Descent Rate on Glide Slope

OP’s not a nag and nothing wrong with questions on here, just wondering where the OP got 500 FPM descent rate on downwind? Also, a 3 degree glide path on base? Is this in the traffic pattern AC or AFH?

The FAA recommends speeds on base and final and to shoot for 3 degrees (stabilized approach) but how you get there will vary with aircraft and pilot.
 
Velocity173 said:
OP’s not a nag and nothing wrong with questions on here, just wondering where the OP got 500 FPM descent rate on downwind? Also, a 3 degree glide path on base? Is this in the traffic pattern AC or AFH?

The FAA recommends speeds on base and final and to shoot for 3 degrees (stabilized approach) but how you get there will vary with aircraft and pilot.
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Re: 500 fpm. I thought I read that as a rule-of-thumb somewhere so I wanted to check the math.

Re: 3 deg. I had it in my head to strive for that (esp. since where I train, we mostly go out to a practice area and come in on a straight final, where I strive for the PAPI lights glide slope), so I thought it would be best to establish that altitude/slope as soon as possible in the pattern.
 
Thanks. What's the name of the book? My malware program (at work) flagged that website as a trojan.
 
See How It Flies: Perceptions, Procedures And Principles Of Flight
by John S. Denker

I was in a similar boat, struggling with approaches and landings. Tried different things and found this book helped me. My instructor liked the thumb angle of descent indicator idea.
 
Much appreciated. I found a pdf on the Internet.
 
Trogdor said:
***DELETIA***

Fly the numbers of your plane (power wise) and then adjust *based on your site picture*. I can't stress that enough.
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Amen. In VFR, it should ALL be sight picture, and minor power/pitch adjustments as needed WITHOUT having to stare at gauges. It's not a swiss watch, it's an airplane.

Downwind (in a strut-wing cessna...which most students are using): Runway 1/2 to 2/3 out the strut. At 1000' agl that is about 3/4 mile. Start slowing the plane up at midfield...it's not a race; power to about 1900. 10 degrees flap. Trim. That should give you 90.

Abeam numbers (look out the window), reduce power to <1500, start descent (clenched fist and a half on top of the panel), trim for 80 (knots or mph...doesn't matter) and when rwy is aprx 45 degrees IN BACK, turn base.
Base leg: threshold about half way up windshield? Add in your second notch if ok. Continue descent, using power/pitch to maintain consistent glide path as you see outside the window.
Turn final.
If runway is starting to flatten out, add power and decrease pitch slightly to gain a little airspeed and lift to pull you back up (i know, counterintuitive...I want to go DOWN!)
Runway starting to stand up? Too high? Do the opposite a little.
Runway aiming point steady in the windshield? Add last notch or full, anticipate pitch trim change, trim away pressure. Pitch for 60-65 (the barn door flaps on Cessnas will make that almost automatic).minor power adjustment as needed.
Land.

If you need to practice, get up to 4 or 5 K feet in your practice area, set your sights on -1000 feet for the field, and run through the drill away from the pattern till you get the muscle memory down. And, oh, practice airspeend and config changes, and slow flight (we used to call it MCA). Knowing how the aircraft responds at all the various speeds and requirements for control movement to accomplish your task are key.

And, oh, if you can find a copy of Ron Fowler's "Making Perfect Landings in Light Airplanes" somewhere...it's a gem.

https://www.amazon.com/Making-Perfect-Landings-Light-Airplanes/dp/1560276312

How I've been doing it, and have passed it on to my own students over the years. Eyes out the window. Feel the airplane and adjust as needed.
 
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BryanAV8R said:
If runway is starting to flatten out, add power and decrease pitch slightly to gain a little airspeed and lift to pull you back up (i know, counterintuitive...I want to go DOWN!)
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See, this is where y'all are going to say I'm overthinking.

"Flatten out" - means I'm too low, right?

"Add power" - Got it--power for altitude--I'm with you so far.

"Decrease pitch" - Now you lost me. I've gathered that adding or reducing power without changing pitch will not affect airspeed (much). Adding power will cause me to pitch up to maintain the airspeed I was at. Now you have me pitching up slightly, which will cause me to slow down. If I had already established my final airspeed, why am I pitching for altitude?
 
Keystoner said:
See, this is where y'all are going to say I'm overthinking.

"Flatten out" - means I'm too low, right?

"Add power" - Got it--power for altitude--I'm with you so far.

"Decrease pitch" - Now you lost me. I've gathered that adding or reducing power without changing pitch will not affect airspeed (much). Adding power will cause me to pitch up to maintain the airspeed I was at. Now you have me pitching up slightly, which will cause me to slow down. If I had already established my final airspeed, why am I pitching for altitude?
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The relationship isn't neither all that linear nor all that immediate. Try it at altitude. Well trimmed for level flight. Let go of the yoke. Add power but don't touch anything else. Yes, the airplane will ultimately settle in a climb at the same airspeed. But notice that the first event in most airplanes will be a pitch up moment as the airflow is increased over the wing which will initially reduce your airspeed too.

