Established glide path

[rezaf_2000]

Hi everyone, long time no see Even though I was not active on the forum, I've been active flying in the past couple of months. I ended up switching to private pilot training in a larger airplane (Piper Archer), since it was much more convenient location-wise and access-wise.

Anyway, I have got to a point that I can control the airplane and understand what's happening with about 50 hours so far. I have around 3 hours of solo so far as well. Having said that, I'm still not happy with my patterns and landings. Abeam the numbers I'm at the right altitude and air speed. I reduce RPMs, pull first notch of flaps and so on. But everytime I end up being 100 feet higher or lower in my turn to final. My skills at this point are developed enough to identify and correct for this (add RPM or go to idle), and my landings are all safe landings, but I'm not happy about them needing correction with RPMs. Basically most of my landings are "saved" landings, not a nice glide from "turn to final" to "touchdown". I'd like to see red over white the whole way, but I typically either see white over white, or red over red at the turn to final.

I assume this is not the way it's supposed to be, since my instructor(s) have hit the mark every single time. But here's my question: We know that winds and other minor issues like the exact point of turning from downwind to base, and from base to final might be different for each landing. Are RPM corrections always part of the game? Or am I still sloppy and need more practice?

Any suggestions on how to improve?

[SportPilot]

.......

[3Dreaming]

Ah, the mysteries of landings. No one simple cookie cutter landing procedure is going to work right every time, because there are to many variables. What you need is a base line to make adjustment from, which it sounds like you have. One thing your instructor might have forgot to mention is that with him out of the airplane it is going to glide farther if you don't make any corrections. To correct for them not being in the airplane you will have to travel farther or reduce power a little more to be at your target altitude turning final.

As a side note the PAPI's are great for landings when transitioning from instruments or at night, but I wouldn't worry about them to much during the day. For daytime approaches I much prefer to be above the glide path and reduce power to idle and achieve the red over white as I am close to the runway, instead of dragging it in under power.

[rezaf_2000]

Ah, the mysteries of landings. No one simple cookie cutter landing procedure is going to work right every time, because there are to many variables. What you need is a base line to make adjustment from, which it sounds like you have. One thing your instructor might have forgot to mention is that with him out of the airplane it is going to glide farther if you don't make any corrections. To correct for them not being in the airplane you will have to travel farther or reduce power a little more to be at your target altitude turning final.

As a side note the PAPI's are great for landings when transitioning from instruments or at night, but I wouldn't worry about them to much during the day. For daytime approaches I much prefer to be above the glide path and reduce power to idle and achieve the red over white as I am close to the runway, instead of dragging it in under power.

Thanks a lot for the answer. So, there is no cookie cutter method. That makes me feel better, knowing that there are too many variables and adjustments are actually part of the game. So all I need to do is to develop my technique to identify deviations earlier and adjust the RPM as soon as I find it out, correct?

I'll ask my CFI too tomorrow morning.

[FastEddieB]

One thing your instructor might have forgot to mention is that with him out of the airplane it is going to glide farther if you don't make any corrections. To correct for them not being in the airplane you will have to travel farther or reduce power a little more to be at your target altitude turning final.

Well, that's only partially true.

Against common sense, a given plane will glide exactly as far as when it's heavy as when it's light*.

That's IF the speed is adjusted appropriately. A heavier airplane needs to go faster to arrive at the same point, and a lighter plane slower.

Best glide speed is normally given at max gross, as are stall speeds. Therefore, when lighter than that, actual best glide speed would be at a slightly lower speed. Most often in primary training that small difference is ignored, but it's real.

Back on point in my next post.


*My "reductio ad absurdum" thought exercise is to imagine identically shaped planes, one made of lead and one of styrofoam. From 10,000', with no wind, each will arrive at exactly the same point on the ground if glided at the appropriate speed. The light plane would come wafting down at a very low speed, while the heavy one would come screaming down like a lawn dart. But both will go the same distance. Now, figure out why "no wind" had to be specified!

[FastEddieB]

Again, you should listen to your flight instructor over the many varied opinions you'll get here.

One thing that works for me is to "play the turn to final". That means changing the angle of the base leg a bit to "fine tune" an approach. If you look high on the base, angle slightly away from the runway. That gives you more time and space to lose altitude. If you look low, angle back in a little bit.

Since primary students are graded on their ability to fly a perfectly rectangular pattern, if you do decide to use this technique, make sure your instructor or examiner are aware that you're varying from it intentionally. Or just save this little "cheat" for later.

[FastEddieB]

Deleted - duplicate.

