LH A320 Rough Landing @ Hamburg
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Sorry to barge in so late but I was busy doing some re-training on the 320 family.
I am now in a country in which any experience on the airplane doesn't count at all and we all start from scratch, i.e re-do a complete type-rating , so I feel I am in a position where I can answer some questions .
(from Basil Seal ) :
"Take it at 250 clean and pull the throttle to idle and pull the stick all the way back and see if the protections can completely keep you out of trouble with the rapid airspeed decay from the zoom. Maybe, maybe not."
Did that one. Exactly that one. Pitch stopped at 25 ° N/u, then Alpha protection came in... nothing to it, kept on losing altitude, IAS into the amber with some 7,8 ° pitch up.
Coming back to the subject, if I may, there was absolutely nothing wrong in that approach (including the decision to continue using the RWY 23 after the change-over to the tower)...until the airplane was blown rather violently to the left, off the centerline.
The only comment another pilot worthy of his licence could make is that, at that point a decision to go around was the preferable option . Why ? so close to the ground, returning to the RWY centerline would have meant (and they attempted it ) an important turn into wind followed immediately - and I'm talking fractions of a second - by a flare-cum-decrabbing maneuver.
That sort of skills is probably outside the competence of most pilots, in whose company I include myself.
As the 320 roll rate is greater than any Boeing pilot could find, I am left with no doubt that had it been another airplane, it could well have ended spread in the clover.
The rest of the speculations about the pilots and the airplane belongs to armchair aviation.
After some 12 years on the 320 while having more than 5500 hrs on the 737, I feel I am entitled to this opinion.
I am now in a country in which any experience on the airplane doesn't count at all and we all start from scratch, i.e re-do a complete type-rating , so I feel I am in a position where I can answer some questions .
(from Basil Seal ) :
"Take it at 250 clean and pull the throttle to idle and pull the stick all the way back and see if the protections can completely keep you out of trouble with the rapid airspeed decay from the zoom. Maybe, maybe not."
Did that one. Exactly that one. Pitch stopped at 25 ° N/u, then Alpha protection came in... nothing to it, kept on losing altitude, IAS into the amber with some 7,8 ° pitch up.
Coming back to the subject, if I may, there was absolutely nothing wrong in that approach (including the decision to continue using the RWY 23 after the change-over to the tower)...until the airplane was blown rather violently to the left, off the centerline.
The only comment another pilot worthy of his licence could make is that, at that point a decision to go around was the preferable option . Why ? so close to the ground, returning to the RWY centerline would have meant (and they attempted it ) an important turn into wind followed immediately - and I'm talking fractions of a second - by a flare-cum-decrabbing maneuver.
That sort of skills is probably outside the competence of most pilots, in whose company I include myself.
As the 320 roll rate is greater than any Boeing pilot could find, I am left with no doubt that had it been another airplane, it could well have ended spread in the clover.
The rest of the speculations about the pilots and the airplane belongs to armchair aviation.
After some 12 years on the 320 while having more than 5500 hrs on the 737, I feel I am entitled to this opinion.
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Lemurian, I know you have a lot of experience in the A320 and
Boing aircraft but looking at the video I didn't see them being blown violently off to the left until the right wing came up and any aircraft with a 25 or 30 knot right crosswind component with the right wing up would follow the same tragectory. Why did the right wing come up? Was full right aileron correction used? If not, why? The one photo someone posted when the left wingtip hit showed little right aileron or right spoiler correction was being used. It doesn't matter how much roll rate the aircraft has if you don't utilize it.
Boing aircraft but looking at the video I didn't see them being blown violently off to the left until the right wing came up and any aircraft with a 25 or 30 knot right crosswind component with the right wing up would follow the same tragectory. Why did the right wing come up? Was full right aileron correction used? If not, why? The one photo someone posted when the left wingtip hit showed little right aileron or right spoiler correction was being used. It doesn't matter how much roll rate the aircraft has if you don't utilize it.
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My neighbor is an A320 pilot and explained how the sidestick aileron control changes bank angle so once established in a bank no sidestick aileron is required unless you want to change your bank. It doesn't matter if the wings are level or in this landing when you would want some right bank to touchdown in case you encountered some gusts during touchdown. Boeing aircraft would require constant right aileron input to do the same. So since I don't see any abrupt roll movement during this landing like a big gust the side stick must have gone to left aileron to let the left wing drop as it did if the controls were working as advertised.
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Originally Posted by Lemurian
there was absolutely nothing wrong in that approach (including the decision to continue using the RWY 23 after the change-over to the tower)...until the airplane was blown rather violently to the left, off the centerline.
