LH A320 Rough Landing @ Hamburg

[Chris Scott]

Quote from exeng Mar02/00:18:
As a former Boeing man the first on limits Xwind landing on a 320 at LHR scared me. The training I had on the sim was just that - training on the sim. I had full sidestick and the wing just kept on coming up. In the end I released some rudder (in panic. I might add, whilst trying to just fly the plane) and landed with a considerable amount of drift on.
Because of this experience I made some considerable noise in the office [....] and was given the advice that I 'probably just wasn't applying the correct techniques'. In other words - just go away.
Fortunately I mentioned this experience of mine to a 320 'old hand' who advised that the rubbish taught in the sim is just that - the drift has to be taken off earlier in the 320 so as to give the 'bus' some small time to rethink.


Trouble is (unless things have changed since my day), the hard-pressed pilot-managers are just too busy flying their desks and issuing memos to get out and remind themselves what the whole thing is really about. And even the trainers don't get enough "polling" themselves (as opposed to watching their students doing it).

It is not necessary or desirable to use the full sideslip technique in a strong crosswind, which is the implication of what you are saying. The sideslip angle required would put you too close to the possibility of pod-scrape/flap-scrape/winglet-scrape (depending on the pitch attitude).

The most reliable technique in my experience is to induce slight sideslip [U]during de-crab, i.e., to pre-empt the tendency of the upwind wing to rise because of the de-crab yaw**, AND to pre-empt a possible gust. 5 degrees of bank is about right. Limit the amount of flare. DO NOT TRY TO "GREASE" HER ON. Then, allow the downwind wheels to touch down immediately after the upwind ones. At this point, FBW ground Law will commence, and a suitable increase in into-wind aileron can be applied. This can be maintained until about 80 kts, to be on the safe side.
In my day, Medium autobrake was recommended in a strong crosswind, but it complicates the situation if you need to use differential brake to correct a swing. Runway length and state permitting, manual brake and idle reverse are the best option for directional control. If memory serves, rudder-fine (nosewheel) steering is not available above 72 kts GS. You may need differential brake to hold straight as the rudder itself gradually loses authority.

** [The FBW should counteract this. In practice, I often observed it fail to do so. Trainers have to teach the "book".]

Quote from lambourne [Mar02/00:59]:
I did not find the AB roll rate algorithm intuitive to adapt to. On this flight, I announced "full left sidestick" to my F/O and we touched down in a manner resembling tossing a pillow case full of doorknobs onto the runway. After we exited he said that hitting the stops was common occurrence on the bus in strong crosswinds. I said I had just spent 6 weeks in training and at no point did anyone in the schoolhouse find it somewhat needful to convey that you might hit the stops.
The bus is a bit like tail wheel airplane. Great on a calm or wind down the runway day, but a handful in strong x-winds


Full roll-demand is not normally necessary if you use the technique I describe above. But gust-induced rise of the upwind wing must be dealt with promptly, i.e., try to keep the wing [U]slightly down until the upwind wheels are firmly on.

Having flown the tailwheel-Dakota (only 450 hrs, admittedly), as well as numerous large jets before the A320, I cannot agree with the last sentence... The A320 behaves like most tricycle-gear jet airliners. Once the nosewheel is on the runway with ground spoilers (lift dumpers) extended, the necessity for differential brake is unusual. On the Dakota, as you allowed the tail to settle at about 50kts, your problems were often just beginning...

[seventhree]

I find it alarming that many of the Bus pilots posting here are under the impression that flight control laws change to direct at 50ft.

It makes me wonder if more and more carriers are using AQP and are providing pilots with heavily redacted training manuals.

[drkraft]

Ihg,

As I stated in a previous post, the last 100 feet of a crosswind landing can be very challenging. During a crosswind landing, the airport layout can come into play. If there are tall buildings, terminals, hangars, or even tall trees adjacent to the runway, the air can become quite unstable. If you've ever driven across a suspension bridge during high sidewinds, notice how unstable your car becomes when it passes the main support beams that block the airflow. In the video the aircraft appears to be fairly stable and tracking the centerline until just about 100 feet. The drift appears to accelerate, there's a correction back to centerline and then during the flare everything starts to go south. Unfortunately, at that point things are happening fast and you only have a few seconds to make a decision. Fortunately, for all involved, everybody walked away.

[PJ2]

seventhree;

Not only do checked-out Airbus pilots believe that the laws change around 50ft, but they also believe that the Airbus will "lower the wing" into wind when decrabbing, to keep the track straight - it's a very widely-held belief.

[marty1468]

If they believe that, why don't they just fly the thing in with one wing low?

[742]

...perhaps after this incident, a segment of tail wheel crosswind landings will become standard.

Stick and rudder skills being valued in 2008?

[PJ2]

Marty1468;
If they believe that, why don't they just fly the thing in with one wing low?
Because they believe the airplane will do it when required :bored: ...

Regardless, there are a number of misconceptions regarding the airplane as witnessed by the 2000+ posts on the TAM accident, many of which did not indicate understanding of the airplane, (while some, I hasten to add, revealed an astonishing depth of understanding which benefitted us all - thinking of ELAC here among others). I can see why though...the airplane itself takes a good six months to a year to get accustomed to and perhaps the same amount of time to get to the stage of "strapping it on" and even then, one may not be aware of all the C* law nuances.

[C M]

@ seventhree:

Pitch goes gradually to direct, roll not. And that makes it tricky...
Rudder is always direct.
Pitch direct is blended in gradually and reached around 50ft and even a light nose down momentum is induced to you make you pull the stick. Stabilizer position is also a key factor for pitch control (if it's bad you can hit the mechanical stop of the stick).

[C M]

@ PJ2:

I'm an Airbus Pilot and I know that the wing will not be lowered automatically. You can decrab an A320 almost like a conventional aircraft, it feels just a little bit different. It's a little bit shaky because you always have to counteract the roll normal law.

[NigelOnDraft]

Pitch goes gradually to direct, roll not. And that makes it tricky...
Rudder is always direct.
Pitch direct is blended in gradually and reached around 50ft and even a light nose down momentum is induced to you make you pull the stick. Stabilizer position is also a key factor for pitch control (if it's bad you can hit the mechanical stop of the stick).
CM - I disagree :ugh: As has been stated numerous times here, Pitch and Roll remain Normal Law until 5s after touchdown...

All that happens @ 50' on Approach is that the "datum" attitude tries to reduce to require a "flare input". Law remains Normal... AFAIK ;)

"Ground Mode" i.e. Direct Law is 5s after landing

NoD

[Ice Man]

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!

[C M]

@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.

[C M]

@ 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).

[Wayne Ker]

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 ?:ok:

[NigelOnDraft]

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

[jetopa]

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.

:ugh:

[asva]

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...

[Firestorm]

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?

[Rumet]

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.

[GMDS]

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.)

[BEagle]

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.

[windytoo]

Don't knock the F/O ,it's very difficult to land in a crosswind when making the coffee.

[Bis47]

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".

[DozyWannabe]

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.

[Chris Scott]

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.

[Chris Scott]

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.

[Right Way Up]

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.

[sleeper]

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.

[Bearcat]

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.

[bushbolox]

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.

[Wader2]

PS: Wader2, Remember, this event is defined as an "incident", not an "accident"!

Thanks Chris, I stand corrected. I made the accident/incident assumption on the grounds that actual damage had occurred as opposed to an incident where damage might have occurred.

In my area it would still be an accident.

[bsieker]

In my area it would still be an accident.


I don't know what "your area" is, but ICAO has quite specific definitions. Particularly, an accident is an occurrence where an aircraft sustains damage adversely affecting performance and requiring major repair or replacement of a component. (There are other conditions that make an occurrence an accident, but this one is the closest for this case.)

It might be argued that this was the case here, although I think the pilots still had full control authority. The wingtip fences' functions are reducing wake vortex ("induced drag") and thereby saving fuel.

However, ICAO Annex 13 makes the specific restriction:


[...] except for engine failure or damage, when the damage is
limited to the engine, its cowlings or accessories; or for
damage limited to propellers, wing tips, antennas, tires,
brakes, fairings, small dents or puncture holes in the
aircraft skin

So this is without doubt an incident, and not an accident according to internationally agreed definitions.

Bernd

[Wader2]

:eek: Did you watch the same video as I did, that approach was incredibly bad, tried to save it and screwed that up too.

Thanks DL, the operative word in my post was appeared. I saw the video clip just once on the TV News and thus my assessment was really a real-time snapshot. I bow to the slow time analysts. (not being rude I assure you).

[Wader2]

an accident is an occurrence where an aircraft sustains damage adversely affecting performance and requiring major repair or replacement of a component.

. . .

It might be argued that this was the case here, although I think the pilots still had full control authority.

Bernd, military.

I am glad that replacement of the end of the wing was a minor repair not requiring extensive checking of the mainplane structure. Fortunately it is unlikely I will be flying LH in the near future.:)

If it's an incident fine, all in a word.

[Starbear]

drkraft (http://www.pprune.org/forums/member.php?u=207276)



I'm surprised no one has mentioned it yet but your best source of realtime information on FMC equipped aircraft during landing is Prog page 2 (Boeing types).

I may be misunderstanding you but I do know that too many pilots refer to the FMC/FMGS wind readouts on approach with regard to their company limits but any such limits are referenced to w/v on the surface (or pehaps more accuaretly 15 metres above the surface).

I always have one of the FMC's on that page during landing.It keeps me legal and keeps me from getting surprised
Or are you saying that you literally have you colleague looking at the FMC page at 50' agl when they should perhaps be closely monitoring other parameters

There is no doubt that the w/v from the FMC has got some value but given the huge variations that can occur between reported surface wind and winds aloft, I would suggest that it's real value is to give a clue to expected shears as you approach touchdown.

[Starbear]

OKhasla

QUOTE]The skipper was : YOURS truly. The F/O... well he has moved on to become a great skipper. The F/E; he probably learnt a lot that day and too took up flying as f/o and is now a junior skipper![[/QUOTE]

Great repect to you for such an honest and very interesting posting.

[drkraft]

Starbear,
It's like any other tool you have in your toolkit. I said I use it as a reference, not a primary instrument. It's just another reminder that you might want to start thinking about plan B in case plan A isn't working out.

[bill_s]

Inside Edition, a syndicated US newsmagizine program heavy on celebrities,
doing a predictable "scared pax" story, led off with "150 mile-per-hour crosswinds". This broadcast was Tues, yesterday. Do these people ever check anything?

[KC135777]

GMDS, you said: "there is definitely a small roll input on the AB when decrabbing, which is not on a B.)"

It doesn't matter if it's a Boeing or an Airbus, ALL swept wing jet aircraft will have some additional roll moment induced upon "decrabbing" (input of downwind rudder). This is due to a reduction of "sweep" on the upwind wing in relation to the relative wind, thus an increase in lift on that upwind wing (as it 'swings' into the wind w/ a lesser angle), and the opposite affect upon the downwind wing- "more sweep" reduces lift on that one. Low, upwind wing required, at that point, to maintain runway track and actually landing on runway.

[PJ2]

KC135777;ALL swept wing jet aircraft will have some additional roll moment induced upon "decrabbing"

I think the point of the post was, Airbus WILL correct that rolling moment due to roll-control laws (as discussed extensively here) and Boeing will not correct the roll. I think we all agree that the aircraft will have a roll moment when de-crabbing, especially a swept-wing design.

My original point about some pilots believing that AB would "put the wing down" remains...some pilots believe that the airplane will de-crab and put sufficient wing down to continue tracking straight. Such an understanding is not correct.

The AB autoland will do this up to a point, perhaps because it has track-guidance, but it will land slightly crabbed, notwithstanding.

I think the post by Bernd, providing the Airbus Bulleting #54/2 (post #243) is worth reading closely.

[PEI_3721]

Very few if any FMS provide ‘real time wind’. Most are heavily damped using averaging laws. If you do not know exactly how your FMS calculates wind then it should be treated with caution especially for ‘precision type’ decisions.

Just because the wind etc, is within legal limits (rules vs FMS or tower report), does not mean that the attempt to land is the safest option; that requires judgement and skilled thinking.
“Its not the pilot’s hands that get them into trouble, its their heads” James Reason.

The recommendations in the report linked in post #136 indicate that a realistic crosswind limit (applied by the crew/operator) should always include the gust.

‘Safety aspects of aircraft operations in crosswind’ (http://www.nlr-atsi.com/downloads/NLR-TP-2001-217.pdf)

[yaw_damper]

If you look at the damages observed in:

http://www.hamburg-airport-friends-f...hread.php?tid=763&pid=2607#pid2607

the pictures show that there is a little more to look at, and work on, that wing and the plane as well. Just take account of the scratches on the underwing-not the tip winglet. My experience as an old certification crew member yields something about the "g"-s of the tip ground contact; the elongation of the deformation was just elastic or... is it inside limits? I remember changing two years official letters with the designers before approving to service a TU154 which touched with the wingtip the snow in Berlin during a low vis app GA back in '80-s.

[misd-agin]

Hideous flying. Check out post #51. Wingtip's on the ground and hardly any control input to stop the roll. :eek:

[yaw_damper]

So what??????????????

[misd-agin]

So what???

Good luck in your longevity planning.

[yaw_damper]

I was saying earlier (NET LOST MY MESSAGE) that according with the pictures in:

http://www.hamburg-airport-friends-forum.de/showthread.php?tid=763&pid=2607#pid2607

it is important the "g" on ground contact. Back in '80-s as RCAR eng., I was changing two years official messages with the designers before clearing to service a TU154, after a wingtip contact with snow in a low viss. app. GA at Berlin SFX.

[Diaz]

If you watch the vid, he turned over rather suddenly- how fast is your reaction time to something you don't expect?

[Chris Scott]

Quote from PEI_3721:
The recommendations in the report linked in post #136 indicate that a realistic crosswind limit (applied by the crew/operator) should always include the gust.


Haven't read the report (46 pages), but the A320 crosswind limits I worked to [U]did include a maximum GUST (component) of 38kts, as has appeared somewhere else on this thread.

What I cannot remember are the limits on a wet runway, which are normally lower.


On a slightly different note, here is one for the genuine A320 pilots who have suggested that the aeroplane is a particular handful in gusty crosswinds, presumably because of its FBW controls:

How come the FAA and CAA - not to mention the other authorities applicable in 1988 - granted type-certification with a maximum crosswind-component of 38 knots in gust?

Do you think they didn't try it out? Or could it be that some of you guys have not been briefed and trained properly?

[idle bystander]

I think we all agree that the aircraft will have a roll moment when de-crabbing

Quite difficult with so many ex-RAF types around, I imagine :}

[seventhree]

" seventhree:

Pitch goes gradually to direct, roll not. And that makes it tricky...
Rudder is always direct.
Pitch direct is blended in gradually and reached around 50ft and even a light nose down momentum is induced to you make you pull the stick. Stabilizer position is also a key factor for pitch control (if it's bad you can hit the mechanical stop of the stick)"

WRONG

Flare mode memorizes the pitch and gradually introduces a nose down trend but the sidestick still commands load factor or angle of attack (mode dependant) Direct control of the elevators does not occur until after touchdown.