[MrMorden]

I was taught that LSA, because of their low inertia, should more or less ignore VASI/PAPI lights, as the standard 3° approach is too shallow for LSA that sink fast and tend to come in steeply. I have found that to be true in my flying. My normal approach has me well above the glide slope (all white lights) for most of the approach. then somewhere close to the runway I'll be on glide slope for a moment, then immediately sink through it to all red lights.

Given that I fly an airplane that generally ignores the standard glide slope...

IMO, It's easier to maintain glide slope from slightly low -- you simply add power until you intercept the glide slope, and then use power adjustments to maintain it.

HOWEVER

I think it's also much *safer* to be on the high side of the approach, so that if there's an engine failure that you can still make the runway. From a high position you have more tools available to adjust your glide slope: power reduction, more flaps (if not yet at full), slipping, or increased sink by pitching for a slower speed.

From below the glide slope, you have one option, more power, and if the engine fails you have no way to make the runway. Above the glide slope, your problem is no longer making the runway, it's just where on the runway you are going to touch down. That is a much more comfortable problem to have.

On glide slope would be ideal, but if you are going to be off of it I'd recommend erring on the side of high. That means recognizing and correcting a "below glide slope" condition ASAP and immediately correcting it. You should probably do the same for "above glide slope" situations, but in my mind the urgency for correcting that is not as great because you have better options and safety margins in that case.

And as always, if the approach is not working out...GO AROUND!

[MrMorden]

One thing that works for me is to "play the turn to final". That means changing the angle of the base leg a bit to "fine tune" an approach. If you look high on the base, angle slightly away from the runway. That gives you more time and space to lose altitude. If you look low, angle back in a little bit.

Great advice, I do this all the time! At towered airports if they are trying to fit you in ahead of other traffic, they will sometimes tell you to "head for the numbers". That's a similar thing, they are angling your base to adjust your flight path, and it's up to you to get there at the right airspeed and altitude to make the landing.

[FastEddieB]

Wow!

I agree with every word in Andy's post.

Good job.

[MrMorden]

Wow!

I agree with every word in Andy's post.

Good job.

Thanks! Even a blind squirrel finds a nut now and again...

[3Dreaming]

One thing your instructor might have forgot to mention is that with him out of the airplane it is going to glide farther if you don't make any corrections. To correct for them not being in the airplane you will have to travel farther or reduce power a little more to be at your target altitude turning final.

Well, that's only partially true.

Against common sense, a given plane will glide exactly as far as when it's heavy as when it's light*.

That's IF the speed is adjusted appropriately. A heavier airplane needs to go faster to arrive at the same point, and a lighter plane slower.

Best glide speed is normally given at max gross, as are stall speeds. Therefore, when lighter than that, actual best glide speed would be at a slightly lower speed. Most often in primary training that small difference is ignored, but it's real.

Back on point in my next post.


*My "reductio ad absurdum" thought exercise is to imagine identically shaped planes, one made of lead and one of styrofoam. From 10,000', with no wind, each will arrive at exactly the same point on the ground if glided at the appropriate speed. The light plane would come wafting down at a very low speed, while the heavy one would come screaming down like a lawn dart. But both will go the same distance. Now, figure out why "no wind" had to be specified!

How does the addition of some power effect how far the airplane is going to travel? What about the removal of weight with the same power setting and airspeed?

[designrs]

they will sometimes tell you to "head for the numbers". That's a similar thing, they are angling your base to adjust your flight path, and it's up to you to get there at the right airspeed and altitude to make the landing.

I'm a little surprised that this phraseology is legal. It could really throw off a student or new pilot that does much better with a standard pattern. Always remember that you can use the option of "unable". As pilot, you have the responsibility fly the plane safely, not the tower. The controller may or may not even be a pilot.

About a year or two ago a pilot spun the plane in after the tower aggressively "ordered" the plane to do something like, "turn right now, hard!".

If Class-D, communication is required. Absolute compliance is not. Being polite helps.

[MrMorden]

If Class-D, communication is required. Absolute compliance is not. Being polite helps.

UNTRUE. FAR 91.123(b) states:

(b) Except in an emergency, no person may operate an aircraft contrary to an ATC instruction in an area in which air traffic control is exercised.

A Class D airspace is "an area in which air traffic control is exercised."

You must comply, or declare an emergency. You might get away with saying "unable" if you have a compelling reason.

[designrs]

Thanks Andy. Apparently, I stand corrected, but I swear, I thought only communication was required in Class-D.

My understanding was that absolute compliance was only required in Class-B, of course emergency situations are always exceptions.

The confusion must result from requirements to enter the airspace:
Class-B: you must hear, "... cleared into the Bravo."
Class-D: you must hear the tower say your N-number (communication established).

Still... "Unable" is always an option... easier to negotiate without further inquiry in Class-D, with reasonable cause.