I also noticed that even in the earliest part of the video (when the aeroplane could very well have been being flown by the ILS, not the pilot) the banks both ways to maintain the crab angle were pretty sharp and jerky - nothing progressive about them.
And there's no doubt that the subsequent banks - attempting to regain the runway line and decrab - were also pretty steep.
Finally, I reviewed the two other examples of A320 go-arounds (kindly provided by CONF iture in Post 425 above) and saw exactly the same thing - steep banks both ways at incredibly low altitudes.
I find it difficult to believe that any professional pilot (leave alone three of them in different incidents) could have INTENDED such steep banks at such a low altitude. It's much more likely that the steepness of the banks was unintended.
To the best of my knowledge no other aeroplanes from either manufacturer have exhibited this tendency. Which makes me wonder, could it simply be the case that the relevant A320 controls (sidestick and ailerons) are just plain more sensitive than they ought to be, not 'progressive' enough? That too little movement of the sidestick produces too much reaction from the ailerons? Or the reverse - that too small a movement of the sidestick produces too little reaction and the pilot finds it necessary to move it more and more before he/she gets a response, which turns out in the end to be 'too much, too late'?
If that's so, it would make a precarious kind of sense. As I said, only the A320 Family seems to exhibit this tendency, A330s/40s and even the A380 don't seem to have the problem? But, of course, they were designed much later, the A320 was the very first 'FBW plus auto-coordination' type, designed back in the '80s?
Sidestick indication on PFD. Habsheim Accident.
Quotes from CONF iture:
1) To go back to the topic and your anecdote, how did you notice your FO was trying to steer with the sidestick ?
2) What has been your view on Habsheim and how did you deal with that event afterward ?
[Unquote]
1) In ground mode, the position of the sidestick(s) is displayed by a white cross on the PFDs.
2) HABSHEIM [off-topic, with grovelling apologies to the Moderators]
Have not read Monsieur Asseline's book. So regret that I shall not be addressing his version of events; merely recalling the scenario as I saw it on video and read in reports. You will not be getting news, I'm afraid, and the following will be almost entirely from memory.
Habsheim was a cowboy manoeuvre – no doubt flown with the best of enthusiastic intentions – poorly planned. Even a simple low flyby of the small airfield should not have been conducted with fare-paying passengers on board, regardless of the type of aircraft. It seems to have been an attempt to exploit and demonstrate several unique features of the A320, but it showed at least one fatal misunderstanding in the repertoire of flight-envelope protections.
I don't remember if the crew created a flight-plan in the FMGS for the short flight from Basel-Mulhouse to the small airstrip at Habsheim. This could have been done easily in about 5 -10 minutes. They may not have, because they seem to have overestimated the very short distance; entering the circuit on the downwind leg at an inconveniently high speed, the CFM-56 engines at flight-idle.
Presumably, the plan was to turn on to final approach at a normal speed in landing configuration, descending at approach thrust to about 50ft. Over the threshold of the runway, they would have levelled off and, without increasing thrust, allowed the aeroplane to slow down through "alpha-prot"; the nose getting higher and higher in level flight. Below that speed, the pilot would have to pull on the sidestick to stop the nose dropping. [The deceleration can be continued to alpha-max, about 5% above the stalling IAS, after which the FBW will gradually lower the nose if necessary to avoid the stall.]
However, the assumption seems to have been that, prior to reaching alpha-max, the "Alpha-Floor" function of the autothrust (A/THR) would command TOGA thrust automatically. From approach thrust TOGA would have been achieved in less than 2 seconds, and the A/C could be rotated into an even higher pitch-attitude for a steep go-around. If the pilot got it right, this extreme and spectacular manoeuvre would be performed right in front of the crowd. At any time before or after Alpha-Floor was triggered, the pilot would have the option of selecting TOGA thrust himself, by pushing the throttles forward in the usual manner.
What appears to have happened, on the day, was that their excessive speed on joining downwind led to a wider circuit than planned, to lose height and speed, while extending gear and slats/flaps. They eventually reached the point above the runway threshold at about 50ft agl, and at or just above the right IAS. Until that moment, the whole circuit would have been flown at idle thrust, and the VIDEO suggests that idle thrust was maintained as they flew along the runway at a steady height – just above the level of the treetops at the far end. The throttle levers were probably in the idle position, with A/THR disengaged. The pilot seems to have decided to allow the aeroplane to initiate the go-around at the moment of its own choosing...
I now have in front of me a copy of the A320 BCAL Flight Technical Manual, 11-50-Page 2, dealing with "ATHR ENGAGEMENT AND ACTIVATION". The page is dated 25 August 1987, the year before the accident.
