landing technique B737NG
Not sure that the rate of attitude change for the flare has been mentioned but I feel this can be a significant factor. Generally I think it is better to start the flare relatively higher at a slower rate rather than flaring lower and then having to change the attitude at a higher rate (which can risk driving the main wheels in also - I wonder if this is what is causing the "firm" landings?).
I am not suggesting of course that the flare is initiated at anything other than what the FCTM suggests but generally it is better to have a few "bites of the cherry" and a slower rate of change of pitch means you have more room for manoeuvre and adjustment.
Ok maybe the landing was "firm" but assuming it was not a "heavy" landing what's wrong with that? Was the landing on or close to the TDZ, on the centreline etc - not sure what you mean by an "untidy" landing - can you be more specific?
I am not suggesting of course that the flare is initiated at anything other than what the FCTM suggests but generally it is better to have a few "bites of the cherry" and a slower rate of change of pitch means you have more room for manoeuvre and adjustment.
Nowhere in my visualisation was the FIRM untidy landing that I managed to achieved!!
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landing
books help to understand how it works
with experience you land the way you want
just make it safe
i have around 18 000 h that is about 6000 landings
when i m tired i land hard
something else :my landings are better when crosswind than no wind
can someone explain
happy landings
with experience you land the way you want
just make it safe
i have around 18 000 h that is about 6000 landings
when i m tired i land hard
something else :my landings are better when crosswind than no wind
can someone explain
happy landings
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50' call-wake up and prepare to do something.
20' call-close eyes and do something.
Quality of resulting landing is entirely dependant on side off hair parting but is just as consistent as all the above
20' call-close eyes and do something.
Quality of resulting landing is entirely dependant on side off hair parting but is just as consistent as all the above
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AirRabbit, no one is trying to insult anyone here. Bit direct at times but just healthy banter.
You have still not addressed my observation about your definition of the straight and level attitude. In your first post you said.
If you select that attitude it is too high. Why ?
Remember Boeing ask you to flare 2-3 degrees from your approach attitude.
Take a calm day. 3 degree glide at a constant Vref +5, constant power and landing config. Now we raise the nose 3 degrees (max Boeing recommend) in order to flare and we will have selected the straight and level attitude for that config at Vref +5. However in reality we know the speed will have decreased in the flare so our nose attitude will in reality be too low for straight and level if we only raise it 3 degrees. Boeing assume Vref at the end of the flare so we have lost 5kts of speed which Boeing equates to 1 degree of nose attitude. So if we want the straight and level attitude at the speed at the completion of the flare, as you recommend, we will have to raise the nose by another degree. That will mean we will have raised the nose 4 degrees overall, from the approach attitude, which is too much.
Why is this significant.
a. its nice to get it correct
b. tailstrike. In a 800 the tail bangs at just over 9 degrees oleos extended. Boeing assume a landing attitude of anywhere between 4 and 7 degrees depending on weight, flare etc. So if you flare 4 degrees you may have just over a degree of grace or put another way just over 5kts of grace. Not so much then.
I would appreciate it if you could address this concern over your definition of the attitude.
Cheers
You have still not addressed my observation about your definition of the straight and level attitude. In your first post you said.
It is whatever attitude that is the “level flight” attitude for that airplane, in that configuration, and at that airspeed. What airspeed? The airspeed you have upon completing the flare.
Remember Boeing ask you to flare 2-3 degrees from your approach attitude.
Take a calm day. 3 degree glide at a constant Vref +5, constant power and landing config. Now we raise the nose 3 degrees (max Boeing recommend) in order to flare and we will have selected the straight and level attitude for that config at Vref +5. However in reality we know the speed will have decreased in the flare so our nose attitude will in reality be too low for straight and level if we only raise it 3 degrees. Boeing assume Vref at the end of the flare so we have lost 5kts of speed which Boeing equates to 1 degree of nose attitude. So if we want the straight and level attitude at the speed at the completion of the flare, as you recommend, we will have to raise the nose by another degree. That will mean we will have raised the nose 4 degrees overall, from the approach attitude, which is too much.
Why is this significant.
a. its nice to get it correct
b. tailstrike. In a 800 the tail bangs at just over 9 degrees oleos extended. Boeing assume a landing attitude of anywhere between 4 and 7 degrees depending on weight, flare etc. So if you flare 4 degrees you may have just over a degree of grace or put another way just over 5kts of grace. Not so much then.
I would appreciate it if you could address this concern over your definition of the attitude.
