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-   -   Thrust on during flare...Q for AIRBUS test pilots... (https://www.pprune.org/tech-log/536616-thrust-during-flare-q-airbus-test-pilots.html)

nitpicker330 26th Mar 2014 06:18

Can't say I've ever heard Retard called 3 times.......I've heard "five" called twice!!

You must have been floating down the runway in the flare? I can't imagine you'd already touched down and forgot to close the thrust?

Our mob used to be anal about the touchdown zone too but have decided that idea was the cause of more than one firm/hard landing so they became a little more practical.

The F/O landing a week or two ago gave a rather large early flare resulting in a float and higher pitch attitude on touchdown, the speed went back to about VLS -2. I didn't say anything to him at the time as it would have been an unnecessary distraction at a critical time, we weren't going to stall. His landing was actually very smooth and didn't give the usual A330 bogey thump!! Maybe he does this all the time:ok:

Anyway like I said if you've got a sink in excess of what you want then leave the thrust on until you touchdown otherwise close the thrust as usual.

737Jock 26th Mar 2014 08:13

Blogs first of all thank you for being so civilized and discussing issues in a normal way instead of ridiculizing people which would only be a sign of intellectual weakness. :SARCASM OFF:
I don't expect you to understand. But there are several ways to skin a cat. Some students have trouble learning how to flare and finding the right pitch attitude.
We are not talking about Boeing's here old chap, but little cessna's. But even so the following is true for a Boeing as well.

A flare is nothing other then arresting the descent rate to zero except its close to the ground. Which happens to be the same when you go from a descent into level flight.
So unsurprisingly the pitch attitude for a flare at a certain configuration is the same as the pitch attitude for level flight in the same configuration.
You want some students to be able to see that picture of the flaring pitch attitude a bit longer so they have more time to understand.
So if you make them fly level at low level they have much more time to store that picture they see out of the window and replicate it in the flare.

But thanks again for showing your complete lack of actual understanding of what you are doing.
When you next read a book on POF try to actually understand what is happening instead reproducing it blindly.

FYI I never said that thrust for speed doesn't work, I said that either statement is correct. Think gliders!

And btw any speedtrimmed aircraft can be flown only with thrust on an approach. If you are low on speed on the approach you clearly didn't trim your aircraft very well.
An aircraft that is trimmed for speed will aerodynamicly lower it's nose to regain it's trimmed speed, thereby increasing it's rate of descent and dipping below the path. Adding power will reduce vertical speed.
And that is POF regarding trimming an aircraft for speed. And yes I have flown light aircraft solely with trim and power to a successful landing.

A speedtrimmed aircraft with lack of energy won't stall, it will hit the ground. The only reason it will stall is because we are trading it's forward energy to maintain the path.
I'd rather be at 200 feet and on speed then at 300 feet and stalling.

Good luck btw with being 7 kts slow. It's still unacceptable to me.

NoodleAir 26th Mar 2014 08:48

737jock, don't even bother, they are the same person and he does not fly jets.

He cannot comprehend simple concepts and principles of flight.

"You belted and hit the nail on the head" ?!!!!??? :ugh:

When he hears 'Retard" 3 times, I suspect its his wife calling while he is on the sim.

737Jock 26th Mar 2014 08:53

RETARD is a reminder to close the thrust in manual flight, in autoland it's an instruction.

nitpicker330 26th Mar 2014 09:01

I don't know why I'm doing this but......

I can assure you that I'm not the same person as Bloggsy, if you'd bother to research you'd see that Bloggsy and I have chatted before on various threads, we've not always seen eye to eye on all matters but I do respect his experience and position.

Yes I am a real A330 Captain based in Australia for a major HK Airline. I hope you have the brains to workout which one. You know the one with the impeccable safety record and worldwide network that employs cockpit crew from all over the world, yes that one.

Once again if you'd bother doing some research it would show that I have a knowledge of the A330 777 and Airline operations that a Flight Sim jockey would not have. Short of posting real photos of my mug sitting in the Jet or my ID card you'll just have to take my word for it I guess.

Now, I'd really appreciate it if you would stop casting aspersions over my qualifications thankyou very much young man.

