You are in IMC, when *everything* fails! Now what?

[Thomas Pappano]

Hello All,

There has been much discussion here about the obvious benefits of
redundant systems, engines, vacuum, electrical etc., when flying in IMC.
We've also read NTSB reports of crashes of very well equipped planes
where the pilot did not make use of redundant instruments.
As for myself and perhaps others, I will most likely never have access
to any aircraft with system redundancy beyond the simple electric
TC/vacuum gyro combo. I fly singles such as the 172 and 182, all
usually at least 25 years old. I did however, obtain my ratings for the
purpose of going places and doing things, and I seem to be flying about
5% of my hours in actual IMC. Being a person that places a high value
on my own ass, and the asses of the people who fly with me, like others
here I carry some backup equipment. A Magellan 315 I have flown 24,000
miles with so far, a JHP-520 portable com, Palm VII/CBAV for weather, and
spare batteries for all. For now I fly well maintained rentals.

So far in my meager 400 hours I have experienced a total electrical failure,
an AI failure, and a few VOR and ILS problems. All these were easy to
work around. I'm satisfied that with a vacuum failure I can fly just fine
on the TC, and vice versa. How about when you lose your vacuum
instruments *and* your electrical system? No nav, no com, no gyros
at all, just your engine and pito-static instruments. The essence of
maintaining control in IMC is being able to determine if you are turning.
I've long figured that even with a 1 second position update rate, the
simplest GPS should give you enough turn data to stay in control
in addition to guiding you to an airport and making a useable approach.
I and iron-gut acro/safety pilot Doug found out yesterday.

Conditions:
Clear, 92 degrees, fairly rough thermal TB about 2000 agl. For warmup,
we did 2 full hours of currency approaches and holds, building a
"pyramid" of stress and fatigue.

The task:
"Fail" all gyros, AI, TC, DG, and all nav equipment. Trying this for the
first
time ever, now navigate 25nm to an airport and make a successful
non-precision approach using only the handheld GPS, the "ball", and
pito-static instruments.

My strategy is to make good use of the inherent stability of the 172,
keeping my hands off the yoke as much as possible and turning with
the rudders. To keep things simple, I plan only 2 turns. The GPS is
simply set for a "go-to" to our airport. Our destination was to
the northwest, so fly due west a while, then 45 to the right to
intercept a long final approach course. The GPS display mode was
a simple numbers-only bearing/heading/distance/speed. Right off the
bat it was very strange and we thought our test might be over in about
1 minute. The GPS, though updating every second, is still giving you "old"
information. Now using the rudder to turn, the airplane takes a while
to respond. With the constant upsetting influence of the thermals, the
plane is always wanting to turn. You see it on the GPS, and by the time
you get some rudder pressure on, you are maybe 10 to the right. Now
you hold the rudder and wait for the plane to respond, and slowly you
come back on course, but overshoot. I try to adjust my inputs to smooth
things out but the TB makes it pointless. I resign myself to the fact that
at best we will make constant small s-turns all the way. Every now and
then a good thermal jolts us into a significant bank. My instinct was to
get the ball centered, check our pitch with the airspeed etc, then check
the GPS to see which way we were now going and slowly urge us back.
Seems to work. Soon I realize we've gone several miles already, and all
this actually seems to be working! Patience seems to be the rule- put a
small amount of pressure on the rudder, hold and wait for results.
Soon we are intercepting our 8 mile final approach course, using a
published NDB approach as a template, and doing our altitude
stepdowns based on GPS distance to the field. Closer to the ground
thermal induced turns made it difficult to get down to MDA as soon
as I would have liked, but we did arrive at MDA right over the field and
a circle to land could have been easily done. In spite of the constant
s-turning, we maintained our final approach course within +- 3 degrees,
better than I could have done with the ADF and the full panel!

We finish up with a partial panel ILS into our home field, and hot and
tired, I manage an embarrasing multi-bounce landing. The conclusion
of course, is that a battery powered GPS is an absolutely essential
piece of backup equipment that can save you even with major system
failures. We did a worse case scenario, but for example, you could use
the GPS to simply hold a course to VFR conditions. At higher altitude
you would have a smoother ride needing only occasional control input.
We must, in an emergency, actually remember to use the backup info
available whether from a portable device or a panel instrument.

Anyone else tried this type of emergency procedure?
Thoughts? Tips?

Tom Pappano, PP-ASEL-IA

ps: Howard Stark's 1-2-3 Method of Blind Flying was Needle-Ball-Airspeed.
This could be the 4-5-6 method: GPS-Ball-Airspeed

[David Rind]

Thomas Pappano wrote:
> Anyone else tried this type of emergency procedure?
> Thoughts? Tips?
>

My only suggestion would be to try this at night under the
hood. I am not convinced that you can adequately simulate
IMC in daytime VMC conditions. I find it *much* easier to
keep wings level under a hood (or foggles) in daytime VMC
than in actual. So if you can pull this off at night under
a hood, I'd believe this would work for you.

Also, if this is to work, you would need to have the GPS
powered up and running at the moment of the failure. It's
not like you'd be able to hold wings level while taking three
minutes for the GPS to power up and acquire satellites....

--
David Rind

[David Megginson]

David Rind > writes:

> Also, if this is to work, you would need to have the GPS
> powered up and running at the moment of the failure. It's
> not like you'd be able to hold wings level while taking three
> minutes for the GPS to power up and acquire satellites....

Another option would be the old whiskey compass, as long as you can
get to an east or west heading.


All the best,


David

--
David Megginson, , http://www.megginson.com/

[Maurice Givens]

If you've lost everything, one thing that semms to work is to:

1. go to East or West heading
2. set power to idle
3. set trim to full up
4. use ruddar only to keep mag compass set to East (or West, which
ever was chosen).