[sevenstrokeroll]

dear diaz:

if you are sitting in your home and a meteor hits it, that is something you might not expect.

If Raquel Welch showed up at your front door, that is something you might not expect.

BUT FOR A PILOT in a storm condition that was making headlines all across europe TO NOT BE READY FOR A WIND CHANGE is NUTS.

YOU EXPECT the worst until you have parked the plane and someone else has the watch. IF NOT, YOU ARE NOT DOING YOUR JOB AS A PILOT.

[asva]

A proposito del mancato incidente di Amburgo, ecco cosa penso come passeggero, ripetendo anche quello che altri hanno detto e cioè:
L'uragano che imperversava su tutta l'Europa NON era un evento imprevisto, di conseguenza se il pilota non aveva previsto un improvviso colpo di vento all'atterraggio è un(a) irresponsabile o un(a) ******** (a).

[pixpax]

Look at the video. Wind from the right. On approach ailerons seem to be at roll right position for flying back to runway centerline. At time 00:38 ailerons are still at roll right position (correct), then touchdown with left gear slightly before right gear and then aircraft bounced off. Then at time 00:39 ailerons seem to be at neutral or slightly roll left position, what allowed for gust of wind to roll the aircraft to the left so that wingtip touched runway. Then was the last moment to go around and it went well.

[sweeper]

an inept attempt at a crosswind landing.
a successful recovery.
if the attention and ability shown in the recovery had been applied to the landing...........
started with a cock up, then got lucky!:sad:

[keltic]

As a fearfull passenger, I thought it was a bit hysterical my not flying every time I checked that the wind speed and weather conditions in my route could be bad. I have cancelled many times, lose money. Now I don´t mind my being a bit whimp.

A pilot once told me, don´t watch the weather forecast, someone will do it for you. I´ve followed his advises but now I go back to check the weather myself everytime I fly.

After seeing these landings in the limit. I will continue canceling my fights in nasty weather conditions. I don´t feel particularly safe, and I feel somehow that sometimes limits are pushed too far. :(

I think this will be devastating for LH image, I am affraid. Did I say I will be flying FRA-DRS in ten days time? :uhoh::uhoh::uhoh::bored::bored::bored::{:{:{

[J.O.]

keltic:

This may sound condescending, but do you drive a car or ride in one as a passenger from time to time? If so, then given the carnage on the roads that kills hundreds daily all around the world, I don't know how you do it!

What I am trying to say is that thousands of successful flights are completed every day, whereas events like this one are very rare indeed, which is why it gets so much coverage. Could it have been done better? Most certainly, and as you should have noticed by now, many professional pilots on this and other forums are talking about it, and believe me, they are learning from it too. That's what's great about our industry. We learn from the errors and accidents from the past so that we can work hard to prevent them in the future. If only our roads and highways got the same level of attention to detail. Countless families would benefit every day.

So, relax and enjoy your next flight.

Jeff

[alf5071h]

Chris, re your #307, the paper is well worth reading. ‘ ‘Safety aspects of aircraft operations in crosswind’ (www.nlr-atsi.com/downloads/NLR-TP-2001-217.pdf)

It covers: The basics of flying in crosswinds; – aircraft are relatively easy to fly within the manufacturers and operational limits, although experience and currency are required in more extreme conditions.
The report continues with a review of wind measurement and reporting; – there are many errors which pilots must be aware of and should consider in their decision making.
The overview of certification and test requirements probably covers your point in #307, again the industry makes many assumptions about the ‘demonstrated limits’.
Finally there is a review of N American crosswind related accidents (1983-95), the contributory causes and risks involved in crosswind operation are examined.
Of interest 70% of accident events involved wing or pod strike; given these statistics then the option of a GA might be ill advised – fly with a damage aircraft?
This would strengthen the argument for an early decision to avoid the hazard, minimise risk, and not getting boxed into a situation where there is no ‘undo’ option.

We should be concerned that many operations are increasingly occurring in marginal conditions; this is not so much the fault of individual misjudgement than the increasing external pressures of inappropriate industry norms.
In a very safe, highly reliable industry, and with the use of safety enhancing technologies, we appear to be continually pushing the margins of safety. Then when someone inadvertently crosses ‘the edge’, we are surprised; there is great concern and there is lengthy discussion in hindsight.
What we need is a bit more foresight, which should include training and briefing as well as basic systems and operational knowledge; good rule making and SOP formulation would also help.

[Perigaeum]

For the analytical minds out here,
a motion compensated version of the critical seconds.


http://www.youtube.com/watch?v=hAl1IJYx0C8

[Chris Scott]

Quotes from alf5071h:
We should be concerned that many operations are increasingly occurring in marginal conditions; this is not so much the fault of individual misjudgement than the increasing external pressures of inappropriate industry norms. ......
What we need is a bit more foresight, which should include training and briefing as well as basic systems and operational knowledge; good rule making and SOP formulation would also help.
[Unquote]

Thanks, I'll try to do justice to that Paper, when I get the chance.
You may have a point about the "press-on" pressure from management, in a world where the accountant is respected, but mother nature is taken for granted.
I am pleased that CRM was introduced during my career, and by my generation (we flew, in our rookie days - didn't we - with an older generation that included some press-on-regardless merchants, who thought they were still on "Ops"). But, before my retirement, I saw signs that (AIRCRAFT) HANDLING skills were already in decline in the 1990s. And many rookie pilots (straight out of flying school on to a £30m-jet) expected to be humoured when they acted like they were the bee's knees... Is that just old-fart syndrome?

Chris

[Rananim]

The co-pilot flew the approach,not the Captain..
I have to reference this to what I know,which is Boeing.If during/after landing,no right-roll input is made by co-pilot,this would be clearly and instantly apparent to the Captain(before the wing has a chance to rise).On the Boeing.However,on the Airbus,he cant see/feel what the co-pilot is commanding so he can only react until/when the upwind wing starts coming up.Plus he has to press an override button for his sidestick to take control.Am I right?
On the Boeing he can follow through with what the co-pilot commands just by resting his hand on the control column.He has tactile feedback,not to mention visual.
If this is the case,the Captain's skill level was indeed very high.The recovery(apart from the obvious fact that it came just an instant too late)was very nice.

Commendable that the Captain let the co-pilot fly the approach.However,in the case of a rising wing during a x-wind landing you have to take control
instantly and how can you do that if theres no tactile/visual feedback
to warn you of any omission by the other pilot?You're forced to take action after it occurs.Too late.

On reflection,there is more good than bad to this whole incident.

[galaxy flyer]

At the liveleak video of the LH landing is a BA 747 landing in similar winds. It is crystal clear example of how do a crosswind landing. Simply beautiful

GF

[KC135777]

wow, good point. now, I believe I remember reading about how the AB sidestick does NOT move, but that the pilots actually put pressure on it? is this correct? if so, like you said, as the 'decrabbing' rudder is inputted by one pilot, the pilot not flying can't tell (in time) whether the appropriate 'wing low' aileron is being 'fed in'. No visual/tactile feel of stick (aileron) control inputs. This is INDEED bad during conditions approaching limitations of the aircraft.

For these (challenging) type landings, the pilot flying (for all practical purposes) is flying solo. BAD- in a crew aircraft.

[NOR116,20]

Maybe it would be a better design if the side stick shows motion for any control inputs.
Then both pilots are aware of any control inputs which would be very helpful in difficult landing conditions.

[Roadtrip]

I'm glad I'm flying a real airplane (Boeing) with real flight controls.

[admiral ackbar]

I'm glad I'm flying a real airplane (Boeing) with real flight controls.

Yes because those darn foreign airplanes keep falling out of the sky everyday due to faulty flight controls...:ugh::ugh::ugh::ugh::ugh::ugh::ugh:

You must be concerned that your whole USAF will crash land when the foreign tankers that will replace your good old American tankers fall out of the sky as well.

Its amazing you sleep at night.

[Bobbsy]

After a bit of searching, I think galaxy flyer was referring to http://www.liveleak.com/view?i=766_1196775900 this video on Live Leak.

To my amateur SLF eye, it is an impressive example of flying skill.

Bobbsy

[212man]

Some Airbus guidance here:

http://www.airbus.com/store/mm_repository/safety_library_items/att00007639/media_object_file_FLT_OPS-LAND-SEQ05.pdf

[Dream Land]

YOU EXPECT the worst until you have parked the plane and someone else has the watch. IF NOT, YOU ARE NOT DOING YOUR JOB AS A PILOT By sevenstrokerollExcellent post and I fully agree with this philosophy!


Commendable that the Captain let the co-pilot fly the approach. By RananimHave to disagree here, although as a captain you must give an opportunity to FO's to gain experience, the number one responsibility is to the passengers and crews safety as sevenstrokeroll points out. In this severe wind case it would have been prudent to brief a point in the approach where control was transfered to the captain rather than assuming you could save any botched attempt made by the junior FO. :ugh:


I'm glad I'm flying a real airplane (Boeing) with real flight controls.Get real! :E

[Ricky1]

Hi everyone,
I have been keeping a close eye on this thread and have found it very interesting. However I havn't seen anything on here with regards an offcial report from LH or airbus. I have looked at both websites and have found nothing related to this event.

Looking at the video over and over, it is shocking the outcome of the landing was not worse than what happened. Safety is number one right... So what happened to the pilots decision making? Should they have gone around? maybe chose rwy 33? But even after all that it looks to me that the pilot flared a little to early and that the wrong portion of landing gear touched down first. Now I am only a fresh out of school commercial pilot here, I have been tought to keep that into wind wing down to aviod what happened in this situation. Looks to me the wing lifted up and a gust cought the underside, leading to the chain of events after. I know things are a lot different on the 320, but are the fundimentals of dicision making and flying along the same lines?

For everyone that has watched the video on YouTube, you will see that there is a related video section on the right side of the video. I tought you's guys should have a look at this video of the event. Might put a smile on your faces. A little bit of humor for you's. apparently it's the real truth behind the landing. lol

http://www.youtube.com/watch?v=8rbZg_Y3AgY&feature=related

Take care all,
Rick

[CONF iture]

Rananim, you're absolutely right in your comments.

On a FBW airbus the PNF is always one step further behind.
He can only monitor airplane attitude and trajectory, but except from the rudder pedals inputs, he knows nothing from the PF flight controls inputs.
Therefore it is much harder to properly evaluate a situation and the tolerance margin must be largely reduced.

For the PF, a direct stick to ailerons connection would be so much more appropriate for the flare in gusty cross wind ... Toulouse could still do something about that … but regarding the side stick philosophy it is obviously too late.
It could have been an excellent option for a single crew operation, but to this day multi crew is still the way to go !

[Dream Land]

Yes if you were choosing an airplane to flight instruct in I feel the comments about being one step behind are prudent, better off with a C-172, this however is a live commercial flight full of passengers and crew, and the aircraft shouldn't be put in a situation where this type of control feed back is absolutely necessary, if the conditions are so critical, the captain (or most experienced) should be the handling pilot, do they really need to indicate this in an FOM? Common sense if you ask me.

[Rwy in Sight]

Maybe the captain was a training captain and thus competent and licensed to teach the FO to land in such conditions...

And obviously how the FO would learn if he is not allowed to fly in some extreme conditions...

Rwy in Sight

[PBL]

asva,

I don't think you will find much sympathy here for your view that, because there was a storm warning for much of northern Europe, then what happened at Hamburg was foreseeable and therefore the pilots were irresponsible.

Reasons are these.

Forecasts are just that. Nobody goes flying when the weather is clearly impossible. Many crews judged that the weather was not clearly impossible. And they were right. Of the hundreds or even thousands of flights which were completed successfully during that stormy weather period, this was the only one which appeared to have control difficulties. If this crew was irresponsible simply because of the weather forecast, then so were each and every other one of those crews who flew. Why single out the PF of this flight in particular?

Second, you suggest that hitting a strong gust of wind exactly at the point of touchdown is "hardly an unforeseeable event". I disagree strongly. I think the chances of that happening exactly at that point are very small indeed.

Here is a comparison. I was sitting in my house during the storm "Cyril" last year (actually, "Kyril", because it's the Germans who name storms), under the one ridge line which extends into the north German plain and which thus disturbs the weather around it, hoping desperately that most of my roof would still be there. During the hours of that storm, tiles came off my neighbors house just once, in one gust. They hit the middle of the road and shattered - and 5 seconds later a car came by (idiots to be driving around in that!). It happened just once. So, given that the heavy part of the storm could be predicted for a period of, say, 8 hours, what are the chances that, as you drive by, the tiles will crash down on your car? Well, *if* a gust hits the house strong enough to take a tile off (and it hit my neighbor's; not mine) and a tile comes off, then two seconds might be a conservative time window for a given passing car, and the chances of it happening exactly as a car passes is about one in 14,400. So now we must multiply this figure by the chances that a strong-enough gust will actually strike a given neighbor's house. I dunno; there are a couple hundred houses around here in three different groups, and I know of two that lost tiles (both my neighbors). So let's say one in a hundred. So the chances appear to have been about one in 1.44 million of getting hit by a tile while out driving around here. That is one thousand times smaller than the chances of dying on the roads in Germany in any one year. When you consider that there are about one thousand eight-hour periods in a year, you will see that, even during that "storm of the century", when everybody was warned to stay indoors and (around here) was legally barred from walking in the woods for two weeks afterwards, your chances of getting hit by falling roof tiles in your car were about equal to your chances of dying in a road accident on a normal day while going shopping. Which is a chance that people take every day, many times, without worrying about it. Even though we were astounded that someone was driving around at the height of Cyril, apparently he was only doubling his chances of dying through driving his car anyway.

So, now, you do the calculations for Emma, a far weaker storm, and the landings of all of those airplanes at all of those airports all over Europe, and let us know what you come up with. (Please feel free to post your results in Italian if you wish.)

PBL

[paulg]

Why is it idiotic to drive a car in a storm but not even irresponsible to choose a runway which other pilots had apparently declined to use?:)

[sabenaboy]

http://www.youtube.com/watch?v=GHrLB_mlir4

Just to show that Airbii can land in crosswinds as well.

[PBL]

paulg,

I think you missed the point of the example.

PBL

[pointbreak]

Landed in HAM yesterday with winds of 14kts steady from the north (ATIS wind). During descend ATC offered a visual 33 or ILS 23. Has never happened before, especially with that little wind. Now that shows that something has gone on within the ATC "background", although kind of lame because of course a visual is not always the better choice than an ILS. Never landed on 33 before, landed on 15 even with tailwind, all due to "Noise abatement". More than idle reverse is not allowed after touchdown due to "noise abatement". One crew a few weeks ago got a visit from officials and had to discuss why they selected more than idle reverse on a dry RWY. Use of APU on GND restricted due to "noise abatement". Whenever I flew to HAM (7 years) my thoughts were: If you need 33 you better declare emergency to get it! Regulations like that also put "pressure" on pilots, not just commercial pressure!