Oh and yes I do have XPlane on my iMac with the A320 setup, works quite well most of the time but I haven't used it for 6 months as the DVD drive is playing up.
As fun as it is it's not really useful for PC RT practice though. You do know what a PC RT is don't you pal?

As you don't seem to have the approach stable I'm going to have to press the Sidestick priority button now, I HAVE CONTROL.

Land, no blue.

Goodnight.

NoodleAir 26th Mar 2014 09:41

Fair enough…

I do not care to do "research" on your previous conversations with Bloggsy or whoever else.
It was mostly Bloggsy that used the "we" repeatedly and raised some eyebrows because he could not explain anything but elected to cover himself behind the "collective knowledge" and your common opinions.

In any case, I stated my view very clearly in my first post, then you replied with the attitude you did, unfortunately with a wrong theory.

I did not say it does not work either way. I only said that the laws of physics and all the fundamentals of flight are opposite to your theory. Now, I have this concept in my mind when I actually do it, you have yours, and it obviously works as well.

Merely trying to highlight the need for proper instruction theory when you need to explain your experience to someone that is asking "how do we do this".

Needless to say that I would have guessed who you might be flying for, judging from your "authority" in the matter and your rigid point of view.
Keep in mind that there are many pilots out there doing the same job without the need to be so uptight.

I stand by my initial request. Open this book you purchased back in '82 or something, and tell me what it says on the PRINCIPLE of what is controlling what.
Forget about the way Cathay is doing it, or how it works when you do it upside down backwards. Its all possible in many ways.
Just give me an honest answer ON THE PRINCIPLE. And then judge my initial post and your negative ones.

You have controls, now let me sleep.

InSoMnIaC 26th Mar 2014 09:41

Think of it this way. The control column acts as a potential(altitude) to kinetic (spd) energy converter. Pushing down increases kinetic energy and reduces potential energy and visa versa.

Thrust introduces more or less energy into that equation. All thing being equal increasing thrust, Firstly pushes the aircraft forward thereby increasing spd over the wing which in turn increases lift which changes the flight path of the aircraft(reduced ROD)
if the total energy (potential+kinetic) of the aircraft is correct but out of balance (low and fast or high and slow) then there is no need to adjust thrust . Simply use the flight controls to re distribute that energy.

if you rely on thrust to change flight path (to arrest ROD in flare) it will work however it will take slighty longer to achieve as you are relying on the secondary effect of adding thrust (similar to flying around and using the rudder to bank)

Capn Bloggs 26th Mar 2014 12:21

Insomniac, I like that description of the situation. :ok:

737Jock 26th Mar 2014 12:49

It won't take longer. That is simply incorrect.

You are all so fond of examples, so if you climb or descent do you first change thrust and then you raise or lower the nose to maintain speed. (in a trimmed aircraft this would happen aerodynamically anyway).
The power excess or deficit is what makes you climb or descent.

Say we have an aircraft at 2000ft, fully configured and stable and trimmed Vapp, there are no external disturbances (wind, up/downdraft) and no weight changes.
This aircraft has a certain energy (performance) that is required to fly a 3 degree path. this energy does not have to change until landing as there are no disturbances, so no changes in pitch or power are needed.
If we then add external factors to this equation the situation changes: say we emcounter a downdraft. The required energy to maintain the desired path increases.
The actual energy of the aircraft (performance) is determined by pitch + power/ thrust. Due to the increased requirement of energy to maintain the path we are faced with an energy deficit.
I have 3 options:
1. increase pitch trading speed for for height, this will result in speed loss which reduces the energy state thus you need to add energy with thrust.
2. increase thrust, this directly increases the energy state balancing it with the energy requirement
3. increase pitch trading speed for height and increase thrust directly adding energy to the airframe

So thrust simply gives us a tool to increase/decrease the energy of the aircraft. whereas pitch only allows us to convert 1 type of energy into another. As with all energy conversions energy is lost (heat/drag/etc) so in the end you will still end up with a deficit that needs to be compensated for.
Both thrust and pitch control the path.

Adding thrust always adds energy, it doesn't always increase speed.

