Use of FLaps in emergency situations

[Tman]

Hi, I've never been in these emergency situations, but have had a few
scenarios where it has come close enough to get me thinking what would I
do if the scenario was a touch worse (and, well, of course, how to avoid
getting that close in the first place). One thing I'd like opinions on
is the use of flaps. I don't see much talk of this in the POH. Now I
do mean to go up to altitude and practice some of this stuff, to see
what the airplane does, but would like to hear what the folks on this
group think about actions in these two dicey situations...

This is for C172R, with electric flaps going out to 30 deg..., if that
matters.


1 -> Nice mostly stabilized approach, just a little steeper than the 3
deg VASI glideslope, 70K, 20 deg flaps, landing not assured yet, aiming
for the numbers since it is a shorter runway. Downdraft, windshear,
whatever makes me sink faster, so I push in the throttle... and the damn
engine sputters and quits.
Planned reaction: Intense focus on the airspeed, keep it as close to
60K, and _immediately_ retract flaps _but only_ to 10 degrees. Keep the
airspeed on 60K, expecting a need for back pressure due to the
now-retracted flaps. Then, 3-5 seconds later, divert attention first to
where ya gonna land, then second to why did the motor quit.
Rationale: the 10deg flaps will keep the slow flight without a stall,
and less drag than 20deg. Retracting from 20deg to 10deg will not
increase the stall speed much, and the only sink will be from the need
for more back pressure (anticipated). The goal here is to reduce drag
to increase options, ASAP.
If I was a little further out and wanted to stretch the glide more, I
think I'd accelerate to ~65K, and then pull all the flaps in as a last
step. With plans to dump them back out if the landing will be a crash,
i.e. won't make the runway.

2-> Normal departure, 55K rotate, accelerate to Vy (~80K) when climbing
out of ground effect. For some reason, it's climbing like a dog, and
not sure going to clear obstructions.
First reaction: Slow down, just a bit, say 70 knots bringing one closer
to Vx to steepen the slope.
Second reaction (if that isn't going to be clearly sufficient): Dump 10
deg only of flaps, and slow right down to Vx, using the momentum to
climb up.
Rationale; I've always been taught that Vx climbs should be with 10deg
flaps to keep the stall further away. I don't see confirmation of this
in the POH (although the short-field obstructed takeoff is done with
10deg of course).

T

[gatt[_5_]]

Tman wrote:

> 1 -> Nice mostly stabilized approach, just a little steeper than the 3
> deg VASI glideslope, 70K, 20 deg flaps, landing not assured yet, aiming
> for the numbers since it is a shorter runway. Downdraft, windshear,
> whatever makes me sink faster, so I push in the throttle... and the damn
> engine sputters and quits.

I would retract flaps to 10 degrees while pitching as appropriate to
establish or hold best glide speed. *IF* you can hold best glide speed
and make the runway with the flaps fully retracted, it's better to do
that than keep in 10 degrees and hit the fence.

> If I was a little further out and wanted to stretch the glide more, I
> think I'd accelerate to ~65K, and then pull all the flaps in as a last
> step. With plans to dump them back out if the landing will be a crash,
> i.e. won't make the runway.

Pretty much.

> 2-> Normal departure, 55K rotate, accelerate to Vy (~80K) when climbing
> out of ground effect. For some reason, it's climbing like a dog, and
> not sure going to clear obstructions.
> First reaction: Slow down, just a bit, say 70 knots bringing one closer
> to Vx to steepen the slope.

That's one way of expressing it, but an examiner or instructor would
think of it in terms of increasing pitch and (hopefully) rate of climb,
rather than slowing down.

Full power, mixture rich, carb heat off, MAGNETOS - BOTH... the latter
comes from personal experience... Then check your flap setting to make
sure they weren't dumped inadvertently.

By the time you roll out you've already checked the POH recommendation
for Vx, so you'll know immediately whether to set flaps for Vx. (You
probably will.)

You also already know whether it's a better idea to chop the power and
land on your remaining runway and risk hitting something relatively
slowly on the ground than at Vx 40 or 50 feet AGL.



-c

[More_Flaps]

On Jul 15, 3:06*am, Tman <x@x> wrote:

>
> 2-> Normal departure, 55K rotate, accelerate to Vy (~80K) when climbing
> out of ground effect. *For some reason, it's climbing like a dog, and
> not sure going to clear obstructions.