I have taught this to my instrument students, and introduce it when I
act as check pilot. One of our instructors was caught on top when she
lost both vaccum and electrical. She used this technique, and was
able to drop below the clouds where she could land safely VFR.

Maurice Givens


Sydney Hoeltzli > wrote in message >...
> Thomas Pappano wrote:
>
> > I've long figured that even with a 1 second position update rate, the
> > simplest GPS should give you enough turn data to stay in control
> > in addition to guiding you to an airport and making a useable approach.
>
> I've long been skeptical of this. Experience reinforced my
> skepticism.
>
> I have to admit, when I tried it, I did NOT use your "rudder only"
> technique. My plane also lacks the "inherent stability" of the
> C172. So it's a bit of a different situation.
>
> But....I do think one receives significant clues under the hood
> in daylight, even if one is actively trying to NOT cheat.
>
> I'd be curious as to the results if you repeated some portion
> of this exercise at night; I don't think it's necessary to
> exhaust yourself first, simply try it on a dark night over an
> unpopulated area with barely enough visual cues for your safety
> pilot.
>
> An interesting exercise, though, thanks for sharing it.
>
> Cheers,
> Sydney

[Maurice Givens]

IFR Magazine reported, that in several tests, pilots were able to
control the aircraft and fly to VFR conditions using only the Garmin
196. Check there web site. The article may have been placed there.

Maurice Givens


Sydney Hoeltzli > wrote in message >...
> Thomas Pappano wrote:
>
> > I've long figured that even with a 1 second position update rate, the
> > simplest GPS should give you enough turn data to stay in control
> > in addition to guiding you to an airport and making a useable approach.
>
> I've long been skeptical of this. Experience reinforced my
> skepticism.
>
> I have to admit, when I tried it, I did NOT use your "rudder only"
> technique. My plane also lacks the "inherent stability" of the
> C172. So it's a bit of a different situation.
>
> But....I do think one receives significant clues under the hood
> in daylight, even if one is actively trying to NOT cheat.
>
> I'd be curious as to the results if you repeated some portion
> of this exercise at night; I don't think it's necessary to
> exhaust yourself first, simply try it on a dark night over an
> unpopulated area with barely enough visual cues for your safety
> pilot.
>
> An interesting exercise, though, thanks for sharing it.
>
> Cheers,
> Sydney

[Sydney Hoeltzli]

Roy Smith wrote:
> (Maurice Givens) wrote:
>>IFR Magazine reported, that in several tests, pilots were able to
>>control the aircraft and fly to VFR conditions using only the Garmin
>>196. Check there web site. The article may have been placed there.

> I've tried stuff like this a couple of times with students. So far, we
> seem to do pretty well using the GPS as a heading reference only, and
> maintaining heading with rudder only.

Roy,

Can you be a bit more specific?

Did you use the GPS as a substitute for DG, otherwise "partial
panel" of TC and pitot-static?

Or did you try Thomas' experiment of "fail all gyro instruments,
only pitot-static"?

What were your wx conditions ie day/night overcast/clear etc?

What GPS?

When you say "most light planes are so stable in pitch" would you
mind sharing which light planes you've tried this in?

I have not tried the "rudder only" trick. But I have to say neither
my Garmin 90 nor our (older) panel-mount GPS update rapidly enough
to serve as an adequate substitute for a DG IMO.

Thanks,
Sydney

[Roy Smith]

"Thomas Pappano" > wrote:
> A work-around for this might be to always power the unit from
> the plane as SOP, so that max battery life would be available in an
> emergency.

One problem with plugging into ship's power is a catastrophic surge or
spike as the alternator self-destructs might take out your handheld at
the same time it takes out the panel.

[Thomas Pappano]

"Roy Smith" > wrote in message
...
> (Maurice Givens) wrote:
> > IFR Magazine reported, that in several tests, pilots were able to
> > control the aircraft and fly to VFR conditions using only the Garmin
> > 196. Check there web site. The article may have been placed there.
>
> I've tried stuff like this a couple of times with students. So far, we
> seem to do pretty well using the GPS as a heading reference only, and
> maintaining heading with rudder only.
>
> We once tried to do unusual attitude recoveries with the nifty new
> Garmin that gives you a simulated instrument panel. We came to the
> conclusion that the pitch information you get from the synthsized
> AI/ASI/Alt/VSI is so bad that you should ignore it completely in a UI
> recovery. It might be of some value in stable cruise, or setting up for
> a controlled 500 fpm descent.
>
> Fortunately, most light planes are so stable in pitch that if you just
> keep the power and elevator trim set to reasonable levels, and keep it
> heading in one direction with rudder inputs, the pitch will take care of
> itself.

Thanks for everyone's comments!

In our experiment, in spite of the rough ride and constant heading
correction,
our altitude remained pretty stable, requiring adjustment only when we
would be tossed into a pretty good bank. Just a little finger back-pressure
on the yoke hub would put things back on track. I just finished skimming
the 196 manual on Garmin's site and gleaned a couple tidbits:

The 196 update rate is still only once per second, (same as inexpensive
units)
but when in "battery saver" mode it drops to once every *three* seconds.
The "up to" 16 hour battery life is only when in battery saver mode.
They gave no hint of battery life when in "normal" mode.
A 196 user would surely want to check the battery mode if needing to
control his plane solely by the GPS. Another thing, they say you only get
about 10 more minutes of operation once you get the "low battery"
warning. A work-around for this might be to always power the unit from
the plane as SOP, so that max battery life would be available in an
emergency.