Cheers
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Well, if it is a crosswind, it's probably gusty. You carry more speed in that situation, which gives you more energy to flatten out your touchdown. That's my guess anyway.
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ashling,
enjoying reading this thread but with the greatest respect, it wasn't healthy banter and it was disrespectful.
given your absolute convictions in your ability and knowledge would it be fair to ask you what your experience level is and what, if any, instructional roles you've held? rabbit has shared his.
having flown the 737-3/4/5 i always was of the opinion that landing the 737 was a flexible feast! haven't flown the -800 but that as you say i have no doubt that that the boeing method works every time. just lacks a little finesse occasionally! like you i totally agree that on the dark wet windy nights impact in the right place is the single most important thing. the are other times when i' might have used up 500ft to grease it on, bad me.
as for the original post. i for one have found on the 2 boeings i've flown that copying the a/p a/land was a good place to start when trying to get my eye in whilst in the sim.
cheers,
thh
enjoying reading this thread but with the greatest respect, it wasn't healthy banter and it was disrespectful.
given your absolute convictions in your ability and knowledge would it be fair to ask you what your experience level is and what, if any, instructional roles you've held? rabbit has shared his.
having flown the 737-3/4/5 i always was of the opinion that landing the 737 was a flexible feast! haven't flown the -800 but that as you say i have no doubt that that the boeing method works every time. just lacks a little finesse occasionally! like you i totally agree that on the dark wet windy nights impact in the right place is the single most important thing. the are other times when i' might have used up 500ft to grease it on, bad me.
as for the original post. i for one have found on the 2 boeings i've flown that copying the a/p a/land was a good place to start when trying to get my eye in whilst in the sim.
cheers,
thh
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FFS
Some of you lot need to get out and fly a few airplanes a bit more . Never heard so much theoretical claptrap in my life.
To think the uk openly discriminates against good honest bush pilots over cadets belies reason. Its plain to see the outcome of such a policy. Its called this thread. A good pilot doesnt need these theories , just a cou[le of goes in the new type and they are sorted.
To think the uk openly discriminates against good honest bush pilots over cadets belies reason. Its plain to see the outcome of such a policy. Its called this thread. A good pilot doesnt need these theories , just a cou[le of goes in the new type and they are sorted.
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Hi Ashling:
Sorry, I didn’t realize you thought that I hadn’t answered your question. I was attempting to do just that in an earlier post … but let me repeat it here. Level flight attitude with landing flaps and a speed between 1.1 and 1.2 times the stall speed in that configuration (the landing configuration) should be between 3 and 6 degrees of nose up pitch. One of the commenters on this thread, chksix, had posted a link to a page copied from a B737NG manual. Here’s the link (thanks again, chksix)
http://img390.imageshack.us/my.php?image=landqq1.jpg
That link clearly shows the B737NG on the ground with the nose at “4 to 6 degrees” of nose up pitch.
What I am advocating is that when you fly the approach, you get to the point where you have determined you should initiate the flare (and chksix’s link shows that the speed up to flare initiation should be Vref+5), initiate the flare to the level flight attitude (which I’m saying – depending on gross weight – will be between 3 and 6 degrees nose up attitude) and that should scrub off some of the airspeed – particularly if you’re the type to start gradually reducing thrust as you initiate the flare (but that’s more of a technique and I really don’t care about that – well, of course, I’d care, but it’s not a huge thing), and that should leave you about 1.1 to 1.2 times the stall speed in that configuration (1.3 times Vstall is Vref). So there should be no time that you should flare the airplane to anything above about 6 degrees nose up pitch. Even with, as you say, the B737-800 risking a tail strike at something just over 9 degrees of nose up pitch – you should be quite comfortably safe from such an occurrence at 6 degrees or less. When you are next in the simulator you should really try to see what it would take to get a tail strike. Try a full stall landing and see if you can put the tail on the runway before the MLG. This is the advantage of a properly built, programmed, and tested flight simulator. You might be surprised.