Why is it climbing like a dog? Did you not check density altitude? If
well past airfield you _could try to climb at 65lk (check RPM
flaps...) but why not just turn away from the obstructions? You are
at 80k so you can take 20 flaps and immediately start a canyon turn.

Cheers

[More_Flaps]

On Jul 15, 6:08*am, gatt > wrote:
> Tman wrote:

>
> By the time you roll out you've already checked the POH recommendation
> for Vx, so you'll know immediately whether to set flaps for Vx. (You
> probably will.)
>

In M & R 172 -no flaps for Vx climb. That may be the case for all
other 172's?

Cheers

[More_Flaps]

On Jul 15, 3:06*am, Tman <x@x> wrote:

>
> 1 -> Nice mostly stabilized approach, just a little steeper than the 3
> deg VASI glideslope, 70K, 20 deg flaps, landing not assured yet, aiming
> for the numbers since it is a shorter runway. *

This makes no sense to me. How can you be in a _stabilised_ approach
and not be assured of the runway? Why is the approach to the short
runway only slightly steeper than VASI -you must have some power on
with 20 flaps if that is the case aso why are you are not in the short
field config?. Best glide in a 172 is 10:1 = 6 degrees with no flaps
(you should know this) and if you are now on or below the VASI
glideslope you won't make the runway so pick a landing spot fast and
go for it.

Cheers

[george]

On Jul 15, 9:07 am, More_Flaps > wrote:


My instructor pounded one lesson into all his students.
No matter what emergency the first requirement is to fly the
aeroplane.
Don't think about making the airfield or trying to extend the glide
The worst things in aviation are.
Runway behind you
Altitude above you
fuel in the bowser.
And fixation upon unusual events

[Tman]

> This makes no sense to me. How can you be in a _stabilised_ approach
> and not be assured of the runway? Why is the approach to the short

I didn't think a stabilized approach was a power-off approach. You can
be in a stablized approach, lose power, and the landing is not assured.
That's what I meant.

Do you do all your approaches at 6 degrees to avoid not making the
runway in the event of power loss? Doesn't sound like a bad policy, but
not what i was taught, and not always possible.

T

[More_Flaps]

On Jul 15, 11:33*am, Tman <x@x> wrote:
> > This makes no sense to me. How can you be in a _stabilised_ approach
> > and not be assured of the runway? *Why is the approach to the short
>
> I didn't think a stabilized approach was a power-off approach. *You can
> be in a stablized approach, lose power, and the landing is not assured.
> * That's what I meant.
>

Ah OK

> Do you do all your approaches at 6 degrees to avoid not making the
> runway in the event of power loss? *Doesn't sound like a bad policy, but
> not what i was taught, and not always possible.
>

Yes, I think that generally all my approaches are steeper than 3
degrees and have minimal power on (I feel comfortable with ~1200 rpm -
don't forget carb heart in non-injected 172's), I start above the 3
degree glide slope and rely on flaps and decaying airspeed to bring me
onto the visual glide slope on short final. If you have a low energy
reserve style approach (i.e. less than 6 degrees slope in a 172) you
need to be sure power is available... Initial aim point is 1/3 down
the runway and I drop that toward the threshold as I approach short
final. I've seen a lot of flat approaches with power on at my local
field and they are often too fast too -remember in a 172R Vso is about
33k so 1.3 Vso is 44k. To fly at 50 k (or thereabouts) requires a
high nose attitude but watching 172s at my local field I more often I
see a very flat touch down (plenty of balloons too) where the mains
and nose wheel touch almost all together. As an exercise, how about
flying the plane at 44k at altitude with 20 or 30 flaps (and power to
hold altitude) to get a feel for the handling at low airspeed (the
first stall warning may peep intermittently). Then _holding_ that
airspeed chop power and see your rate of descent. The nose high
attitude adds lots of drag so you descend very fast and that's how you
can get it into a really short field over obstructions. Don't forget
to add the gust factor to these speeds (often ~5k in my experience)
for the real approaches. Also if you have a long runway work out the
POH stopping distances compared to runway markers and try to always
meet that performance. It should be possible to easily beat the POH
figures as most of the time you fly you are not at MTOW. Talk this
over with your instructor.

As I understand it, (and ATP's here may correct me) the 3 degree
flatter approach is better for jets who need to keep power on as they
have poor spool up performance.

Cheers

[[email protected]]

On Jul 14, 8:00 pm, More_Flaps > wrote:

> As I understand it, (and ATP's here may correct me) the 3 degree
> flatter approach is better for jets who need to keep power on as they
> have poor spool up performance.

