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LH A320 Rough Landing @ Hamburg

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LH A320 Rough Landing @ Hamburg

Old 5th Mar 2008, 07:09
  #261 (permalink)  
 
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Please lets keep it simple. Regardless of the control laws with which all of us experienced Airbus pilots are farmiliar with, don't forget the the actual control surfaces themselves, in particular the rudder are basically no different than on any other aircraft in terms of the primary and secondary effect that they will produce.

Primary erffect of rudder = yaw
Secondary effect = roll

It isn't Rocket Science!
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Old 5th Mar 2008, 07:23
  #262 (permalink)  
C M
 
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@nigelondraft:

You are right - it's not the conventional direct law in pitch, but it gives a direct "stick-to-surface" connection plus nose down momentum, so it's quite similar (exept the nose down momentum) and to make it easier I called it direct law. Full direct law is achieved 5s after touchdown, that's right.
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Old 5th Mar 2008, 07:27
  #263 (permalink)  
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@ iceman:

I totally agree with you! It's just a plane. And when I look back the one I like most besides the MD80 (which I loved but don't want to fly anymore in an environement like we have nowadays).
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Old 5th Mar 2008, 08:03
  #264 (permalink)  
 
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It is simple, just fly the aircraft and apply x-wind landing technique. The pilot involved was flying in pretty extreme conditions. 'nuff said.....can we move on ?
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Old 5th Mar 2008, 08:12
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Wayne.. will move on in a sec

CM - sorry still disagree IMHO there is no direct "stick-to-surface" connection until 5s after touchdown. Until that point stick fore/aft is demanding "Load Factor" albeit with the (progressive) offset discussed...

NoD
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Old 5th Mar 2008, 08:37
  #266 (permalink)  
 
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Pilot Flying

Would you believe that: since it has been released that the 24 year old female F/O was handling the controls until the PIC commanded and executed the go-around, now the German public is discussing, how that can be...

I'm not disputing whether it's wise or not to let your F/O drive the ship under such conditions - this is a judgement call.

But I can already see the yellow press eagerly jumping at this story ('the handsome female copilot tried to land until the experienced Captain took over with 131 terrified pax on board..') and probably even forcing LH to be defensive in this matter.

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Old 5th Mar 2008, 08:38
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thoughtlessness

I am a passenger and with respect to the case of Hamburg I say that in those conditions weather the pilot did not have absolutely to try to land. Question: in case of catastrophe of who it would have been the responsibility? This is for me, as passenger, is lack of responsabiliy and prevision or thoughtlessness...
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Old 5th Mar 2008, 08:52
  #268 (permalink)  
 
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without knowing the fuel state and so on I'd have thought the proper decision would be to find a runway with a smaller crosswind component. At my airline everyone would be too worried about covering their arse to continue a landing like this. The decision making process would be governed by the phrase: "what would the lawyers say?" landing outside manufacturers limits (demonstrated or otherwise). Also, our FOs are only allowed to land in 2/3 of the max demonstated crosswind (max demonstrated being 35 knots, so FO limit is 23). Whilst I admire yer mauns ability, I think that he probably made a poor decision to land there in the first place. Was it commercial pressure or some sort of bravado that lead to that decision?
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Old 5th Mar 2008, 08:55
  #269 (permalink)  
 
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Since direct law kicks in 5 secs after touchdown, can someone please explain what the correct use of the sidestick is to keep wings level during decrabbing ?

I see it clearly after those 5 seconds, but before that how is commanding a roll rate with both main landing gears on the ground made equivalent to applying a required aileron deflection ?

Thanks in advance guys.
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Old 5th Mar 2008, 09:02
  #270 (permalink)  
 
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I think it's fun.
Even after more than 20 years in service there's the everlasting debate HOW this thing works .......

Anyway, i am no specialist, but reading this thread bring to my mind Jack O'Neil who once said: One thing you should never ask Carter: "How?"