I will also try a repeat of all or part of this excercise at night for a
closer
to IMC experience. My experience has been that "actual" is easier to
fly because the sun, shadows, and glimpses seem to distract more
than help. 8-)

Tom Pappano, PP-ASEL-IA

[Sydney Hoeltzli]

Thomas Pappano wrote:

> The 196 update rate is still only once per second, (same as inexpensive
> units)

Interesting!

Well, when able, I will try the "rudder only" bit and report on
my experience. In theory, if the heading info is all that matters
and the update rate is 1 per sec, any GPS should do...

I'll confess my suspicion.

My suspicion is that some GA aircraft, such as little Pipers and
Cessnas esp. fixed gear models of same, are sufficiently stable
that the plane will stay in control so long as the pilot doesn't
flagrently get in its way.

My suspicion is that other GA aircraft, such as Mooneys and
Bo's and perhaps little fixed-gear Grummans, Katanas, maybe
the RV series (basically anything with a reputation for being
'sporty' to fly, are sufficiently light and sensitive in pitch
that this has to be paid attention, it really won't take care
of itself.

I think there's some evidence to this regard. I don't think it's
coincidence that in the vacuum failure study, the C172 and Archer
pilots all kept control of the plane and a good portion of the Bo
pilots "lost it".

It's possible that there's a work-around -- power back and dirty
it up perhaps.

Please note I'm not trying to say these planes can't be flown
partial panel or with limited instruments. They can. But I don't
think a GPS for heading info suffices, no how no way.

> I will also try a repeat of all or part of this excercise at night for a
> closer
> to IMC experience. My experience has been that "actual" is easier to
> fly because the sun, shadows, and glimpses seem to distract more
> than help. 8-)

They may distract your conscious mind, but what research I'm aware
of suggests that they are keeping your primitive vestibular system
calibrated and happy (whether you know it or not), so that you don't
have to deal with your reptile brain screaming at you "WE'RE TURNING!
WE'RE STILL TURNING YOU DAMNED FOOL TURN THE OTHER WAY! RIGHT NOW!".

Thanks again for posting,
Sydney

[Thomas Pappano]

"Roy Smith" > wrote in message
...
> "Thomas Pappano" > wrote:
> > A work-around for this might be to always power the unit from
> > the plane as SOP, so that max battery life would be available in an
> > emergency.
>
> One problem with plugging into ship's power is a catastrophic surge or
> spike as the alternator self-destructs might take out your handheld at
> the same time it takes out the panel.


Ha! Excellent point! Now then, I wonder how many would buy a
modestly priced transient voltage protector for their expensive
GPSs, PDAs, laptops, CD/DVD players, XM radios, etc?
My little company could turn them out easy enough...

Tom Pappano, PP-ASEL-IA

[Sydney Hoeltzli]

Thomas Pappano wrote:

> Ha! Excellent point! Now then, I wonder how many would buy a
> modestly priced transient voltage protector for their expensive
> GPSs, PDAs, laptops, CD/DVD players, XM radios, etc?
> My little company could turn them out easy enough...

I was just thinking about posting a query re inexpensive
voltage protector.

If the price was modest, I'd just as soon buy it as cobble
it together.

Cheers,
Sydney

[Julian Scarfe]

"Sydney Hoeltzli" > wrote in message
...

> My suspicion is that some GA aircraft, such as little Pipers and
> Cessnas esp. fixed gear models of same, are sufficiently stable
> that the plane will stay in control so long as the pilot doesn't
> flagrently get in its way.
>
> My suspicion is that other GA aircraft, such as Mooneys and
> Bo's and perhaps little fixed-gear Grummans, Katanas, maybe
> the RV series (basically anything with a reputation for being
> 'sporty' to fly, are sufficiently light and sensitive in pitch
> that this has to be paid attention, it really won't take care
> of itself.

Pretty much without exception GA aircraft are stable in pitch and unstable
in the spiral divergence mode. If displaced in pitch a Mooney will take
more phugoid cycles to get back to equilibrium when you release the
controls, but it *will* get back there. By contrast, if you stick almost
anything into a 45 degree bank, things are only going to get worse. The
difference between the C172 and the Bo is only to do with the speed at which
things happen, as more slippery aircraft will tend to reach red line speeds
more quickly.

So the key is always "get and keep the wings level". Anything else is
finesse. The only advantage that I can think of of doing this with rudder
is that it avoids inadvertent pitch inputs. If you're calm and experienced
in IF, I'd guess you'd have a more successful time with the ailerons.

Julian Scarfe

[Gary L. Drescher]

"Thomas Pappano" > wrote in message
. ..
> I've long figured that even with a 1 second position update rate, the
> simplest GPS should give you enough turn data to stay in control
> in addition to guiding you to an airport and making a useable approach.
> I and iron-gut acro/safety pilot Doug found out yesterday.

I've often wondered if a pendulum, in lieu of a GPS or compass, would
provide sufficient yaw information to keep the wings. But I've never tried
the experiment.

--Gary

[Gary L. Drescher]

"Gary L. Drescher" > wrote in message
. net...
> provide sufficient yaw information to keep the wings.

Er, meant to say "to keep the wings level". Though I guess it sort of made
sense the way I typed it, too. :)

[Roy Smith]

"Julian Scarfe" > wrote:
> So the key is always "get and keep the wings level". Anything else is
> finesse. The only advantage that I can think of of doing this with rudder
> is that it avoids inadvertent pitch inputs. If you're calm and experienced
> in IF, I'd guess you'd have a more successful time with the ailerons.

The other advantage to using rudder is that the rudder is more effective
in a stall or spin. In a fully developed spin, the ailerons are
probably useless. When I teach stall recovery, I stress use of the
rudder to pick up a dropping wing.