Perhaps I should make this more clear as well. Lets assume that 5 degrees nose up pitch and 1.2Vs is what would be necessary to maintain level flight. This means that if you added power and held both that attitude and airspeed, you would fly down the runway without climbing, descending, accelerating, or decelerating. However, you are not going to be adding power … your airspeed will continue to decrease even though you are in the level flight attitude for the speed reached at the end of the flare. If you initiated the flare at 15 – 20 feet and took between 1.5 and 3.0 seconds to flare (and 3.0 seconds is a very long time to flare … but …) you would likely be something like 5 feet above the runway. Because you are descending (while you have a level flight attitude, you don’t have the airspeed to maintain level flight) and because you are decelerating (you’ve put the airplane in an attitude where it cannot maintain the airspeed without additional power – in fact you may have already started to reduce the power – although that isn’t absolutely necessary yet), you are going to continue to “go down” (although at a slower rate, because you are now at that “level flight attitude”) and you will continue to “slow down.” The idea is to have the throttles at flight idle at (or just prior to or just after) MLG touchdown. The most you will have the nose in the air would be 6 degrees at touchdown, giving you adequate airflow over the rudder to maintain directional control until you fly the nose to the ground and can control that with rudder pedal steering. What’s more, since you are going to be getting slower in this attitude (which is what is wanted) and getting lower (which is also what is wanted) the airplane will want to “nose-over.” Additional back-stick pressure will be needed to keep the nose at the desired attitude – not raise it, just maintain it.
The height above the runway you are at the end of the flare and the time it takes you to close that distance will give you the rate of descent at touchdown. Like I said earlier, probably somewhere between 100 and 600 fpm. Obviously 600 is something a little more firm than “firm,” and 100 is a little light – for most, that is, although that is still some distance away from a round of applause from First Class. What is nice is that you have considerable control over that rate of descent because of the attitude in which you have the airplane. How? Merely “goosing” the throttles (sorry, American term, meaning stabbing the throttles forward and then back almost immediately) will temporarily reduce your rate of descent without you having to do anything with the pitch, which, of course, you are just maintaining. Not screwing around with the pitch attitude is a desirable practice at such close distances to the runway surface. And, this is why it is not necessarily advisable to have the throttles in flight idle too quickly – it might take the engines a small bit longer to spool up from flight idle if a “goose” is needed.
Sorry, I didn’t realize you thought that I hadn’t answered your question. I was attempting to do just that in an earlier post … but let me repeat it here. Level flight attitude with landing flaps and a speed between 1.1 and 1.2 times the stall speed in that configuration (the landing configuration) should be between 3 and 6 degrees of nose up pitch. One of the commenters on this thread, chksix, had posted a link to a page copied from a B737NG manual. Here’s the link (thanks again, chksix)
http://img390.imageshack.us/my.php?image=landqq1.jpg
That link clearly shows the B737NG on the ground with the nose at “4 to 6 degrees” of nose up pitch.
What I am advocating is that when you fly the approach, you get to the point where you have determined you should initiate the flare (and chksix’s link shows that the speed up to flare initiation should be Vref+5), initiate the flare to the level flight attitude (which I’m saying – depending on gross weight – will be between 3 and 6 degrees nose up attitude) and that should scrub off some of the airspeed – particularly if you’re the type to start gradually reducing thrust as you initiate the flare (but that’s more of a technique and I really don’t care about that – well, of course, I’d care, but it’s not a huge thing), and that should leave you about 1.1 to 1.2 times the stall speed in that configuration (1.3 times Vstall is Vref). So there should be no time that you should flare the airplane to anything above about 6 degrees nose up pitch. Even with, as you say, the B737-800 risking a tail strike at something just over 9 degrees of nose up pitch – you should be quite comfortably safe from such an occurrence at 6 degrees or less. When you are next in the simulator you should really try to see what it would take to get a tail strike. Try a full stall landing and see if you can put the tail on the runway before the MLG. This is the advantage of a properly built, programmed, and tested flight simulator. You might be surprised.
Perhaps I should make this more clear as well. Lets assume that 5 degrees nose up pitch and 1.2Vs is what would be necessary to maintain level flight. This means that if you added power and held both that attitude and airspeed, you would fly down the runway without climbing, descending, accelerating, or decelerating. However, you are not going to be adding power … your airspeed will continue to decrease even though you are in the level flight attitude for the speed reached at the end of the flare. If you initiated the flare at 15 – 20 feet and took between 1.5 and 3.0 seconds to flare (and 3.0 seconds is a very long time to flare … but …) you would likely be something like 5 feet above the runway. Because you are descending (while you have a level flight attitude, you don’t have the airspeed to maintain level flight) and because you are decelerating (you’ve put the airplane in an attitude where it cannot maintain the airspeed without additional power – in fact you may have already started to reduce the power – although that isn’t absolutely necessary yet), you are going to continue to “go down” (although at a slower rate, because you are now at that “level flight attitude”) and you will continue to “slow down.” The idea is to have the throttles at flight idle at (or just prior to or just after) MLG touchdown. The most you will have the nose in the air would be 6 degrees at touchdown, giving you adequate airflow over the rudder to maintain directional control until you fly the nose to the ground and can control that with rudder pedal steering. What’s more, since you are going to be getting slower in this attitude (which is what is wanted) and getting lower (which is also what is wanted) the airplane will want to “nose-over.” Additional back-stick pressure will be needed to keep the nose at the desired attitude – not raise it, just maintain it.