And they glide better, too.

Dan

[[email protected]]

On Jul 14, 11:06 am, Tman <x@x> wrote:
> Hi, I've never been in these emergency situations, but have had a few
> scenarios where it has come close enough to get me thinking what would I
> do if the scenario was a touch worse (and, well, of course, how to avoid
> getting that close in the first place). One thing I'd like opinions on
> is the use of flaps. I don't see much talk of this in the POH. Now I
> do mean to go up to altitude and practice some of this stuff, to see
> what the airplane does, but would like to hear what the folks on this
> group think about actions in these two dicey situations...
>
> This is for C172R, with electric flaps going out to 30 deg..., if that
> matters.
>
> 1 -> Nice mostly stabilized approach, just a little steeper than the 3
> deg VASI glideslope, 70K, 20 deg flaps, landing not assured yet, aiming
> for the numbers since it is a shorter runway. Downdraft, windshear,
> whatever makes me sink faster, so I push in the throttle... and the damn
> engine sputters and quits.
> Planned reaction: Intense focus on the airspeed, keep it as close to
> 60K, and _immediately_ retract flaps _but only_ to 10 degrees. Keep the
> airspeed on 60K, expecting a need for back pressure due to the
> now-retracted flaps. Then, 3-5 seconds later, divert attention first to
> where ya gonna land, then second to why did the motor quit.
> Rationale: the 10deg flaps will keep the slow flight without a stall,
> and less drag than 20deg. Retracting from 20deg to 10deg will not
> increase the stall speed much, and the only sink will be from the need
> for more back pressure (anticipated). The goal here is to reduce drag
> to increase options, ASAP.
> If I was a little further out and wanted to stretch the glide more, I
> think I'd accelerate to ~65K, and then pull all the flaps in as a last
> step. With plans to dump them back out if the landing will be a crash,
> i.e. won't make the runway.
>
> 2-> Normal departure, 55K rotate, accelerate to Vy (~80K) when climbing
> out of ground effect. For some reason, it's climbing like a dog, and
> not sure going to clear obstructions.
> First reaction: Slow down, just a bit, say 70 knots bringing one closer
> to Vx to steepen the slope.
> Second reaction (if that isn't going to be clearly sufficient): Dump 10
> deg only of flaps, and slow right down to Vx, using the momentum to
> climb up.
> Rationale; I've always been taught that Vx climbs should be with 10deg
> flaps to keep the stall further away. I don't see confirmation of this
> in the POH (although the short-field obstructed takeoff is done with
> 10deg of course).
>
> T

"Somewhat" steeper than 3 degrees? As was pointed out, 172s don't
glide very well, and where I live we mostly are landing into a head
wind. 10 kts of wind will very significantly alter the glide angle
with respect to the earth. If your goal is to make the field should
you have an engine failure when you're somewhere past the numbers on
downwind you're going to have to manage energy a lot better than
you've indicated here., in terms of combining higher airspeed and
higher altitudes. A simple reality check is to simply pull back the
throttle close to idle passing the numbers downwind when you're number
one to land and getting used to the sight picture that'll get you to
the runway. I haven't flown a 172 in a long time, but seem to
remember any amount of flaps increased glide angle. I'd keep 'em up
until pretty late in the game.

[Vaughn Simon]

> wrote in message
...
> A simple reality check is to simply pull back the
> throttle close to idle passing the numbers downwind when you're number
> one to land and getting used to the sight picture that'll get you to
> the runway.

Where I fly (KLNA) that is too often simply impossible. When you have
multiple planes in the pattern, the pattern tends to get bigger...much bigger.
I often fly at odd hours just so that I can practice things like you suggest,
but it is a skill that may do me little good if I am routinely forced to turn
final more than a mile from the airport.

I was first a glider pilot. One of the first things we learn/teach in
gliders is that you never want to get caught simultaneously low and downwind of
the field. When I started taking airplane lessons, I was amazed to find that
everyone was routinely flying patterns that were beyond gliding range of the
airport. I am not just talking about the turn from base to final, I mean the
much of the downwind leg and the entire base leg!