[NOR116,20]

Pointbreak,
very good point!
Same applied for Zurich advising RWY 28 instead of 14 or 16 causing fatal accidents.

[EMIT]

Just a side note:
All that noise abatement stuff, and then one look at Google maps to see how the city has totally enclosed the airport - makes you wonder where all those scientifically educated city planners have their brains stored?

[King Halibut]

Bah, just a normal day at Leeds that :}

[keltic]

Thanks J.O. It seems that there are 50.000 flights worldwide flying at the same time than our flight. Sounds great. The possitive thing of this, is that the best moment to flight in an airline which had suffered an incident/accident, is doing it shortly after.

Extra precautions are taken. Anyway, only the weather is not good, is matter of concern :O

[fendant]

No, NOR 112.60

RWY 28 must be used because a little Southern German politician with a huge ego made a big story about the intolerable incredible noise jets make 12 miles away from runway thresholds 14 and 16. He got elected:uhoh:. Sadly he got the attention from some other incompetent German politicians who also needed to get reelected and manadated a new tight and "demanding" approach regime for ZRH early morning and in the evening.

ZRH ATC unfortunately has no other choice than to offer you the steep approach to 28 or the Southern approach over densely populated city areas.
Frank

[fireflybob]

Maybe the captain was a training captain and thus competent and licensed to teach the FO to land in such conditions...

And obviously how the FO would learn if he is not allowed to fly in some extreme conditions...

Rwy in Sight

Yes but one of THE fundemental rules of training/instruction in never getting into a situation with a trainee where if he/she mishandles it YOU do not have time to take over and recover with safety. The most important words in handling training are "I have control".

[sevenstrokeroll]

BS

landing is a demanding task. you must expect the unexpected. winds, tire burst, steering problems (nose gear) animals on the runway, go around due to traffic on the runway, even failure to stop (rio).

BS...noise abatement, FLying out of KDCA, when offered the shorter Northwesterly runway (formerly33) instead of the northerly runway (formerly 36 now 1) to expedite things, we all finally said hell no. and that was in good weather.

BS...as to worrying about those tankers for the USAF based on the airbus, that might just not stand. so don't buy stock yet!

Unless massive control failure is found ( unlikely as the plane is flying again right now) we have a situation where the crew wasn't up to the task of landing in a high crosswind. It was a terrible crosswind landing and a lucky recovery to a go around.

Does anyone have the total time on type and total time for the pilot landing?

NEVER give up flying the plane.

[lamer]

instructional video (http://www.youtube.com/watch?v=LRilx-a3Hro) about the degree of airbus stick movement during gusty landings.....

[Knotti]

Hi folks,

I`m a new forum-member and I have a stupid question:

As a former Tornado-driver, I had to obey a lot of x-wind limits.
Is it true, that you civil aviators don`t have any of those "hard" limits? Only recommendations? :confused:

[37846]

Civil aircraft have a recommended (demonstrated) x-wind limit. It is derived from whatever wind was present at the day of the test.

It is, for all practical purposes, a hard limit. I'd like to see the captain that bust the limit, have something go wrong, and that explain why he busted the limit....:{:\

[wilyflier]

To deviate slightly( I havent read all the posts)
I have seen one take off and one landing crash where everyone died after the aircraft got too low and touiched a vital part of the structure subsequently going into pullup and uncontrolled flight.Snce then Ive always had it in mind that, knowing I had such an unexpected contact, I would put the aicraft down at once regardless
Hind sight says that on this occasion the go around was successful , probably the pilot did not know if they had touched. If he HAD stuffed it down it would have been very messy .Ive also seen a couple which did stay on the ground with good passenger survival ; my personal rule stands for me as the safest bet.
Hindsight also says i would have called go around far earlier

[galaxy flyer]

Reference the posts about "noise abatement". Airlines and manufactures spent sheds of money on technologies to reduce noise. We had Stage I, II, and III and now further certification standards for the newest jets. But the noise abatement programs, ridiculous rules and noise monitors continue on as if we were all flying JT-3D and Conways. I had mistakenly thought the technololgy would eliminate the silliness of the Sixites and Seventies. Just proves a government project once in motion, obeys the Law of Inertia.

GF

[chefrp]

I am not a pilot, just someone who has much respect for flying and your chosen profession.

I have read this thread for the past few days and agree with many of the points made:

*the captain should have been at the controls during the 1st attempt because of the extreme conditions
*he should have called for a go around sooner...

the fact of the matter is these pilots found themselves in a very difficult situation, and on top of that it was recorded for all the world to view and dissect.

I think it is importatant to look at this incident and ask why did they pull out of it instead of the dreadful alternative. Has all the training and technology paid off?

As a pax I have complete confidence in Luftansa, Airbus and Boeing...for that matter.

Once again the pilots fell into a bad situation and may have made some judment errors. But when the S#*t hit the fan they had the ability to get it right and real quick, right in front of out eyes.:D

[bubbers44]

It looks like after watching their x-wind landing technique they will be practicing in the sim for a while before going back on the line.

[NOR116,20]

fendant,

I mentioned ZRH to point out that there are very often considerations other than air safety for allocating a certain runway.
I didn’t want to say that all circumstances in ZRH and HAM are equal.
But thanks for your explanations anyway.

[Huck]

Once again the pilots fell into a bad situation and may have made some judment errors. But when the S#*t hit the fan they had the ability to get it right and real quick, right in front of out eyes.

That's not what I saw. I saw a modern airliner with pax aboard that was out of control for a time, low to the ground. I would have broken that sidestick off before I'd let that right wing up like that. They may have fixed it eventually, but not real quickly.

[chefrp]

Aviators,

I am not a pilot, just someone who has much respect for flying and your chosen profession.

I have read this thread for the past few days and agree with many of the points made:

*the captain should have been at the controls during the 1st attempt because of the extreme conditions
*he should have called for a go around sooner...

the fact of the matter is these pilots found themselves in a very difficult situation, and on top of that it was recorded for all the world to view and dissect.

I think it is importatant to look at this incident and ask why did they pull out of it instead of the dreadful alternative. Has all the training and technology paid off? After all, the Titanic was a similar situation, the ship was put into a compromising position by errors of judgment, but they could have recovered her, unfortunatly technology and training failed.

As a pax I have complete confidence in Luftansa, Airbus and Boeing...for that matter.

Once again the pilots fell into a bad situation and may have made some judment errors. But when the S#*t hit the fan they had the ability to get it right and real quick, right in front of our eyes.:D

[chefrp]

S#*t hit the fan meant "out of control"

sorry :(

[Denti]

It looks like after watching their x-wind landing technique they will be practicing in the sim for a while before going back on the line.

As far as i know both pilots are allready back on the line.

[Clandestino]

Seemingly the respected forummembers, who have reached the definite verdict on crew performance during the attempted landing, know what was the last wind passed from ATC to crew, what was the wind recorded in TWR as A320 touched down, what was the stick(s) displacement by the pilots and what did the spoilers and ailerons do as the upwind wing rose.

So would they please come forward and share it with us, please.

Thanks for the educational video, Lamer. It just shows how not to fly A320 (ref. post #243 by Bernd Sieker)

[sevenstrokeroll]

clandestino:

I too would like to know the winds at touchdown and the way the control stick was being manipulated (rudder and throttles too).

we are responding to the video. a horrific video.


a video that we should be happy to have to remind us of how things can go to hell in a handbasket quickly.

I think chefrp is right:

<<<*the captain should have been at the controls during the 1st attempt because of the extreme conditions
*he should have called for a go around sooner..>>>

[no more nite flights]

:ooh:Watched video with interest.If crosswind component within Co and A/C limits...no big deal.Usually,F/O s have crosswind limits in most companies so I guess Capt. should have been handling pilot.Aircraft was on centreline until Pilot corrected drift with Left rudder nicely but someone forgot to tell him that the induced yaw from such a large rudder input would cause the wing to lose lift and he should have applied down aileron (co-ordinated with rudder input) on the opposite wing.Flown both Boeings and Airbus in similar conditions and provided you coordinate rudder/ailerons ,should not be a problem.Interesting though,in 35yrs of flying never been given max crosswind tasks in Sim!!...maybe time to go back to basic airmanship checks?

[bubbers44]

I've seen some interesting x-wind techniques used by high time FO's that would make your hair stand on end like putting the nose downwind and side slipping with full rudder to the runway with a 15 knot x-wind component. No taildragger pilot has ever done that more than once however.

[TyroPicard]

GMDS said..

(Just to complete a earlier contribution:
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,
Sorry, that's incorrect. In normal law the FBW does NOT return the a/c to the original bank angle - it merely tries to maintain the roll rate demanded by the side-stick. The bank angle is irrelevant.

KC135777 said...
I believe I remember reading about how the AB sidestick does NOT move, but that the pilots actually put pressure on it? is this correct?
No, the sidestick moves! Perhaps you are thinking of the original F-16 side stick....

TP

[412SP]

I've seen some interesting crosswind "techniques" from "left seaters" that have made me a bit anxious. It goes both ways.:}

[D&M]

Yep, Airbus sidestick definitely moves!!

Notice the flight controls check at 1:45 on this video... http://www.youtube.com/watch?v=MFkm_x454ks

Original F-16 didn't I believe, although it was later revised to a small movement all around.

[Chris Scott]

Quote from Rananim [Today/00:57, currently#320]:
I have to reference this to what I know,which is Boeing.If during/after landing,no right-roll input is made by co-pilot,this would be clearly and instantly apparent to the Captain(before the wing has a chance to rise).On the Boeing.However,on the Airbus,he cant see/feel what the co-pilot is commanding so he can only react until/when the upwind wing starts coming up.Plus he has to press an override button for his sidestick to take control.Am I right?
[Unquote]

For an ex-A320 pilot's thoughts on sidestick aspects, see my post #229 [Mar04/19:07]. CONF iture [Today, 04:59, currently #330] has put the case against the Airbus sidestick succinctly. You have read his post. But he is wrong when he argues for Direct Law – in roll only – for the final approach. At what stage would it be introduced, and how suddenly? I can assure him that the transition from Normal Law to Direct Law with gear extension – in some failure cases – is one most A320 pilots contemplate with trepidation, because the handling changes so much in roll, as well as pitch.

The differences between Airbus and Boeing are honourable ones, dating from the mid-1980s, when Bernard Ziegler (head of Airbus FBW engineering design) made at least two radical and irrevocable decisions on A320 design. These were based, I believe, on engineering considerations of simplicity, reliability, and weight-saving; as follows –
1) The throttle levers would be FBW; with no cable connections, and no motors to drive them forward or backward in mimicry of autothrottle commands. In manual thrust, however, their transducers would send throttle-by-wire signals to the FADECs in response to the pilot's movement of the levers.
2) The sidesticks would: (a) not be interconnected [to save the weight and jamming risks of cables]; and (b) not move to mimic AP commands when the autopilot was engaged. The inputs of the sticks would be algebraically summed, except that there would be a means of one stick being prioritised by its AP-disconnect push-button.

BALPA pilots, as well as others engaged in technical study, tried hard to persuade Airbus to change some or all of the above, but Mr Ziegler prevailed. On the first conversion course at Blagnac, ordinary airline pilots first flew the simulator in January 1988, and the aeroplane in February/March. We found that - although some of us still had reservations on the throttle and sidestick logics – the bottom line was that the OVERALL PACKAGE was more than acceptable. Twenty years later (14 of them line-flying the A320 family), I think this assessment has been vindicated by the safety record, which compares very favourably with other types.

The A320 was formally type-certificated while we were on the course, and we put it into service in the Spring. Even as late as 1989, however, IFALPA was in formal discussion with Bernard Ziegler at a meeting hosted by Airbus test/training pilots. My talented copilot from our conversion course, Richard P, put a strong case for modifications to the auto-thrust logic on our behalf; but was successful only in obtaining a DMC mod to improve the presentation of current IAS on the PFD. The non-driven-autothrottle-lever debate was over, and we had decided that the sidestick logic was acceptable, if not ideal for training/monitoring situations.

So is the current crop of Airbuses over-automated, leading to pilots being out of the loop and/or lazy?
Has Boeing found a better balance, or is it merely following in the safe wake of Airbus?
Automation was nothing new in 1988. For example, even the ageing B707s I flew in the 1970s had a yaw-damper, anti-skid brakes, and thrust-reverser inhibition in flight.
But we had to select our own spoilers on landing (no lift-dumpers) and there was no autothrottle, no auto-land, and no rudder-fine steering.
Like Airbus; all the others – including Boeing – have moved a long way in automation since then, and the trend continues inexorably...

[HalloweenJack]

http://www.flightglobal.com/articles/2008/03/06/222034/crew-of-wing-strike-lufthansa-a320-was-offered-different.html

German investigators have yet to release initial findings about the recent highly public wing-strike incident involving a Lufthansa Airbus A320 at Hamburg (http://www.flightglobal.com/articles/2008/03/02/221942/video-lufthansa-a320-escapes-after-wing-tip-strike-in-hamburg-storm.html), but the carrier says the crew was offered an alternative runway before embarking on its crosswind approach.


they were offered 33 but opted for 23 based upon better ILS and guidance systems

[Chris Scott]

The LLZ-DME approach (ILS localiser-element only, but with distance-to-go information) on Hamburg Rwy 33 is a cinch on the A320, because of the FPV (Flight-path vector) flight-director. [Improvements in its presentation on the PFD, and in the selections display on the FCU, were made after the Strasbourg accident.]

Given the W/V that posters (and the video) suggest, the choice between Rwys 33 and 23 would have been a "no-brainer".

However, I am not convinced, yet, that ATC would have made such an offer – without caveat. See my post of Mar05/10:53 [currently #284], re ATC at Hamburg in particular, and in Germany generally.

[XPMorten]

To me it looks like a case of no aileron into wind.
In fact, I dont think they gave aileron at all during the whole maneuver;

Below, the moment before decrab. Crab angle about 15 deg.

http://www.xplanefreeware.net/morten/DIV/LH1.jpg

1. Below, rudder gets kicked in
2. Plane decrabs to 0 deg, beta angle now about 15
3. Wing comes up due to yaw induced roll. No sign of roll spoilers.

http://www.xplanefreeware.net/morten/DIV/LH2.jpg

4. Pilot releases rudder pedal, wing hits ground, STILL no sign
of aileron or rollspoiler.
http://www.airliners.net/uf/536882887/middle/phpOltUWB.jpg

5. Being in a beta angle and bank without any controls input, the acf will now
swing back to equlibrium. The nose will swing back to 0 beta (crab 15)
and the wing will drop.

http://www.xplanefreeware.net/morten/DIV/LH3.jpg

So, no gust or aileron input needed for this to happen.