The height above the runway you are at the end of the flare and the time it takes you to close that distance will give you the rate of descent at touchdown. Like I said earlier, probably somewhere between 100 and 600 fpm. Obviously 600 is something a little more firm than “firm,” and 100 is a little light – for most, that is, although that is still some distance away from a round of applause from First Class. What is nice is that you have considerable control over that rate of descent because of the attitude in which you have the airplane. How? Merely “goosing” the throttles (sorry, American term, meaning stabbing the throttles forward and then back almost immediately) will temporarily reduce your rate of descent without you having to do anything with the pitch, which, of course, you are just maintaining. Not screwing around with the pitch attitude is a desirable practice at such close distances to the runway surface. And, this is why it is not necessarily advisable to have the throttles in flight idle too quickly – it might take the engines a small bit longer to spool up from flight idle if a “goose” is needed.
in fact you may have already started to reduce the power – although that isn’t absolutely necessary yet), you are going to continue
Keep in mind that Boeing assume the landing technique is based on a performance limiting runway length - not a 8000 ft highway.
The slow thrust lever closure favoured by many pilots often ensures touch down is further in than ideal and often with the thrust levers still not closed on wheel impact. Not good technique in my book - nor Boeing's if I hazard a guess.
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AirRabbit
Look at your quote on the definition of the attitude from your original post.
That is what I want you to address.
It is wrong as I have demonstrated.
If there is an error in my demonstration please point it out.
It is because you gave the wrong attitude and then hung so much on it that I have chased it. If that attitude is wrong so is the rest.
By the way the diagram he gave you is incorrect, not in current manual, its 2-4 degrees on approach 4-7 degrees after flare. Current Boeing FCTM. You said you had access to that.
Look at your quote on the definition of the attitude from your original post.
That is what I want you to address.
It is wrong as I have demonstrated.
If there is an error in my demonstration please point it out.
It is because you gave the wrong attitude and then hung so much on it that I have chased it. If that attitude is wrong so is the rest.
By the way the diagram he gave you is incorrect, not in current manual, its 2-4 degrees on approach 4-7 degrees after flare. Current Boeing FCTM. You said you had access to that.
That's interesting Centaurus.
I have the greatest of respect for someone such as Mr Zizovski, I really do.
I'm just trying to imagine what difference whacking the thrust levers closed makes compared to taking one or two seconds to close the thrust levers to idle and allowing them to gently rest against the stops.
As far as time verses engine thrust is concerned, I see no difference.
As far as freaking out the pilot next to you, I see a difference.
Some points worth considering.
1. If I start reducing thrust at the same time as Mr Zizovski, but take 2 seconds longer to reach the idle stops, at the very worst, all you could say is that I am adding 2 seconds worth of energy to the aircraft. Compare this to the total amount of kinetic energy 60 tons of metal has at 130 kt and you will find that it is insignificant.
But even this is not true. You are not adding two seconds of thrust because the majority of the thrust is reduced at the same time. Remembering that Thrust vs % N1 is not linear but more parabolic. i.e. reducing N1 from 60% to 42% reduces the thrust by half. Reducing from 60% to 30% reduces it to a quarter of what it was.
2. What is the absolute minimum time it takes the engines to reduce from approach thrust to flight idle? (60% to 25% N1) Three seconds? (that would be an absolute minimum I reckon).
If so how does taking three seconds to bring the thrust levers to idle make any difference to the rate of engine thrust reduction? In other words I am moving the thrust levers as fast as the engines can react, moving them any faster would make no difference to what the engines do.
Same thing if I am increasing thrust. If the thrust levers are at idle and I want go-around thrust, if the engines take 5 seconds to spool up, it doesn't matter if I take 1 second or 3 seconds to move the thrust levers to the fwd stops, it will still take 5 seconds for the engines to spool up.
3. How long does the auto-throttle take to close the thrust levers during an autoland? My guess is somewhere around five seconds.
May I throw a cat amongst the pigeons??
Jacobson Flare.
There have been numerous discussions about that one.
(Yes I do think it works well.)