Thrust for speed is just a tool to allow people to easily manage the energy. But that is only because we use speed as a measure. whereas energy is more then just speed, its also mass, height etc....
In a balloon you could dump mass to counter for a downdraft.

vilas 26th Mar 2014 14:17

InsoMniAc
Adding power without changing flight path will not work in Airbus FBW as Flare mode is pitching the aircraft down from 30 FT . You will end up hitting the ground harder. On other aircraft there is no defined thrust parameter which will give you consistent flare for you. So you are taking a chance too much will cause ballooning too little hard landing. As far as flare and touchdown is concerned it is flare with elevator and close thrust. You don't add thrust. None of the certification trials have been done with additional thrust. We are talking about a technique that gives you consistent results and not what is possible. It is not impossible to do a good landing from an unstable approach but we don't do it.

misd-agin 26th Mar 2014 14:25

Nitpicker - "Remember that in a Jet Pitch controls Sink rate and thrust controls Speed."




Two examples -


I do a loop. In afterburner and my thrust to weight is less than 1:1.


450 kts, full afterburner, and I pull back on the stick. What happens to speed? Remember the quote is "thrust controls speed".


Aviation Week and Space Technology's latest issue has several articles about stalling airliners. And they talk about the wrong reactions the majority of pilots have. Thrust is the not the primary recovery tool.


Wait a minute, I thought thrust controlled speed? If that's true wouldn't thrust be the first response?


The reality is in normal line ops the difference between thrust vs pitch controlling airspeed, if you're close to normal speed/sink, is tiny. It's when people get to the edge of the envelope that it becomes obvious which is the ultimate controller.

Capn Bloggs 26th Mar 2014 14:27

Vilas, I think insomniac was using the power-up-to-flare only as a general example of the secondary effect of controls, not as an actual technique that should be used.

737Jock 26th Mar 2014 14:39

vilas the discussion is hard enough without adding airbus particularities. Airbus's fancy computers dont change the physics of flight.

vilas 26th Mar 2014 15:28

Misdagain
What Nitpicker is saying is about flare and landing. Also your reference to stall recovery is not correct because stall is an angle of attack phenomenon which needs to be reduced and that can only be done by using elevators adding thrust aggravates recovery because of the thrust vector.

Chris Scott 26th Mar 2014 22:02

Guys,

With a few exceptions, this thread is an embarrassment!

BTW, vilas is perfectly justified to mention flare mode, because the OP's title specifies Airbus, whose a/c have been mainly FBW for over a quarter of a century.

nitpicker330 26th Mar 2014 22:50

misd-agin-----looks like you missed the point of the whole exercise yet AGAIN.:D

Do you think I'm stupid pal? Really?

Of course in flight Pitch controls the IAS ( as can thrust if required. ) I'm fully aware that during a "flight level change"( Boeing ) or Open Descent ( Airbus ) the elevator controls the pitch ( hence IAS ) while the thrust is at idle.
I'm also aware that during climb with THR REF VNAV SPD ( Boeing ) THRCLB CLB A/THR ( Airbus ) pitch also controls the IAS.

Then there are modes where the THR is controlling the IAS such as SPD VS ( Boeing ) SPEED VS ( Airbus ) there are horses for courses my friend.

If you are hand flying at 10,000' with manual thrust and you wish to increase IAS from say 220 to 250 YOU DONT PUSH THE NOSE DOWN DO YOU? YES THATS RIGHT YOU INCREASE THUST THEN AS A CONSEQUENCE PUSH FORWARD ( if req depending on a/c type ) TO MAINTAIN ALT.

We are taking about the approach phase mate and the touchdown part, NOT about doing loops in an F18.....( fun I'm sure :ok: )

For goodness sake get a grip.

Just like your stupid comment on page 1 you just don't get it.


With regards to the Stall recovery, a quick read of your QRH will reveal the current Approach to stall recovery technique. Obviously number 1 is to reduce the AOA via your primary flight control surface called the ELEVATOR......Thrust is secondary....wow Rocket Science pal hey!!

I'LL NOW PUT IT INTO CAPITALS FOR YOU SO YOU UNDERSTAND......

ON APPROACH IN BOEING AND AIRBUS JET AIRCRAFT THE PILOT CONTROLS IAS USING THRUST AND THE SINK RATE USING PITCH.

