Stall/Spins at 2 feet agl!!

Louie1975

Well-Known Member
Hi all:
I am a fairly new private pilot and this question struck me some time back and I've been meaning to ask it ever since. While I have never had any formal stall/spin training, from what I've heard/read about its basic cause is as follows: a spin happens when an airplane is stalled in an uncoordinated condition, essentially, when the ball is out of center. During my training I was under the impression that it was imperative to NOT stall the airplane uncoordinated. Well enough.
Here comes the question. When a pilot is landing in a crosswind, and/or gusty winds, and the controls are cross-controlled/or the pilot is dancing on the rudder, the plane is obviously uncoordinated and the ball obviously leaves center. And the airspeed approaches, and in many landings reaches, the stall speed. So why isn't spinning a concern in this scenario? Or is it? Any help on this would be greatly appreciated.

Thanks

Louie
 

braidkid

New Member
Wow, that's a tough question.
I would say that a spin is of concern anytime you are in an uncoordinated stalled situation. However, during landing you shouldn't stall
until you are just about to touch down. Keep your speed at around 60-70 knots (172) up until you cross over the runway threshold.
Once you cross over the runway threshold reduce power to idle and level off at about 10 ft AGL. Let the airplane's induced drag
slow the airplane down and keep the nose off as long as you can until the main's touchdown. The stall horn should be going off just before
touchdown.
The only way you could stall the airplane in a landing situation is if you are too high over the runway and increase your
angle of attack too much.
And remember, the most important thing to remember while landing is pitch for airspeed and power for altitude.
That's my stab at it, hope it helps....
 

DrBenny

New Member
In any event, it probably is unwise actually to fully stall your aircraft over the runway. This may be advisable for light tailwheels, although there are many who would argue against it even here.

If you look in the POHs of many popular GA aircraft, you'll see the recommended approach and landing speeds are above stall. Additionally, in some aircraft the pitch attitude required for a true full-stall landing is quite extreme, and the controls are mushy. IMO, unless you have a very short runway, a full-stall landing isn't necessary.

Now, to the cross-control question. Yes it is true that a crosswind landing requires cross-controlling the aircraft. But the AOA required for a stall should still be relatively far away from a typical landing, and this condition is ameliorated somewhat by watching the airspeed. In other words, one shouldn't be flying near the stall on final, anyway. Now, if you prefer the crab, kickout method (as I do), that cross-controlled condition doesn't occur until you are a foot or so above the ground.

Remember that *control* of the aircraft is always a high priority. Cross-controlling the aircraft with a high AOA and/or slow airspeed may be hazardous to your health!
 

Michigan_Flyer

Well-Known Member
Here is the short, simple answer:

On final approach in a crosswind, you are flying uncorodinated but the plane does not spin because you do not let it stall (by controlling pitch and airspeed).

As you touch down, the plane should be entering a stall, but it cannot enter a spin because the plane stops descending when the tires touch the ground.
 

justme

New Member
Hey Braidkid, do you actually use the theory of "pitch for airspeed, power for altitude"? I didn't think anybody taught that bass-ackward theory anymore.
 

braidkid

New Member
Whenever you are in the region of reverse command such as during slow flight or approach to landing you are using the throttle
for altitude control and pitch for airspeed. If the student uses pitch for altitude recovering during slow flight they will increase the
angle of attach to the point of a stall.
Is there something wrong with "pitch for airspeed, power for altitude"? What do you recommend?
 

canuck goose

New Member
I've been taugh pitch for airspeed and power for altitude too and that's the way all the pilots I know have been taugh. If you would pitch for altitude, for example in slow flight you notice you're too low, you would pitch up and you would at some point be very near the stall AOA and on approach and that's not a good thing.

On the other hand if you add power, you'll will reduce the aircraft rate-of descent or even level the aircraft until you're on a good glidepath without nearing a stall AOA.
 

I_Money

Moderator
I was taught pitch for airspeed power for atitude, and I think it is a great way to learn. Mainly because if you are slow you will put your nose down which is the most important thing to prevent a stall. I think once you have mastered controlling the aircraft you will do a bit of both, however reacting to being slow then you want by lowering your nose is a very good way to stay safe.
 

farwellbooth

Well-Known Member
[ QUOTE ]
Hey Braidkid, do you actually use the theory of "pitch for airspeed, power for altitude"? I didn't think anybody taught that bass-ackward theory anymore.

[/ QUOTE ]

Is this ass backwards? This is how I was taught and how the airplanes that I fly fly... What are they teaching you guys at academies? If you want to go up, what do you do? I'd add power...
 

E_Dawg

Moderator
-----
I'll have a go at Louie's question:
The reason it's not a concern is simply because you are too close to the ground for it to be an issue. You would NEVER stall the plane at 100AGL on final, however even in no wind situations you go for a nice stall at 2" AGL. In a hefty crosswind (one that would really reqire some footwork), you're not going to touch down in a full stall (or at least you're not trying to). The point is to just get the low tire on and keep it there.