2.1 ENGAGEMENT
......
By the ALPHA-FLOOR in flight if the radioaltitude is higher than 100 feet. Engagement is indicated by:
– the illumination of the ATHR pushbutton on the FCU
– the A-FLOOR message on FMA
......
When ATHR is engaged, it can be active or inactive:
· Active: Thrust is controlled by A / THR
– by setting thrust levers between IDLE and MCT......
– by the ALPHA-FLOOR condition. In this case, A / THR commands the TO / GA thrust computed by FADEC whatever thrust levers position is and until A / THR is disengaged
. ALPHA FLOOR condition is inhibited on ground and below 100 ft during approach.
The video goes on to show the A/C continuing to fly towards the forest of trees in a nose-high attitude. Just before reaching them there are signs of power increase, if memory serves (disturbed air behind the engines), but the aeroplane starts to lose height. As it descends into the treetops, they are slightly flattened by a swathe of exhaust air from both engines. The A320 descends, apparently gently, through the treetops – wings exactly level – and disappears from view. Shortly after that, the sound of the engines spooling up finds its way to the camera microphone.
Presumably, the pilot realised that Alpha-Floor was not engaging (see FCOM above, re its inhibition below 100 ft), and finally selected TOGA himself. Unfortunately, the thrust was still at idle. This in itself would not have inhibited Alpha-Floor, but the certification requirement for jet engines allows up to a maximum of about 8 seconds for spool-up from idle thrust. The CFM-56 is somewhat quicker than that...
The fuselage remained mainly intact, if memory serves, but one passenger died in the evacuation.
It was soon suggested by the usual pundits in the media that the A320 had suffered a major failure of the engines or, more likely, of the FADEC "black boxes" controlling them. Or the computer had "decided" that the A/C was going to land, and stopped the pilot from doing otherwise. These theories were eagerly seized on by many of our pilot colleagues, particularly those flying Boeings; they had been anti-Airbus since the A310 showed Boeing how a "glass cockpit" could be designed better than on the B767/757. Perhaps understandably, the crew did nothing to set the record straight, and the conduct of the French accident investigation itself left much to be desired.
Within hours, we had decided provisionally that there was no evidence of technical failure, encouraged by the video footage. We were genuinely happy to continue flying carefully, and selling the aeroplane to our customers. Our initial diagnosis proved to be sound. It did remind some of us that the A320 was, ultimately, a flying machine subject to Newtonian Physics.
We were fortunate to have no major incidents during the years that followed; but to some extent you make your own luck.
1) To go back to the topic and your anecdote, how did you notice your FO was trying to steer with the sidestick ?
2) What has been your view on Habsheim and how did you deal with that event afterward ?
[Unquote]
1) In ground mode, the position of the sidestick(s) is displayed by a white cross on the PFDs.
2) HABSHEIM [off-topic, with grovelling apologies to the Moderators]
Have not read Monsieur Asseline's book. So regret that I shall not be addressing his version of events; merely recalling the scenario as I saw it on video and read in reports. You will not be getting news, I'm afraid, and the following will be almost entirely from memory.
Habsheim was a cowboy manoeuvre – no doubt flown with the best of enthusiastic intentions – poorly planned. Even a simple low flyby of the small airfield should not have been conducted with fare-paying passengers on board, regardless of the type of aircraft. It seems to have been an attempt to exploit and demonstrate several unique features of the A320, but it showed at least one fatal misunderstanding in the repertoire of flight-envelope protections.
I don't remember if the crew created a flight-plan in the FMGS for the short flight from Basel-Mulhouse to the small airstrip at Habsheim. This could have been done easily in about 5 -10 minutes. They may not have, because they seem to have overestimated the very short distance; entering the circuit on the downwind leg at an inconveniently high speed, the CFM-56 engines at flight-idle.
Presumably, the plan was to turn on to final approach at a normal speed in landing configuration, descending at approach thrust to about 50ft. Over the threshold of the runway, they would have levelled off and, without increasing thrust, allowed the aeroplane to slow down through "alpha-prot"; the nose getting higher and higher in level flight. Below that speed, the pilot would have to pull on the sidestick to stop the nose dropping. [The deceleration can be continued to alpha-max, about 5% above the stalling IAS, after which the FBW will gradually lower the nose if necessary to avoid the stall.]
However, the assumption seems to have been that, prior to reaching alpha-max, the "Alpha-Floor" function of the autothrust (A/THR) would command TOGA thrust automatically. From approach thrust TOGA would have been achieved in less than 2 seconds, and the A/C could be rotated into an even higher pitch-attitude for a steep go-around. If the pilot got it right, this extreme and spectacular manoeuvre would be performed right in front of the crowd. At any time before or after Alpha-Floor was triggered, the pilot would have the option of selecting TOGA thrust himself, by pushing the throttles forward in the usual manner.