On the other hand, the most likely unusual attitude you're going to get
into in IMC because of gyro failure is a steep spiral, in which case the
ailerons should be completely effective. But, do you trust yourself to
diagnose a steep spiral from a spin in IMC, with failed gyros, spatial
disorientation, and maybe a bit of panic setting in too?

[Robert Moore]

"Gary L. Drescher"wrote
> Er, meant to say "to keep the wings level". Though I guess it
> sort of made sense the way I typed it, too. :)


Great idea Gary! You just may have saved me a lot of
money on that new gyro based Attitude Indicator that
I need.

Bob Moore

[Sydney Hoeltzli]

Julian Scarfe wrote:

> Pretty much without exception GA aircraft are stable in pitch and unstable
> in the spiral divergence mode. If displaced in pitch a Mooney will take
> more phugoid cycles to get back to equilibrium when you release the
> controls, but it *will* get back there.

*if* you keep the wings level, right?

But how about if you're struggling to figure out what "level" is?

Perhaps I'm mistaken, but I don't see the two as unrelated problems.
Yes, from an airplane design standpoint, little Cessnas and Pipers
are also "unstable in the spiral divergence mode", but anyone who
has flown same vs. Grumman/Mooney/Bo will say that the latter are
much lighter in both pitch and roll, and that they require more
attention to fly. I'm no aeronautical engineer type, but someone
told me once that Cessnas are designed to have something like 'positive
roll stability' (meaning if you take your hands off the yoke in a turn,
they want to return to level flight) whereas Grummans (dunno about
Mooney and Bo) are designed for 'neutral roll stability' (meaning if you
take your hands off the stick, they want to stay where you put them).
(even money I've got the terms wrong)

Add this factor to pitch light enough that someone shifting around in
the cockpit will alter the trim, and the chances of it getting "back
there" hands off are much less in any sort of unstable air. IME.

My point is that within your generalization about GA aircraft
design, I think there are details which differ, and those details
make a difference.

> The difference between the C172 and the Bo is only to do with the
speed at
> which things happen, as more slippery aircraft will tend to reach red
line
> speeds more quickly.

That's definately a difference, and I don't have beans in Bo time so
I can't comment, but I don't think that's the only difference.

Otherwise, they'd fly the same, right, and people wouldn't be talking
about "sweet" "nimble" planes vs. "stable trucks".

I guess I'm not certain how being "experienced in instrument flight"
helps very much either, when the topic is "You are in IMC when
*everything* fails!" meaning "all gyros -- AH, DG, TB". This seems
to me to call for a different set of skills than holding 2,2 and 20
on a full panel or even conventional 'partial panel'

Best regards,
Sydney

[Roy Smith]

> Julian Scarfe wrote:
> > Pretty much without exception GA aircraft are stable in pitch and unstable
> > in the spiral divergence mode. If displaced in pitch a Mooney will take
> > more phugoid cycles to get back to equilibrium when you release the
> > controls, but it *will* get back there.

Sydney Hoeltzli > wrote:
> *if* you keep the wings level, right?
>
> But how about if you're struggling to figure out what "level" is?

If the only thing you've got is a GPS, you have no way to directly know
what "level" is. All you know is what your course over the ground is,
and you can see which way it's changing. Here's the emergency control
strategy:

Use opposite rudder to keep the course from changing.

That's it.

There's a fun exercise I do with some more advanced students. Take your
hands off the yoke and fly with just rudder, power, and trim. It's
ugly, it's sloppy, and it's uncomfortable, but it works. Most can
actually get the plane over the runway and in a position to make a
survivable landing after a few trips around the pattern (I don't
actually let them land like that, just get close enough to demonstrate
that it's possible). The biggest key is to make very small power and
trim changes and then be patient and wait for the fugoids to damp out
before deciding if you got the descent rate you were looking for.
Go-arounds can be kind of exciting too!

I've done another exercise with people who insist on trying to use
aileron to pick up a wing drop in a stall. I take control of the yoke
and they get the rudders. The game is for them to keep the plane on a
constant heading while I try to turn us. The rudder wins every time!

[chris grotewohl]

My advise, Definately find out where VFR conditions exist in relationship
to your route PRIOR to taking off and highlighting the area on the LE chart.
At least you'll which way to turn. I put together a backup electrical
system.
Small 12 volt battery..16.00
Small padded bag.........3.00
Lighter jack parts, female, male, fuses etc...
I can power up a hand held GPS, handheld radio etc...
You still have to fly the plane first, but you can talk, ya know where you
are, and you can get the hell out of the situation. The battery will power
both for hours. I have a male to male that could backfeed power to the
xponder is some AC to at least squawk the 7600,7700 or what ever the case
may be.
Chris Grotewohl
--
http://irish5string.homestead.com/chrisG.html
http://home.kc.rr.com/grotewohl/CFI.html

[Thomas Pappano]

"chris grotewohl" > wrote in message
...
> My advise, Definately find out where VFR conditions exist in relationship
> to your route PRIOR to taking off and highlighting the area on the LE
chart.
> At least you'll which way to turn. I put together a backup electrical
> system.
> Small 12 volt battery..16.00
> Small padded bag.........3.00
> Lighter jack parts, female, male, fuses etc...
> I can power up a hand held GPS, handheld radio etc...
> You still have to fly the plane first, but you can talk, ya know where you
> are, and you can get the hell out of the situation. The battery will power
> both for hours.