Let's take it worst case: you fully stall the airplane uncoordinated during an Xwind at 1' AGL (a tad high for a smooth touchdown). The airplane will begin to yaw in the direction of rudder application (away from the wind in this case); the plane will also descend. Well, you're only a foot high, and any yaw that develops won't have a chance to get bad enough when you're that close to the ground. You'll be in for a rough touchdown but no damage. Now that would be a different story if you flare at 50'.

I definately suggest spin training; you get a great awareness of what a spin actually is, and how to prevent it. Probably the best thing I got out of it was a vast increase in my confidence in handling the plane, not to mention learning first hand what I could / could not do.
-----


As for what controls what; elevator controlls angle of attack and throttle controlls what happens at that angle of attack (climb, descent, cruise). But who cares; as long as they all work I'm happy!
 

justme

New Member
So for everybody that uses pitch for airspeed and power for altitude:

what controls airspeed on the ground? Pitch or power?

Why do we rotate on takeoff, why not just add more power?

If you are 3 feet above the ground, do you lower the nose to speed upor do you add power first?

If you're cruising along at MEA and want to speed up, do you add power or lower the nose?(can't go below MEA can ya)?

So if you add power to gain airspeed on those last two examples, what is the magical altitude that you change to pitch?

If you are on final approach, ON glide path, do you lower the nose to gain airspeed? (not supposed to fly below the glide path)

If a GPWS wants you to climb, why doesn't it say "add power", instead of "pull up"?

In steep turns when losing altitude, do you pull back or do you add power?

If you are on an ILS approach with the needles centered, are you going to lower the nose to gain airspeed?

Just for the record, and to give credit where credit is due, the above arguments are form a paper of someone elses writing...not my own. However, I think they are all valid arguments that are hard to refute.

As far as Iain's comment about lowering the nose if you are slow to prevent a stall....and this being a safe thing to do, how safe is that if you are close to the ground? I would say not very! So if close to the ground you would not pitch down for airspeed what is the magic altitude that you should start pitching dwon for airspeed?
 

EatSleepFly

Well-Known Member
[ QUOTE ]
Is there something wrong with "pitch for airspeed, power for altitude"? What do you recommend?

[/ QUOTE ]

Yes, because it implies that when in the region of reverse command (i.e. behind the "power curve") you only have to change power to increase your altitude, or only change pitch to increase your airspeed.

You can't (usually) change one without changing the other simultaneosly or soon after.

Example: You're out doing slow flight with a student. You've told him to maintain 65 kts., to practice getting the feel for the airplane at final approach airspeeds. He gets set up at 65 kts., and puts in about 2100 RPM to maintain altitude and airspeed. But then the airspeed starts slowly bleeding off. Its at 55 now. OK, so by that theory, he pitches down for 65 without changing power. What happens? Up you go. He's got an excess of power in now because he didn't change it, and he just lowered the pitch attitude to regain the target airspeed.
 

Captain_Bob

Well-Known Member
Hold on now folks... before you go flaming justme's response...

Just take a few minutes and read a very informative view on the subject by John Deacon, a 35,000 hour pilot.

http://www.avweb.com/news/columns/182148-1.html

To paraphrase... "Everything controls everything..." If you can't follow this line of thought... then just think about the pink elephants...

Bob
 

EatSleepFly

Well-Known Member
justme,

First off, we're talking about the region of reverse command/backside of the power curve/whatever you desire to call it here, not basic flying skills like changing airspeeds or altitudes in normal cruising flight.

Secondly,
[ QUOTE ]
As far as Iain's comment about lowering the nose if you are slow to prevent a stall....and this being a safe thing to do, how safe is that if you are close to the ground? I would say not very!

[/ QUOTE ]

Well you certainly don't RAISE the nose. You apply full power and lower the nose simultaneously. This allows you to gain airspeed and at the same time get climbing as quickly as possible. If you add power without lowering the nose, you're going to keep sinking before you start climbing. Also, if you had it trimmed properly, the nose will contine to rise. Why? Because you trim an airplane for an airspeed. It wants to "seek out" whatever airspeed you had it trimmed for. You MUST lower the nose no matter what...there's no magic altitude where you start only adding power instead. The only way to break a stall is to lower the Angle of Attack, and the quickest way to do that is by lowering the nose. Adding power will do it too, but it takes longer. Doing them both at once is the most efficient.
 

E_Dawg

Moderator
Bring it on:

So for everybody that uses pitch for airspeed and power for altitude:

1)what controls airspeed on the ground? Pitch or power?
On the ground the airplane is no longer performing the activities for which it was built; it is only positioning itself so it will be able to do them.

