose much in a slip of less than 30 or so degrees -
then there is the fence at 1.2m to consider - what am I achieving, other than to
demonstrate my poor judgment by practicing slips into the flare?

Just because it was standard procedure some years ago, with a glider that had
design faults with inadequate drag controls does not mean it should still be
standard practice. The discussion about spin demonstration in the circuit is an
example. Eventually the BGA dropped this after a number of fatal accidents. Why
do people have to die demonstrating something that is marginally useful, and has
so low probability of happening, relative to the probability of injury
demonstrating it?

Imagine a fighter pilot having to demonstrate a successful ejection at each
flight review. Same question, why on earth would you expect that?

I must take issue with that Mark. I am a much less experienced pilot than you, but let's look at this from my perspective. As safety officer at my club I would exercise my prerogative of referring anyone who wanted to perform slips into the flare for any reason to the CFI for review of their permission to fly.

Hopefully, your CFI is competent and experienced enough to actually
decide based on real evidence that this is "dangerous". Or, if he
does not have adequate experience in this mode, go to altoitude and
try it? As a CFI,this is what I do when faced with the unknown.

I slip Pawnees through the flair many times per day when towing -
probably 5000+ landings worth. All one has to do is maintain adequate
energy - kind of like most other landings.

A few comments -
1] I know it can be done, and even reasonably safely.

2] I know it is dangerous to do this in anything with long wings...

Not true. Remember all those 1000's of documented landings in
AS-W12's in horrendous conditions? The '12 is 19m. Is that not long
winged? The AS-W17 is 20m. i have slipped these to landings several
times. Based on actual experience, it is difficult to keep the wingtip
below the bottom of the main gear in a Steady-State slip in any of
these ships.

Do not believe? Go fly a steady-state slip at altitude and measure
the bank angle. Go get a pile of real DATA! Go fly and judge for
yourself.

While all of this sounds extreme and dangerous, it is most definitely
not. The techniques were developed by some of the most experienced,
analytical and conservative pilots in the sport. As I said
previously, I have actually tried all of these techniques, first at
altitude and then in many gliders to full stop landings. While it is
considerably more difficult than conventional landings, it is not
superhuman nor dangerous. If this were the case, most of the 12's
would be scrap of balsa and glass and the pilots dead. Neither is the
case! There is a very large amount of empirical evidence from many
different locations in the wildest weather to support this theory!


Stalling in severe slips results in the nosefalling through and out of
the slip to a wings level recovery with very little effort or altitude
loss. Dragging a wingtip in glass during a Steady-State slip is
difficult as the wingtip is never lower than the main wheel. These
gliders are severely rudder-limited. If the ship touches down in a
slip, it bounces up and straightens itself out (at least for the '12.
Never had it happen in any other ship!)

While I am high-time in power and glider and was flying more than
full-time (7 days /week for many months, for many years) when I was
training for the '12, I do not consider myself a super pilot and
several of my less experienced friends were able to consistently land
their 15m / std glass ships spoilerless in less than 2000 ft. It
became something to practice so that our skill set and experience was
incresead - a Good Thing.

6] Experience is less indicative of safety than is attitude, ask someone like JJ where most of the repair jobs come from.

Heck, ask JJ about the ships HE busted! From that data set, one would
argue that racing and flying X-C was extremely dangerous and thus
should be avoided. He has not quit flying X-C or racing. Neither
have I.

Our club's founder - Dieter Henschell learned to fly in the 1940s.
His favorite demonstration to pupils who insisted on too high
approaches was to make a normal approach in the Blanik and then
proceed up the 2km runway with the brakes closed from around 10m
height and 100km/h. All the way reciting in his gentle German accent,
look the speed is X and I am still flying.. Look the speed is now x-5
and I am still flying...Most students got the point in one.

What is the point? That a Blanik glides along way with the brakes
closed? What has this got to do with high approaches? You already
established that all modern gliders glide very flat in ground effect.

It is possible to turn downwind abeam the touchdown point at 10,000 ft
AGL (3000 m AGL) in Blaniks, G103, and K21 (among many others) and fly
a normal size pattern by applying full brakes and mantaining
maneuvering speed or higher (a 3:1 glide +/-). What would then be too
high a pattern? 15,000 ft (5000 m) AGL?

