Moose Stall

[jrenwick]

The "Moose stall" or "Moose hunter's stall" was mentioned in another thread. A friend of mine who flies out of Homer, AK used to be part-owner of a 170 in which her partner, his fiance and two others were killed in an accident that looked very much like the result of such a stall/spin situation. I'm sure many of us have known someone who was lost in this kind of tragic accident.

I myself am always trying to understand it better, because I don't have personal experience of that situation, and I would really like to be able to give a good lesson in how it happens, and avoiding it. So here's how I understand it, and if you've got ideas or experience relating to this, please chime in:

In principle, circling an object on the ground to get a good look at it should be no different from the "turns around a point" maneuver we all had to master and demonstrate for our Private Pilot checkride. Done correctly, this is a perfectly safe maneuver, even though it's done between 600' and 1000' AGL, where a spin wouldn't be recoverable in most circumstances. The maneuver is done by entering downwind, where the bank is steepest. The bank gets shallower until you're directly upwind, and then it gets steeper again, etc, as you maintain a constant distance from the object. When you're downwind of the object, you're crabbed toward it. When you're upwind of it, you're crabbed away from it. So -- how is the moose stall situation different from this?

Possibilities:
1. You aren't consciously executing the PPSEL required maneuver; you're focused on that moose, not on keeping your airspeed within +/- 10 knots.
2. The entry isn't planned; it's willy-nilly, and could be anywhere relative to the wind. You might not even be thinking about the wind direction, because that planning didn't take place.
3. The best view of the object might be on the side where the airplane is most vulnerable, i.e. where the wind is on your tail and the bank is steepest (stall speed is highest).
4. If the airplane is a high-wing, the bank angle required as it points downwind may cause the wing to obscure the object you're trying to look at; you might be tempted to lift the inside wing for a better view, but hold inside rudder pressure to keep the airplane in close enough for viewing.

#4 is a setup for an unintended spin. (Incidentally, it's the same setup we teach as the cross-controlled stall: you're on base leg, you overshoot the turn to final and use inside rudder to tighten the turn so as not to get too far off the final course, while simultaneously using opposite aileron to avoid banking too steeply.)

So I believe that as a primary instructor, I need to include dual in this kind of situation. While flying fairly low for one reason or another, point out something to the student that I'd like to get a better look at. Then teach the student to take a mental step back and plan the maneuver just as if it were a point you were going to do "turns around." It should work out safely then, even at an altitude lower than 600'.

Here in the prairie country, many instructors teach a technique of choosing a point at an intersection of two section-line roads (sections are 1 mile on a side). Then you can fly a 1/2-mile radius circle, say, by identifying the 1/2-mile points on each of the four roads extending out from the point, and simply flying over those points. It makes the instructor's job pretty easy, and almost guarantees that the maneuvers work out every time. The examiners in my area think this is fine, even expect it.

I didn't learn turns around a point this way, because there are no section lines in Hawaii, where I learned to fly. I tend to think this is actually a lousy way to teach the maneuver; it blunts its purpose, which is to be able to fly safely with reference to a [single] outside reference point on the ground, with your attention focused outside the airplane, and simultaneously looking for traffic.

OK, I've gone on long enough. I'd love to hear anybody's thoughts on this!

John

[voorheesh]

I was flying with a friend in a decathalon this weekend and noticed that he made a pronounced skid during a left turn from xwind to downwind at an air strip that has a mountain right next to the left downwind. He probably was overly anxious to turn downwind. We had plenty of speed and power available so I did not feel it was too unsafe. He apologized ( really wasn't necessary) but it made me think about skidding turns. A skid really doesn't do anything for you. There should never be a reason to do a skid unless you are an instructor teaching a cross controlled stall or the consequences of a skid during a turn. A skid and a stall at a low altitude can kill. A slip, on the other hand is a safe maneuver that can help out in situations where we need to lose altitude or correct for wind drift. You could still get in trouble if you stall during a slip. Maybe when you are trying to keep that moose in sight you might inadvertantly push bottom rudder and get in trouble if you don't have enough airspeed.