(Just to complete a earlier contribution:
We all agree that if we decrab, the upwind wing gets a little more lift, mostly resulting in a small roll downwind. We all agree that in roll demand mode the AB strives to keep the demand, which before decrab was the actual bank angle. Logically the computer then commands a slight roll to get back to that bank angle. THAT's the input i was mentioning, it is not intended to compensate for the crab and consequent track alteration. But there is definitely a small roll input on the AB when decrabbing, which is not on a B.)

Last edited by GMDS; 5th Mar 2008 at 09:19.
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Old 5th Mar 2008, 09:05
  #271 (permalink)  
 
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Summarising the adaptation of basic control law objectives:

- Ground phase : ground mode
Direct relationship between stick and elevator
available before lift-off and after touch-down

- Take-off phase : take-off mode
For smooth transition, blend of ground phase law
and Nz command law over 5 seconds after lift off.

- Landing phase : landing mode
At 50ft the attitude is memorized as reference pitch
attitude.
At 30ft this value is progressively reduced to 2°
nose down to induce gentle positive pilot action for
a conventional flare.


Also note:

Sidestick free with pedal deflection results in stabilized
sideslip and bank angle facilitating “de-crabbing” in
crosswind landings.

Last edited by BEagle; 5th Mar 2008 at 09:31. Reason: Wrestling with the wretched editing function!
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Old 5th Mar 2008, 09:37
  #272 (permalink)  
 
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Don't knock the F/O ,it's very difficult to land in a crosswind when making the coffee.
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Old 5th Mar 2008, 09:39
  #273 (permalink)  
 
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Judgement call

Originally Posted by Jetopa
I'm not disputing whether it's wise or not to let your F/O drive the ship under such conditions - this is a judgement call.
Should I take the risk?

In tricky conditions, when split decision is required, when there are no clear-cut criteria ... I think that the the captain is the person to fly the aircraft, in order to get the feeling of the situation early, and so as to decide a go around without any undue hesitation.

In this case, a go around was obviously due when it became evident that the aircraft, after an overcorrection to the right, needed a turn to the left during the flare. A flying Captain, being in the loop, would have reacted sooner than a non flying captain just supervising a young co-pilot.

Let us not forget that the captain was not even able to physicaly get full control at once of the fbw controls !

Shall we have the opportunity to read or better to hear the CVR? Much to be learned, I think. I hope that LH will accept to share that experience.

Sorry if I seem to be so sure about the chain of events :
- allowing drift down wind
- overcorrection upwind with a real turn
- downwind turn during the flare to keep on the centerline
- touching ground with low wing downwind, and a drift downwind as well.
The fact is that, as an instructor, I have observed this scenario a few hundred times during basic training. It is such a "classic".
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Old 5th Mar 2008, 09:53
  #274 (permalink)  
 
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Bis47:
Let us not forget that the captain was not even able to physicaly get full control at once of the fbw controls !
He was you know. There's a button on the sidestick that transfers full authority to the controls on that side when pushed.

J.
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Old 5th Mar 2008, 09:53
  #275 (permalink)  
 
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ATC Considerations

asva [Today, 09:38],

I sympathise with your concerns, but would ask you to recognise that very few professions have the results of their decisions (and skills) subjected to such close scrutiny.

No one on this Forum - I guess - knows the full scenario that this captain and copilot were faced with, so we are not in a position to criticize the decision-making process - whatever that was. All we can do is to criticize, in some cases with a degree of hypocrisy, the handling skills of the pilots. I say "pilots" because there is every possibility that - if the copilot was the one making the approach - the recovery was achieved by the captain taking over.

As far as the decision to make the first (videoed) approach on Rwy 23 is concerned, we don't know exactly what conditions the Tower was reporting at the time. With our 20-20 hindsight, it seems ill-advised.

There is another issue, however, that has already been touched on by previous postings. The captain is the person who has ultimate responsibility for the safety of his/her aircraft - not ATC.