I would propose that wafting along at very low speed very close to the
ground exposes you to significant hazard of getting puonded into the
ground by turbulence or falling to the ground when the gust dies or a
thermal breaks loose in front of you. Should your mentor have avodied
this exercise due to these hazards? I have personally seen perhaps
5-10 gliders that were damaged this way.

What am I achieving, other than to demonstrate my poor judgment by practicing slips into the flare?

That you have additional control and mastery of your aircraft? That
you more fully understand its limitations and therefore its
possibilities? that you have more experience that may one day save
you from the unexpected?

And again, Empirical evidence DOES NOT support your hypothesis that
slipping through the flair or landing via slips is dangerous. I have
watched tow pilots and Ag pilots slip through the flair routinely for
several decades. I have done it myself for several decades and
thousands of landings accident-free.

This real-world DATA.

However, You should certainly Believe and Fly as fits your needs,
skills, mind set, and risk tolerance.

Come to California and we can go fly!

Best, Mark

Clearly I have a lot to learn here, but I still think such exercises should not
be routine. Too high risk for no tangible benefit.

Will go and experiment though (just not close to the ground).

You don't find tangible benefits for slipping in final? In my case it helped
save an outlanding in a mountain area, with only a short field available to
me. It was uphill, with an elevated road just before. Had to get a high
descent rate to clear the obstacle and still have field enough to stop.
Without slipping the glider I think I wouldn't been able to stop in time and
I'd have damaged the plane.
Better to learn how to slip in a controlled environment rather than in a
high stress situation (as an outlanding to a short field).
It can come in handy if you turned to final too high, true that you can
avoid the situation, but then again I prefer having the tools ready just in
case I need them, then work for not needing them. Just my opinion here of
course.

Good landings,
Jose M. Alvarez.

"Bruce Greeff" escribió en el mensaje
...
Clearly I have a lot to learn here, but I still think such exercises
should not
be routine. Too high risk for no tangible benefit.

Will go and experiment though (just not close to the ground).

J.A.M. wrote:
You don't find tangible benefits for slipping in final? In my case it helped
save an outlanding in a mountain area, with only a short field available to
me. It was uphill, with an elevated road just before. Had to get a high
descent rate to clear the obstacle and still have field enough to stop.
Without slipping the glider I think I wouldn't been able to stop in time and
I'd have damaged the plane.
Slipping on final - 100% agreement it is something to learn to do , especially
if you fly XC and may need to land out over obstacles as you have described.

What I am disagreeing with is practising landing with no drag controls other
than side slip, and holding the slip into the flare. Knowing that you can do it
in an emergency is one thing, doing it as a matter of course is not.
Better to learn how to slip in a controlled environment rather than in a
high stress situation (as an outlanding to a short field).
Agree - just like I think everyone should be competent at spins. Same principle,
practice away from the hard stuff...

It can come in handy if you turned to final too high, true that you can
avoid the situation, but then again I prefer having the tools ready just in
case I need them, then work for not needing them. Just my opinion here of
course.

Mine is only an opinion too, and maybe an "old woman" one at that.
Good landings,
Jose M. Alvarez.

"Bruce Greeff" escribió en el mensaje
...

Clearly I have a lot to learn here, but I still think such exercises

should not

be routine. Too high risk for no tangible benefit.

Will go and experiment though (just not close to the ground).

Bruce Greeff wrote in message ...
What I am disagreeing with is practising landing with no drag controls other
than side slip, and holding the slip into the flare. Knowing that you can do it
in an emergency is one thing, doing it as a matter of course is not.

So it was a nice sunny day with no lift here in CO, so I took another
pilot up in the L-13 for some fun. Temp was about 60F and wind down
the runway at around 10 mph. Our airport elevation is 7000' MSL.

Tried a few slips at altitude, and entering at a bit under 50 KIAS the
ship flew very nicely with full rudder and the low wing still well
above the horizon. Stalls were nonevents with a very noticeable
reduction in sound level before the 'break' which involved the nose
going straight forward and a slight drop. Overall, no big deal.

Entered downwind at around 600' and this was actually too low to fly
the pattern in a slip all the way. Used a slip on the turns to base
and final, then a slip the last 150' or so of altitude. Flared just
beyond the approach end, touched a bit farther than I would have with
spoilers and got stopped less than 500' beyond the threshold.