This has been the case since the advent of Jet transport Aircraft. The fact that you and Noodle say otherwise reflects on a very poor basic understanding of handling a jet Aircraft, a lack of training, sheer ignorance, stupidity or all of the above.

No matter how many times Noodle insults me and says I shouldn't command anything bigger than a Kite DOESN'T CHANGE THE FACTS.:D

Capn Bloggs 26th Mar 2014 23:05


Originally Posted by Chris Scott
With a few exceptions, this thread is an embarrassment!

Oooh, I love it when someone tantalises me! What camp are you in, Chris? The loonies who use power to stay on the glideslope or the normal ones who get low on the GS and use the stick to put the aircraft back on it, then worry about the speed (in a lot of cases, with nothing needing to be done to it [the power] anyway). :)

misd-agin 27th Mar 2014 00:43

So your on speed, stabilized sink rate, and you're two dots high. Do you push over for the glideslope and then throttle back OR do you reduce power slightly and settle to the glideslope?


Is one solution really wrong and the other really right?

Capn Bloggs 27th Mar 2014 01:14


So your on speed, stabilized sink rate, and you're two dots high. Do you push over for the glideslope and then throttle back OR do you reduce power slightly and settle to the glideslope?
No question: put the aircraft back on the glideslope with the stick. In all probability, the speed will not increase at all because of the relative amount of drag, certainly not enough to worry about. And if it did, the speed would soon settle back to where it was before when you were back stabilised on the GS.

If you did this is a C150, yes, you would see a increase in speed and yes, you probably would have to throttle back a bit and yes, you could descend back to the GS by pulling off the power. But we're not in a C150. The 737 by virtue of it's pitch/power coupling may also let you get away with using the throttles to fly the GS, but that's trick-flying and I contend that it's not the speed-stability effect, it's only because of the underslung engines.

737Jock 27th Mar 2014 01:15

Increasing Thrust adds energy to the aircraft, this energy can be converted into speed or a change in vertical speed or simply maintaining the status quo.

RAM777 27th Mar 2014 01:19

Well i keep slight power only when its very windy or in summers due to the updrafts.If my speed is approaching the VLs i reduce the power a little late.This has helped me in making smooth landings..Other then that i dont think so its a good idea to land with power because that eats up lot of runway..

InSoMnIaC 27th Mar 2014 01:38

Vilas - I wasn't advocating using thrust to control RoD. Quite the opposite actually. Please re-read my post. My point was although controlling RoD by thrust is possible (just like controlling bank with yaw is possible) it is not preferred.

nitpicker330 27th Mar 2014 01:38

Yes Ram777 that's how it should be done. You decide, depending on situation, the exact time to close the thrust, sometimes you may have to leave a bit on until touchdown.


Q---2 dots high? Ans:- Ease forward on the elevator to reduce the pitch attitude by say 1 to 2 deg? That increased your ROD ( obviously ) then perhaps you "may" have to reduce thrust a little, say 5% N1 to keep the IAS nailed. Then when back on slope ease up 1 to 2 deg and apply 5% more N1 to maintain the slope. All Jet Pilots are trained in what pitch attitude and thrust setting to aim for in approach, initially on conversion you fly these NUMBERS. Later on you "just do it"

Haven't you guys see the unreliable Airspeed checklist which contains a table showing you PITCH ATTITUDE and THRUST settings ??

Any of you flown the A330 using the BUSS? ( yes Noodle do you know what the BUSS is? )

Airbus strongly recommend and teach that during an approach flown by the BACKUP SPEED SCALE ( BUSS ) that to maintain in the green you fly a fixed pitch and then adjust THRUST to keep it IN THE GREEN. Why? Because that's the easiest way to remain "stable" AND keep the process as normal as is possible.

This is "their training" using Thrust to control speed just as you do ON A NORMAL LANDING.


P.s. I would have loved to read what 411A would have said about his beloved L1011. That beast used DLC and in theory your Pitch attitude remained constant, still they used Thrust for Speed though!!