What appears to have happened, on the day, was that their excessive speed on joining downwind led to a wider circuit than planned, to lose height and speed, while extending gear and slats/flaps. They eventually reached the point above the runway threshold at about 50ft agl, and at or just above the right IAS. Until that moment, the whole circuit would have been flown at idle thrust, and the VIDEO suggests that idle thrust was maintained as they flew along the runway at a steady height – just above the level of the treetops at the far end. The throttle levers were probably in the idle position, with A/THR disengaged. The pilot seems to have decided to allow the aeroplane to initiate the go-around at the moment of its own choosing...
I now have in front of me a copy of the A320 BCAL Flight Technical Manual, 11-50-Page 2, dealing with "ATHR ENGAGEMENT AND ACTIVATION". The page is dated 25 August 1987, the year before the accident.
2.1 ENGAGEMENT
......
By the ALPHA-FLOOR in flight if the radioaltitude is higher than 100 feet. Engagement is indicated by:
– the illumination of the ATHR pushbutton on the FCU
– the A-FLOOR message on FMA
......
When ATHR is engaged, it can be active or inactive:
· Active: Thrust is controlled by A / THR
– by setting thrust levers between IDLE and MCT......
– by the ALPHA-FLOOR condition. In this case, A / THR commands the TO / GA thrust computed by FADEC whatever thrust levers position is and until A / THR is disengaged
. ALPHA FLOOR condition is inhibited on ground and below 100 ft during approach.
The video goes on to show the A/C continuing to fly towards the forest of trees in a nose-high attitude. Just before reaching them there are signs of power increase, if memory serves (disturbed air behind the engines), but the aeroplane starts to lose height. As it descends into the treetops, they are slightly flattened by a swathe of exhaust air from both engines. The A320 descends, apparently gently, through the treetops – wings exactly level – and disappears from view. Shortly after that, the sound of the engines spooling up finds its way to the camera microphone.
Presumably, the pilot realised that Alpha-Floor was not engaging (see FCOM above, re its inhibition below 100 ft), and finally selected TOGA himself. Unfortunately, the thrust was still at idle. This in itself would not have inhibited Alpha-Floor, but the certification requirement for jet engines allows up to a maximum of about 8 seconds for spool-up from idle thrust. The CFM-56 is somewhat quicker than that...
The fuselage remained mainly intact, if memory serves, but one passenger died in the evacuation.
It was soon suggested by the usual pundits in the media that the A320 had suffered a major failure of the engines or, more likely, of the FADEC "black boxes" controlling them. Or the computer had "decided" that the A/C was going to land, and stopped the pilot from doing otherwise. These theories were eagerly seized on by many of our pilot colleagues, particularly those flying Boeings; they had been anti-Airbus since the A310 showed Boeing how a "glass cockpit" could be designed better than on the B767/757. Perhaps understandably, the crew did nothing to set the record straight, and the conduct of the French accident investigation itself left much to be desired.
Within hours, we had decided provisionally that there was no evidence of technical failure, encouraged by the video footage. We were genuinely happy to continue flying carefully, and selling the aeroplane to our customers. Our initial diagnosis proved to be sound. It did remind some of us that the A320 was, ultimately, a flying machine subject to Newtonian Physics.
We were fortunate to have no major incidents during the years that followed; but to some extent you make your own luck.
Last edited by Chris Scott; 12th Mar 2008 at 15:46. Reason: Minor improvements in syntax.
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Lemurian, I know you have a lot of experience in the A320 and
Boing aircraft but looking at the video I didn't see them being blown violently off to the left until the right wing came up and any aircraft with a 25 or 30 knot right crosswind component with the right wing up would follow the same tragectory by Bubbers44
Boing aircraft but looking at the video I didn't see them being blown violently off to the left until the right wing came up and any aircraft with a 25 or 30 knot right crosswind component with the right wing up would follow the same tragectory by Bubbers44
Not sure that it was necessarily 'blown,' Lemurian - after reading your post I looked again (for the nth. time) at the video, and noted that early in the sequence (immediately after it passes overhead) the aeroplane appears to bank noticeably to the left. So maybe it was that, rather than the wind, which caused the aeroplane to deviate left by RWA
The rest of the speculations about the pilots and the airplane belongs to armchair aviation.