I have the greatest of respect for someone such as Mr Zizovski, I really do.
I'm just trying to imagine what difference whacking the thrust levers closed makes compared to taking one or two seconds to close the thrust levers to idle and allowing them to gently rest against the stops.
As far as time verses engine thrust is concerned, I see no difference.
As far as freaking out the pilot next to you, I see a difference.
Some points worth considering.
1. If I start reducing thrust at the same time as Mr Zizovski, but take 2 seconds longer to reach the idle stops, at the very worst, all you could say is that I am adding 2 seconds worth of energy to the aircraft. Compare this to the total amount of kinetic energy 60 tons of metal has at 130 kt and you will find that it is insignificant.
But even this is not true. You are not adding two seconds of thrust because the majority of the thrust is reduced at the same time. Remembering that Thrust vs % N1 is not linear but more parabolic. i.e. reducing N1 from 60% to 42% reduces the thrust by half. Reducing from 60% to 30% reduces it to a quarter of what it was.
2. What is the absolute minimum time it takes the engines to reduce from approach thrust to flight idle? (60% to 25% N1) Three seconds? (that would be an absolute minimum I reckon).
If so how does taking three seconds to bring the thrust levers to idle make any difference to the rate of engine thrust reduction? In other words I am moving the thrust levers as fast as the engines can react, moving them any faster would make no difference to what the engines do.
Same thing if I am increasing thrust. If the thrust levers are at idle and I want go-around thrust, if the engines take 5 seconds to spool up, it doesn't matter if I take 1 second or 3 seconds to move the thrust levers to the fwd stops, it will still take 5 seconds for the engines to spool up.
3. How long does the auto-throttle take to close the thrust levers during an autoland? My guess is somewhere around five seconds.
May I throw a cat amongst the pigeons??
Jacobson Flare.
There have been numerous discussions about that one.
(Yes I do think it works well.)
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Hi Ashling:
I guess you and I are just failing to communicate. I have gone back and re-read my original post, with particular scrutiny directed to how I used the term “attitude.” I’ll quote below the way I defined “level flight attitude,” the areas with which I think you had an “issue.” Here is what I said in my original post:
…and here is what I said later on in that same posting…
I don’t see any change from my original reference to “attitude” in any of my subsequent references to that term. As I read your concerns, in your rebuttal post you said, and, again, I’ll quote…
Because of what you said in your 6th sentence (“Irrespective of the runway available if you keep raising the nose to prevent the aircraft descending you will bang the tail before you stall on.”), I was of the opinion that you misunderstood what I had said. Please note, nowhere have I said that once achieving the “level flight attitude” (the “landing attitude”) the pilot was to continue to raise the pitch attitude; and, in fact, I have determinedly said that the pilot was to maintain that level flight attitude (the “landing attitude”) through the touchdown.
In my attempt to clarify this position further, I have said that the “level flight attitude” (the “landing attitude”) I was describing would only maintain level flight if power were added to maintain that airspeed … which, of course, you would not do. The only other way to maintain level flight at that time would be to increase the pitch attitude … and that is what I have said should not be done.
I am sorry, Ashling. I just don’t see where you have, as you say, “demonstrated” that my description is “wrong.” You say that that diagram that chksix provided is wrong. You also said that I had indicated that I had access to that manual. Well, I checked, and I no longer have the manual I thought I still had – my excuse is that if I kept all the manuals I once had I’d need a larger place to live. Sorry. But my comment stands as stated. I DO read and comply with the FCTM and FCOM for any airplane I fly – and I was responding to what I thought was your allegation that I had not done so. As for that diagram being in error – it seems to be correct from my memory – and, with respect, you’d have to take up that accusation with chksix. However, I’m quite sure that he copied that page from an “NG” manual since I’m reasonably sure that he didn’t make it up himself.
You say that I “gave the wrong attitude” in my postings and then “hung so much on it” that you’ve chased the error. I’m not sure what attitude you’re referencing. The only “attitude” I’ve described is the attitude that would produce level flight for the airplane in the existing configuration, gross weight, and airspeed reached at the end of the flare. That attitude is the attitude from which the landing should be made – the landing attitude. I have also provided 2 separate approximations – one for a speed range and one for a pitch range – depending on gross weight. The speed range, again, is 1.1 to 1.2 times Vstall, where Vref is 1.3 times Vstall. The pitch range, again, is 3 to 6 degrees of pitch. The attitude I’m describing (the “level flight attitude,” the “landing attitude”) is the attitude that would provide level flight, presuming one had sufficient power to maintain the 1.1 to 1.2 times Vstall airspeed (the airspeed reached at the end of the flare) while at a constant pitch attitude of between 3 and 6 degrees, depending on the existing gross weight. Perhaps we would do well to recall that we’re discussing an airplane with full landing flaps operating within ground effect.