2)Why do we rotate on takeoff, why not just add more power?
When you are moving on the ground, you have very little AOA. By pulling back, you increase the AOA, thereby giving the throttle the chance to do it's work. See answer #1. Ever try a no power takeoff? Me neither...

3)If you are 3 feet above the ground, do you lower the nose to speed upor do you add power first?
Depends on current AOA and what I intend to do. If you say I ONLY want to speed up; I will add power and decrease AOA.

4)If you're cruising along at MEA and want to speed up, do you add power or lower the nose?(can't go below MEA can ya)?
Add power AND lower the nose; thereby decreasing the AOA to allow for more speed, and increasing power to hold altitude at that faster speed. If you were to lower the nose and decrease AOA, you'd descend at your faster airspeed. By adding power you allow the plane to keep the same altitude. See the relationship?

5)So if you add power to gain airspeed on those last two examples, what is the magical altitude that you change to pitch?
Didn't add power to gain speed; lowered AOA to gain speed, added power to keep the altitude.

6)If you are on final approach, ON glide path, do you lower the nose to gain airspeed? (not supposed to fly below the glide path)
No. Add power and lower the nose. See #s3 and 4.

7)If a GPWS wants you to climb, why doesn't it say "add power", instead of "pull up"?
The initial increase of AOA will result in excess lift, allowing a more immeadiate climb (sustained climbs are achieved through excess thrust). You won't go very high if you keep the throttles back.

8)In steep turns when losing altitude, do you pull back or do you add power?
Depends on how much altitude has been lost. Assuming we are still within private PTS, pull back (in addition to slightly decreasing bank angle). See answer #7.

9)If you are on an ILS approach with the needles centered, are you going to lower the nose to gain airspeed?
No. Add power and lower the nose. See answers 3 and 4.

Just for the record, and to give credit where credit is due, the above arguments are form a paper of someone elses writing...not my own. However, I think they are all valid arguments that are hard to refute.
Pilots will argue both ways for a long, long time. As long as the end result is achieved, the rest is semantics.

As far as Iain's comment about lowering the nose if you are slow to prevent a stall....and this being a safe thing to do, how safe is that if you are close to the ground? I would say not very! So if close to the ground you would not pitch down for airspeed what is the magic altitude that you should start pitching dwon for airspeed?
This is how people get in trouble after losing the engine. They think they can pull back all day and go that extra distance. This has been proven incorrect many times over. I'm sure the larger jet pilots (ahem... pilots who fly larger aircraft!) will say they fly more power for speed and pitch for altitude. This is due to excess power in abundance that we simply don't have in smaller aircraft. If a bigger jet were to lose all it's engines the pilot would always pitch for speed. Just remember that no one climbs to altitude with the throttles back, and no one descends to a landing with the throttles at the stop.
 

DrBenny

New Member
Read Wolfie\'s Book

I like his argument that we need to know what those doodads always do. Label the thottle "altitude," and the stick "airspeed."

If you add power, the plane will want to go up, or at least not descend as fast.

If you raise the nose, the plane will want to go slow.

Now, what you should do in certain situations depends on those situations.
 

SaabFO

New Member
Re: Read Wolfie\'s Book

One thing to keep in mind is that the elevator controls the angle of attack, which in turn has an effect on airspeed. I'm sure most of you have heard pitch + power = performance. One reason why the pitch for airspeed and power for altitude argument started is because pilots were stalling planes and spinning them into the ground. A pilot who unintentionally stalled an airplane would suddenly feel the nose drop on him, so his first reaction was to pull back, which only got him into bigger trouble.

Wolfgang Langewiesche was a big advocate of this in his book Stick and Rudder. It's definitely a book worth reading and he does a good job of explaining things in a very simplified manner, but some of the stuff in there is a little far fetched (like unstallable and rudderless airplanes.)

Pilots have to remember that if you change one thing (pitch or power) you're probably going to have to change the other. If you're doing slow flight and you start to get too slow, you have to lower the nose to get the speed back, but then you start to sink so you have to add power to hold your altitude. When doing steep turns, if you start to descend, you pull back on the yoke, but then your airspeed starts to drop so you add power.

There are times when it's appropriate to initially pitch for an airspeed, and then adjust things with power, such as slow flight, and other times when you should initially pitch for a climb or descent rate and use power to control airspeed, such as on an ILS. Whether you want to believe pitch for airspeed power for altitude, or pitch for altitude power for airspeed, they are both right to some extent, as long as you remember that if you change one thing you have to change the other.
 

DrBenny

New Member
Re: Read Wolfie\'s Book

See, and that's the difficulty some people are having in this thread. It really is very simple:

Point #1: There are things the plane will do if you operate a single control.

Point #2: There are things one should do in certain situations.

Understand those two points separately, and we can all agree.
 
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