> I have a male to male that could backfeed power to the
> xponder is some AC to at least squawk the 7600,7700 or what ever the case
> may be.
> Chris Grotewohl
> --
> http://irish5string.homestead.com/chrisG.html
> http://home.kc.rr.com/grotewohl/CFI.html
>
>

Hi Chris,
This is something I have planned, have not yet tested, but should work
great. Carry a small gel-cell equipped with a fuse and male lighter plug.
When electrical is lost, turn off master switch, turn off non-critical
equipment, lights, etc. Plug in the battery, which will then backfeed the
bus. This should power the electric TC, radios, and transponder long
enough to get down with a more or less "normal" instrument approach.
A pair of 7 amp/hr 12 volt gel-cells total about 10 lbs & $40.

Tom Pappano, PP-ASEL-IA

[chris grotewohl]

Tom, The battery I have is a Gel and bought it from Batteries plus. They
have many sizes etc. It is cheap insurance.Chris

--
http://irish5string.homestead.com/chrisG.html
http://home.kc.rr.com/grotewohl/CFI.html

[Julian Scarfe]

"Roy Smith" > wrote in message
...

> The other advantage to using rudder is that the rudder is more effective
> in a stall or spin. In a fully developed spin, the ailerons are
> probably useless. When I teach stall recovery, I stress use of the
> rudder to pick up a dropping wing.
....
> I've done another exercise with people who insist on trying to use
> aileron to pick up a wing drop in a stall. I take control of the yoke
> and they get the rudders. The game is for them to keep the plane on a
> constant heading while I try to turn us. The rudder wins every time!

There's a great deal of debate in this part of the world at least on the
issue of which control to use to pick up a dropped wing.

http://www.pprune.org/forums/showthread.php?s=&threadid=75116

is one such thread. I've not really thought fully through the arguments.
Is yours simply about control authority or is there more to it than that?
Perhaps we should take this one out of .ifr?

Julian Scarfe

[Roy Smith]

"Julian Scarfe" > wrote:
> There's a great deal of debate in this part of the world at least on the
> issue of which control to use to pick up a dropped wing.
>
> http://www.pprune.org/forums/showthread.php?s=&threadid=75116

To be honest, I don't see much debate in that thread. Sounds like
pretty much everybody is saying the same thing I am -- that rudder is
the right thing to use to recover from a wing drop during a stall.

> I've not really thought fully through the arguments.
> Is yours simply about control authority or is there more to it than that?
> Perhaps we should take this one out of .ifr?

Yup, control authority. That's pretty much it. The rudder has control
authority over a much wider range of conditions than the ailerons do.
When things are happening fast, you want to have a plan that always
works, without having to put any thought into it. Hence, my
recommendation to use the rudder to maintain heading.

This started in .ifr because we were talking about how to control the
plane in IMC with no gyros. The basic assumption is that you've got
*some* heading reference, be it the wet compass, the ADF pointing at a
distant station, or a GPS course line. Even with the GPS (which is by
far the most useful of the three), you've got limited information, so
your best plan is to stick with something which always works, even if it
doesn't work very elegantly. That's the rudder.

[Sydney Hoeltzli]

Julian Scarfe wrote:

> Well yes, but solving the roll problem and getting the wings level will
> solve the pitch problem. Solving the pitch problem doesn't solve the roll
> problem.

I'll have to try this again next time I'm out playing, but I guess I'm
trying to say (at least in my plane) I don't think they're separable.
That is to say it's not enough to *get* the wings level, if the pitch
is oscillating a wing will drop. (this is a practical observation)

> I can't speak for the others but the Mooney doesn't feel lighter in roll
> than anything else.

I defer to your experience, but I thought the Mooneys I had a chance
to fly were quite a bit more positive in roll control and also lighter
and faster in roll than a small Cessna or Piper. Once banked, it seemed
happy to stay banked, just like Tigger.

I'm not sure I'd agree that an IR pilot, lacking major portions of the
normal feedback from gyro instruments, would be better able to separate
pitch and roll input. I guess we'd have to do the experiment. :)

Cheers,
Sydney

[Doug Carter]

Julian Scarfe wrote:
> "Roy Smith" > wrote in message
> ...

> Is yours simply about control authority or is there more to it than that?

In the airplanes that I've tried using ailerons to recover from a
incipent spin (Decathlon, YAK52, Pitts) the adverse yaw accelerates the
spin. If I've got either wing stalled I always use the rudder first.

In the case described in this thread I would use rudder only.

[David Megginson]

Roy Smith > writes:

> The biggest key is to make very small power and
> trim changes and then be patient and wait for the fugoids to damp out
> before deciding if you got the descent rate you were looking for.
> Go-arounds can be kind of exciting too!

It's been a few months since I've flown a Cessna, but in my Cherokee,
with the big trim wheel on the floor between the seats, it is actually
possible to damp out phugoids actively with a light touch and a bit of
anticipation.


All the best,


David

--
David Megginson, , http://www.megginson.com/

[David Megginson]

Roy Smith > writes:

> The biggest key is to make very small power and
> trim changes and then be patient and wait for the fugoids to damp out
> before deciding if you got the descent rate you were looking for.
> Go-arounds can be kind of exciting too!

It's been a few months since I've flown a Cessna, but in my Cherokee,
with the big trim wheel on the floor between the seats, it is actually
possible to damp out phugoids actively with a light touch and a bit of
anticipation.


All the best,


David

--
David Megginson, , http://www.megginson.com/

[David Megginson]

"Julian Scarfe" > writes:

> There's a great deal of debate in this part of the world at least on the
> issue of which control to use to pick up a dropped wing.

There shouldn't be. Using ailerons to pick up a wing in a stall and
actually cause the wing to drop further (by increasing its angle of
attack). It's ugly stuff.


All the best,


David

--
David Megginson, , http://www.megginson.com/

[David Megginson]

"Gary L. Drescher" > writes:

> I've often wondered if a pendulum, in lieu of a GPS or compass,
> would provide sufficient yaw information to keep the wings. But
> I've never tried the experiment.