One last thing, regarding my tendency to provide very long replies to what some think are easy, direct, simple questions. In my view, there are 3 types of instructors: The perfect one, who provides the perfect amount of information in a perfect way; the one who provides not quite enough information for the pilot to understand what is going on; and the one who provides more information than is necessary for the pilot to understand what is going on. I recognized, quite a long time ago that I am far from perfect. In that I am not perfect, and know it, I’ll let you guess as to which of the other 2 possibilities I would rather plead guilty.
I guess you and I are just failing to communicate. I have gone back and re-read my original post, with particular scrutiny directed to how I used the term “attitude.” I’ll quote below the way I defined “level flight attitude,” the areas with which I think you had an “issue.” Here is what I said in my original post:
Originally Posted by AirRabbit
…the flare is pulling back on the elevator controls to raise the nose (increase the pitch attitude) to “break” or “reduce” the rate of descent prior to touchdown. But, where is it you want the nose to go? Can you put it anywhere? No, certainly not. Well, if that’s true, then you want it to go to some specific spot. What is that spot? It is whatever attitude that is the “level flight” attitude for that airplane, in that configuration, and at that airspeed. What airspeed? The airspeed you have upon completing the flare.
Originally Posted by AirRabbit
Airplanes are designed, for the greater part, to be landed from the level flight attitude; and by that I mean the attitude that would produce level flight at the airspeed achieved at the end of the flare, the existing GW, and the existing configuration.
Originally Posted by Ashling
You are NOT trying to find a level attitude. When you flare you are merely slowing the rate of descent.
You do NOT allow the airplane to float and certainly not for 3 seconds.
Boeing are very clear on both these points and it is a boeing we are talking about. That said its true for any aircraft.
Irrespective of the runway available if you keep raising the nose to prevent the aircraft descending you will bang the tail before you stall on.
To flare the NG you start at about 15' then increase pitch attitude by 2-3 degrees. After you initiate the flare smoothly retard the thrust levers to idle aiming for idle as the wheels touchdown. Make small pitch adjustments after the flare to maintain the desired descent rate to the runway.
You do NOT allow the airplane to float and certainly not for 3 seconds.
Boeing are very clear on both these points and it is a boeing we are talking about. That said its true for any aircraft.
Irrespective of the runway available if you keep raising the nose to prevent the aircraft descending you will bang the tail before you stall on.
To flare the NG you start at about 15' then increase pitch attitude by 2-3 degrees. After you initiate the flare smoothly retard the thrust levers to idle aiming for idle as the wheels touchdown. Make small pitch adjustments after the flare to maintain the desired descent rate to the runway.
In my attempt to clarify this position further, I have said that the “level flight attitude” (the “landing attitude”) I was describing would only maintain level flight if power were added to maintain that airspeed … which, of course, you would not do. The only other way to maintain level flight at that time would be to increase the pitch attitude … and that is what I have said should not be done.
I am sorry, Ashling. I just don’t see where you have, as you say, “demonstrated” that my description is “wrong.” You say that that diagram that chksix provided is wrong. You also said that I had indicated that I had access to that manual. Well, I checked, and I no longer have the manual I thought I still had – my excuse is that if I kept all the manuals I once had I’d need a larger place to live. Sorry. But my comment stands as stated. I DO read and comply with the FCTM and FCOM for any airplane I fly – and I was responding to what I thought was your allegation that I had not done so. As for that diagram being in error – it seems to be correct from my memory – and, with respect, you’d have to take up that accusation with chksix. However, I’m quite sure that he copied that page from an “NG” manual since I’m reasonably sure that he didn’t make it up himself.
You say that I “gave the wrong attitude” in my postings and then “hung so much on it” that you’ve chased the error. I’m not sure what attitude you’re referencing. The only “attitude” I’ve described is the attitude that would produce level flight for the airplane in the existing configuration, gross weight, and airspeed reached at the end of the flare. That attitude is the attitude from which the landing should be made – the landing attitude. I have also provided 2 separate approximations – one for a speed range and one for a pitch range – depending on gross weight. The speed range, again, is 1.1 to 1.2 times Vstall, where Vref is 1.3 times Vstall. The pitch range, again, is 3 to 6 degrees of pitch. The attitude I’m describing (the “level flight attitude,” the “landing attitude”) is the attitude that would provide level flight, presuming one had sufficient power to maintain the 1.1 to 1.2 times Vstall airspeed (the airspeed reached at the end of the flare) while at a constant pitch attitude of between 3 and 6 degrees, depending on the existing gross weight. Perhaps we would do well to recall that we’re discussing an airplane with full landing flaps operating within ground effect.
