Getting slow on final

berge7f9

berge7f9

Well-Known Member
I must confess that I am a relatively new CFI that is just starting to teach my students how to land. So far I am having problems having them maintain a stabilized approach upon landing. Most of them are getting slow especially on the base to final turn (10 knots). I am having them use the power for altitude, pitch for airspeed relationship up until the point where they are about to turn final, where I reverse the relationship so it conforms with the Airplane Flying Handbook. Is this a common problem that some people experience? If so, how do I fix or correct it?
 
Perhaps pull up some literature from the NTSB about stall/spin awareness and why it's important to maintain a stable airspeed on base-to-final.

Always worked for my students when they had a peek at the information.
 
berge7f9 said:
I am having them use the power for altitude, pitch for airspeed relationship up until the point where they are about to turn final, where I reverse the relationship so it conforms with the Airplane Flying Handbook.
Click to expand...

Yuck. Don't you think students will be confused that physics changes on final?;)

berge7f9 said:
Is this a common problem that some people experience? If so, how do I fix or correct it?
Click to expand...

Yes, it's common. First, trim. Your elevators control airspeed and trim controls your elevators. Hold a light grip on the yoke so that the pilot can recognize a needed trim change and doesn't override the trim that's there. If they're getting slow, they're either not trimmed, or they are unconsciously pulling back on the yoke. The latter happens more as they approach the ground, particularly if they're undershooting a bit. You can control altitude in an intuitive way with the yoke only on the front side of the thrust curve. Once you slow below that point, pulling back on the yoke will make you undershoot more, which is why this isn't a desirable thing to teach. Why teach slow flight at altitude if we're going to ignore its lessons in the flight regime it's supposed to duplicate?

The single most imporant lesson I can teach a student pilot is if they want to go faster, PUSH! If you're low to the ground, you'll need power, maybe lots of it to keep from hitting the ground. I will not solo 'em unless I see that push.
 
I agree that the pitch for airspeed and power for rate of descent is the best method. Despite which portion of the pattern they are in. A lesson on load factor and stall/spin awareness will illustrate the need for airspeed control on the base to final turn. You can also illustrate that by doing some accelerated stalls at altitude. I have been limited to ground instruction so far, but this has produced some positive results so far.
 
berge7f9 said:
So far I am having problems having them maintain a stabilized approach upon landing. Most of them are getting slow especially on the base to final turn (10 knots).
Click to expand...

When you point out to your students that they are 10 knots slow is their response A) Gee, thanks I didn't realize I was slow. B) yeah, I know I'm slow but its hard to maintain a steady speed. or C) So what if I'm a little slow on base to final. ?
 
berge7f9 said:
I am having them use the power for altitude, pitch for airspeed relationship up until the point where they are about to turn final, where I reverse the relationship so it conforms with the Airplane Flying Handbook.
Click to expand...
Well, that's strange. That's exactly backwards from what most of the "pitch-to-airspeed" advocates do.

Most of the 'pitch-to-airspeed' people switch to that on final, but pitch to altitude - power to airspeed elsewhere. Do you mean you are flying the downwind powering to altitude and pitching to airspeed?

Anyway, however you do it, it should be consistant - that is the biggest problem I can see. There is no reason to change methods on final.

Unless you are intentionally going to slow to 1.2 or less times stall, then you are in the 'area of reverse command', then you do need to pitch to airspeed, but you're not doing that with new students, so keep it consistant.
 
nosehair said:
you're not doing that with new students, so keep it consistant.
Click to expand...

But he will. Remember that the power curve isn't as relevant as the drag curve for an approach. Any slowing below best glide means that the descent angle is getting steeper. The short field speeds are pretty close to best glide with full flaps in the Cessnas, as I recall.

I do agree that consistent is better than what he's currently teaching, but better still is consistent and correct. ;)
 
The only times "Pitch for altitude, power for airspeed" makes sense to me are:
1) On the ground roll for takeoff
2) To maintain altitude while adjusting airspeed in level flight
3) To maintain altitude while performing steep turns

Any other time (climbs, descents, slow flight, approach to landing), it's "Pitch for airspeed, power for altitude", regardless of what the FAA handbook says.
 