Here's an easier experiment: take a carpenter's level and duct-tape it
to your bicycle's handlebars. Now, go around a few turns fairly fast
(i.e. the bicycle is at a good bank). Does the level show that the
handlebars are tilted during the turn, or is the bubble still in the
centre?

The answer will help show why you need gyroscopic instruments (or
newer expensive equivalents) to fly in IMC.


All the best,


David

--
David Megginson, , http://www.megginson.com/

[Julian Scarfe]

> "Julian Scarfe" > wrote:
> > There's a great deal of debate in this part of the world at least on the
> > issue of which control to use to pick up a dropped wing.
> >
> > http://www.pprune.org/forums/showthread.php?s=&threadid=75116

"Roy Smith" > wrote in message
...
> To be honest, I don't see much debate in that thread. Sounds like
> pretty much everybody is saying the same thing I am -- that rudder is
> the right thing to use to recover from a wing drop during a stall.

Really?

"As for rudders - I teach - rudder to STOP yaw. Not to pick the wing up...."

"I taught stall recoveries as:
Centralise aileron
Rudder to stop *further* yaw (NOT raise the wing NOR prevent further wing
drop)
Reduce AoA eg to ~ glide attitude
...."

"I have found that teaching the stude to use rudder at the stall to 'limit
further wingdrop' can actually lead to 'EXCESSIVE AND OVER ENTHUSIASTIC'
opposite rudder.......leading to SPIN!"

All three of those correspondents seem to oppose the idea of the use of
rudder for roll control.

> > I've not really thought fully through the arguments.
> > Is yours simply about control authority or is there more to it than
that?
> > Perhaps we should take this one out of .ifr?
>
> Yup, control authority. That's pretty much it. The rudder has control
> authority over a much wider range of conditions than the ailerons do.
> When things are happening fast, you want to have a plan that always
> works, without having to put any thought into it. Hence, my
> recommendation to use the rudder to maintain heading.

I'm not convinced by that. I can see two arguments against it:

1) The use of rudder for roll control works as a secondary effect of yaw.
At speeds approaching stall, that yaw can make the difference between
spinning or not. (Of course, so can an abrupt aileron input :-))

2) In any control loop the timing of the effect of control inputs has a
significant impact and an unhelpful lag can lead to divergence. Thomas wrote
in his original post:

"Now using the rudder to turn, the airplane takes a while
to respond. With the constant upsetting influence of the thermals, the
plane is always wanting to turn. You see it on the GPS, and by the time
you get some rudder pressure on, you are maybe 10 to the right. Now
you hold the rudder and wait for the plane to respond, and slowly you
come back on course, but overshoot. I try to adjust my inputs to smooth
things out but the TB makes it pointless. I resign myself to the fact that
at best we will make constant small s-turns all the way."

That wouldn't happen with the ailerons.

Julian Scarfe

[Roy Smith]

"Julian Scarfe" > wrote:
> "As for rudders - I teach - rudder to STOP yaw. Not to pick the wing up...."

We're starting to diverge a bit here in what we're talking about. The
original thread had to do with what you do in IMC with no gyros. The
ONLY information you have is what you can get from thw wet compass and
(as the argument evolved) a moving map GPS giving you a course line.

All you can deduce from a GPS moving map is heading, and even that, only
if you assume that heading more or less equals course (certainly
d(heading)/dt is very close to d(course)/dt for small values of heading
change. So, as I said, you use the rudders to correct deviations off
the GPS course line. This corresponds exactly to stopping yaw. In IMC
with no direct roll or bank information, picking a wing up isn't even
possible, except as a by-product of holding heading.

Perhaps we're just arguing different arguments. I'm assuming that you
just lost your entire panel in IMC, in which case it's not unlikely that
you've entered an unusual attitude by the time you figured out you had a
problem. Maybe you're in a steep spiral. Maybe you're close to stall,
or have stalled already. Maybe you're in a spin. Using rudder to
counter course change indicated on the GPS is the only thing I can think
of which will work in all those cases.

As for "I resign myself to the fact that at best we will make constant
small s-turns all the way", If I've lost all my instrumnts in IMC, I'll
be very happy if the worst I do is make small s-turns until I get into
visual conditions.

I certainly agree that once the plane is on an even keel and stable,
using coordinated aileron and rudder is superior to just using rudder.
It would be foolish to argue otherwise. But if you're not sure if
you're upside down or not, I'd stay away from the ailerons.

[David Megginson]

"Gary L. Drescher" > writes:

> Sorry, I wasn't very clear as to what I was proposing. I wasn't
> suggesting to let the pendulum hang down to get bank information.
> Rather, the idea is to let it swing from side to side to get yaw
> information. As the plane changes its heading, the pendulum's
> direction of motion changes relative to the plane.

It would have a very significant lag, since pendulums tend to keep
going for a long time with a single push. Were you looking for
something bigger than the ball in the TC?


All the best,


David

--
David Megginson, , http://www.megginson.com/

[Michael]

Sydney Hoeltzli > wrote
> Julian Scarfe wrote:
> > Well yes, but solving the roll problem and getting the wings level will
> > solve the pitch problem. Solving the pitch problem doesn't solve the roll
> > problem.
>
> I'll have to try this again next time I'm out playing, but I guess I'm
> trying to say (at least in my plane) I don't think they're separable.
> That is to say it's not enough to *get* the wings level, if the pitch
> is oscillating a wing will drop. (this is a practical observation)

I have another practical observation. If an unusual attitude has
developed, then even regaining perfect control over roll may not
salvage the situation. I tried this experiment once (link and text at
end of post).