737Jock 27th Mar 2014 08:19


If you did this is a C150, yes, you would see a increase in speed and yes, you probably would have to throttle back a bit and yes, you could descend back to the GS by pulling off the power. But we're not in a C150. The 737 by virtue of it's pitch/power coupling may also let you get away with using the throttles to fly the GS, but that's trick-flying and I contend that it's not the speed-stability effect, it's only because of the underslung engines.
Well then you just disqualified yourself for lack of aerodynamic understanding. It's the basic principle of trimming the aircraft for speed. It's how aircraft have managed to land without any elevator control.
Why do you think the stabilizer can be trimmed?

Never heard such a bunch of crap in my life from someone who is supposed to be a line trainer. Then again I recognize the type.

In a 737 or any other speedstable aircraft you can reduce thrust and the nose lowers simultaneously if it's too slow for you can push on the yoke and help it. This will increase your rate of descent while maintaining airspeed. As you approach the glideslope you simply add thrust which also raises the nose to reduce the rate of descent. You should not need to retrim the aircraft as it is still trimmed the same way as when you started the excercise.

In a airbus (manual thrust) (an airbus in normal law is not speedstable although the airframe design is) you will reduce thrust and simultaneously push on the sidestick as you know you would lose speed otherwise. (Hey maybe that's the same as saying: I push on the stick and the airspeed increase so I need to reduce thrust)

Pitch and thrust /thrust and pitch go hand in hand. The starting point doesn't even matter in fact a reasonably experienced pilot who doesn't consistently use the a/p and a/t does it simultaneously.
But apparently someone decided that stupid pilots need a more simple method as they don't understand the link between pitch and power?
So someone came up with thrust is speed. Which basicly means you are always reacting after the fact with thrust due to a speed change that happened because of a pitch change. Instead of being proactive and anticipating the effects of your inputs.

One of the reasons to reduce thrust in the flare is because you enter the groundeffect. Another is that runway lenght is limited and you want to slow down as soon as you can.

I find it very interesting though that someone keeps power on to compensate for updrafts that by definition increase the energy of the aircraft. And that someone else then says that this is the way to do it??? I reduce thrust when I encounter updrafts (and I add or maintain when I sink).
But maybe as the aircraft starts to balloon due to the updraft you then just point the nose at the runway for a nice nosewheel landing in order to manage your path? Or you just float and call it a smooth landing?

No wonder statistics show more long landings in summer if this is how you manage energy.

NoodleAir 27th Mar 2014 08:43

I told you earlier, it is obvious he does not fly a jet.

Thats the reason I suspected both of them being the same person, they support each other's views and have a history of doing so.

Post pairs 92-97 and 99-100 are the finest example of it.

Misd-agin gives some clues in a tricky manner that they (the same person or both?) don't understand, exactly like he did in his first post, and then they come back with some laughable examples that have nothing to do with reality (post 97, the example being about LEVEL FLIGHT!!!!!). AND he stated "like your stupid comments on page 1, you just don't get it". !!!!! :ugh:

We are talking about someone who does not understand the balancing force of steady level flight………

Regarding Bloggs, don't bother at all, he needs to complete his PPL first.

Nitpicker may have been too long on an Airbus (he insists on quoting Airbus FCTM parts etc), but he still hash' answered on what his old book (the one he bought in '82) says about PRINCIPLES of Flight.

Responding to his post #97, on approach (in a Boeing) you control speed with pitch NOT with thrust. Thrust controls your path.
I do not expect you to agree or accept anything.

Over and out

737Jock 27th Mar 2014 09:32

http://www.faa.gov/regulations_polic.../00-80T-80.pdf

I have taken the liberty to find your manual Noodle. And I would like to quote from page 360. Noodle's statement is in bold.


The proper coordination of the controls is an absolute necessity during the approach. In this sense, due respect must be given to the primary control of airspeed and rate of descent for the conditions of the steady approach. This the proper angle of attack will produce the desired approach airspeed; too low an angle of attack will incur an excess speed while an excessive angle of attack will produce a deficiency of speed and may cause stall or control problems. Once the proper airspeed and angle of attack are attained the primary control of rate of descent during the steady approach will be the power setting.
and this is the answer from the manual regarding the question posted earlier about being high on glideslope


For example, if it is realized that the airplane is above the desired glide path, a more nose-down attitude without a decrease in power will result in a gain of airspeed. On the other hand, if it is realized that the airplane is below the desired glide path, a more nose-up attitude without an increase in power will simply allow the airplane to fly more slowly and - in the region of reversed command- eventually produce a greater rate of descent.