One last thing, regarding my tendency to provide very long replies to what some think are easy, direct, simple questions. In my view, there are 3 types of instructors: The perfect one, who provides the perfect amount of information in a perfect way; the one who provides not quite enough information for the pilot to understand what is going on; and the one who provides more information than is necessary for the pilot to understand what is going on. I recognized, quite a long time ago that I am far from perfect. In that I am not perfect, and know it, I’ll let you guess as to which of the other 2 possibilities I would rather plead guilty.
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Hi. I edited my post with the schematic above but I'll clarify here that I took screenshots from a 737 manual with the following info:
http://img209.imageshack.us/img209/4554/afmqa2.jpg
It's outdated so not to be used in real flight etc......
I need it for performance tuning of one of the xplane versions of the 737 NG.
http://img209.imageshack.us/img209/4554/afmqa2.jpg
It's outdated so not to be used in real flight etc......
I need it for performance tuning of one of the xplane versions of the 737 NG.
Last edited by chksix; 1st Sep 2007 at 17:45.
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I quite agree with Centaurus that the landing process should be adequate for all runways – with the particular emphasis placed on those that are more performance limiting… and I certainly wouldn’t want to stand toe-to-toe in a flying technique argument with the likes of Joe Zizovsky! For performance limited runways, I think I understand completely his preference for maintaining Vref+5 knots to the initiation of the flare – particularly were he describing initiating the flare at 10 to 15 feet above the runway with the “aiming” point on the runway something short of the 1000-foot fixed distance markers (FDM). In that particular instance, I would presume Mr. Zizovsky would not appreciate taking 3 seconds to reach the flare attitude (what I’m calling the level flight attitude). In fact, I would suspect his preference would be more in the neighborhood of 0.5 to 1.0 second flare and something similar from flare to touchdown. Sawing the power levers to idle – “whack bang” – with the initiation of that 0.5 to 1.0 second flare, would be perfectly appropriate when landing on a performance limited runway. Such an abrupt change of attitude and change in power, would allow the airspeed to bleed down more quickly; initiating the flare closer to the runway would cause you to reach the landing attitude closer to the runway; and with the aim point short of the FDM, the process would likely result in placing the MLG tires ON the 1000-foot FDM, at the appropriate attitude and airspeed. After all, THAT is what the B737 was originally designed to do – be able to get into and out of airport runways that simply would be inadequate for the B727 and B720 aircraft. However, relaxing this particular method of approach and landing just slightly would be perfectly acceptable, and appropriate, when the runway isn’t so performance limited.
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Air Rabbit
Read my post, numbered 95, that is were I deomstrate why the attitude as you define it is incorrect.
Boeing clearly ask you to flare 2-3 degrees based on the APPROACH attitude and speed. As speed bleeds in a flare you will not achieve a straight and level attitude, even momentarily, even if you flare the full 3 degrees. So Boeing clearly do not intend you to select any kind of straight and level attitude. To suppose they do is an simply incorrect and a misrepresentation of what is in the FCTM.
Like you I do not claim to be perfect, I have done a great deal of instructing and taught instructors their trade. I very much like simple repeatable techniques that the individual can use as a framework to develop from.
My view is that in this case you are both technicaly and conceptualy in error.
Technicaly because if you flare to a straight and level attitude based on the speed after the flare you must change the nose attitude by more than the recommended 3 degrees.
Conceptualy because you are overcomplicating things by a margin in my view.
Sorry but unless you, or someone else, can correct my demo in post 95 then that is my view.
Read my post, numbered 95, that is were I deomstrate why the attitude as you define it is incorrect.
Boeing clearly ask you to flare 2-3 degrees based on the APPROACH attitude and speed. As speed bleeds in a flare you will not achieve a straight and level attitude, even momentarily, even if you flare the full 3 degrees. So Boeing clearly do not intend you to select any kind of straight and level attitude. To suppose they do is an simply incorrect and a misrepresentation of what is in the FCTM.
Like you I do not claim to be perfect, I have done a great deal of instructing and taught instructors their trade. I very much like simple repeatable techniques that the individual can use as a framework to develop from.