M

[bubbers44]

She just needs 5 hrs of x-wind landings in a J3 cub and she will be good to go.

[ihg]

@XPMorten: Thanks for your illustrative posting...although I guess it is hardly possible to identify definitive control surface deflections at this resolution, your description resembles pretty much of what I think has happened.... no 'unfortunately timed' gust , but simply insufficient, or no, roll compensation during decrab to keep the upwind wing down....no reason for reviving popular Airbus FBW discussions, but maybe more an opportunity to see basic flight mechanics at work...

Just my 2cents,

regards, ihg

[NOR116,20]

XPmorten,

I think you made a valid point.
Having seen the video it seems after or while de-crabbing no upwind aileron at all has been applied.

Some pictures in this link:

http://www.hamburg-airport-friends-forum.de/showthread.php?tid=763&page=1

The 3rd picture shows LH044 on its landing on RWY33 in the second attempt.
Landing takes place using a good side slip technique: upwind gear touches first due to upwind aileron and rudder to opposite direction.

[yaw_damper]

Is it true that the stick was in a 24 y old lady's hand???:eek:

[bubbers44]

24 year old girl is what I heard was the pilot flying as FO. I always looked at my yoke to see what the FO was doing during a wild approach knowing I could fix it. You don't get that feedback in the AB so you have to see the result before you can intervene. Not a good way to monitor an approach. I am so happy I retired flying a Boeing. Most of the wild approaches were pilot induced even though they always claimed turbulence. Monitoring the yoke you could see if the roll came before or after aileron input and knew the truth. Military pilots were prone to overcontrol a lot on short final causing their own turbulence. Flame away.

[Old Fella]

Obviously Bubbers44 does not have a high opinion of Military pilots with his comment claiming "Military Pilots were prone to overcontrol a lot on short final causing their own turbulence".

Having had both a military and civil flying career as a Flight Engineer I flew with many pilots from both sides. To make a "broad brush" comment regarding one group or another is both unfair and unwise.

From where I sat the great majority of pilots displayed consistent high standards of airmanship and flying skills. Overcontrolling is not the sole province of Military, or ex-Military, pilots. There are some, thankfully very few, from both Military and Civil backgrounds who do not instill confidence in fellow crew members.

I firmly believe that it is usually unproductive to make comment on accidents or incidents in which one was not involved, however in the case of the LH incident at Hamburg the evidence presented would indicate that the decision to land in the prevailing conditions was not prudent and the missed approach should have been made somewhat earlier than was the case.

[Chris Scott]

Yes, XPMorten [Mar26/21:00] (and others),
The aeroplane does seem to sort itself out pretty well. But, after that, there's a definite point at which the flying improves...

Hi, galaxy flyer Mar26/01:22, currently post#321] and Bobbsy [post #326],
Ref the B747 video, I agree that the pilot on any type would be reasonably satisfied with this landing, in a fairly stiff crosswind. Don't pretend to know the conventional technique in the B747, so can only speak in general terms.
To be hyper-critical, it is evident that the de-crab is only about half complete at main-gear touchdown, which is marginally on the downwind (right) main-gear first – presumably not what the pilot had mind. The rest of the de-crab is smoothly completed even as the 4 bogies (sorry, "trucks") are settling firmly on the runway. In this sequence, it's not possible to see the ailerons and spoilers, but – when it comes into view – a substantial amount of downwind (right) rudder is shown for the de-crab, as expected. The wings are virtually level throughout, which probably indicates the vulnerability of the outer engine pods that ex-B707 drivers can identify with. [Touchdown with considerable drift may be standard 747 technique, for all I know, but is not on most types.]
On a very large aeroplane, flying at similar speeds to an A320, the success of the landing is even more dependent on the quality of the approach, which is beautifully stable in this case. The rest follows, because there is so much inertia.

Hi sabena boy [Mar26/08:06, currently post #335],
Ref the A380 video, it's shot from less-than-ideal angles. The aeroplane seems to have landed in one direction, then taken off in the opposite direction on the same runway (is it Brussels 02/20?). Later, in the dusk, it seems to be landing on the same runway as the first.
It is possible to see the drift being kicked off AND a tiny amount of into-wind bank being applied (by pilot OR auto-pilot input) during de-crab.

On the take-off, at rotation, the upwind wing is allowed to rise slightly – a common mistake on the A320, as on all types.
The A380 is likely to achieve similar handling characteristics to the other Airbus FBW types, for which there are various previous posts on this thread, including:

the Airbus link which 212man repeats, above;
my post of Mar04/13:35 (currently #207);
my post of Mar04/17:28 (currently #222);
bsieker's post and quotes of Mar04/21:07 (currently #243)
my post of Mar05/01:43 (currently #260);
PJ2's posts of Mar05/04:43 & 06:46 (currently #263 & #266), and Mar05/16:19 (currently #300);
and others.

It needs to be pointed out that we cannot tell if the videoed landings were "manual", or autolands!

[Dream Land]

It needs to be pointed out that we cannot tell if the videoed landings were "manual", or autolands!I thought about that also when I saw the 747 film, it's smooth.

[cessna_dave]

where, when is the ultimate landing made?

[CONF iture]

I suspect in max crosswind at flare time most observing pilots are not looking inside at either a Byoke or an ABidestick
No real need to look inside as even an AByoke is naturally in the PNF sight.
Even better, a light hand on the yoke, in a strictly damping mode will provide all kind of useful information.

I can't tell if it really was the case in that LH episode, but the PNF would have probably appreciated to know in live that there were maybe no or too little aileron solicitation ... The information, just a fraction of second earlier, it's all it takes to simply do the job, or at least to stay out of trouble.

[bubbers44]

No one is looking at the yoke during an unstable approach to landing but out of curiosity I could see out of the corner of my eye if the weather and conditions were doing it or the pilot was. Sorry about the military pilot observation but I think their training is accelerated making them more prone to fly mechanically. Have you ever flown with a buff, B52, pilot? That is what I am talking about. I have flown with outstanding ex military pilots that don't fit into this category by the way. The video doesn't have the resolution to see the aileron input when she kicked the rudder in for landing but the results of the roll to downwind indicates she didn't use the required aileron to keep the wing from coming up as is required in that kind of cross wind landing.

[Dream Land]

The information, just a fraction of second earlier, it's all it takes to simply do the job, or at least to stay out of trouble.My guess is that they were fully aware of the wx conditions at least 100 nautical miles out, give me a break.

[GMDS]

TyroPicard quotes me and writes:

Quote:
(Just to complete a earlier contribution:
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,
Sorry, that's incorrect. In normal law the FBW does NOT return the a/c to the original bank angle - it merely tries to maintain the roll rate demanded by the side-stick. The bank angle is irrelevant.


OK, maybe wrongly put, i am still learning AB and English........

To get better please tell me: If you approach with a constant small bank angle and then you kick in the rudder and a small roll will ensues that was not demanded. Does the AB roll back to what was demanded or does the new rudder induced roll prevail?

[PBL]

XPMorten,

I think there are a few issues here as to how the A320 flight control works

In fact, I dont think they gave aileron at all during the whole maneuver;

You don't know what the crew did by looking at the outside of the airplane; you only know what the airplane did under the commands given by the crew. If the stick is neutral and the airplane starts to roll, the FBW will countermand the roll because 0 roll rate is commanded by the crew. And to countermand that roll the ailerons may well actuate.

Indeed, on your first grainy still, I see a shadow in the position of the starboard aileron which might will indicate it has risen.

Wing comes up due to yaw induced roll.

Sorry, as I understand it this does not happen. If sidestick is neutral, wing does not come up due to yaw-roll coupling. The FBW control system compensates for the coupling. (This also answers GMDS's question.)

I think it was a gust.

PBL

[Chris Scott]

Quote from GMDS:
To get better please tell me: If you approach with a constant small bank angle and then you kick in the rudder and a small roll will ensues that was not demanded. Does the AB roll back to what was demanded or does the new rudder induced roll prevail?


No, she will not roll back (that is to say, not automatically).
Yes, the bank-angle resulting from the displacement will become the new datum, and the FBW will try to maintain it.

These displacements are normal during de-crab, in my experience. Whether they are due to coincident gusts, is arguable. I have seen this happen on crosswinds from moderate to strong; smooth and gusty. That is why it soon became my practice on the A320 to pre-empt the undesired roll by "putting the wing down" slightly, during de-crab, i.e., inducing a slight sideslip.

I agree with PBL [above] in at least one respect:
this aeroplane was not only conducting an approach in a MEAN crosswind-component that was at or above limits; it was also affected by [U]at least 2 gusts that, in my opinion, were outside the gust limit.

In my 14 years' experience, the roll-yaw coupling was not something to be relied on.

The take-off, which – prior to lift-off – is conducted in Roll-Direct Law (if memory serves), is also worthy of comment. On rotation, prior to lift-off, the upwind wing invariably rises, even though the pilot is easing off the usual slight downwind rudder. [You would expect the upwind movement of the rudder, at the latter point, to counteract the tendency of the upwind wing to rise, but it is not enough, in practice.] The solution, again, is to pre-empt it with aileron; just like a conventional aeroplane

Hope this helps.

[PBL]

Chris,

I guess we only disagree on how effective any roll-yaw decoupling is. You flew the airplane for 14 years, and suggest it doesn't work quite "as advertised". Thanks for the datum.

I imagine the engineers who designed the airplane knew that there would regularly be displacement to a new baseline datum in bank, not only because mother nature does not follow engineering models to the letter, but also because one wants to consider stress allevation on the airframe and "go with the flow" quite often.

However, the official recommended technique on landing in gusty conditions, as I understand it, is still not to wiggle the stick around to compensate but to use steady, deliberate motion as necessary.

PBL

[CABUS]

I am no doubt going to touch on a previously mentioned and very personal subject to all pilots, so sorry to all whom this offends.
I personally feel this is an advert for a cross control approach setting off the drift early on allowing the PF to assess the x wing comp before 20feet. This probably would of ended in an earlier GA or a more controlled touch down and would be much more comfortable for the pax and crew in the back. I only say this because this is how I have been trained and demonstrated to me.

[EDDHATC]

just to stop this endless discussion wether RWY 23 or RWY 33 was better : Working at EDDH TWR as one of the ATCO´s during that incident, here´s a short summary of R/T and coordination with Approach:
10 min prior DLH 040, TWR issued information to Approach about winds getting stronger ( from 250/30 changing to 270/34-45). RWY 33 as altenative landing RWY was offered to all approaching aircraft. DLH 040 choosed RWY 23. After freq change to TWR, TWR reported increase of Wind and velocity (280/40-50)and offered swing over for RWY 33. Crew of DLH 040 asked about percentage of go-arounds within the last 20 Minutes ( total 50%...). Crew stated:" we try one for RWY 23..." Last windcheck by TWR at 1NM final.The rest is known...

[pixpax]

flycheaper I want to learn from this incidentI learn from this incident that if the runway is not straight ahead of pilot's eyes and aircraft's ground track is not on runway centerline at runway threshold then a safe landing is not possible. It may be possible with small plane on a long runway, but big aircraft on suitable runway for normal operations with nasty crosswind - no.

[bubbers44]

Cabus, you are right, and using this technique a pilot would be forced to keep the upwind wing down or do as they did and go off the downwind side of the runway. Doing the decrab in the final touchdown stage works too but you can't test for drift if you float. Letting the upwind wing come up is poor airmanship either way. If the public thinks they are heros I think the pilots know they just screwed it all up.

[Chris Scott]

Quote from Rumet [Mar05/09:55, currently post#278]:
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 ?


My previous have not covered this 5-second period (which I confess was news to me, but makes sense if you consider the case of a bounced landing, with or without go-around). I've argued that, as soon as the second main gear is firmly on the ground, you can use into-wind AILERON to hold the wings level.

This is obviously not strictly correct; with into-wind stick you are actually commanding a roll-rate during those 5 seconds after touchdown. In practice, though, a moderate amount of stick - very much like you would use on a conventional aeroplane - is not enough to lift the downwind gear off the runway, but [U]will counteract the tendency of the upwind wing to lift.

Quote from CABUS [above]:
I personally feel this is an advert for a cross control approach setting off the drift early on allowing the PF to assess the x wing comp before 20feet. This probably would of ended in an earlier GA or a more controlled touch down and would be much more comfortable for the pax and crew in the back.
[Unquote]

The problem with the FULL sideslip technique, for the A320, has already been covered by me and others. The sideslip angle required in a limiting crosswind would probably lead to winglet-scrape.


By the way, I have had to EDIT my post earlier today, in respect of an error I made in the take-off case. [Nobody spotted it...] :=

[PBL]

EDDHATC,

just to stop this endless discussion wether RWY 23 or RWY 33 was better

Unfortunately, your intervention will only do that if everyone believes you are who you say you are and were where you say you were. I've no reason to doubt it, but I can't speak for others.

Wind at 280 is 50° from runway heading of both Rwy 23 and Rwy 33, so I don't imagine wind direction played a role in choice of runway.

PBL

[EMIT]

The only practical point I can add to the above post by PBL is the common phenomenon (northern hemisphere) that during a gust the wind usually veers, so that gusts would increase the problem for RW 23 and decrease the problem for RW 33.
Interesting in the ATC post is the term by the crew - give it one try. Indeed, with a parameter as variable as wind, you can try, and perhaps land in a quiet spell, or go around during a gust.
Whether the aircraft handling was proper or not is difficult to ascertain from a distant camera shot - I expect that recorder readout will provide the necessary details, also solving all the riddles about flight control inputs versus actual control surface deflections.

[bubbers44]

PBL, I agree with you that the x-wind component of either runway was equal. Their problem was after decrabing unless you keep the bank into the wind you will drift across to the downwind side of the runway. You learn this as a student pilot. Letting the upwind wing come up after decrabing will have very consistent results, going off the downwind side of the runway. She didn't understand how to do a cross wind landing to let that happen. If it was a gust that lifted that wing an experienced pilot would have gone around but it didn't look like a gust.

[Dream Land]

I am no doubt going to touch on a previously mentioned and very personal subject to all pilots, so sorry to all whom this offends.
I personally feel this is an advert for a cross control approach setting off the drift early on allowing the PF to assess the x wing comp before 20feet. This probably would of ended in an earlier GA or a more controlled touch down and would be much more comfortable for the pax and crew in the back. I only say this because this is how I have been trained and demonstrated to me.Agree with Chris, with extreme xwinds you can easily get a donk or wing tip on the small bus.

[Willit Run]

Lets see, The German pilots are touted as heros and the Cathay pilot is dangerous and reckless for a simple flyby??

[Clandestino]

A320 will always try to correct the uncommanded roll (in normal law, of course).

There is a caveat, though.

The way she tries to do it is nice, easy & smooth. First, it's not the way to fly the airplane in moderate turbulence, second, the inbuilt lag makes legions of busdrivers believe (wrongly) that she doesn't pick up the dropped wing.