Trackdiamond 27th Mar 2014 09:36

pitch and power debate
 
Guys..this is one of those long historic banters of course..lemme join in!
(Pitch +/- power)trim 〓performance..is widely understood.

The argument of what controls vertical speed and what controls forward speed depends on which flight phas we plan to be in..or happen to find ourselves in.

Straight and level..Power controls speed. Pitch controls Altitude(Vert speed)

Climb....Power controls Vert Speed. Pitch controls forward Spee:sad:d.

Descent...Power(or lack there of) controls Vert speed...Pitch controls forward speed.

Approach Power controls forward speed pitch controls Vert speed(glide path)..however...if excess deviation occurs on glide..use power reduction(if above sope) or power increase(if below slope) appraching half FSD.When at or beyond half scale dev..consider Go Around.

Missed Approach; Pitch first and Power to TOGA setting.Arrest sink and inject further climbing energy.

Flare: Pitch...to arrest sink from that required to maintain Glideslope..and gently retard from the recommended power reduction Radio height..eg 20-10ft depending on weightyn wind etc...and that should give you if gentle with pitch demand rate and your distant vision should assist in gauging your bum sink rate...shoud settle you on terra forma with a subtle 200-300 fpm close to or just past the touch down zone.

If you have passed the touch down zone markers and haven't gotten ypur greaser..you will probably raise hell if you continue.Abort landing and Go Around..eat your Ego out!

737Jock 27th Mar 2014 09:44

http://www.faa.gov/regulations_polic...apter%2004.pdf


If, during the landing phase of flight, the aircraft is brought into ground effect with a constant AOA, the aircraft experiences an increase in CL and a reduction in the thrust required, and a “floating” effect may occur. Because of the reduced drag and power-off deceleration in ground effect, any excess speed at the point of flare may incur a considerable “float” distance. As the aircraft nears the point of touchdown, ground effect is most realized at altitudes less than the wingspan. During the final phases of the approach as the aircraft nears the ground, a reduced power setting is necessary or the reduced thrust required would allow the aircraft to climb above the desired glidepath (GP).

Trackdiamond 27th Mar 2014 09:47

keeping the power during the flare on Airbus FBW
 
Guys..this is one of those long historic banters of course..lemme join in!
(Pitch +/- power)trim 〓performance..is widely understood.

The argument of what controls vertical speed and what controls forward speed depends on which flight phas we plan to be in..or happen to find ourselves in.

Straight and level..Power controls speed. Pitch controls Altitude(Vert speed)

Climb....Power controls Vert Speed. Pitch controls forward Speed.

Descent...Power(or lack there of) controls Vert speed...Pitch controls forward speed.

Approach Power controls forward speed pitch controls Vert speed(glide path)..however...if excess deviation occurs on glide..use power reduction(if above sope) or power increase(if below slope) appraching half FSD.When at or beyond half scale dev..consider Go Around.

Missed Approach; Pitch first and Power to TOGA setting.Arrest sink and inject further climbing energy.

Flare: Pitch...to arrest sink from that required to maintain Glideslope..and gently retard from the recommended power reduction Radio height..eg 20-10ft depending on weightyn wind etc...and that should give you if gentle with pitch demand rate and your distant vision should assist in gauging your bum sink rate...shoud settle you on terra forma with a subtle 200-300 fpm close to or just past the touch down zone.

If you have passed the touch down zone markers and haven't gotten ypur greaser..you will probably raise hell if you continue.Abort landing and Go Around..eat your Ego out!

nitpicker330 27th Mar 2014 10:03

Noodle, what type do you fly exactly? Are you an FO? SO? Or heaven help us CN?

What's you experience?? Sounds to me like you must be a US Navy Top Gun test Pilot guru that knows the books inside and out by the holier than thou attitude you display.