Dazzler said:
The only times "Pitch for altitude, power for airspeed" makes sense to me are:
1) On the ground roll for takeoff
2) To maintain altitude while adjusting airspeed in level flight
3) To maintain altitude while performing steep turns

Any other time (climbs, descents, slow flight, approach to landing), it's "Pitch for airspeed, power for altitude", regardless of what the FAA handbook says.
Click to expand...

I agree that it's sometimes helpful to use the "pitch for altitude" paradigm, but I try to teach people why that occurs, once they reach a certain level of training. By changing your airspeed, you slide your aircraft up and down the power required curve, creating power excesses or power deficits.

Even in the scenarios you mention, reality doesn't change:

1) On the ground roll for takeoff. Rotating changes your AOA to the point where the present airspeed will provide positive lift on the aircraft. The subsequent climb depends on having sufficient thrust to overcome the drag at that airspeed. If your AOA is too high, or thrust too small, you may not leave ground effect.

2) To maintain altitude while adjusting airspeed in level flight. Small changes in AOA change the drag on the airplane allowing small climbs and descents.

3) To maintain altitude while performing steep turns. If you don't increase your AOA during the turn, the aircraft will accelerate to an airspeed where lift = weight. Unfortunately, you will be in a steady descent due to increased parasite drag. You can return to level flight by adding power, but your airspeed is still too high, because your angle of attack is too small for your weight at that load factor. The only way to slow the airplane down to your original speed is to increase the AOA.
 
tgrayson said:
I agree that it's sometimes helpful to use the "pitch for altitude" paradigm, but I try to teach people why that occurs, once they reach a certain level of training. By changing your airspeed, you slide your aircraft up and down the power required curve, creating power excesses or power deficits.

Even in the scenarios you mention, reality doesn't change:

1) On the ground roll for takeoff. Rotating changes your AOA to the point where the present airspeed will provide positive lift on the aircraft. The subsequent climb depends on having sufficient thrust to overcome the drag at that airspeed. If your AOA is too high, or thrust too small, you may not leave ground effect.

2) To maintain altitude while adjusting airspeed in level flight. Small changes in AOA change the drag on the airplane allowing small climbs and descents.

3) To maintain altitude while performing steep turns. If you don't increase your AOA during the turn, the aircraft will accelerate to an airspeed where lift = weight. Unfortunately, you will be in a steady descent due to increased parasite drag. You can return to level flight by adding power, but your airspeed is still too high, because your angle of attack is too small for your weight at that load factor. The only way to slow the airplane down to your original speed is to increase the AOA.
Click to expand...

Right, I understand that in all cases the aircraft doesn't "know" if you're pitching or powering for altitude or airspeed, and that pitch + power = performance, but I was referring to teaching the pitch/power relationship, and the ease of which the student can understand what's going on.

Apart from the above 3 instances, I teach pitch for airspeed, power for altitude - even for Instrument approaches, but let's not get into that!
 
Dazzler said:
Right, I understand that in all cases the aircraft doesn't "know" if you're pitching or powering for altitude or airspeed, and that pitch + power = performance, but I was referring to teaching the pitch/power relationship, and the ease of which the student can understand what's going on.

Apart from the above 3 instances, I teach pitch for airspeed, power for altitude - even for Instrument approaches, but let's not get into that!
Click to expand...

I agree. Just wanted to make sure that people understand that the aerodynamics is consistent.

But there is a saying that is applicable: "A little lie saves a world of explanation."
 
You might try practicing some slow flight at altitude. That'll help engrain what control inputs are required to control airspeed and altitude. If they can do it well in slow flight, they should be able to do it well on final. Also, what works for me when my students get slow on final is keep telling them "its okay to be a litle to fast, its NOT okay to be a little to slow" Hold them to airspeed +15 or -0, stress the importance of a stabalized, controlled airpeed on final, and don't let them solo until they demonstrate that to you.
 