Typical encounter with gust that is too much for ELACs and SECs to handle immediately, makes Average Joe Busdriver slam the stick into wind. Bad news is that startled FBW has just started to pick up the wing and now it adds its automatic command to stick request and then plane rolls rapidly into wind, zooming past wings level. Now stick goes to opposite side and nice airplane-pilot coupling in roll ensues - sometimes with the tipical bus sound of stick clackclackclackclackclackclacking against the roll stops. I've seen the guys hitting the stops in 9G14 and I never had to use more than ha'f-a-stick in 17G29. Mind you, in both cases bank was maintained within 5° of wings level. FCOM says pilot should filter his stick inputs. Way I interpret (and do) it is; when the wing drops, I help ELACs by giving approximately half the deflection, but return stick to neutral slightly before wings level. Maybe even this is excessive, but for me works like a charm.

As for rudder: kicking out the drift is too much for FBW to handle but if you squeeze it out, bank will stay constant with stick in neutral.

On rotation, prior to lift-off, the upwind wing invariably rises, even though the pilot is easing off the usual slight downwind rudder.

This is another of A320 quirks, on take-off the rudder has to be briskly moved to neutral as soon as rotation is initiated. In everything except the gustiest of weather, the airplane settles into wind with zero bank and zero stick input as if by magic. First time I've was briefed on this technique, I thought that my instructor was pulling my leg. It turned out that he wasn't and that the thing that lifts the wing is the rudder held too long and not the wind.

[bubbers44]

Boeing guys are lucky, we just fly it like an airplane not a computer hand shaking experience.

[XPMorten]

PBL,

Sorry, as I understand it this does not happen. If sidestick is neutral, wing does not come up due to yaw-roll coupling. The FBW control system compensates for the coupling. (This also answers GMDS's question.)
I think it was a gust.

Wrong, according to Airbus FCOM the A320 will "Roll Conventionally when
using fast or large rudder inputs" (below).

If it had been a gust, the aircraft would have crashed. At the point
where the wing hit ground, there still was no (or very little) roll input.
This picture proves it;
http://www.airliners.net/uf/536882887/middle/phpOltUWB.jpg

The acf was saved by the laws of physics.

http://www.xplanefreeware.net/morten/DIV/LH4.jpg

Cheers,

M

[efatnas]

looks like clear case of copilot behind the airplane and captain behind the copilot; letting your copilot land in gusts to 55kts??? nice safe though, cosidering the wing could have been missing......anyway lufthansa pilots don't do that; it must have been a nasty gust; only everybody else....

[fireflybob]

Have flown both B737 and A320 and landed both in limiting crosswinds. There is nothing special about landing the A320 in a crosswind compared to the B737.

I dont like the phrase "kicking" off the drift. I have never had an occasion where it was necessary to kick the rudders. I think the phrase "straighten (or align) the a/c with the runway track" is far more appropriate. The further effect of rudder is and always has been roll in any a/c which I have encountered. Therefore as you apply the rudder you need to apply opposite aileron to keep the wings level. If you are going to make any mistakes apply too much aileron rather than not enough.

[Me Myself]

Never had a problem landing into max X winds with an Airbus, great aircraft.Flying a Boeing now, great aircarft to. infact no such thing as bad aircraft, I only see bad pilots. The only time I almost landed in the grass in lower than limit X winds in Milan was when ..............I stuffed up.
Don't see anything here than poor aircraft control. Sounds harsh but that's that !
LH PR department had to make them heroes. The in house debrief may have been a tad less enjoyable.

[PBL]

You learn this as a student pilot. Letting the upwind wing come up after decrabing will have very consistent results, going off the downwind side of the runway.


Well, exactly, bubbers. Every student. Let alone the PF of a Lufthansa A320 landing in the middle of a storm with 50kt gusts. It's a gust.

She didn't understand how to do a cross wind landing

I would guess the PF, as an ATPL and a Lufthansa pilot, probably knew very well how to do a crosswind landing.

XPMorten,

you quote me the training manual. Are you trying to say that you believe that when the rudder is moved abruptly, the yaw-roll decoupling rules take a holiday? Or is it more likely that the training manual is saying that abrupt movement of the rudder can be faster than the decoupling? Just as the aircraft's reaction to a gust with stick neutral may well be a roll, despite the control-system compensation.

That wing comes up pretty fast. I don't think it's solely because of yaw-roll coupling. I think there was a gust.

PBL

[Avionista]

Many of the posters on this thread seem a tad too ready to criticise the performance of the LH flight crew for this incident at Hamburg last Saturday. Is it just possible that they encountered a gust of exceptional velocity at the most vulnerable stage of their landing?

I live in Tayside, Scotland and last weekend we experienced wind gusts which I thought were 'unusual' in relation to the mean wind speed. From figures recorded at Perth airfield, the mean wind speed was around 30-35 kts but some of the gusts were exceptionally strong (85 kts) and of short duration (10-15 seconds). If the LH A320 crew were unlucky enough to encounter a sudden gust of similar velocity at Hamburg, it may well have caught them out. It certainly caught out one of my golfing companions last weekend. He was blown flat on his back while hitting one of his tee shots! (PBL: Is it normal for the gust/mean windspeed ratio to be around 3?)

On the 'evidence' presented on this thread, together with the nature of the wind I experienced personally last weekend, I'm inclined to give Maxi J. and her captain the 'benefit of the doubt' on this occasion.

Mariners seem to have a healthy respect for the sea/weather and accept that, just occasionally, mother nature can produce conditions which will overwhelm the largest ships crewed by the finest seamen. Perhaps, aviators should show a similar humility with regard to the capabilities of their aircraft and their prowess as pilots.

[XPMorten]

Or is it more likely that the training manual is saying that abrupt movement of the rudder can be faster than the decoupling? Just as the aircraft's reaction to a gust with stick neutral may well be a roll, despite the control-system compensation.


"Roll conventionally" are words used by Airbus, not me.
If you think it should say "Roll-unconventionally", you better tell Airbus
to rewrite their manual.

I think there was a gust.

Right, a strong gust that starts exactly at decrab and
by miracle STOPS 1 second later when the wing hits the ground
so the wing doesnt get ripped off.

M

[PBL]

Wise words, Avionista.

As to gusts, I think we don't know much about them. There are a bunch of wheatfields around here, and every year as I cycle past, I notice roughly circular areas some 5-10m in diameter *flattened*. Now, that's in normal weather, and I think it would take some 50+kts to break a stalk in the middle of a dense wheat field. There are small, narrow, tornado-like funnels in most normal storms, it seems.

I used to live in an apartment that backed onto a meadow at the end of a long funnel of parks that came down from the hills. The meadow was about 100m wide, and in the middle was a copse of tall conifers, about 20m wide. There was a fair wind storm a few years ago, and after the storm I noticed some areas of flattened grass. The grass stalks were some 1m high at that point. I went to look. On the lee side of the copse was a circle about 2m diameter in which the grass had been completely flattened, in a circular pattern. Everything outside that circle was standing upright. That is, a funnel of unusual strength had grounded exactly there, all 2m of it. 60kt or more, in circular form, and confined to 2m diameter, in a storm of average 30kt or less.

Now, something like that isn't going to disturb an A320, because it is too localised (I once had a dust devil go right over me, and my parked airplane, at the Mammoth Lakes airport in the Sierras. Entertaining, not worrying). But widen it three or four times, as in a serious storm, and you have something that could kip a wing. Or flatten a golfer.

PBL

[PBL]

XPMorten,

that's sort of about the level from which I guessed you were coming. Thanks for confirming.

I don't consider that what is written in AI training manuals predicts Nostradamus-like what would happen at EDDH at 1255Z on 01.03.08. I think it's a gust.

PBL

[ihg]

Sorry. PBL, I have to support XPMorton here. The yaw-roll-decoupling cannot take ' a holiday', since there is no 'real' yaw-roll decoupling as far as I have understood Airbus FBW control law logic! But well, correct me if I'm wrong....

If a roll is commanded, Normal Law will adjust pitch to provide additional lift to keep level flying as well as rudder for a coordinated turn.

But vice versa, if you apply rudder, the A320 will (initially) exhibit a roll due to yaw-roll-coupling as any other swept wing aircraft. The control law does not automatically and simultaneously compensate this roll moment by opposite aileron deflection.

But yes, the FBW control logic will nevertheless react to this roll, but different as you might assume reffering to a true 'yaw-roll-decoupling'.

As far as I understand, the Normal Law provides 'roll stabilization' as long as there is no stick input, i.e. it will counteract any uncommanded roll and try to return to previous bank angle. Thus the Normal Law does 'see' the rolling of the A/C due to rudder deflection like an 'external' disturbance resulting in an uncommanded roll ('as long as the stick is untouched).

So there is a kind of 'yaw-roll decoupling' through the back door.

But this is a significant difference to a true 'feed-forward' yaw-roll deccoupling where the controller would know in advance about the A/C behaviour to a rudder deflection and thus would apply the appropriate aileron. But if the controller sees the roll as an external disturbance, the controller does not 'know' about the size of the disturbance and thus not the required control action. The reaction will be a result of actual/nominal value difference, applied control law, and gain factors and thus can be significantly slower up to the fact that depending on the implemented law a finite residual error might remain....

And thus as the manual cited by XPMorton points out or Chris practical experiences report, into the wind aileron has to be applied to keep wings level or the upwind wing down during fast decrab.

And I guess we don't need to discuss that rudder on swept wing A/C is a very strong roll control that can even outperform aileron capacity (remember 737). So no wondering that the wing coms up fast durind this 'significant' decrabbing'....

Regards, ihg

P.S.: I don't believe in the gust story....mean cross wind component was high enough to have the A/C drifting across the runway as seen ...

[CONF iture]

Chris,
If I remember correctly, flying in DIRECT LAW during initial training was one the many exercises to be practiced. To do so I believe the instructor had to switch a few (?) flight control computers off and airplane was behaving like any conventional one with the necessary use of manual pitch trim.
Flight Crew Training Manual
Handling characteristics are natural, of high quality aircraft

The example you mention is part of some emergency situations where some flight controls surfaces are inhibited and therefore cannot be placed in a similar category.

As you mentioned, take-off is conducted in Roll Direct Law, once airborne a few conditions apply FCOM 1.27.20 P1 and within 5 seconds Roll and Pitch blend in the flight mode.
I don’t see how a reverse process couldn't occur sometime before the flare ?
Adequate flight test program would tell how and where the switch is more appropriate, my guess would be around 1000 ft …

Regarding sidestick philosophy:
Standard Operation Procedures require any Flight Crew Member to advise the other one whenever any control is manipulated … and strangely enough, the most important control is manipulated in complete darkness !?

I say it again loud and clear:
Invisible sidestick for a single crew operation: ANYTIME !
Invisible sidesticks for a crew operation: NON SENSE !

Dream Land,
Forecast were windy, and last wind check (if EDDHATC information is reliable) was even more, but in the chart considering runway condition.
So what do you do ?
Wait for the blue blue sky to hit again ?
I would feel comfortable to monitor even a low time PF as long as I can follow any of his control inputs … but I’m afraid FBW Airbus just does not provide that ultimate tool.

[bubbers44]

#400 post says the manual states with a smooth rudder decrab little aileron correction is needed but with aggresive rudder decrab, which was the case here, opposite aileron is required to keep the wing from rising like all non AB aircraft. The bank seems to have followed the rudder input putting the upwind wing up causing the downwind drift. The FDR will tell the story if we ever see it here.

[Old Fella]

Hi Bubber44. Thanks for clarifying your comment re military pilots being prone to overcontrol on finals. No, I have never flown on a B52. My Boeing experience is limited to the B707 and the B747. Lockheed C130's (A-E-H) and L1011 were the others. Happy landings, Old Fella.

[PBL]

ihg,

thanks for explaining carefully to those who didn't understand it how yaw-roll decoupling works on the A320.

But I do admit to being a bit puzzled by some of your post, as in:
there is no 'real' yaw-roll decoupling as far as I have understood ...... So there is a kind of 'yaw-roll decoupling' .....
where you contradict yourself. I am not sure what you mean by "real", or "true" here. You do say:
a true 'feed-forward' yaw-roll deccoupling where the controller would know in advance about the A/C behaviour to a rudder deflection and thus would apply the appropriate aileron
but I think you're trying to make a distinction without a corresponding technical correlate.

The ELAC gets signals from roll-rate sensors somehow and if the stick is neutral it signals the control-surface actuators to counter the roll. How else is decoupling supposed to work?

I don't believe in the gust story....mean cross wind component was high enough to have the A/C drifting across the runway as seen ...

I wasn't talking about drift. I was talking about the wing lifting and what caused it. That is what let to the strike.

PBL

[Dream Land]

I would feel comfortable to monitor even a low time PF as long as I can follow any of his control inputs Right, follow up and assist if necessary, ok fine, I understand and agree. My technique would have been to do the landing, anyone who is experienced in flight instructing understands that a student can learn quite a bit without actually being the flying pilot. Again, I think she needs practice in a light airplane before she bends another airplane, had she been with me I wouldn't have given her the opportunity. Had the aircraft crashed, what opinions do you think investigators would have concerning the decision by the captain to let the FO have a go? :ugh::ugh:

[ihg]

The ELAC gets signals from roll-rate sensors somehow and if the stick is neutral it signals the control-surface actuators to counter the roll. How else is decoupling supposed to work?

...to put my understanding (from an at least 'part-time control engineers point of view...) a bit clearer:

A 'true' or 'real' yaw-roll decoupling would mean to me a 'model based controller', i.e. A controller which incorporates a numeric model of the aircraft flight mechanics characteristics. That means the controller 'knows' in advance how the A/C 'will' react to a certain rudder deflection and thus commands the appropriate amount of aileron deflection 'simultaneously' and 'instantly' to fully compress the yaw-roll coupling induced roll. Depending on the actual implementation and the actuator rate capacity you wouldn't see any roll then.

But your statement fully complies with my understanding of what actually happens and what I call 'yaw-roll decoupling through the back door'.

This 'version' of yaw-roll coupling is a 'side-effect' of the ELAC roll stabilization. When you deflect the rudder, the A/C will show a yaw-roll coupling induced roll. As you say, the controller records a 'roll rate' with the stick being 'neutral' and thus sees this as an 'uncommanded roll' being a case for the 'roll-stabilization' and accordingly will try to counter that roll.

But this implies already the significant difference: The 'roll-stabilization' of the ELAC does not know what the uncommanded roll is caused by, may it be a rudder deflection or a gust, it just sees it as an 'external' disturbance', as a 'nominal-actual value' discrepancy. And it can only 'react' to such a disturbance. There has to be already some amount of nominal-actual value error, i.e a certain roll angle has already to have passed, before the roll-stabilization takes action.

And the action (amplitude and rate) taken, as in any control loop, will depend on the time constants of the implemented control law, gain factors etc.