You're on final with 200-300 feet to go. You don't want to let go of the yoke, add power, and wait while the airplane pitch wallows a bit. So, while I would not refer to it as decreasing pitch, it is a forward pressuring of the yoke to maintain the - sorry - visual pitch picture you had.

The other part is that it's not a pure pitch = airspeed; power = altitude relationship. There have heated arguments about it and the reverse forever, including incredibly stupid examples to prove one side or the other is right. It's really about coordinated use of both. Ultimately, one predominating over the other is nothing more than a teaching technique to move the new pilot from the 2-dimensional world to the 3-D world of flying where the relationships are a bit different than driving a car where hitting the gas pedal means "go."
 
I like the contrast between the art and the science of this subject. Which one is right (maybe more righter?).

For a more art than science discussion there is always "Stick and Rudder" by Wolfgang Langewiesche. A must read in my opinion. I know my copy has a few dog eared pages. I like the old style writing and illustrations.
 
Rgbeard said:
I’m lost at the OP’s assumptions and purpose.

No one’s doing 2,000 ft/min in a GA traffic pattern
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Unless you're flying a tow plane and the gliders are waiting and you're trying to avoid the baby Cessna pilots flying bomber patterns. But not under normal circumstances, no.
 
Keystoner said:
I'll talk to my CFI about this but what would you recommend as more practical?
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Step 1: Look out the window at the runway
Step 2: Do the needful

If your CFI is teaching you per the OP and not the steps above, find a new CFI.
 
Lindberg said:
Unless you're flying a tow plane and the gliders are waiting and you're trying to avoid the baby Cessna pilots flying bomber patterns. But not under normal circumstances, no.
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That's advanced stuff, we mere private pilots really have no need to fly like that.
 
midlifeflyer said:
You're on final with 200-300 feet to go. You don't want to let go of the yoke, add power, and wait while the airplane pitch wallows a bit. So, while I would not refer to it as decreasing pitch, it is a forward pressuring of the yoke to maintain the - sorry - visual pitch picture you had.
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I wasn't questioning the direction of pitch, just the act of pitching at all.

The scenario was that we were low.

@BryanAV8R said add power and "decrease pitch." I understood this to mean pitch up. Fine. We'll slow down a bit but we won't be low anymore.

What I understand you to be saying is add power and add *forward* pressure to the yoke. Power + Nose down pitch = definitely increases airspeed. Why am I pitching down when I want to increase my altitude, that is, achieve a shallower glide path?
 
Keystoner said:
I wasn't questioning the direction of pitch, just the act of pitching at all.

The scenario was that we were low.

@BryanAV8R said add power and "decrease pitch." I understood this to mean pitch up. Fine. We'll slow down a bit but we won't be low anymore.

What I understand you to be saying is add power and add *forward* pressure to the yoke. Power + Nose down pitch = definitely increases airspeed. Why am I pitching down when I want to increase my altitude, that is, achieve a shallower glide path?
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It's about descent rate, not increasing altitude, you are still descending.
 
Keystoner said:
I wasn't questioning the direction of pitch, just the act of pitching at all.

The scenario was that we were low.

@BryanAV8R said add power and "decrease pitch." I understood this to mean pitch up. Fine. We'll slow down a bit but we won't be low anymore.

What I understand you to be saying is add power and add *forward* pressure to the yoke. Power + Nose down pitch = definitely increases airspeed. Why am I pitching down when I want to increase my altitude, that is, achieve a shallower glide path?
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When you add power, the airplane may try to pitch up. Hence the forward pressure on the yoke to maintain your pitch attitude.
 
PaulS said:
That's advanced stuff, we mere private pilots really have no need to fly like that.
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Being able to land from pattern altitude abeam the numbers and get down and off the runway before the larval airline pilot turning base in the next county calls short final is a skill anyone can benefit from.
 
midlifeflyer said:
The other part is that it's not a pure pitch = airspeed; power = altitude relationship. There have heated arguments about it and the reverse forever, including incredibly stupid examples to prove one side or the other is right. It's really about coordinated use of both. Ultimately, one predominating over the other is nothing more than a teaching technique to move the new pilot from the 2-dimensional world to the 3-D world of flying where the relationships are a bit different than driving a car where hitting the gas pedal means "go."
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I'm with you on this. Pitch affects airspeed and altitude. My first inclination is to use it for airspeed though. If I want to increase my cruise airspeed, I'll use both pitch and power in coordination, and stay at the same altitude but at a faster airspeed. Pitching down + Adding Power, in a coordinated manner will accomplish that. Gas pedal on a car isn't just "go." Letting up on it will slow down. Totally with you on this point.
 