My view is that in this case you are both technicaly and conceptualy in error.
Technicaly because if you flare to a straight and level attitude based on the speed after the flare you must change the nose attitude by more than the recommended 3 degrees.
Conceptualy because you are overcomplicating things by a margin in my view.
Sorry but unless you, or someone else, can correct my demo in post 95 then that is my view.
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My stars. You guys are all out of you minds. Way way to complicated. Just get the bird close to the ground, cut the power, check the descent rate a little and let it settle onto the ground. The more you do the better you will get at it. It is that simple. Some things cannot be explained, they have to be practiced.
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7
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C´mon guys! It´s only a bloody aircraft, not rocket science
Practise makes perfect, it´s tricky in the begining, but hey, it does´nt take a doctors diploma to land... GL
Cheers
Practise makes perfect, it´s tricky in the begining, but hey, it does´nt take a doctors diploma to land... GLCheers
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OK Ashling. Please feel welcome to disregard everything I've said. As I've said repeatedly, everyone is free to fly and train in anyway they, their company, and their regulator say is OK. I wish you well and hope that you stay safe.
Uh ... for what its worth, I wasn't able to identify your post #95, as you suggested. I think this post will be #60 in this thread.
Cheers.
Uh ... for what its worth, I wasn't able to identify your post #95, as you suggested. I think this post will be #60 in this thread.
Cheers.
airbus757
I know of good people who's airline career was ruined (promotion training terminated or self funded jet endorsement failed) because for whatever reason they just couldn't make it happen in the last 50 ft.
They were otherwise smart and co-ordinated people. All they needed was some guidance or framework to work off while they got the experience you talk about.
It might be difficult for someone like you or I to understand what the real problem is, but then in my case I have had my own landing framework since I was flying C-152's. It's called the Jacobson Flare. There have been numerous discussions about it here in PPRuNe.
Here's the last one: http://www.pprune.org/forums/showthread.php?t=280481
Obviously there is a need for guidance in this area:
It's this sort of advice that simply isn't helpful. I mean don't you think they've landed an aeroplane before? They were probably flying Barons or C 310's in their previous jobs.
I think one of the problems people have is that below about 100 ft they don't have the confidence to continue driving the aircraft down the 3 degree path to the aiming point because they can't identify with any certainty when to give up that aiming point and concentrate on the next one, which is the centre of the far end of the runway.
The Jacobson Flare determines that point and gives you the confidence. This change in aiming point does not rely on the "look" of the picture outside, and therefore not influenced by such things as runway width, or slope, or flap setting. I won't go through it all again here. Anyone interested should simply do their own search both here on PPRuNe and else where. Or PM me for information I can send via email.
Jacobson would beg to differ.
PS It's comments like those made by Whaledog and paperdragon that can destroy a pilot's confidence. They are simply left thinking to themselves "I'm #$%^ hopeless." "There must be something wrong with me". If I can't do this now I will never be able to".
It doesn't have to be that way.
I know of good people who's airline career was ruined (promotion training terminated or self funded jet endorsement failed) because for whatever reason they just couldn't make it happen in the last 50 ft.
They were otherwise smart and co-ordinated people. All they needed was some guidance or framework to work off while they got the experience you talk about.
It might be difficult for someone like you or I to understand what the real problem is, but then in my case I have had my own landing framework since I was flying C-152's. It's called the Jacobson Flare. There have been numerous discussions about it here in PPRuNe.
Here's the last one: http://www.pprune.org/forums/showthread.php?t=280481
Obviously there is a need for guidance in this area:
Just get the bird close to the ground, cut the power, check the descent rate a little and let it settle onto the ground.
I think one of the problems people have is that below about 100 ft they don't have the confidence to continue driving the aircraft down the 3 degree path to the aiming point because they can't identify with any certainty when to give up that aiming point and concentrate on the next one, which is the centre of the far end of the runway.
The Jacobson Flare determines that point and gives you the confidence. This change in aiming point does not rely on the "look" of the picture outside, and therefore not influenced by such things as runway width, or slope, or flap setting. I won't go through it all again here. Anyone interested should simply do their own search both here on PPRuNe and else where. Or PM me for information I can send via email.
Some things cannot be explained.
PS It's comments like those made by Whaledog and paperdragon that can destroy a pilot's confidence. They are simply left thinking to themselves "I'm #$%^ hopeless." "There must be something wrong with me". If I can't do this now I will never be able to".
It doesn't have to be that way.