.......many words....bottom line: this version of 'yaw roll' decoupling is a 'reactive' system being 'relatively' slow and limited. The reaction will need a finite amount of time. It will not be able to counter a sudden, strong and persistent roll moment as during decrab sufficiently in the available time.

And I guess, this may not even be expected from this system, as it may primarily be designed for 'roll stabilization' during cruise and standard turns and thus may act more 'harmonic' and not overly 'dramatic'...

Thus to compress the yaw-roll coupling induced roll during such a massive rudder deflection as during the decrab-manoeuvre seen here, a aileron input by the crew is necessary and has, at least in my judgement, not taken place sufficiently.

I wasn't talking about drift. I was talking about the wing lifting and what caused it. That is what let to the strike. I guess only the crew will actually know what has really happened. To me, the wing comes up during decrab due the yaw-roll coupling induced roll moment not being sufficiently coutered by into the wind aileron. And after the wing is up, the A/C is taken by the cross-wind. But well, that's just my judgement. Maybe the BFU report will give some more insight....

Regards, ihg

[bsieker]

Please only answer to this if you are sufficiently qualified, i. e. have the technical/engineering background and/or documentation to prove your answer.

I am still uncertain about the bank angle stabilisation algorithms.

Say, a gust starts rolling the aircraft to the left (with stick neutral), would the FBW system (read in this case: ELAC)

- dampen the roll until the commanded roll rate (i. e. 0 degrees/s) is achieved again, leaving the bank angle wherever it ends up

or

- try to restore the bank angle that was present when the (uncommanded) roll started, by rolling to the right?

My current understanding is that, as the FCOM and other docs say, it really only controls roll-rate, and not at all actual bank angle. (With the exception that it will reduce the bank angle to 33 degrees, if that value is exceeded, with stick neutral.)

This would still leave a residual bank angle from the yaw-roll-coupling induced roll, and would require a stick input to level the wings again.

This also means that any deviation from the desired bank-angle has to be corrected by the PF, although to a lesser degree than in a conventionally-controlled aircraft, because he/she does not have to "fight" the cause of the roll in addition to achieving the desired roll rate.

The phrase from FCOM Bulletin 54/2 "the fly-by-wire system counteracts the effects of gust, even with the sidestsick in the neutral position" is sufficiently vague, and may mean either control law (restoring bank angle, or restoring commanded roll-rate).


Always trying to learn,

Bernd

[grobace]

I am not and never have been an airline pilot, though I have on occasion been at the controls of a passenger/freight aircraft. There are published xwind limits for virtually every aircraft, and if you continue an approach knowing that the wind is outside limits, then you are taking a risk. Do this in a single-seater and you are generally endangering yourself only (though perhaps others if it goes really pear-shaped). Similar situation in a military 2-seater, though most of us would allow the GIB to have a veto. But in a civilian airliner with fare-paying passengers?? In my view the captain was justified in allowing his fo to conduct the approach, but made a gross error of judgement bordering on negligence not to order a GA when it was clear (as the YouTube video clearly demonstrates) that the situation was deteriorating. Had the aircraft drifted further downwind before the wing strike occurred, tbe results would have been disastrous.
I have been flying aircraft for some 45 years and have made my fair share of cock-ups. The last mistake I made in the air (yesterday?) will, regrettably, not be my last. However, if I was upwind (in the chain of command) of this Lufthansa captain, I would suspend him wie and return him to line operations only after a thorough review of his decision-making abilities.

[vaschandi]

Come on and tell!

[Chris Scott]

Quote from fireflybob [Mar07/15:09 currently #402]:
I don't like the phrase "kicking" off the drift.

Mea culpa, on at least one occasion. I agree a snap-movement is inappropriate for any large aeroplane. [As you do it with your foot, could we call it a slow kick?] Don't take too long de-crabbing; it's a time of vulnerability to gust, and you would have to start the process even before the comparatively small flare that is advisable on a crosswind landing. This is difficult to get right, and may lead to the necessity of adopting the FULL sideslip configuration, with (as previously agreed) risk of wing-tip contact.
[Interestingly, the DC10-30 Autoland used to start the de-crab at about 130ft, because of the fairly long body; but I don't think we used it in strong crosswinds.]

Hi, Clandestino [Mar07/14:37, #398],
You have raised some interesting points, and you are in current practice, apparently, to try them out (unlike me). Is "17G29" your highest so far? Keep working on it, and have fun.
It is refreshing to receive support for my contention that the A320 family is not particularly difficult (or different) in crosswinds. Me Myself [Mar07/15:17, #403] evidently agrees.

Not sure about releasing the rudder [U]suddenly on take-off rotation, though. Exactly when would you do it? My first reaction is that it sounds more like a simulator pilot's technique than an airline pilot's. Perhaps you can persuade me otherwise?
I would rather stick with the smooth method of pre-empting wing lift with a little into wind aileron. The pilot should already have been applying this throughout the take-off run. Remember that the FBW has been in Roll-Direct Law for the take-off, so has been no different from a conventional aeroplane.

Thanks, XPMorten [Mar07/14:55, #400], for the Airbus Training-Manual extract. I don't think it is really practicable to avoid using large and/or rapid rudder inputs in a strong, gusty crosswind. So I would take their advice and use pre-emptive aileron, as I have been advocating in all my posts.

"If it had been a gust, the aircraft would have crashed."
[Unquote]
I think in the absence of the data (that, no doubt, LH and the pilots have been scrutinising), we cannot be certain. My money, though, would be on a gust. Have not analysed the footage as painstakingly as you have, but 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.

"At the point where the wing hit ground, there still was no (or very little) roll input. This picture proves it..."
[Unquote]
I am not sure it does. The left aileron is obscured by spray; the right aileron looks a bit up to me, but it is hard to tell. Remember, the neutral position is drooped when flaps are extended.

Am still catching up on some recent posts. The arguments of the formidable German technocrat-trio – ihg, bsieker and PBL – are going to stretch some of us ordinary mortals to the limit!

Quote from CONF iture [Mar07/23:18, #411]:
As you mentioned, take-off is conducted in Roll Direct Law, once airborne a few conditions apply FCOM 1.27.20 P1 and within 5 seconds Roll and Pitch blend in the flight mode.
I don’t see how a reverse process couldn't occur sometime before the flare ?
Adequate flight test program would tell how and where the switch is more appropriate, my guess would be around 1000 ft …
[Unquote]
If you are arguing that the pilot would need those 90 seconds to adapt to Direct Law, I have to agree with you (!), but I don't think we need Direct Law to cope with crosswinds, whether they are inside or outside the certificated limits (preferably the former)...
You repeat your critique of the non-connected sidesticks, and I'm not going to disagree with the logic of your argument. See my various posts on the subject; not least "Airbus FBW – Background" [Mar06/16:47, currently #364]. Twenty years on, the argument is purely rhetorical for the current crop of Airbuses, whether we like it or not.

[bubbers44]

Chris, I agree the video does not have the resolution to see the aileron position but given the aggresive rudder input to swing the nose before touchdown would require an equally aggresive aileron input to keep the wing from coming up as it did. Anything short of to the stops aileron to control the roll as the wing came up is hard to understand no matter if it was a gust or the yaw factor that caused it. Our friends are saying a gust caused it but it still was avoidable in my opinion on the wingtip strike. My background is only with a yoke or stick in front of me, it might be different with the side stick coordinating with a lot of rudder.

[Clandestino]

Thanks Chris, G29 is my personal best and I don't have much room for improvement as my company's crosswind limit is 30kt, take-off or landing, gusts included.

Not sure about releasing the rudder suddenly on take-off rotation, though. Exactly when would you do it? My first reaction is that it sounds more like a simulator pilot's technique than an airline pilot's. Perhaps you can persuade me otherwise?

For a few years I've spent flying fly-by-cable ATR, take-off technique in crosswind was conventional; maintain centerline with rudder and keep wings level with wheel. In significant crosswind this lead to cross-controlled lift off and when positive rate was established, I'd gently release the rudder and turn into wind. Trying to apply this technique to Airbus sim lead to upwind wing lifting, me increasing stick input and then roll into wind as normal law kicked in. Only then I was briefed on let-the-rudder-go technique. I tried it, and it worked in the sim. However, I was not convinced. I thought that it was the sim quirk and that no real aeroplane can fly like that. On my first serious crosswind take off I was back into using my familiar motions. The plane rolled downwind and "You've kept the rudder on takeoff for too long" remark from my instructor was given as soon as we passed FL100. So next time I've centered it as soon as I've pulled the stick back and I thought it to be mightily premature. It turned out it wasn't - airplane just settled into wind with no bank and exactly the right crab angle to maintain the runway track.

I'm aware that airplane is basically in direct law untill 5 secs after lift-off so this manuever has nothing to do with FBW's flight augmentation (EDIT: NOT TRUE - see further posts for explanation). I really can't explain how it works but it does work - I'll bet my wingtips on it anytime.

Anything short of to the stops aileron to control the roll as the wing came up is hard to understand

In normal roll law, stick to the stop will give you only about 40% of available aileron travel. Please do acquaint yourself with contents of FCOM 3.04.27 and FCOM bulletin No54 to see how A320's roll control works. Anyone wishing to argue that Airbus' roll controll is inadequate is most welcome to explain why Airbi don't feature more often in wingtip/podstrike statistics than other types.

[PantLoad]

Well, I've read many of these threads concerning takeoffs and landings in crosswinds in the A-320 series Airbus. Interesting....

I have to strongly suggest that you all not listen to others' 'techinques'...especially some of the nonsense (feel free to substitute another eight-letter word) that 'instructors' are teaching....AND READ THE BOOK FOR YOURSELF!!!!! The FCOM is good reading...The FCTM is even better reading...And, the 'Getting to Grips' series (along with other Airbus publications) will separate the nonsense (again, feel free to substitute another eight letter word) from truth.

I get so frustrated with so called instructors (i.e. 'experts') who teach nonsense....(again...well, you get the idea). READ THE BOOK FOR YOURSELF!!!!

One of the big caveats is...and you have to read for yourself to find this...is that any crab over 5 degrees risks damaging the landing gear. When Airbus published this...they made no distinction between takeoff or landing. If the main gear are still on the runway...and your crab angle exceeds 5 degrees...you risk damaging the gear.

The Airbus flies like any conventional airplane!!!!

Yes, it's true, almost immediately after liftoff, the roll input changes to roll rate. (I can't remember...I think the roll transfers to 'normal law' something like 1/2 second after liftoff....not 5 seconds.)

The correct way to do a crosswind takeoff is to maintain alignment with the runwy until AFTER LIFTOFF...and KEEP THE WINGS LEVEL WITH ROLL CONTROL. It's not difficult. The airplane flies like a normal airplane. However, with roll after liftoff, you're stopping roll rate...stopping the upwind wing from coming up. Again, let me reiterate: Keep the aircraft aligned with the runway UNTIL AFTER LIFTOFF...and KEEP THE WINGS LEVEL. After liftoff, gently relax the rudder pressure...you'll find the roll rate command (which should be ZERO if you're doing things correctly) continues to keep the wings level. You'll be doing runway track...naturally. It's a beautiful thing.

On landing, you align the aircraft with the runway centerline just before touchdown. If a slight wing-down input is necessary to eliminate drift, then that's what you do. In extrememly strong crosswinds, a combination of crab and wing-down will be necessary....and, if the necessary crab angle exceeds 5 degrees...along with the necessary bank angle being too much bank angle to where you scrape a wing tip....(I can't remember offhand the maximum angle...), then you're trying to land in too much crosswind...you either need to select another runway...or, if that's not possible...divert to another airport. In the limitations section, you'll see the published maximum crosswind....if you don't exceed this...you won't exceed crab angle and/or scrape a wingtip.

It's that simple!!!!


READ THE BOOK FOR YOURSELF!!!!

(Now, if your company's SOP says otherwise...then, that's what you gotta do. You have no choice!)


Fly safe,


Pantload

[XPMorten]

Clandestino

In normal roll law, stick to the stop will give you only about 40% of available aileron travel. Please do acquaint yourself with contents of FCOM 3.04.27 and FCOM bulletin No54 to see how A320's roll control works.

At about how many % stick deflection does roll SPOILERS get
activated on an A32x?
On e.g. the B757, roll spoiler activation starts at about 10% control wheel
deflection.

If we look at the pictures again;

http://img529.imageshack.us/img529/2745/undhp089zu5.jpg
This picture clearly shows roll spoiler deflection on the left wing.

http://www.airliners.net/uf/536882887/middle/phpOltUWB.jpg
Much less here - if any...

M

[CONF iture]

bsieker,
I won’t pretend to be sufficiently qualified but I’d like to add a little something:

A320 FCOM BULLETIN 54/2
Aircraft Handling in Final Approach
"the fly-by-wire system counteracts the effects of gust, even with the sidestsick in the neutral position"

You think “the phrase is sufficiently vague” now try this one:

A330 FCOM BULLETIN 813/1A JUN 04
Aircraft Handling in Final Approach
"The flight control system of Airbus fly-by-wire aircraft partially counteracts roll movements induced by the effects of gust, even with the sidestick in the neutral position"

Airbus could be more confused than we are … or is it that difficult to put it in words even 20 years later ?

On top of Flight Crew Operation Manuals + Flight Crew Training Manual + Standard Operation Procedures, Airbus feels the need for a few Flight Crew Operation Manual Bulletins related to early and late phases of a flight, when pilot manual skills mater!

- Avoiding tailstrikes
- A/C handling in final approach
- Avoiding hard landing

Quite ironic after the following statement pronounced by B.Ziegler himself:
“le 320, même ma concierge pourrait le piloter” (not sure how to translate it)
It does also give an idea how the head of Airbus FBW engineering design was valuing the pilot profession.

Chris,
Thanks for the clarity of your posts and also for your honesty.
You was part of the 320 early operational days, it must have been exciting but also quite challenging … Was it under the British Caledonian Airways colors ?

As you told it here (http://www.pprune.org/forums/showpost.php?p=3960642&postcount=364), pilots put pressure for modifications … “but Mr Ziegler prevailed”

I believe Mr Ziegler has been somehow too prominent in the FBW Airbus conception and took some “radical and irrevocable decisions on A320 design” without properly consulting.

A table on long haul flight is nice for sure, but I don’t mind waiting to be at destination for an even proper table with red wine, candle, and nice company, and retain the privilege of fully visible connected flight controls in always possible adverse approach conditions.

I believe Boeing fully understood it … Also, they opted for more simple flight control laws, that could be a reason they’re not part of these rocking wings shows on YouTube:
Lisbon (http://youtube.com/watch?v=p0kADC-nrTw)
Hamburg (http://youtube.com/watch?v=S1OG8NUqZSo&feature=related)
Bilbao (http://www.diariodelviajero.com/2008/01/18-aterrizaje-abortado-de-un-avion-de-iberia-en-bilbao)

Regarding Thrust Levers, I’ve heard they were not supposed to have any, just Push Buttons for different settings, and therefore no possibility for Manual Thrust … but it could be just part of the myth, maybe you know more ?