Vaughn

[[email protected]]

On Jul 15, 12:48*pm, "Vaughn Simon"
> wrote:
> > wrote in message
>
> ...
>
> > A simple reality check is to simply pull back the
> > throttle close to idle passing the numbers downwind when you're number
> > one to land and getting used to the sight picture that'll get you to
> > the runway.
>
> * *Where I fly (KLNA) that is too often simply impossible. *When you have
> multiple planes in the pattern, the pattern tends to get bigger...much bigger.
> I often fly at odd hours just so that I can practice things like you suggest,
> but it is a skill that may do me little good if I am routinely forced to turn
> final more than a mile from the airport.
>
> * *I was first a glider pilot. *One of the first things we learn/teach in
> gliders is that you never want to get caught simultaneously low and downwind of
> the field. *When I started taking airplane lessons, I was amazed to find that
> everyone was routinely flying patterns that were beyond gliding range of the
> airport. *I am not just talking about the turn from base to final, I mean the
> much of the downwind leg and the entire base leg!
>
> Vaughn

We are told, Vaughn, that engine failures sometimes happen when power
is first reduced after take off. I don't know what the statistics are,
but think failures in the downwind/base/final portions of flight are
not very common. My own SEL experience and practice would put me at
serious risk if they were common, I'd make the field only if the
failure happened inbound of the middle marker a lot of times. I need
power to stay on the glide slope. That 'chop the power and make the
field" probably has more to do with learning how to figure out what
you can glide to if you have a power failure sometime. It might be
worth doing something like that when you're near a not-so-busy field,
just to make sure the sight picture you think you know works is valid
and if you still remember how to manage the energy your airplane has
left.

I'm reminding myself I have not done that sort of thing in too long a
time.

[[email protected]]

On Jul 15, 12:09 pm, wrote:
> We are told, Vaughn, that engine failures sometimes happen when power
> is first reduced after take off. I don't know what the statistics are,
> but think failures in the downwind/base/final portions of flight are
> not very common.

Failures at power reduction are no more common than any other
sort, except perhaps in ultralights with their two-strokes that tend
to seize up if they're not fully warmed up before takeoff, and they'll
sometimes stop when power is reduced but they were going to quit soon
anyway.
Failures can happen anywhere. I've had an engine fail in the
glide and another busted its crankshaft on climbout. Most common
failures, by a wide margin, are attributed to carb ice, and it will
get you anywhere at all if you're not educated enough to be aware of
(A) what causes it, (B) when the risk is highest, (C) and what is
sounds like. Every so often I hear of another airplane that had its
engine quit, the conditions were perfect for carb ice, and the engine
ran fine for the accident investigators. Carb ice could cause engine
failure on power reduction, as the ice will be closing off the carb
throat and the closing throttle valve will finish it. Maybe that's
where the OWT comes from?
Next most common cause is fuel starvation, more commonly called
running out of gas or, sometimes, mismanaging tanks. Water in the fuel
is third, then practice forced landings (when the thing iced up or got
cold enough it didn't wake up for the overshoot), and the fifth is oil
starvation. Not very common, that one. Catastrophic mechanical failure
is rare (like the broken crank) and is usually found in airplanes that
are poorly maintained or maybe abused.

Dan

[Private]

"Vaughn Simon" > wrote in message
...
>
> > wrote in message
> ...
>> A simple reality check is to simply pull back the
>> throttle close to idle passing the numbers downwind when you're number
>> one to land and getting used to the sight picture that'll get you to
>> the runway.
>
> Where I fly (KLNA) that is too often simply impossible. When you have
> multiple planes in the pattern, the pattern tends to get bigger...much
> bigger. I often fly at odd hours just so that I can practice things like
> you suggest, but it is a skill that may do me little good if I am
> routinely forced to turn final more than a mile from the airport.

When the circuit is full of students making xc circuits and dragging in long
finals,
We all (should) know that it is improper to cut in front of another aircraft
in the circuit and also that controllers will seldom direct one aircraft to
turn inside of another in the circuit, however......

The code words for requesting this action are to 'request a simulated engine
failure exercise' when making your downwind call abeam of the runway. The
controllers are well aware of what you are trying to do and will often
accommodate this if they are able and have confidence in your ability to
execute. If they are unable they will just decline your request and you are
free to make it again on your next circuit. A little planning and
situational awareness on your part can place you in the correct position to
allow the controller to approve your request.

The alternative is to land for 1/2 hr to get out of sequence with the flight
schools and to make your circuits while they are between air time.