Trackdiamond knows what he's talking about. I suppose I'm him too?:D

I'm only telling you the way I was taught to fly Jets 15,000 Jet hours ago in 1988. Since then I've managed more than a few approach and landings including ones in Typhoons at Kai Tak on the famous IGS ( you've heard of Kai Tak haven't you? )

Go on, I've waved my willy out.......how bigs yours? Put you experience levels on the table so we can all judge..:oh:

You too 737Jock....:ok:

Capn Bloggs 27th Mar 2014 10:04

Thank you, Track Diamond.

Aerodynamics For Naval Aviators is just that. Modern airliners do not operate near the region of reversed command!

Jock, let me get this straight...

Originally Posted by 737jock
In a 737 or any other speedstable aircraft you can reduce thrust and the nose lowers simultaneously if it's too slow for you can push on the yoke and help it. This will increase your rate of descent while maintaining airspeed. As you approach the glideslope you simply add thrust which also raises the nose to reduce the rate of descent. You should not need to retrim the aircraft as it is still trimmed the same way as when you started the excercise.

Could you confirm that if you get fast whilst on the glideslope (for whatever reason-maybe a windshift), you will first pull the nose up to get back on speed and that this is what you would teach a newbe?

737Jock 27th Mar 2014 10:16

Bloggs, aerodynamically speaking If I get fast on an approach a speedstable aircraft will reduce its vertical speed aerodynamically. Remember speedstable, I explained that a few times but maybe you check this link:http://www.faa.gov/regulations_polic...apter%2004.pdf . To increase the rate of descent I reduce thrust.
oh BTW even if you would not notice the decreasing vertical speed, you still approach the runway at a faster rate. so your path over the ground gets more shallow.

Sure thing nitpicker, flight instructing for about 500 hours, 737 about 2500 hrs, A320 about 3500 hours. A320 Command about 1500 hrs. I clocked up my hours quite a bit faster nitpicker.

FullWings 27th Mar 2014 10:26


In a 737 or any other speedstable aircraft you can reduce thrust and the nose lowers simultaneously if it's too slow for you can push on the yoke and help it. This will increase your rate of descent while maintaining airspeed. As you approach the glideslope you simply add thrust which also raises the nose to reduce the rate of descent. You should not need to retrim the aircraft as it is still trimmed the same way as when you started the excercise.
This is true up to a point but you are relying on secondary effects rather than directly controlling pitch. That technique doesn't work so well on the 1-11/DC-9/CRJ, etc. or FBW aircraft that modify/remove the pitch/power couple.

In free flight, such as a climb or descent, allowing the aircraft to reach equilibrium by using pitch/power against trim works well. If you are constrained to a path, e.g. close to landing or needing to maintain a given altitude, controlling pitch directly through the elevator leads to a more stable profile and less of an excursion from the desired path.

Capn Bloggs 27th Mar 2014 10:28

737Jock, I say again:

Could you confirm that if you get fast whilst on the glideslope (for whatever reason-maybe a windshift), you will first pull the nose up to get back on speed and that this is what you would teach a newbe?

A Yes/Yes, No/Yes, Yes/No or No/No will be fine thanks.

737Jock 27th Mar 2014 10:38

I'm not going to answer a question that is more complex then you clearly understand with a yes or no answer.

I'm not talking to a newbie, I'm talking to an experienced pilot who should know his aerodynamics. I'm not joining you in your black and white world of ignorance.

As I said before, a speedstable aircraft will raise its nose aerodynamically after an increase in speed thus reducing its vertical speed. This happens in a phugoid movement that will find a new equilibrium at its original trimmed speed and reduced vertical speed. Reducing the thrust will increase the vertical speed.

You may remember the feeling of the aircraft ballooning when you hit an updraft. the speed itself might not even increase, did you ever consider that the speed increases because you stick to the path by pushing the nose down.

An experienced pilot controls thrust and pitch simultaneously! Simply because they interact with each other all the time.

Trackdiamond 27th Mar 2014 10:48

thrust hold during flare on Airbus FBW
 
I posted earlier specifically for the Airbus FBW case but mods dropped it..wonder why? Here I am re posting the same.

With AT engaged 20ft Retard call is advisory(not command) to start retarding PL to idle.
The retard audio advisory repeats all the way to 5 ..and after repeated calls at 5 ft...it silences. That can be taken as an alarming silence(especialy when you have crossed the 3000ft..even on an average long runway.