After some 12 years on the 320 while having more than 5500 hrs on the 737, I feel I am entitled to this opinion. By Lemurian
After some 12 years on the 320 while having more than 5500 hrs on the 737, I feel I am entitled to this opinion. By Lemurian
Actually I'd be much more impressed if you had ten years experience on the Beech 18 or DC-3. And putting all other opinions other than your own in the arm chair category is a laugh, in reality, other than the crew that was operating, the only way we will actually know what happened is to analyze the data from the black boxes, I'm sure it's already been accomplished, until that information is presented, we are all arm chairing it, by the way, it's much more challenging to do a crosswind landing in a Pitts S-1 than some flying bus.Cheers, D.L.
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Originally Posted by Dream Land
Yes, appears to me the poor method of de-crabbing was the culprit (armchair opinion only).
) I can say with absolute conviction that I'd have decided to go around.
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D.L. I also flew the D18 Twin beach hauling freight and felt as you did that it was the best test of how well your x-wind landing technique was doing. It works equally well in the 757/767 and all other aircraft ever built. Airplanes like to touch down with the wheels lined up with the direction the airplane is going, hopefully going straight down the runway. The right wing going up without input from the side stick with their control logic seems unlikely.
Quote from Nichibei Aviation:
Let's take the next example to illustrate the explanation:
-headwind component 150kts.
-x-wind component 30kts
In this case the total relative airflow is at an angle of 11.3 degrees from centerline.
[Unquote]
Think what you intended to say was "150kts TAS" ?
Otherwise, you have argued the advantages of applying slight upwind sideslip during de-crab brilliantly - thanks.
Without trying to arbitrate in the slight disagreements between Dream Land and Lethurian, I must say that the former is absolutely correct to point out that the A320 (and, presumably, the B737) is considerably less demanding on take-off and landing than many smaller types, particularly the tail-draggers. In my own experience, the DC-3 and "Dash-One" Chipmunk come to mind.
By the way, I recently asked (elsewhere on this Forum) whether my perception that the B737 main gear has limited castoring ability is correct? If so, touchdown on dry runways without full de-crab would be a safer option than it is on the A320. Perhaps you can answer that one for us, Dream Land ?
Let's take the next example to illustrate the explanation:
-headwind component 150kts.
-x-wind component 30kts
In this case the total relative airflow is at an angle of 11.3 degrees from centerline.
[Unquote]
Think what you intended to say was "150kts TAS" ?
Otherwise, you have argued the advantages of applying slight upwind sideslip during de-crab brilliantly - thanks.
Without trying to arbitrate in the slight disagreements between Dream Land and Lethurian, I must say that the former is absolutely correct to point out that the A320 (and, presumably, the B737) is considerably less demanding on take-off and landing than many smaller types, particularly the tail-draggers. In my own experience, the DC-3 and "Dash-One" Chipmunk come to mind.
By the way, I recently asked (elsewhere on this Forum) whether my perception that the B737 main gear has limited castoring ability is correct? If so, touchdown on dry runways without full de-crab would be a safer option than it is on the A320. Perhaps you can answer that one for us, Dream Land ?
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Not rated on the 737 but have you ever watched a 737 taxi directly in front of you, they don't appear to be pointed in the same direction as the taxiway? 
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Of tail draggers and others
Chris Scott
"...the A320 (and, presumably, the B737) is considerably less demanding on take-off and landing than many smaller types, particularly the tail-draggers...."
Off topic. I,too, have -and still do -flown those, not the Pitts, but all Cubs and Zlins... On this subject, a Twin Otter is in my experience, a lot more of a handful than a Dak (even during taxi ).
The argument that they are more difficult to land (and I've never seen one do in the Ham conditions we are talking about ), doesn't -shouldn't - allow us to criticize the handling of that landing... only discuss the choice of persisting in attempting to land when the situation became less and less manageable.
My argument is that
1/- we weren't there in those conditions
2/- a careful observation of the origin of the difficulties they encountered, i.e the movement of the aircraft to the left at time-frame 30s, while the wings were level, with a drift angle that - until this moment - perfectly controlled the centerline tracking, should teach us some humility.
"...the A320 (and, presumably, the B737) is considerably less demanding on take-off and landing than many smaller types, particularly the tail-draggers...."
Off topic. I,too, have -and still do -flown those, not the Pitts, but all Cubs and Zlins... On this subject, a Twin Otter is in my experience, a lot more of a handful than a Dak (even during taxi ).
The argument that they are more difficult to land (and I've never seen one do in the Ham conditions we are talking about ), doesn't -shouldn't - allow us to criticize the handling of that landing... only discuss the choice of persisting in attempting to land when the situation became less and less manageable.