From a student's perspective, when I was training for my Private, I had a similar problem getting slow on final, and I attribute a lot of the problem to not having a good visual Idea in my head of what the descent angle should look like. Looking back, I think it would have been a good idea to go up in the pattern one day and "trade-off" landings. This being I do one, instructor do one, i do one etc..so I could have seen how she did it, and compare it mentally with mine. Not having to worry about the landing, I could have studied not only the visuals outside the plane, but also the instruments and how the instructor handles the plane. I just think this will help them "feel" the landing a little better and will help in wind corrections in the future...

cheers.
 
When I was a student pilot, one thing that helped me a lot was that my instructor made me say the airspeed for each leg of the pattern out loud.
 
flyguy said:
You might try practicing some slow flight at altitude.
Click to expand...
Remember that 'slow flight' is just above a stall. It is called 'area of reverse command' because at those low speeds pitch does control airspeed and power to the altitude. Reverse from normal, which is where you are on a normal approach. You are not in the area of reverse command so you pitch too the altitude or glide path angle and control the airspeed with throttle.

Insistance on doing it the other way is because that is how you were taught and it has become comfortable, and you don't wanna change.
That is your personal preference, but professional instructors, or professionalisim itself demands that we grow with the times and changes.

It is not professional for a teacher to 'be a rebel' and go with his/her personal preference when a significant amount of evidence indicates that he/she should at least explore the possibilities of the changing environment.

I do it because my students find the ability to make more precise approaches when using power, and it doesn't require a 'change' in control input habits when redicing power on the downwind.

The change of control input only comes about when we are doing a very slow approach, usually below the published recommended speeds for a short field. Most of today's trainers have published short field approach speeds above 1.3 x Vso, so the energy is there to safely maintain glideslope with pitch even on an FAA short field.

On a real life short field, I will be about 1.2 x Vso and THEN I will pitch to airspeed. Maybe that is what drives this discussion; fear of getting behind the power curve and still trying to pitch to altitude. If that is the case, I still maintain that it is the instructor's responsibility to teach this to the student.

Yeah, that's maybe harder that opting for the easy way; 'Just always pitch to airspeed and you'll always be safe'.

Yeah, but you'll have more difficulty later when you are trying to make a precision spot landing or ILS approach.
 
nosehair said:
Hmm...let's see, which 'hazardous attitude' is that?...Anti-Authority?...Macho?...
Click to expand...

No, it's being accurate (mostly). The FAA is no authority on how airplanes fly, so he can't be acting anti-authority. In fact, many of their statements in the past editions of the airplane flying handbook (Flight Training Handbook) have been ludicrous.

The present edition is less ludicrous only because it talks less about aerodynamics. In some places it merely says "adjust pitch and power to maintain airspeed and glidepath" leaving the pilot to figure out what to adjust.

To be more correct, it's AOA that controls airspeed, always, front or backside of the power (or thrust) curve. And it's excess power (or thrust) that controls rate (or angle) of climb, always. These concepts are fundamental to the study of aerodynamics.

If any FAA publication says differently, then it's as incorrect as if it said the sun orbited the earth.
 
nosehair said:
Yeah, that's maybe harder that opting for the easy way; 'Just always pitch to airspeed and you'll always be safe'.

Yeah, but you'll have more difficulty later when you are trying to make a precision spot landing or ILS approach.
Click to expand...

Why would someone have difficulty? I still use pitch for airspeed, power for altitude for spot landings or instrument approaches, and I do just fine.
 
nosehair said:
Remember that 'slow flight' is just above a stall. It is called 'area of reverse command' because at those low speeds pitch does control airspeed and power to the altitude. Reverse from normal, which is where you are on a normal approach.
Click to expand...
Is that last statement accurate? Isn't the region of reverse command any airspeed below L/D Max due to the increase in induced drag? I'm pretty sure normal final approach-to-landing speeds qualify, especially in the scenario that is the subject of this thread: "Getting slow on final."
 
You must log in or register to reply here.
Back
Top