[hilltop170]

John-
Your #4 possiblility on what causes the moose hunter's stall is exactly what happens. The inside wing is held up to see the target on the ground and the plane is ruddered around while backpressure is held to keep the turn radius tight. Stall, spin, impact, about that quick. When looking down into trees to see a target on the ground from low altitude, most planes cannot do a coordinated circle in a tight enough radius to keep the target in sight, hence the moose hunter's stall.

What is recommended as an alternative is to fly a figure eight maneuver with the cross-over point right over the target and direction reversing turns done away from the target while concentrating on coordinated turns. Then the target can be crossed over in level flight at a safe speed without worring about looking while in a turn. It works very well but the target has to be mentally marked so you fly directly back over it.

[AR Dave]

The Moose Stall has always made me nervous especially while scouting moose, sheep, goats, whatever. Whomever put the bubble windows in my plane sure helped me out. That is the one place that they make a difference!

[jrenwick]

Thanks for the confirmation, Richard. I like the figure-8 idea. I'll go out and try it, and figure out how to work it into my flight review routine.

[dacker]

John, isn't one of the golden rules for instructors to not let the student ever, ever put you into a nonrecoverable regime. While 600' isn't very high to recover from a student initiated spin, it is plenty to recover from the stall that might begin to happen first. At 200' a student initiated stall probably would have you in the ground before you can recover. In other words you probably wouldn't want to teach the conditions that create a mose stall at 200'. Maybe that isn't what you were saying?

Another method to consider for low level observational passes would be an altitude modified crop duster pattern. A pass followed by a slight climb and 45 degree turn downwind for a few seconds then a turn in the opposite direction (45/225) to put you back in line for the next pass. Just another trick to put in the bag,

Of course there are many methods, but none of them are perfect unless we use a good scan and cross check our instruments with outside visual references.

David

[jrenwick]

John, isn't one of the golden rules for instructors to not let the student ever, ever put you into a nonrecoverable regime. While 600' isn't very high to recover from a student initiated spin, it is plenty to recover from the stall that might begin to happen first. At 200' a student initiated stall probably would have you in the ground before you can recover. In other words you probably wouldn't want to teach the conditions that create a mose stall at 200'. Maybe that isn't what you were saying?

No, I didn't mean to suggest actually doing this at so low an altitude. Turns around a point are done between 600' and 1000' AGL, and that's low enough to practice any ground reference maneuvers. My thinking is, if you teach "moose observation" as if it were turns around a point or a figure-eight, there should never be any uncoordinated flight involved.

CFIs are also required to demonstrate a cross-control stall, which is an uncoordinated turn from base to final with inside rudder and outside aileron, but those must be done high enough to assure recovery above 1500' AGL from anything that develops. I go up to at least 3000' AGL and line up on a road for my simulated runway.

[1SeventyZ]

Coincidentally I found myself doing tight observation circles this weekend while flight-seeing over my grandparents' ranch, which abuts some very steep terrain. I had 20 deg flaps out, circling at about 70-80 mph, 2100 rpm or so, at about 2500 AGL (I'm a weenie.) The 170 can make a VERY tight turn at that speed (I've practiced 180 degree canyon turns with 40 deg flaps in the past with an instructor), and a few times I caught myself cross controlling to keep the inside wing up as I maintained enough inside rudder to coordinate. I mentally smacked my face my own face with some leather gloves.

That's something I've always struggled a bit with though: Response to overbanking in a tighter coordinated turn. My first tendency is to arrest it with opposite aileron.

[futr_alaskaflyer]

One thing often discussed but not mentioned here is the danger of encountering your own wake vortices while circling in tight turns. Another reason for the figure eight maneuver, to allow them to dissipate before flying through the same air again.

[mit]

But I like flying through my wake.......

[flyguy]

One thing often discussed but not mentioned here is the danger of encountering your own wake vortices while circling in tight turns.

And the turning "downwind" optical illusion can make a pilot think his air-speed is a little higher and the object being viewed is slipping under the wing faster than expected so he pulls back harder on the stick and guess what ? ? ? an accelerated stall! That is a killer of the worst kind because it usually happens too close to the ground to make a safe recovery! Take a Super Cub or your 170, up to altitude and do those slow tight, high angle of bank turns, then really haul back on the stick and see how much altitude is lost before you can recover

[GAHorn]

John, isn't one of the golden rules for instructors to not let the student ever, ever put you into a nonrecoverable regime. ...