My argument is that
1/- we weren't there in those conditions
2/- a careful observation of the origin of the difficulties they encountered, i.e the movement of the aircraft to the left at time-frame 30s, while the wings were level, with a drift angle that - until this moment - perfectly controlled the centerline tracking, should teach us some humility.
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Of Yaw / Roll coupling
Coming late in this discussion, I haven't had time to read all the posts, but this is what I've experienced on the 320 family :
From a stable straight flight, pushing - not kicking - the rudder pedal and keeping a pressure on the pedal will cause the aircraft to bank on the applied rudder side...Nullifying the bank with the sidestick will naturally put the aircraft in a (forward ) side-slip and in order to maintain that sideslip, the pilot would need successive applications of lateral stick to prevent the airplane from returning toeards a turn on the rudder side.
Apparently, after a few such applications, it looks as if the flight control system acquires a new "zero , equilibrium point and would continue flying the sideslip.
Another description from a USAirways pilot, E Parks from the sister site "Airbus Drivers.net" :
"Crosswind Landings – Despite rumors, the Airbus uses conventional crosswind landing technique. Two points however; first, as the Airbus uses roll rate for the ailerons the pilot cannot HOLD the sidestick in the crossed control position. The sidestick must be released once the bank angle is established. Think of “bumping” in the needed bank. It is more intuitive than it sounds! Second, the sidestick is as sensitive in the flare as in cruise. Care must be taken to use measured inputs to the sidestick. "
My last comment on the handling technique used on the LH 320 in the video is this :
According to Airbus recommendations, it is quite obvious that the crew elected to land with flaps in CONFIG 3. Fair enough. Problem is that in that configuration, the behaviour of the aircraft in control response is with a faster response, both in pitch (flare is *flatter, shorter *) and in roll (*faster, more incisive* )... The pilot had an airplane that's quite different than he is used to.
My two cents.
From a stable straight flight, pushing - not kicking - the rudder pedal and keeping a pressure on the pedal will cause the aircraft to bank on the applied rudder side...Nullifying the bank with the sidestick will naturally put the aircraft in a (forward ) side-slip and in order to maintain that sideslip, the pilot would need successive applications of lateral stick to prevent the airplane from returning toeards a turn on the rudder side.
Apparently, after a few such applications, it looks as if the flight control system acquires a new "zero , equilibrium point and would continue flying the sideslip.
Another description from a USAirways pilot, E Parks from the sister site "Airbus Drivers.net" :
"Crosswind Landings – Despite rumors, the Airbus uses conventional crosswind landing technique. Two points however; first, as the Airbus uses roll rate for the ailerons the pilot cannot HOLD the sidestick in the crossed control position. The sidestick must be released once the bank angle is established. Think of “bumping” in the needed bank. It is more intuitive than it sounds! Second, the sidestick is as sensitive in the flare as in cruise. Care must be taken to use measured inputs to the sidestick. "
My last comment on the handling technique used on the LH 320 in the video is this :
According to Airbus recommendations, it is quite obvious that the crew elected to land with flaps in CONFIG 3. Fair enough. Problem is that in that configuration, the behaviour of the aircraft in control response is with a faster response, both in pitch (flare is *flatter, shorter *) and in roll (*faster, more incisive* )... The pilot had an airplane that's quite different than he is used to.
My two cents.
Last edited by Lemurian; 12th Mar 2008 at 12:46. Reason: grammar
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Thanks Lemurian. It has been 10 years since I was on the Bus and I frankly could not remember what the zoom maneuver from 250/10000 would yield. I think the point my instructor was trying to bring across was that one should not grow complacent with the protections and that they are designed to "protect" but not necessarily "save!" A bit TIC there of course, but I was just struck by some very subtle posts here that hinted that the Bus would correct the rise of the right wing etc. as if in complete bewilderment that the machine did not "stop" a deteriorating flight path/profile. That is why I was impressed with some of the posters who would proffer quite detailed explanations of the technical aspects of the flight control laws, but then add the caveat that it is still an airplane and quite understandably is subject to the normal laws of aerodynamics.
I just wish we could see the data!
I just wish we could see the data!
Gusts. Flaps 3? "Bumping" stick to hold sideslip.
Quotes from Lemurian:
(1) a careful observation of the origin of the difficulties they encountered, i.e the movement of the aircraft to the left at time-frame 30s, while the wings were level, with a drift angle that - until this moment - perfectly controlled the centerline tracking, should teach us some humility.