[Clandestino]

Thank you for your most considerate post mr. PantLoad. It made me review my FCOM and now I see that illustration on page 1.27.20 P1, that showed time for blending in normal law after lift-off as 5 seconds has been changed. The new scheme now splits mode row in two rows - pitch and lateral control. Pitch row still shows 5 secs for flight mode to take over after lift-off, but the newly featured lateral contol row now shows this time to be only 0.5 seconds.

Therefore, I stand corrected, it is indeed FBW that keeps our wings level immediately after lift-off. Mea culpa - I've really should check out the FCOM updates more thoroughly.

but..

A320 FCOM 3.04.27 P4 SEQ 001 REV 36

For crosswind takeoffs, routine use of into wind aileron is not recommended. In strong crosswind conditions, some lateral control may be used, but care should be taken to avoid using large deflections, resulting in excessive spoiler deployment which increases tendency to turn into wind, reduces lift and increases drag. Spoiler deflection starts to become significant with more than one third stick deflection. As the aircraft lifts off, any lateral control applied will result in a roll rate demand.

I absolutely agree that wings have to be kept level during take-off run by using lateral control. From my experience, lightly loaded A320 in 25kt crosswind will take almost... no stick deflection to keep wings level therefore, I agree with FCOM that lateral control may be used but I'd also add that it will be seldom needed.

Thank you for pointing out 5° crab angle on ground generic limit for Airbi, from 300 to 380, but rest assured that I've never approached this limit, even as I eased the pedals during rotation, with significant crosswind, on wet runway (and I ment eased, not kicked them to neutral or beyond). You see, even as rudder goes to neutral during rotation, airplane doesn't immediately weathercock into wind but rather gently crabs so the actual lift-off is achieved with so little drift it's almost imperceptible.

Actually, out of disbelief, I did initially try maintain alignment with the runwy until AFTER LIFTOFF by using rudder. It works fine when winds are light and I assume that ELACs have the capability to fight pilot's rudder input and light winds at the same time. However, with stronger winds rudder goes further and things get a bit more complicated for FBW as you lift off, wing goes up and you're stopping roll rate (with stick, i.e. roll demand)...stopping the upwind wing from coming up.

So I've tried both methods and I know which one gives me lesser roll excursions after liftoff. Hint: I'm still convinced that FBW can compensate roll from 30kt xwind by itself but 30kt wind and opposite rudder is a different story.


Happy contrails

[Basil Seal]

First post on PP but I had to jump in after following a most interesting thread. It seems that this incident can be broken down into a number of components all of which have been touched on at some point in the thread. What were the winds that tower reported to the LH flight when it was cleared to land? What are LH's (not my carrier or yours, but LH's) X-wind limits for the 320? Did the tower reported winds fall in excess of that limit? What was the time interval between the LH approach and the last measured peak gust? Was the runway reported as wet? Is it grooved? Were there any log items in the mx section of the dispatch that I would need to be aware of? How many hours has each pilot flown in the last 30/60/90?

These are all questions whose answers I still do not know (unless I missed them in the thread - entirely possible) but are questions that are germane to the incident and when realeased, will dispel what heretofore has been a lot of speculation.

I only have a little of 1000 hours in the Bus (although 15 years of airline flying for what that is worth - which may be nothing!) but I remember my intitial instructor's comments that the Bus FBW makes corrections and has the famous protections, but it is not an instantaneous effect. 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.

With that in mind, I can see when one applies the rudder as rapidly and vigorously as the handling pilot did in this case that I would have to throw my lot in with XPMorten that being a swept wing aircraft you are certainly going to need to control the right winging generating lift and rising irrespective of rolls rates/direct law/design comprises and other fine argumentative points.

I will have to admit that I remain very intrigued about the decision making process and have to be open to what a lot of the unanswered questions would reveal. The captain flew a damaged aircraft away from the ground and landed safely. Yet I read a book recently entitled The Outer Whorl by a guy who flew in the same military reserve unit that I did. No endorsement needed from my humble literary skills as it is an outstanding aviation read and more than stands on its own merits, but I remember he had one chapter about pessimism and expecting the worst. It has made me think a lot about decision making in the jet and to sharpen up a little when it comes to mentally preparing for something bad. Should not, when operating at or above the carrier's limits for X-winds, have been cause to think that a bad gust could be problematic? When at limits (again what were the last reported winds?) was the skipper expecting the worst?

I do not know the answers to those questions but I wish that I did. I guess what I am trying to say in my first post is that any incident/accident has a lot of layers. There are things that we do not know and I will be anxious to not only know them, but also to learn from them. Give me a dollar for every mistake I have made in an airplane and I would be rich beyond my dreams. Goat or hero for the skipper? I will leave the jury out for now.

This is a good thread. Good tech talk. Keep it going.
Basil

[Chris Scott]

Have had a manic weekend, and now see at this late hour (in UK) that this interesting discussion has been continuing apace. Will have to catch up tomorrow, but can try to answer a few questions from CONFI ture:

Quite ironic after the following statement pronounced by B.Ziegler himself: “le 320, même ma concierge pourrait le piloter” (not sure how to translate it)
[Unquote]
Surprised that a bilingual/multilingual Francophone would baulk at translation! "Even my doorman could fly it," will do. We overpaid pilots felt it was a bit of a "put down", but he probably didn't mean it that way.

I believe Mr Ziegler has been somehow too prominent in the FBW Airbus conception and took some “radical and irrevocable decisions on A320 design” without properly consulting.
[Unquote]
If my quoted remark is justified (and I think it is), you should remember the history of many aircraft projects, some of them British, in the post-war years. Sometimes you have to have one very strong, even - bloody-minded - person, who will take a project by the scruff of its neck and push it along. That means it will have his/her stamp all over it; "warts and all". So lesser mortals have to hope the "warts" are not serious.

Regarding Thrust Levers, I’ve heard they were not supposed to have any, just Push Buttons for different settings, and therefore no possibility for Manual Thrust … but it could be just part of the myth, maybe you know more ?
[Unquote]
Yes, had almost forgotten that one. Either it was just a bargaining gambit by BZ, or perhaps we pilots were not entirely ignored. I only mentioned the design changes sought by the pilots' unions, but it goes without saying that the 3 launch-customer airlines (AF, BCAL and Air Inter) were in constant discussion with Airbus. In BCAL's case, the management-pilot input was led by George H, A320 Project and Development Pilot. We ended up with a beautiful manual throttle, which I used on 95% of my manual landings; including limiting crosswinds.

OFF-TOPIC
The one A320 painted with a complete BCAL colour sceme had it on the L/H side only, if memory serves. The R/H side, I think, was in Air France livery (or Air Inter). Can't remember if that one was used for my base training at Blagnac in March 1988. BCAL's AOC was effectively transferred to BA on 1/4/88, which was the day our first A320 (as G-BUSB, a dash-100, with no winglets) was delivered to Gatwick - in BA colours. We operated them out of the newly-opened North Terminal on a mixture of day schedules and night charters for the first 6 months. In October/November, the expanding fleet moved to Heathrow. In due course, we received the total BCAL order of 5 "100"s and 5 "200"s, ending with G-BUSK.
In 1988, we were a very happy and dedicated small team of ex-BCAL pilots, and we all loved the little aeroplane from Day1. Our success eventually persuaded some "real" BA pilots and ground engineers to join us, the former led by Colin W, who became our first proper BA management pilot at the time we moved to Heathrow, and a great ambassador for A320 in Boeing Airways [er, sorry - BA]. :uhoh:
We continued to fly a successful operation for many years, hoping BA would buy A340s and/or A330s. Instead, we ordered B767-300s... :ugh: It was many years before BA ordered Airbuses for the first time, and then they were IAE-A319/321/320. 20 years after we started, as everyone knows, their narrow-body Airbus fleet is enormous. But no wide-bodies, yet...

[NOR116,20]

Fortunately the incident in HAM caused no fatalities.
However, under the assumption that wrong handling in flying the airplane led to the incident, what is the lesson to learn?
I think consequences should be considered both for training requirements and future design of airplanes.

Pilots are increasingly considered as “cockpit managers”. Good flying skills seem more and more to belong to a phase-out model of a pilot. I heard recently about plans to license pilots with zero flight time gaining all their experience in simulator sessions only.

However, events like on LH044 show that excellent handling skills in piloting are not dispensable and have to be developed in training with small aircraft. If pilots get their first seat in an airliner it is too late for training basic handling skills. Side-slip technique is a good example for this. I think the current training setup and requirements particularly for beginner F/Os in legacy carriers contains too little flight experience until being released on airliners. The focus is too much on “cockpit managers”. Managing cockpit systems is increasingly important in modern airplanes though not enough.

Automation in airplanes is a vital tool for our daily work and undoubtedly contributes to flight safety, however cannot substitute good flying skills entirely. There are situations where even the smartest technical features cannot cope with human skills, e.g. pilots know about the lower wind limits for an automatic versus manual landing.
The conclusion that pilots are the weakest part in air safety contributing mostly to accidents by their mistakes is inappropriate and unilateral. The overwhelming majority of occurrences when pilots cover system failures does not show up in any statistics or in the press, yet is our daily work. Engineers should take this into consideration for future generations of airplanes. Flying in unmanned airplanes as a passenger – no thanks with my experience as pilot! :=

[PantLoad]

Use as much (or as little) roll as is necessary to maintain wings level. If this means no roll input, so be it. Usually, in strong crosswinds, a little ("a little") is needed.

The FCTM goes into more detail on this...as does the "Getting to Grips" series.

I have to emphasize that this airplane really does fly like a regular airplane. I know many disagree, but it's just a damn airplane. You, the pilot, have control of three axis. The fact that you have computers helping you doesn't change the fact that you have three axis of control. Use the controls necessary to acheive the desired flight path. If the computers assist to the point where you need no control input for a particular flight path correction, so be it. If you must add a bit of your own input, then do it. The end result should be the same as with any conventional airplane.

Yes, the blend from ground mode of normal law to flight mode of normal law is split between pitch and roll. So, with that, you have to be aware that immediately after liftoff, your aileron command changes a bit.

I'm not a salesman for Airbus, and I DO prefer a Boeing. But, there are some really nice features of the Bus that I love....The FBW is great.

PantLoad

[PBL]

igh,

As I said, I think you're trying to make a distinction without a difference.

A 'true' or 'real' yaw-roll decoupling would mean to me a 'model based controller', i.e. A controller which incorporates a numeric model of the aircraft flight mechanics characteristics. That means the controller 'knows' in advance how the A/C 'will' react to a certain rudder deflection and thus commands the appropriate amount of aileron deflection 'simultaneously' and 'instantly' to fully compress the yaw-roll coupling induced roll. Depending on the actual implementation and the actuator rate capacity you wouldn't see any roll then.

1. An ELAC and any FCC in any FBW airplane is run by a bunch of code. I don't know what you want to mean by "incorporate a numerical model" in such a way that other FCCs have it but ELACs don't. They all have numerical calculations built in, and those numerical calculations are obviously based upon the numerical flight characteristics of the airplane, otherwise how could you get those wonderful Bode and Nyquist plots?

2. Controllers don't "know" anything. They run code. No FBW controller I know controls the airplane according to internal parameters alone (thank heavens!). All such systems are feedback control, which means that
* there are target values for parameters
* actual values of those parameters are obtained by sensing
* the controller issues actuation commands to bring the actual values closer to the target values

Now, this all happens at the speed of electrical signals through copper wiring, which some significant fraction of the speed of light, and the signals only have to go a few meters.

3. Nothing happens in advance in a feedback controller. And neither is there any significant latency in the digital control. Sensing, computing and commanding happen to all intents and purposes instantaneously. Sensing in unstable airplanes such as the F-16 happens at about 200Hz; I don't know the sensing rate for roll on the A320. There may be some latency due to the physical characteristics of the actuators, but this has little to do with how the controller is designed (except, of course, that such latency will be accomodated where needed).

4. Nobody is suggesting the decoupling is completely, rigorously effective in all situations. Indeed, posts from Chris Scott and others say most clearly that it isn't. But I don't see that the strength of the decoupling has anything to do with "back door" or "front door". The kit is clearly designed to decouple roll from yaw, as other posts (for example from Clandestino) show, and as you seem to agree.

5. I doubt decoupling is properly describable as a "side effect" of the control SW design in the ELAC, as you suggested. Decoupling is, obviously, designed in and is there quite intentionally. It's in the manuals, as we have seen. As are its limitations.

PBL

[PBL]

igh,

As I said, I think you're trying to make a distinction without a difference.

A 'true' or 'real' yaw-roll decoupling would mean to me a 'model based controller', i.e. A controller which incorporates a numeric model of the aircraft flight mechanics characteristics. That means the controller 'knows' in advance how the A/C 'will' react to a certain rudder deflection and thus commands the appropriate amount of aileron deflection 'simultaneously' and 'instantly' to fully compress the yaw-roll coupling induced roll. Depending on the actual implementation and the actuator rate capacity you wouldn't see any roll then.

1. An ELAC and any FCC in any FBW airplane is run by a bunch of code. I don't know what you want to mean by "incorporate a numerical model" in such a way that other FCCs have it but ELACs don't. They all have numerical calculations built in, and those numerical calculations are obviously based upon the numerical flight characteristics of the airplane, otherwise how could you get those wonderful Bode and Nyquist plots?

2. Controllers don't "know" anything. They run code. No FBW controller I know controls the airplane according to internal parameters alone (thank heavens!). All such systems are feedback control, which means that
* there are target values for parameters
* actual values of those parameters are obtained by sensing
* the controller issues actuation commands to bring the actual values closer to the target values

Now, this all happens at the speed of electrical signals through copper wiring, at some significant fraction of the speed of light, and the signals only have to go a few meters.

3. Nothing happens "in advance" in a feedback controller. And neither is there any significant latency in the digital control. Sensing, computing and commanding happen to all intents and purposes instantaneously. Sensing in unstable airplanes such as the F-16 happens at about 200Hz; I don't know the sensing rate for roll on the A320. There may be some latency due to the physical characteristics of the actuators, but this has little to do with how the controller is designed (except, of course, that such latency will be accomodated where needed).

4. Nobody is suggesting the yaw-roll decoupling is completely, rigorously effective in all situations. Indeed, posts from Chris Scott and others say most clearly that it isn't. But I don't see that the strength of the decoupling has anything to do with "back door" or "front door". The kit is clearly designed to decouple roll from yaw, and does in many normal situations, as other posts (for example from Clandestino) show, and as you seem to agree.

5. I doubt decoupling is properly describable as a "side effect" of the control SW design in the ELAC, as you suggested. Decoupling is, obviously, designed in and is there quite intentionally. It's in the manuals, as we have seen. As are its limitations.