Question is..is it SOP to disengage the Auto Thrust?

If on mnual Thrust and "keeping power ON"..what % Thrust are we looking at?Same as Approach thrust or reduced Aproach thrust?
(To cushion your perhaps alarming sink rate??)
In any case if you are FORCED to keep power ON something is not right and unless you have the luxury of a very long runway..beer do a Balked Landing and Go Around.

737Jock 27th Mar 2014 10:56


Straight and level..Power controls speed. Pitch controls Altitude(Vert speed)

Yet as the speed increases the pitch is lowered, so they interact!

Climb....Power controls Vert Speed. Pitch controls forward Speed.

You could also argue that Power controls forward speed. if you reduce thrust while maintaining pitch the speed reduces. Then if you lower the pitch it controls the vertical speed as well as forward speed. Pitch and power interact!

Descent...Power(or lack there of) controls Vert speed...Pitch controls forward speed.

See above

Approach Power controls forward speed pitch controls Vert speed(glide path)..however...if excess deviation occurs on glide..use power reduction(if above sope) or power increase(if below slope) appraching half FSD.When at or beyond half scale dev..consider Go Around.
Increasing power adds energy to the airplane, the pitch determines if this is converted into speed/vertical speed/both. If power response is fast enough nothing might happen as the energy added counterbalances the upset that required the extra energy.
Likewise with decreasing power.

Capn Bloggs 27th Mar 2014 11:13


Originally Posted by 737Jock
I'm not going to answer a question that is more complex then you clearly understand with a yes or no answer.

Rubbish. You won't answer because it'll prove your method doesn't work well. The answer is simple, so simple even a newbie can understand without all that scientific energy stuff.

You get fast, you pull the power back until you get on speed, then put the power up. You get high on slope, you put the nose down to get back on slope. If the speed changes (if only a smallish pitch correction, the speed probably won't change enough to worry about) you fix it with the throttles, just like the autopilot/autothrottles do it. Handfly an ILS and watch the throttles work.

Answer? Yes/Yes.

Simple!

You may have a few or many seconds to sit on the approach (off slope and/or off speed) waiting for the secondary effects of controls to fly your aeroplane but I don't. Pitch for glideslope and throttles for speed. Simple!

nitpicker330 27th Mar 2014 11:35

Exactly, seems to me that any other way is too damn complicated.

KISS method.

Noodle or 737Jock haven't answered my question regarding:--
1/ Unreliable Airspeed checklist in the QRH containing Pitch and Thrust tables for Approach.

2/ Flying the BUSS on the Airbus is taught BY Airbus to hold a constant Pitch and Adjust Thrust to stay "in the green" ( correct AOA and therefore IAS for the Config )

nitpicker330 27th Mar 2014 11:44

Still rummaging through the newly issued revised A330 FCTM and found these:--

( my bolding )

USE OF A/THR The pilot should use the A/THR for approaches as it provides accurate speed control The pilot will keep the hand on the thrust levers so as to be prepared to react if needed.

TRAJECTORY STABILIZATION The first prerequisite for safe final approach and landing is to stabilize the aircraft on the final approach flight path laterally and longitudinally, in landing configuration, at VAPP speed, i.e: • Only small corrections are necessary to rectify minor deviations from stabilized conditions • The thrust is stabilized, usually above idle, to maintain the target approach speed along the desired final approach path


FINAL APPROACH Roll out of the turn on the extended runway centreline and maintain VAPP. Thrust should be stable by 1 000 ft. Use the speed trend arrow to anticipate thrust changes and the FPV to monitor approach path deviations. Use available G/S and/or PAPIs as well as the visual picture to assist in maintaining a stable approach. A continuous visual/instrument scan is required to fly a successful approach. An effective scan will assist in highlighting small errors, allowing small, early corrections to be made. A 3 ° slope will normally be flown with a ROD of approximately 700 ft/min; a higher ROD is an indication that the aircraft is about to descend below the ideal approach path. A small correction of approx 1 ° of pitch will change the ROD by approximately 100 ft/min. Azimuth errors will require bank angle changes both to stop the drift and then to recover to the centreline. Avoid using bank angles greater than 10 ° for small corrections.


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