(2) According to Airbus recommendations, it is quite obvious that the crew elected to land with flaps in CONFIG 3. Fair enough. Problem is that in that configuration, the behaviour of the aircraft in control response is with a faster response, both in pitch (flare is *flatter, shorter *) and in roll (*faster, more incisive* )... The pilot had an airplane that's quite different than he is used to.
(3) "Two points however; first, as the Airbus uses roll rate for the ailerons the pilot cannot HOLD the sidestick in the crossed control position. The sidestick must be released once the bank angle is established. Think of “bumping” in the needed bank. It is more intuitive than it sounds!"
[Unquote]
(1) I agree. Have said as much in at least one of my posts [#420, Mar09/00:12]:
...the roll-rate seems to increase quite suddenly half way through de-crab, at about the time the A/C leaves the ground in bounce. prior to that, I can see negative and positive gusts at around 50ft. ***
(2) If they were using "Flaps" 3, your comment is spot-on relevant, and was something I grumbled about for many years on the A320.
Also, I have a perception that the control laws may be slightly different for Flap 3, because it is a setting also used for take-off.
The other differences include higher pitch-attitude, and lower thrust - particularly with GS-Mini doing its job. Why do we not also practise Flaps 3 landings occasionally in calm weather?
You will, no doubt, catch up on the previous posts in due course.
Here is a link to another thread - the "Iberia Aborted Landing in Bilbao". There is much interesting discussion on it about A320 crosswind technique. Also see my posts #56 & #73.
http://www.pprune.org/forums/showthr...=iberia+bilbao
(3) I think the text you quote is also absolutely spot-on. I'm sure we do it without even realising it.
*** [Editorial] The loss of tracking at about 50 ft should have provoked an immediate go-around, in my opinion. You cannot fly upwind so close to the ground in a limiting crosswind. If you needed to correct a bit downwind, that might be a different matter.
(1) a careful observation of the origin of the difficulties they encountered, i.e the movement of the aircraft to the left at time-frame 30s, while the wings were level, with a drift angle that - until this moment - perfectly controlled the centerline tracking, should teach us some humility.
(2) According to Airbus recommendations, it is quite obvious that the crew elected to land with flaps in CONFIG 3. Fair enough. Problem is that in that configuration, the behaviour of the aircraft in control response is with a faster response, both in pitch (flare is *flatter, shorter *) and in roll (*faster, more incisive* )... The pilot had an airplane that's quite different than he is used to.
(3) "Two points however; first, as the Airbus uses roll rate for the ailerons the pilot cannot HOLD the sidestick in the crossed control position. The sidestick must be released once the bank angle is established. Think of “bumping” in the needed bank. It is more intuitive than it sounds!"
[Unquote]
(1) I agree. Have said as much in at least one of my posts [#420, Mar09/00:12]:
...the roll-rate seems to increase quite suddenly half way through de-crab, at about the time the A/C leaves the ground in bounce. prior to that, I can see negative and positive gusts at around 50ft. ***
(2) If they were using "Flaps" 3, your comment is spot-on relevant, and was something I grumbled about for many years on the A320.
Also, I have a perception that the control laws may be slightly different for Flap 3, because it is a setting also used for take-off.
The other differences include higher pitch-attitude, and lower thrust - particularly with GS-Mini doing its job. Why do we not also practise Flaps 3 landings occasionally in calm weather?
You will, no doubt, catch up on the previous posts in due course.
Here is a link to another thread - the "Iberia Aborted Landing in Bilbao". There is much interesting discussion on it about A320 crosswind technique. Also see my posts #56 & #73.
http://www.pprune.org/forums/showthr...=iberia+bilbao
(3) I think the text you quote is also absolutely spot-on. I'm sure we do it without even realising it.
*** [Editorial] The loss of tracking at about 50 ft should have provoked an immediate go-around, in my opinion. You cannot fly upwind so close to the ground in a limiting crosswind. If you needed to correct a bit downwind, that might be a different matter.
Last edited by Chris Scott; 12th Mar 2008 at 16:59. Reason: Go-around added.
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A 320 cross wind technique
I write as an ex Boeing driver, with just one sim session on the A320 about 20 years ago (actually to evaluate a TCAS display). But I thought I understood (roughly) what the A320 series flight controls were trying to do in pitch and roll. The stick commands roll rate until touchdown, so it cannot be right to describe the procedure during de crab as 'holding some into-wind aileron' . You don't hold into wind aileron with the side stick if you are airborne in an A320. If you apply a steady roll input as you would in a conventional aircraft, will command a steadily increasing roll in an A 320. Maybe that 'holding a little aileron' is just a simple short hand of a subtly different process so perhaps I am being a bit picky, but somehow I don't think so. The post from Lemurian that describes the process as 'bumping' to get the right steady slip must surely be right. My only quibble with the chap who originally wrote it was his introduction that said
I wouldn't describe applying essentially zero roll demand, once the side slip is established, as conventional. The aircraft certainly behaves in a totally conventional manner as Lufthansa has just proved so publicly, but that is a different matter.