The "student" never "puts" the instructor into a non-recoverable regime. The instructor is the responsible party if the aircraft is allowed to enter such conditions.

The problem can be very elusive, however. What if it's not a "student-instructor" relationship. What if it's just two pilots.... one a new owner and the other actually a passenger who simply offers advice?
Imagine if you have a buddy who wanted you to help him sell an airplane he, himself was unqualified to fly. Imagine he called you to tell you that a buyer wanted to "check out" the airplane, and your buddy asked you if you'd mind riding along to show the plane to the buyer, since you've flown that plane yourself in the past.
The new owner shows up, and you're in the right seat. He's got it on base leg, only a few hundred feet AGL about to turn final (and it's the windi-est week of the year with winds howling across the runway left-to-right) and it's an uncertificated, experimental kit-plane. Since the guy flying is the new owner, and the entire excersize is intended to allow him to "get the feel" of his new plane, you're probably not inclined to "take it away" from him too quickly.... he skids onto final... maybe cross-controls it a bit .... and it IS and uncertificated design......

It might not be as unlikely as you might think to suddenly read about an experienced pilot who gets killed in such a circumstance.

[Bruce Fenstermacher]

George,

Is this story just that, a story that likely could happen? I surely can see this happening. The experienced pilot lets his guard down or thinks the other pilot whom he is not familiar with knows what they are doing.

Or do you know a bit more about the accident that recently took the life of Earl Eastabrook?

BTW, I wanted to say how much I appreciate this discussion. As some of you remember or can see from my signature I also have a Clipped Wing Cub. This Cub now has a C-85 with the 0200 crank installed and it is a real performer. This aircraft is a real hoot to fly. It would SEEM that this Cub can do anything including full cross control slips AND SKIDS at any attitude. The phrase "It would seem" is the operable one here.

And while we don't have Moose in PA you might think we've spotted a Moose when you see how tight we've been guilty of turning about a point. Of course I'm rarely at an altitude that I could recover from an inadvertent unexpected spin, even in a Cub.
While I'd like to say they are all coordinated turns, well if you believe that I've got some land I'd like to sell you.

It's time to start thinking (and teaching) some basics. Thanks guys.

[c170b53]

Its an excellent post, just thinking about the comments and my flying techniques makes me realize that I've been letting my guard down. I have only once banked my aircraft sharp and close to the ground whilst in a strong crosswind. The illusons due to drift are very strong /shocking in that instance and they will stay with me. I also had the good fortune to have a good outcome.

[GAHorn]

George,

Is this story just that, a story that likely could happen? ...
Or do you know a bit more about ....

I read several accounts (and heard a few others) relating that day at La Porte. I do not know for certain what happened. While the NTSB is investigating... I don't know that we'll ever have a definitive answer. And I abhor the arm-chair, Monday-nite accident investigations that we usually hear. But here's the pertinent info I know to be true, and some anecdotes I came to learn:

It was the windi-est week in recent memory. All week long 18 wheelers were being blown over and off the highways in north-central Texas and in the Houston/La Porte area winds gusting 30-40 and higher were being reported. The eye-witness (as quoted by the newspaper..... take that for what it's worth) said he watched the KitFox being flown by it's new owner (with Earl along for "familiarization") in the traffic pattern on base-leg. He said it looked kinda "mushy" . He turned away to talk to a friend when his friend made a startled exclamatory remark about the KitFox. When the eyewitness turned around the aircraft was hitting the ground.

I do not have any special inside information, but I do recall allowing rated pilots to have more leeway in aircraft I was "familiarizing" them with (as opposed to checking them out in)... and as opposed to how I handled inexperienced or student pilots in genuine flight-instruction flights. I have many times allowed those rated pilots to transgress much farther into haphazard manuevers, and recall being reluctant to "take away" their PIC authority. I can't help but wonder if Earl didn't politely allow this unknown pilot, the new owner, to progress farther into sloppy flying than he might have with a student pilot. I know I've done that myself, in the past.

I think I've learned something from this sad tragedy, whether the "hunch" is correct or not.