Landing Technique Question.

[tgrayson]

I also teach them that with a static power setting, if they reduce the angle of attack, they will gain airspeed.

If you remove the "with a static power setting," it becomes perfect. If you lower your AOA, you go faster no matter what.

 

[tgrayson]

If a pilot increases the throttle in level flight, retrims (perhaps without thinking about it), and continues along at the same altitude but a higher airspeed, does he perceive that he has changed his speed with the throttle or the yoke?

Oh, he absolutely perceives that. In fact, that's probably the source of the bulk of the confusion on this subject.

This is a really tough medium via which to convince the skeptics. The seed will take root only in very fertile soil. However, I put on a great whiteboard presentation.

Fully addressing this topic requires the lift equation, an understanding of static longitudinal stability, thrust and power curves, and a basic understanding of Newton's laws.

 

[Fly_Unity]

Either way, both methods are exactly the same thing.
In a C152 if your trimmed out on the glide-slope and add power... the nose will pitch up, and airspeed will actually decrease if your keep your hands off the yoke. In a Seminole (T-tail) the nose will stay close to the same pitch, and airspeed will increase.

out of the 140 hours of multi time I did, I always did Power for Airspeed for everything, including slow flight, and it worked awesome for me, and my flight partners at ATP.
however Im teaching in a 152 at the moment and teaching pitch for airspeed because no one I talked to here at my flight school even heard of teaching the other way, and I dont want to cause a ruckus

 

[Pilot2087]

If the FAA recommends that we use power for airspeed on an instrument approach, why change it on a visual approach? what about if your doing a visual ILS approach? what about if your doing a VASI approach?

Just teach landings, stalls, slow-flight, cruise, and approaches all on the same method, That's my theory

 

[tgrayson]

Either way, both methods are exactly the same thing.

Unless you're very slow and very close to the ground. No pitching for altitude here. And no powering for airspeed in a glider. The differing rules for different flight regimes are a key that something is amiss with the theory.

If the Seminole truly will keep the same pitch during a power change on approach, then there must be a compensatory nose-down moment provided by the thrust, although I have a hard time imagining it in that airplane (I haven't flown it.) In comparison to the C152, it will clearly lack the nose up moment associated with the prop wash over the horizontal stabilizer. However, the general rule that an aircraft strives to maintain its trimmed airspeed applies to T-tails as well. Adding power and keeping a constant pitch attitude means that the AOA must have decreased, but from your description, the mechanism isn't clear. I still suspect a small trim change.

 

[tgrayson]

If the FAA recommends that we use power for airspeed on an instrument approach, why change it on a visual approach?

You're very far on the front side of the thrust curve, as I pointed out earlier, and aren't likely to get behind the thrust curve while on instruments. Minute changes in AOA will change your angle of descent nicely.

Hopefully, by the time a pilot reaches instrument training, he fully understands that AOA controls airspeed and offering a different model won't upset that.

Teaching that elevators provide some degree altitude/descent/climb control is entirely appropriate, because they do. You have an initial zoom/dive effect, followed by an increase or decrease in drag that establishes a flight path change. However, I do think it's a mistake to have a student get the idea that the elevators are the *primary* control for altitude, because there are some occasions when you pull back and you go down, and some occasions when you push and you go up.

 

[Fly_Unity]

Unless you're very slow and very close to the ground. No pitching for altitude here. And no powering for airspeed in a glider. The differing rules for different flight regimes are a key that something is amiss with the theory.

If the Seminole truly will keep the same pitch during a power change on approach, then there must be a compensatory nose-down moment provided by the thrust, although I have a hard time imagining it in that airplane (I haven't flown it.) In comparison to the C152, it will clearly lack the nose up moment associated with the prop wash over the horizontal stabilizer. However, the general rule that an aircraft strives to maintain its trimmed airspeed applies to T-tails as well. Adding power and keeping a constant pitch attitude means that the AOA must have decreased, but from your description, the mechanism isn't clear. I still suspect a small trim change.

or if your really high and fast you dont want to pitch for an airspeed either. You will have to use a combination of both, just like if you are slow and low you use both.

Also there is a slight pitching up in the Seminole when adding power, just not as dramatic as a 152 or 172. My first Multi Instructor tried (and failed) to demonstrate a trim stall to me in the T-tail, but adding power did not decrease airspeed. (unlike a 152)

 

[tgrayson]

or if your really high and fast you dont want to pitch for an airspeed either. You will have to use a combination of both, just like if you are slow and low you use both.

Sure. If you're high and fast, you must increase your AOA to slow down, but if you do that without reducing power, you're going to zoom higher. So you throttle back to steepen your descent, followed by a pull back on the yoke to reduce your airspeed. The power reduction sorta neutralizes the zoom.

If you're low and slow, however, you need to add power and push the yoke, otherwise you may be stuck behind the power curve and not get a climb at all, if the aircraft doesn't have lots of excess power. You may initially descent a little more, but then a climb should result, if you haven't hit the ground yet. If you pitched for altitude, you'd either stall or get further behind the power curve.

 

[derg]

Just add lukewarm beer and a couple of unkempt, albeit unnaturally popular ladies and we could call this a classic example of a Riddle party.

 

[MidlifeFlyer]

If the FAA recommends that we use power for airspeed on an instrument approach, why change it on a visual approach? what about if your doing a visual ILS approach? what about if your doing a VASI approach?

Just teach landings, stalls, slow-flight, cruise, and approaches all on the same method, That's my theory

That theory works. So do others. The other is that the methodology that is used to teach should be based on the target audience and the instructional goal.

For example, despite my disagreement with tgrayson on the "gospel" or "science" of it (I've heard scientific explanations exactly opposite his by true believers on the other side of the issue), I teach pitch for airspeed, power for altitude at the primary level because the instructional goal is to get the pilot to think in three dimensions and I personally think that this is a more effective method for me to use at that stage where the intuitive "pull up and the houses get smaller" is potentially dangerous in most critical situations. With an engine failure on takeoff, I want that first reaction to be pitch down to maintain flying speed, not pull up to maintain altitude. But that's just me.

On the other hand, when teaching an instrument approach, I think that we generally do better making the very small pitch changes needed to stay on glideslope with the yoke than with the throttle and that the accompanying changes in airspeed are small enough to be acceptable. But again, that's an instructional goal.