My friend then repeated the performance, again using less than 500' of
runway.

I then decided to turn final at a "normal" height and did some
slipping S-turns. Got to the same flare point as before but with
about 5 knots more airspeed, so flew along sideways as I began the
flare. DIdn't realize how low the tail was until it tapped the ground
and dropped us in a bit sideways. Side load was no worse than some of
my students trying a X-wind landing. We used about 1000' of runway
this time, but I never touched the wheel brake, either - as I was
aiming to stop where we did.

-Tom

Interesting. There seem to be a couple of significant differences in the
weather conditions between your flights and mine - I wonder how much they
contribute to the drag of the slip and the subsequent float distance. First,
I had zero wind, and in my experience a 10 mph headwind makes a *big*
difference in the rollout distance, and probably cuts short the float as
well. Second, our field elevation is 1500' MSL, so there's a 5500'
difference in the density.

"Tom Serkowski" wrote in message
om...

So it was a nice sunny day with no lift here in CO, so I took another
pilot up in the L-13 for some fun. Temp was about 60F and wind down
the runway at around 10 mph. Our airport elevation is 7000' MSL.

Tried a few slips at altitude, and entering at a bit under 50 KIAS the
ship flew very nicely with full rudder and the low wing still well
above the horizon. Stalls were nonevents with a very noticeable
reduction in sound level before the 'break' which involved the nose
going straight forward and a slight drop. Overall, no big deal.

Entered downwind at around 600' and this was actually too low to fly
the pattern in a slip all the way. Used a slip on the turns to base
and final, then a slip the last 150' or so of altitude. Flared just
beyond the approach end, touched a bit farther than I would have with
spoilers and got stopped less than 500' beyond the threshold.

My friend then repeated the performance, again using less than 500' of
runway.

I then decided to turn final at a "normal" height and did some
slipping S-turns. Got to the same flare point as before but with
about 5 knots more airspeed, so flew along sideways as I began the
flare. DIdn't realize how low the tail was until it tapped the ground
and dropped us in a bit sideways. Side load was no worse than some of
my students trying a X-wind landing. We used about 1000' of runway
this time, but I never touched the wheel brake, either - as I was
aiming to stop where we did.

-Tom

Bruce,

I do not think there have been any fatal accidents in the U.K. where a spin
was deliberately entered below 1,000 ft. If you know different, could you
please tell us about it.

I know of one fatal accident where a spin was deliberately started at about
1,400 ft., this was during instructor training and it is known that recovery
was started too low.

The report on the accident last January where both pilots were killed has
not yet been published. However, it is known that the spin was started
above 1,000 ft.

In practice, some clubs and some instructors never did this low spin entry
exercise; the wording in the BGA Instructors' Manual meant that in fact it
was optional, since it was open to any instructor to judge that not all the
caveats were met.

The relevant wording was:
"As this training progresses, it is necessary to introduce _brief_ spins
where the ground is noticeably close. This is to ensure that the trainee
will take the correct recovery action even when the nose is down and the
ground approaching. A very experienced instructor flying a docile two
seater in ideal conditions may be prepared to initiate a _brief_ spin from
800'. A less docile two seater with a less experienced instructor, or less
than ideal conditions, should raise the minimum height considerably."

Unfortunately, there have been many fatalities in the U.K. from an
inadvertent stall/spin entered below 1,000 ft. The belief was that the low
height spin entry exercise, done correctly under the right conditions (type
of glider, C. of G. position, weather etc. conditions, experience skill and
currency of instructor) would help to reduce the number of these accidents.

W.J. (Bill) Dean (U.K.).
Remove "ic" to reply.


"Bruce Greeff" wrote in message
...

snip

Just because it was standard procedure some years ago, with a glider that
had design faults with inadequate drag controls does not mean it should
still be standard practice. The discussion about spin demonstration in
the circuit is an example. Eventually the BGA dropped this after a
number of fatal accidents. Why do people have to die demonstrating
something that is marginally useful, and has so low probability of
happening, relative to the probability of injury demonstrating it?

Imagine a fighter pilot having to demonstrate a successful ejection at
each flight review. Same question, why on earth would you expect that?