From the evidence of the previous 450 odd posts, assuming the Ppruners are a fair cross section, then there is a substantial body of A320 pilots (including the fellow whose hand appears in the video some way back - I have sat jump seat behind other coffee stirrers like him - and all those who regularly hit the roll stops) who really don't know what their flight controls are doing, haven't thoroughly thought through how the machine works, and haven't been taught to do so. I find that rather worrying.
Despite rumors, the Airbus uses conventional crosswind landing technique'
From the evidence of the previous 450 odd posts, assuming the Ppruners are a fair cross section, then there is a substantial body of A320 pilots (including the fellow whose hand appears in the video some way back - I have sat jump seat behind other coffee stirrers like him - and all those who regularly hit the roll stops) who really don't know what their flight controls are doing, haven't thoroughly thought through how the machine works, and haven't been taught to do so. I find that rather worrying.
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Originally Posted by RWA
Which makes me wonder, could it simply be the case that the relevant A320 controls (sidestick and ailerons) are just plain more sensitive than they ought to be, not 'progressive' enough? That too little movement of the sidestick produces too much reaction from the ailerons? Or the reverse - that too small a movement of the sidestick produces too little reaction and the pilot finds it necessary to move it more and more before he/she gets a response, which turns out in the end to be 'too much, too late'?
Wasn't this 'increased roll sensitivity on approach an issue related specifically to the A321 which already resulted in some actions by Airbus (see http://www.smartcockpit.com/data/pdfs/flightops/flyingtechnique/A321_Lateral_Control_In_Turbulence_and_Icing_Conditions.pdf) like different recommended flap-settings and modifcations of the ELAC?
Regards, ihg
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Originally Posted by Chriss Scott
1) In ground mode, the position of the sidestick(s) is displayed by a white cross on the PFDs.
Is it just me or ... during a landing run, between the mandatory calls regarding spoilers, reverses, braking, speed, and the overhaul situation awareness, I just don't think or simply don't have the natural resources to go and keep an eye on that tiny white cross ... !?
If you have ... hat off !
But I still stand that such vital information is so much easier to get through a fully prominant and visible connected control wheel.
Nevertheless, the worst part in your anecdote is not that the controls were applied in the wrong direction, but that the PF argued ... ???
Regarding Habsheim, you make interesting comments, in the same time I note some inexactitudes that are more relevant than we may think. I need first to read my documentation and I’ll have some more questions and comments. Maybe we can even start another thread for the subject ...
To go back to HAM, what I can see from the video is something typical from a flying school, not more not less, the proper technique simply not applied in due time for these unforgiving conditions.
And I even wonder (pure speculation !) if the side stick has not been solicited (only in a slightest way) in the wrong direction ?
I also wish we could have the data ...
Originally Posted by Nichibei Aviation
To captains: do not leave your life and that of hundreds of passengers in the hands of a 600 hour F/O in a 30kts/G50kts landing!
His FO will acknowledge: “Nothing like Experience” and Experience needs TIME + PRACTICE
MY OWN PERSONAL view:
- Adverse weather
- Low time PF
- FBW Airbus
- PNF CAPT willing to supervise
These all together are the perfect ingredients for a YouTube glory, but change only one of them and HAM is a non event.
Considering the general trend in the Industry regarding formation, and the accessibility for video recording and sharing, we’ll see only more of these sequences, time will tell if a specific type of equipment is more at stake ... ?
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Question CONF.
Are you some kind of self-hating Frenchman or something? Disgruntled ex-AB employee perhaps? You seem to take every opportunity to rag on the FBW A3x0 series soemthing fierce, yet I never seem to find you on any other subject.
Yokes are old. They are on their way out. Yesterday's technology. Get used to it.
Are you some kind of self-hating Frenchman or something? Disgruntled ex-AB employee perhaps? You seem to take every opportunity to rag on the FBW A3x0 series soemthing fierce, yet I never seem to find you on any other subject.
Yokes are old. They are on their way out. Yesterday's technology. Get used to it.
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I agree with CONF. What part don't you agree with? Probably the FBW part. Exactly when do you suppose the captain took over to go around? If he first countered the FO's input does the computer average the two opposite inputs? When he selects priority on his side does it disengage from the averaging of the two side sticks to full authority on the left side stick? With the good old fashioned obsolete yoke this is not a problem.