Pitch stability is one of those terms that doesn't necessarily have
any meaning outside of control theory. Inside of control theory it's
too dull to think :)

No, seriously - positive dynamic pitch stability, as it's generally
understood, basically means that if you have the plane trimmed out to
a certain speed, and then make a step change to that speed, the plane
will undergo some oscillations but eventually return to the trim
speed, within a certain tolerance. However, it's pretty obvious that
it won't do that for arbitrarily large step changes. The magnitude of
the step change is defined by certification rules - and if you've
allowed the speed to diverge outside those limits, then even if you
bring roll under control you're still a test pilot.

Michael

http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF-8&safe=off&threadm=449a3d6e.0205151133.762560cb%40posting.goo gle.com&rnum=1&prev=/groups%3Fsafe%3Doff%26ie%3DUTF-8%26oe%3DUTF-8%26as_usubject%3Dautopilot%26as_uauthors%3Dcrwdog 69%40hotmail.com%26lr%3D%26num%3D30%26hl%3Den

One piece of advice that non-instrument pilots are always given should
they blunder into IMC inadvertently is to turn on the autopilot if
they have one. The reason is obvious - an autopilot, assuming it
works properly, will maintain wings level in the clouds whereas an
untrained person may not. Makes sense, right?

I've never owned a plane with an autopilot, and when I did
inadvertently blunder into IMC I kept the plane under control and flew
RADAR vectors based on the training all private pilots get in basic
attitude instrument flying. But what if I had an autopilot?

Recently I installed an Autocontrol III in my Twin Comanche. I tested
it in both wing level mode and heading hold mode (it has no altitude
hold) and I was satisfied that it would be a good tool for reducing my
workload at night or in IMC. But would it help the untrained pilot in
IMC?

So I tested it under nearly ideal conditions. I had the plane loaded
about 400 lbs under gross, and with the cg toward the forward part of
the envelope for good stability. I slowed the plane to about 120 kts,
trimmed it up, and released the controls at a safe altitude. I wanted
to see what would happen. For a minute or so, the plane wandered in
heading but continued to hold altitude (plus or minus a bit - there
were some bumps) and wings mostly level. Eventually, of course, it
got a wing lifted by a bump, and off it went into a graveyard spiral.
At 50 degrees of bank, the speed had built to about 160 kts and the
descent rate was over 1000 fpm. I decided that this was a classic
nose-low unusual attitude. So I engaged the autopilot in wing leveler
mode.

Immediately and smoothly, the autopilot leveled the wings. So far, so
good. The airplane immediately began to climb and slow down. "Wow,
this actually works!" I thought. Not so fast. The airplane blew
right through its trim speed, and the nose kept coming up. The wings
did stay approximately level, and the heading stayed pretty constant,
but airspeed bled off. I put my hand on the throttles, sensing what
was coming. Sure enough, I was slowing right through red line. The
power setting I used was low enough for a power-on stall, and the
altitude was high enough, so I kept my feet lightly on the rudders,
ready to recover. The plane slowed through 65 mph (power-off stall is
over 70) and then nosed down and dove. At the bottom of the dive, I
think it may have been doing even more than 160 kts - but then it
began to climb again. At the top, I felt the bite of the stall, but
before I could take action the nose dropped again. Still the wings
were level.

As the nose began to drop again, I lost my nerve. As the nose crossed
the horizon, I held the yoke for a few seconds to hold that attitude.
Then I let go. The plane flew, holding wings level and maintaining
altitude reasonably well in the bumps.

Maybe it's a good thing I had the instrument rating and the confidence
to use it before I had an autopilot...

Michael

[Gary L. Drescher]

"Michael" > wrote in message
m...
> "Gary L. Drescher" > wrote
> > Sorry, I wasn't very clear as to what I was proposing. I wasn't
suggesting
> > to let the pendulum hang down to get bank information. Rather, the idea
is
> > to let it swing from side to side to get yaw information. As the plane
> > changes its heading, the pendulum's direction of motion changes relative
to
> > the plane.
>
> Sounds great. How is that different from the ball (inclinometer)?

Two differences. First, the ball is not given a shove to keep it
oscillating back and forth even when the plane is going straight (any such
oscillation damps out almost instantly). Second, the ball is constrained to
move in only one plane. The idea of the pendulum is to start it swinging
side to side (say, east-west if you're heading north) but let it move
freely; then, if the plane yaws, the pendulum is still swinging east-west,
so the yaw is detectable. At least in principle.

--Gary

>
> Michael

[Greg Esres]

<<There shouldn't be>>

Many people feel there is no need to "pick up a wing". Just lower the
AOA and then return to level flight using coordinated controls.

This is what I teach, and is what is in the FAA's Airplane Flying
Handbook.

[Greg Esres]

<<In a spin you use the rudder to stop the rotation >>

We were talking about stalls.

[Doug Carter]

Greg Esres wrote:
> <<In a spin you use the rudder to stop the rotation >>
>
> We were talking about stalls.
>

You may have noticed that often a wing drops in a stall; beginning of
the incipit phase of a spin. Use rudder to stop the rotation (wing
dropping), elevator to lower the AOA...

I was basiclly agreeing with the earlier post.

[Greg Esres]

<<Use rudder to stop the rotation (wing dropping), >>

Isn't necessary. No stall, no spin.

You should read the Airplane Flying Handbook for the proper recovery
procedure, rather than what some instructor taught you.

[Roy Smith]

Greg Esres > wrote:
><<Use rudder to stop the rotation (wing dropping), >>
>
>Isn't necessary. No stall, no spin.
>
>You should read the Airplane Flying Handbook for the proper recovery
>procedure, rather than what some instructor taught you.