Hamburg is a busy aerodrome with two runways which, unfortunately, are not independent, i.e., they cross one another. When the wind is (roughly) from the west, ATC likes to use Rwy 33 for departing aircraft; Rwy 23 for arrivals. An aeroplane taking-off on Rwy 33 soon crosses the intersection point with Rwy 23. From that moment, ATC can give landing clearance (permission) to the next aeroplane on the approach to Rwy 23. This normally works quite well, and enables more movements of arrivals and departures, than using only the into-wind runway. If there is a very strong wind between west and NNW, however, there is a problem for the landing traffic. As the wind increases, eventually one of the landing captains is going to "request" a landing on Rwy 33.

When this happens, in my experience, ATC will warn the captain that there will be a considerable delay before an approach will be possible. This puts pressure on the captain, particularly if he/she has not loaded plenty of extra fuel to allow for this. The delay is very difficult to estimate. From ATC's point of view, they know that, if every arriving aircraft has to use Rwy 33, there may be a gradual build-up of delays. This would make the situation worse for everyone, and itself lead to diversions.

So ATC has their problems - pilots have theirs. Again, in my experience, German Air-Traffic Controllers tend to take a very robust attitude to "requests" by pilots, if it is not a part of their game-plan.

Last edited by Chris Scott; 5th Mar 2008 at 10:10. Reason: Syntax error
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Old 5th Mar 2008, 10:04
  #276 (permalink)  
 
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When to go-around?

Quote from Bis47:
Sorry if I seem to be so sure about the chain of events :
- allowing drift down wind
- overcorrection upwind with a real turn
- downwind turn during the flare to keep on the centerline
- touching ground with low wing downwind, and a drift downwind as well.
[Unquote]

I would go one further. The runway is about 45 metres wide. At about 100ft on the approach in a strong crosswind, a large jet needs to be tracking parallel to, and within about 10 metres of, the extended centreline. If not, a go-around should be made. As the height reduces, the tolerance should reduce to about 5 metres before and during the flare.


Editing PS:
Reviewing the video again, the incident aircraft appears to have been on the centreline at 100ft, and tracking correctly. Just before 50ft, an apparent increase in crosswind-component causes it to start moving downwind. At about 50ft, right bank is applied to track the aircraft back to the centreline, and the resulting heading represents a much larger deviation from the runway bearing than before. This is the situation at main-gear touchdown (left gear only) on the runway centreline...
I think Bis47 might agree that a go-around should have been initiated at about 50ft, given that the approach had continued that far.

Last edited by Chris Scott; 5th Mar 2008 at 17:06. Reason: Sentence added. PS added, for extra relevance. Title
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Old 5th Mar 2008, 10:10
  #277 (permalink)  
 
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I have heard the term "bumping" the control stick when decrabbing. Slowish rudder input allows the aircraft to keep the wing level but a quick bump just makes sure the wing remains level if not wing down into wind. I am not sure if it has been mentioned but there is the chance this may be a "dual input" episode. Very easy to do when in a tense situation such as this.
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Old 5th Mar 2008, 10:28
  #278 (permalink)  
 
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Bis47

Quote ... I think that the the captain is the person to fly the aircraft... unquote

Consider the next situation (I have been there):
F/O: 6 years on type,
Captain: just released out of route training on his first captaincy and on a, for him, new type. In the route training month there wasn't really any serious windy weather.

Now in this case I think it is prudent to let the first officer fly. In the remote case that he is not up to it, or when it gets hairy, just call for go around.
Don't forget that your F/O is also fully trained for go-arounds.

Incase of a junior F/O, I doubt that the captain will be junior. So then it is clear cut.
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Old 5th Mar 2008, 10:44
  #279 (permalink)  
 
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10 Mths on the line LHS is more than sufficent to deal with all situations......once the aircraft began to drift left @ 50 ft a GA should have been made. Imagine the feeling and the immence pressure on the 2nd approach that (a) the farm was nearly bought and (b) there is damage to the aircraft.
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Old 5th Mar 2008, 11:16
  #280 (permalink)  
 
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Forget the bloody control logic, forget the gender or rank of the PF.
Consider only the following. Why was the approach made, why wasnt a diversion to a better runway made if a request for 33 was denied/delayed.
If the approach had to be made why wasnt the most experienced pilot at the controls.In most cases that will be the skipper.
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