Lindberg said:
When you add power, the airplane may try to pitch up. Hence the forward pressure on the yoke to maintain your pitch attitude.
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Understood, but I want it to pitch up. I'm low. (Not arguing here, just trying to keep this back and forth until I have it down.)
 
Google "Region Of Reverse Command". Or visit code7700.com for good technical information.
 
Keystoner said:
Understood, but I want it to pitch up. I'm low. (Not arguing here, just trying to keep this back and forth until I have it down.)
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If you're low on final, when you're flying something like 1.3 VS0, and you pitch up without adding power, you'll slow down, near stall speed, and steepen your approach. This is bad.

If you increase power and maintain pitch attitude, you will increase your speed and shallow your approach. This is good.
 
PaulS said:
It's about descent rate, not increasing altitude, you are still descending.
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Agreed. We want to decrease the descent rate if we're low, not increase altitude. Again, I don't want to pitch down to accomplish that.
 
Lindberg said:
Being able to land from pattern altitude abeam the numbers and get down and off the runway before the larval airline pilot turning base in the next county calls short final is a skill anyone can benefit from.
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Yeah, not at 2000 fpm from 10,000 feet.
 
Lindberg said:
If you're low on final, when you're flying something like 1.3 VS0, and you pitch up without adding power, you'll slow down, near stall speed, and steepen your approach. This is bad.

If you increase power and maintain pitch attitude, you will increase your speed and shallow your approach. This is good.
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This why I'm pounding this: in my head, I've already established (with pitch and trim) the airspeed I want to land and I don't want to change it. If I'm high or low, I only want to touch the power to correct it.
 
Keystoner said:
I wasn't questioning the direction of pitch, just the act of pitching at all.

The scenario was that we were low.

@BryanAV8R said add power and "decrease pitch." I understood this to mean pitch up. Fine. We'll slow down a bit but we won't be low anymore.

What I understand you to be saying is add power and add *forward* pressure to the yoke. Power + Nose down pitch = definitely increases airspeed. Why am I pitching down when I want to increase my altitude, that is, achieve a shallower glide path?
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Because you don't want to slow down too. You press forward, as others said, to maintain pitch. You are in a dynamic aerodynamic event.

I guess there's also a potential misunderstanding of the word "decrease." I took him to mean, "lower."
 
Keystoner said:
This why I'm pounding this: in my head, I've already established (with pitch and trim) the airspeed I want to land and I don't want to change it. If I'm high or low, I only want to touch the power to correct it.
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The highlighted phrase doesn't mean anything to me. And I'm not sure what you intend it to mean. But if you're low, you haven't established anything. You can't be low and on speed. Think about it as an energy state, and you have potential and kinetic energy. Being too low = being too slow. If you try to shallow your approach, you'll slow down, so you must add power. Being too high = being too fast. If you just try to steepen your decent, you'll accelerate, so you have to decrease power (if you have it in, otherwise dissipate potential energy without accelerating by slipping or using drag devices).
 
Lindberg said:
The highlighted phrase doesn't mean anything to me. And I'm not sure what you intend it to mean. But if you're low, you haven't established anything. You can't be low and on speed. Think about it as an energy state, and you have potential and kinetic energy. Being too low = being too slow. If you try to shallow your approach, you'll slow down, so you must add power. Being too high = being too fast. If you just try to steepen your decent, you'll accelerate, so you have to decrease power (if you have it in, otherwise dissipate potential energy without accelerating by slipping or using drag devices).
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I want to land between 65-70 mph. I'm on final and I'm trimmed for that airspeed, but I'm low, so I'll "power for altitude," and that will shallow my descent--decrease my descent rate. No?
 
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Keystoner said:
This is exactly what I want to verify the next time I fly, and vice versa.
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Most airplanes will maintain their trimmed airspeed, or close to their trimmed airspeed for the pendants here, when you change power.

You can be low, below your desired glide path and fast too. In that case, a slight pitch up will slow your descent and slow your airspeed bringing you back on glide path, most likely not requiring messing with power.

Don't overthink it. When I first learned to land I would hit my airspeed, it was 65 or 70 knots, I don't remember, then use power to maintain the glide path.

The more advanced stuff will come, and once you get it, it's really not that advanced.
 
Keystoner said:
I want to land between 65-70 mph. I'm on final and I'm trimmed for that airspeed, but I'm low, so I'll "power for altitude," and that will shallow my descent--decrease my descent rate. No?
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Yes. But with no forward pressure to maintain pitch, it will also initially decrease your airspeed. It may even cause a momentary balloon, increasing your altitude. And if it decreased your airspeed to the reverse side of the power curve, it will increase your descent rate.

You may be an engineer but I think your equations may be off by focusing on only one variable.

when I teach primary students I try to remind them that the theory of a maneuver is a way of anticipating what control inputs may - emphasis on "may" - be necessary. But we fly airplanes, not theories.
 
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