Surely you're not saying that an FAA document is the be-all and
end-all when it comes to understanding aerodynamics, are you?

[Michael]

(Teacherjh) wrote
> One piece of advice that non-instrument pilots are always given should
> they blunder into IMC inadvertently is to turn on the autopilot if
> they have one. The reason is obvious ...
>
> I'm not sure I agree.

With what? That it's a good idea? Obviously it's not always a good
idea, as my experiment showed. That it's common advice? I think it's
common enough that most people have heard it.

Michael

[Ray Andraka]

i think you also need to restrict vertical movement of the pendulum's fulcrum
(and therefore vertical translation of the pendulum), which is not practical in
an airplane that can move in 3 dimensions. Regardless, just in keeping the
pendulum swinging, you probably have as much complexity as a gyro.

Michael wrote:

> "Gary L. Drescher" > wrote
> > Two differences. First, the ball is not given a shove to keep it
> > oscillating back and forth even when the plane is going straight (any such
> > oscillation damps out almost instantly). Second, the ball is constrained to
> > move in only one plane. The idea of the pendulum is to start it swinging
> > side to side (say, east-west if you're heading north) but let it move
> > freely; then, if the plane yaws, the pendulum is still swinging east-west,
> > so the yaw is detectable. At least in principle.
>
> OK, now I get it. You're using the principle that the plane of
> oscillation in a pendulum is rigid in space, just like the plane of
> rotation of a gyroscope. Sure, that makes a lot of sense. Should
> work just like a gyro. Only issue is how you're going to keep it
> swinging. You would need a drive system and an escapement.
>
> Michael

--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email
http://www.andraka.com

"They that give up essential liberty to obtain a little
temporary safety deserve neither liberty nor safety."
-Benjamin Franklin, 1759

[Ron McKinnon]

"Michael" > wrote in message
om...
> "Gary L. Drescher" > wrote
> > Two differences. First, the ball is not given a shove to keep it
> > oscillating back and forth even when the plane is going straight (any
such
> > oscillation damps out almost instantly). Second, the ball is
constrained to
> > move in only one plane. The idea of the pendulum is to start it
swinging
> > side to side (say, east-west if you're heading north) but let it move
> > freely; then, if the plane yaws, the pendulum is still swinging
east-west,
> > so the yaw is detectable. At least in principle.
>
> OK, now I get it. You're using the principle that the plane of
> oscillation in a pendulum is rigid in space, just like the plane of
> rotation of a gyroscope. Sure, that makes a lot of sense. Should
> work just like a gyro. Only issue is how you're going to keep it
> swinging. You would need a drive system and an escapement.
>
> Michael

I think the pendulum's 'rigidity in space' is a qualified
circumstance, and depends upon the accelerations imposed
upon it.

Consider the typical bob-on-a-string pendulum. At the top of
the swing the bob has zero velocity, maximum potential energy,
at the bottom, maximum velocity and minimum potential energy.

Potential energy with respect to what? - with respect to
whatever net forces are involved, which are also the forces
that cause the bob to accellerate to maximum, and back to 0.

What is there about the pendulum bob that will cause it to
swing back in the same plane as it was formerly swinging?
Normally it will be its position relative to the pendulum
anchor and with respect to the external forces upon it.

There are other ways to make pendulums, of course,
but I think you'll find they all share this limitation.

Move the anchor point in some direction perpendicular
to the direction of the forces, or change the direction of
the forces, and you will in general change the plane in
which the pendulum swings. Both of these can be
expected to occur in a moving aircraft, which should
make the pendulum useless.

[Julian Scarfe]

Julian Scarfe > wrote:

> >In a nose-low attitude the ailerons will be more effective than the
rudders
> >at recovering to wings level, but rudder may well do the job too.

"Roy Smith" > wrote in message
...
>
> Well, just to pick a nit, in a spin, you're very much nose low, but
> the ailerons won't work at all.

Ah, er yes thanks for the picking. It feels better without that nit. I've
seen smaller ones... :-)

Julian

[Doug Carter]

Greg Esres wrote:
> <<Use rudder to stop the rotation (wing dropping), >>
>
> Isn't necessary. No stall, no spin.
>
>

Gee, make up your mind. First you complained that we were talking about
stalls, not spins; now you say "No stall, no spin." Well, yeah, no
airplane, no stall... :)

Seriously though, if you look back you will see that I was responding to
another poster saying: "...Using ailerons to pick up a wing in a stall
and actually cause the wing to drop further (by increasing its angle of
attack)." Which I clearly agree with.

Considering the core topic of the thread, under the conditions of
"everything failed" are you suggesting that if you suspect that you have
the beginnings of a stall and possibly a roll into the more stalled wing
that you should pitch "down" and then roll level? Good luck with that!

Perhaps because I fly mostly aerobatics in the Pitts I automatically
stop any rotation while either wing is stalled before changing pitch or
roll.

[Teacherjh]

>>
> I'm not sure I agree.

With what?
<<

I am not sure I agree that a non-pilot (or non-instrument-rated pilot) should
just turn on the autopilot if they end up in IMC (or even if a non-pilot needs
to take over for a disabled pilot). An autopilot can take you quickly to where
you don't want to go, and didn't think you were going to be headed.

One needs to understand how to work the autopilot first, and know what it's set
for (and what needs to be un-set, if anything). Ditto a GPS - the advice often
given to non-pilots acting as pinch hitters is to use the GPS - fine but the
GPS is often a fussy device that takes the head out of the windshield, to the
detriment of the flight.

The interface is hard enough for a pilot, let alone a non-pilot facing an
emergency.

But, once mastered it's handy.

Jose

(for Email, make the obvious changes in my address)