Happy landings,


> I was first a glider pilot. One of the first things we learn/teach in
> gliders is that you never want to get caught simultaneously low and
> downwind of the field. When I started taking airplane lessons, I was
> amazed to find that everyone was routinely flying patterns that were
> beyond gliding range of the airport. I am not just talking about the turn
> from base to final, I mean the much of the downwind leg and the entire
> base leg!
>
> Vaughn
>

[Brian[_1_]]

<snip>
> * *Where I fly (KLNA) that is too often simply impossible. *When you have
> multiple planes in the pattern, the pattern tends to get bigger...much bigger.
> I often fly at odd hours just so that I can practice things like you suggest,
> but it is a skill that may do me little good if I am routinely forced to turn
> final more than a mile from the airport.
>
> * *I was first a glider pilot. *One of the first things we learn/teach in
> gliders is that you never want to get caught simultaneously low and downwind of
> the field. *When I started taking airplane lessons, I was amazed to find that
> everyone was routinely flying patterns that were beyond gliding range of the
> airport. *I am not just talking about the turn from base to final, I mean the
> much of the downwind leg and the entire base leg!
>
> Vaughn

True due to traffic you may have to fly beyond gliding distance of the
airport. The mistake I typically see when this happens is that the
pilot will start descending abeam the numbers. . Then they end up at
500 feet and a mile from the airport. I teach to stay at pattern
altitude until you are in a position to make a normal descent to the
runway. At least this way if you have a power failure you have a 1000
feet to work with, Which is the altitude we usually where we practice
power failures from.

Brian
CFIIG/ASEL

[Brian[_1_]]

I think the basic Idea behind you question is in #1 is should you
retract the flaps to try to extend your glide. The answer is it
depends mostly on how high you are. Below about 400 feet don't mess
with them. You will not gain enough to be significant and you should
be concentraiting on flying the airplane. Above 400 feet retracting
them can have some benefit, The higher you are the more it will help.
As I recall in the 172 going from 30 to 20 would give a signficant
drag reduction. From 20 to 10 does not do much and from 10 to 0 does
even less.

Best answer is find a willing flight instructor and go out and try it.
I do scenerio's like these all the time with students and on flight
reviews.

For Senerio #2, If landing ahead is no longer an option then get the
airplane configured as close to the Vx configuration and speed as
possible. I don't recall what flap setting this is for the R model 172
as I recall some 172's recommend 10 degrees of flaps and other say
that the 10 degrees doesn't help over an obstacle. I would be inclined
not to mess with them as long as they were 10 degrees or less.


Brian
CFIIG/ASEL

[Stealth Pilot[_2_]]

On Tue, 15 Jul 2008 11:32:42 -0700 (PDT),
wrote:

>On Jul 15, 12:09 pm, wrote:
>> We are told, Vaughn, that engine failures sometimes happen when power
>> is first reduced after take off. I don't know what the statistics are,
>> but think failures in the downwind/base/final portions of flight are
>> not very common.
>
> Failures at power reduction are no more common than any other
>sort, except perhaps in ultralights with their two-strokes that tend
>to seize up if they're not fully warmed up before takeoff, and they'll
>sometimes stop when power is reduced but they were going to quit soon
>anyway.
> Failures can happen anywhere. I've had an engine fail in the
>glide and another busted its crankshaft on climbout. Most common
>failures, by a wide margin, are attributed to carb ice, and it will
>get you anywhere at all if you're not educated enough to be aware of
>(A) what causes it, (B) when the risk is highest, (C) and what is
>sounds like. Every so often I hear of another airplane that had its
>engine quit, the conditions were perfect for carb ice, and the engine
>ran fine for the accident investigators. Carb ice could cause engine
>failure on power reduction, as the ice will be closing off the carb
>throat and the closing throttle valve will finish it. Maybe that's
>where the OWT comes from?
> Next most common cause is fuel starvation, more commonly called
>running out of gas or, sometimes, mismanaging tanks. Water in the fuel
>is third, then practice forced landings (when the thing iced up or got
>cold enough it didn't wake up for the overshoot), and the fifth is oil
>starvation. Not very common, that one. Catastrophic mechanical failure
>is rare (like the broken crank) and is usually found in airplanes that
>are poorly maintained or maybe abused.
>
> Dan

no I think the boy is right. your problem is that you've flown
correctly adjusted carburettors all the time.

if the idle metering of the carby isnt setup correctly then changes in
power settings can move the mixture out of the combustible range.

dont ask me how I know this but my old carby is now back on the
aircraft after being refurbished.

Stealth Pilot