PBL

[Chris Scott]

Quote from NOR116,2 [Today, 02:42, currently#429]
Pilots are increasingly considered as “cockpit managers”. Good flying skills seem more and more to belong to a phase-out model of a pilot...
However, events like on LH044 show that excellent handling skills in piloting are not dispensable and have to be developed in training with small aircraft. If pilots get their first seat in an airliner it is too late for training basic handling skills.
[Unquote]

Just one part of an excellent posting.

The introduction of CRM in the 1980s - much of it researched by NASA and owing, no doubt, a lot to Jim Lovell's crew's experience on Apollo 13 – was generally "A GOOD THING". The snag was that the guys who could have most benefited from it were the ones that pooh-poohed it.
Initially, CRM emphasised the inter-personal skills elements. The problem-handling guidelines came later, though, with things like "DODAR".

There did seem to be a period, around the early 1990s, when we had become so politically-correct that it had become acceptable for inexperienced copilots to criticize the captain, but not the other way round. A tiny element of them were encouraged to become overbearing pre-madonnas. [I'm talking mainly about male madonnas, if that's not an oxymoron.]

Irrespective of the fact that I was flying the A320 throughout the 1990s, it became clear that basic handling skills were taking a back seat in ab-initio training. I once flew with a pleasant female copilot, newly converted on the A320 as her first airliner-type, who applied aileron the wrong way on a landing in a (fortunately) light crosswind, and then argued that you could use the roll-control of the sidestick to "steer" the aeroplane on the runway...

[CONF iture]

Thanks Chris for sharing your memories on the 320 first years operation.
Your tone is quite similar to what M.Asseline was describing in his book, everybody was enthusiast to transform this Adventure in a Success story.
What has been your view on Habsheim and how did you deal with that event afterward ?

To go back to the topic and your anecdote, how did you notice your FO was trying to steer with the sidestick ?

NOR116,2 I also share your view.
Earlier you mentioned the idea of interlinked sidesticks, so I’d like to refer to another posting from last year, here (http://www.pprune.org/forums/showpost.php?p=3215283&postcount=78)

PantLoad, I didn’t really get your point when you mention the takeoff phase, with main gear still on the runway ... and crab exceeding 5 degrees ... ?
I don’t think anybody would or even could attempt that without visiting the grass, unless rwy surface is very slippery ... !?

[PantLoad]

I was referring to some 'techniques' taught by some....

The aircraft needs to be aligned with the runway while it's on the runway. Exception is when crosswinds are 'strong' (as stated by Airbus), where crab and wing down may be necessary.

So, I'm saying...you maintain the aircraft on the runway centerline with rudder during the takeoff roll, maintain wings level with roll control. After liftoff (not during) you relax the downwind rudder while continuing to maintain wings level with roll control.

Regardless of takeoff or landing, Airbus claims that if the aircraft is 'crabbing' on the runway in excess of 5 degrees, main landing gear damage may result.

Again, there is nothing special or magic about this aircraft. It flies the same as any other....just a different flight control system. The basics of flying still apply.

PantLoad

[Lemurian]

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.

[bubbers44]

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.

[Lemurian]

Sorry, but that's what I see, and see again.

[bubbers44]

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.

[RWA]

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.

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?

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?

[Chris Scott]

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 ?


1) In ground mode, the position of the sidestick(s) is displayed by a white cross on the PFDs.

2) [U]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.

[Dream Land]

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 Bubbers44Yes, fully agree.

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 RWAYes, appears to me the poor method of de-crabbing was the culprit (armchair opinion only).

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:= 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.

[RWA]

Yes, appears to me the poor method of de-crabbing was the culprit (armchair opinion only).

Just for clarification, Dream Land, the left bank I'm referring to is much earlier on - at the moment that the video camera swings round and begins to film the aeroplane from behind. That was the moment that they got seriously off line downwind - AND the moment at which (from the unhurried safety of my computer stool :)) I can say with absolute conviction that I'd have decided to go around.

[bubbers44]

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.

[Chris Scott]

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.


Think what you intended to say was "150kts [U]TAS" ?

Otherwise, you have argued the advantages of applying slight upwind sideslip during de-crab brilliantly - thanks. :ok:


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 ?

[Dream Land]

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? :}

[Lemurian]

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.

[Lemurian]

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.

[Basil Seal]

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!

[Chris Scott]

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/showthread.php?t=308926&page=3&highlight=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.

[gonebutnotforgotten]

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

Despite rumors, the Airbus uses conventional crosswind landing technique'

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.

[ihg]

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'?
... I didn't follow the respective threads for the incidents shown in the afore mentioned videos, so I hope I'm not repeating things already said:

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 (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

[CONF iture]

1) In ground mode, the position of the sidestick(s) is displayed by a white cross on the PFDs.Sweet and short answer but still ... so true !

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 ...

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! The captain probably learned his lesson, the hard way but not the hardest one. Up to this event, he had probably never realized how much his beloved FBW Airbus could reduce the maneuver margin for proper supervision.
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 ... ?

[DozyWannabe]

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.

[bubbers44]

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.

[Rananim]

Yokes are old. They are on their way out. Yesterday's technology. Get used to it.

Sorry,I dont get it.Old is bad?New is good?Is the gee-whiz factor of the A320 so blinding that it prevents you from honest appraisal.Give me a pilot who readily recognizes his own aircraft's idiosyncracies/pitfalls and discusses them honestly.
Boeing wont relinquish the moving yoke/ thrust levers for their air transports.No sir,not just yet.When the role of the pilot has been consigned to the rubbish-bin of history,then they might.
At the moment of touchdown at HAM,this air-transport was being flown single-crew with zero feedback for the hapless PNF.Give me an answer as to why this is good.

[alf5071h]

CONF iture, your personal view (#454) provides a succinct summary, but shouldn’t you have referenced the limiting crosswind, or at least the possibility that it was limiting, albeit unknown to the crew? Re earlier references to inaccuracies in wind measurement and reporting.
Was the steady value (30kts) within or at the demonstrated value / limit, or if greater was the attempted approach inadvisable?
Alternatively do you or any other operator consider the gusts as the limiting value? I note Chris Scott’s positive response earlier.
Is there a compromise for a limiting condition between the steady state and a gust, if so what would it be?
How many operators make the demonstrated crosswind value a limit? Why?

DozyWannabe, I don’t take CONF iture's comments on Airbus as harsh as you do. Although the aircraft in the incident was an Airbus and from the discussion above its systems (or the crew’s understanding of them) may have been a factor, these are all points which can apply to many aircraft types.

There has been a vast amount of debate on the knowledge (or lack of) of the control systems and ‘how to’, but very little on what I believe could be a major contributor, that of the crosswind limit, a crew’s knowledge (or lack of) of limit derivation, wind measurement and reporting, and thus the risks that crew’s are prepared to take.
Thus the debate should not be so much about knowing how to conduct a crosswind landing, but instead consider the assessment of whether it is safe to do so in the conditions, and thus if any safety margin is required when planning to operate within ‘a limit’.

[bubbers44]

During certification x-wind landing capability has to be demonstrated. The last aircraft I flew it was 29 knots because the day they certified it that was the actual wind. If the wind had been 30 knots that day, that would be the limit, that is why they call it demonstrated x-wind limit. It does not mean you can't land with a higher x-wind because the aircraft can't do it. Proper x-wind landing technique will always assure a safe approach and landing up to the limit every time. Improper technique as seems to be the case here will not. You never let the upwind wing come up in a x-wind landing. It doesn't matter if you do it with a yoke or side stick.

[bsieker]

[...] does the computer average the two opposite inputs?

Their inputs are added (limited to full deflection of a single stick), not averaged. This form of cross-controlling is strictly discouraged, but possible. There are indications on the glareshield, as well as an aural warning: "DUAL INPUT".

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?

Yes. The other stick is then ignored. This is the SOP for taking over control, along with announcing "I have control", or whatever wording your airline prescribes.


Bernd

[bubbers44]

I assume the captain's button to take full control and disable the FO's side stick is almost never used so would not be instinctive like taking over with a yoke. If she was using left stick and he countered with right stick to prevent hitting the left wing but didn't press the disengage button how would you add his right input to her left? You said it is additive, not averaged up to full stick deflection. What you said seems to say he could not counter the left aileron without disengaging her side in the above example. Is that correct?

[bsieker]

bubbers44,

the resulting control input from both sticks is just the simple algebraic sum of both sticks' deflections. If the F/O makes a control input of, say, 7 degrees to the left (call it "-7"), and the Captain makes a 12 degree input to the right ("+12"), then the resulting control input is -7 + 12 = +5.

If the F/O had been using full left input, the best the Captain could achieve without using the takeover priority button would be neutral, by applying full right deflection.

There is a known incident in which the Takeover button was used successfully in an emergency situation. The Captain's sidestick was connected in such a way that the roll input was reversed. The F/O noticed the problem just in time, pressed the takeover button, and landed the aircraft safely. See also the entry Lufthansa A320, incorrectly-wired sidestick, Frankfurt am Main, March 2001 (http://www.rvs.uni-bielefeld.de/publications/compendium/incidents_and_accidents/A320-FRA.html) in our Compendium CRICA (http://www.rvs.uni-bielefeld.de/publications/compendium/).

There are also cases where cross-controlling without using the takeover button occurred. I assume it's a matter of training, and the fact that this happens is the strongest argument against the non-backfed, uncoupled sidesticks. For this to develop into a real problem usually also involves a serious breakdown of CRM.

The takeover button also serves to disconnect the autopilot, e. g. when taking over for the manual landing after an autopilot approach, so it may be a well-trained thing to do when starting to move the stick. (One can also disconnect the A/P by overcoming a restraining force that is keeping the sidestick "lcoked" with A/P active.)


Bernd

[DozyWannabe]

The training *makes* it instinctive - it's the whole point of training.

Rananim - I know how you feel about cockpit automation because we've butted heads over the subject before. I'm more than happy to agree that the AI FBW does have some drawbacks as well as numrous advantages, but a lot of the perceived disadvantages that you bring up are more to do with your distaste for what you see as marginalisation of the pilot than actual, known problems with the design.

Boeing didn't consider changing their flight control input method for financial, not technical reasons - they already had 5 or 6 jetliner types in the sky to maintain as much commonality between as possible, whereas Airbus, who had 2 (effectively one, A300/310) did not have the asme baggage. Of course, the press-induced backlash in the wake of Habsheim and Strasbourg as well as a distaste for FBW by some in the pilot community probably strengthened the case for them. But still, their latest offering is full digital FBW with a computerised backdriven force-feedback system - just as prone to problems as the A320 digital FBW setup.

[bubbers44]

Thanks bsieker, That makes sense now.:)

[cjt]

bubbers44,

why app autopilot (autoland) is limited to just 20 kts xwind component
while manual operation limits are much higher however typical
(33G38 kts) ?

[PJ2]

bernd;

"Dual input" on sidesticks was considered so serious an operational issue that when we created our FDM 320 event set we designed and included an event to monitor such dual input. We do see the event trigger from time to time, sometimes in training circumstances, sometimes not.

We are also working on in-depth TCAS events but that is another thread.

PJ2

[alf5071h]

bubbers44 Re:… The last aircraft I flew it was 29 knots because the day they certified it that was the actual wind. If the wind had been 30 knots that day, that would be the limit, that is why they call it demonstrated x-wind limit.You assume too much. It is not necessarily true that 30kts would be the limit; the test team on another day might find that 30kts could not be demonstrated. In that case, the demonstrated value (29kt) would be moved to the limitations section of the AFM as a 'limit' (CS 25 AMC 25.158). The terms used are ‘demonstrated’ or ‘limit’, not both together.

It does not mean you can't land with a higher x-wind because the aircraft can't do it. Proper x-wind landing technique will always assure a safe approach and landing up to the limit every time.
Answers to the questions in #458 might conclude that a crew should not consider landing above any demonstrated value.
Even landings within the limit cannot be assured to be safe; consider the occurrence of a gust which might mean ‘at that critical time’ the wind is well above the demonstrated value.

The industry applies a safety margin to most parameters which if encountered in normal operation could be hazardous, e.g. approach speed / stall speed 30%, or landing distance 60%+. Then why not consider a safety margin for crosswind, which is a parameter that can result in loss of control?

cjt, crosswind values for manual landings are determined from a qualitative assessment by a test team. Normally they are judged not to be limiting nor require exceptional skill or knowledge (certification requirements).
For autoland certification, the manufacturer has to show statistically and in part by demonstration, that the landing will be safe (a high level of probability); this normally results in a lower crosswind value, which is published as a limit

[Lemurian]

gonebutnot forgotten
Quote : My only quibble with the chap who originally wrote it was his introduction that said :
"Despite rumors, the Airbus uses conventional crosswind landing technique'"

It may be an unfortunate choice of words but he meant that , contrarily to existing wisdom - one could side-slip an Airbus.
After all, as pilots we just make do with the tools we are given ; for example, in order to maintain a steady turn on a big aircraft , we usually need to apply reverse aileron and to my knowlwdge, that has bothered nobody. Same technique -the sideslip -, different ways of achieving it.

Quote : "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. "
I can undestand your feeling, and to a point -though it pains me - I could agree with you. Perhaps have we gone too far in trying to insist on how NOT different the 320 is ? It is also a matter of demography :The populations who got the gospel from Airbus are fewer and fewer, the generation of the airmanship-holding baby boomers is no longer and they are being replaced by younger generations with less and less time (constraints of growth, mainly) to pass on the good practices.
But that problem is not only an Airbus one but general.

Regards

[gonebutnotforgotten]

Lemurian, you are probably right, maybe the chap was talking about sideslip, and not how to achieve it, but there are many contributors to this thread who really do appear to think conventional control inputs work for an A 320, including all those who talked about into wind aileron.

I remember many years ago a thread running on the BA/BALPA compuserve forum which started with some A 320 chap complaining about the lack of roll authority and how this was the first aircraft he had flown that required full aileron in gusts and how that often wasn't enough. Many others joined in to agree (some to their credit didn't) and the discussion droned on until it was abruptly shot down by the intervention of none other than Bill Wainwright, then Airbus CTP (how did he get into the private forum?). He patiently explained as was done earlier in this thread, that full stick gave 10 deg/sec roll rate, but that the controls were capable of much more (did I see 25 deg/sec?), and that a roll rate control just wasn't the same as aileron after the intial application. That shut everyone up. But the real issue is how on earth did such erroneous ideas take hold in the first place. What were the guys being taught? I think someone in Toulouse should be thinking very carefully about the standard of understanding being shown here, and what to do about it. There is a lot to learn when one changes the fundamentals of flying (and a lot to unlearn when one converts back to a conventional machine). With any luck , there are many A 320 crew who have read this thread and are thinking about what they do, but what about the rest out there?

Note for potential flamers out there, I am not saying there is anything wrong with the machine or the way it works, just that it needs to be taught properly and respected. I fully agree with Lemurian:

Perhaps have we gone too far in trying to insist on how NOT different the 320 is ?

[Dream Land]

With any luck , there are many A 320 crew who have read this thread and are thinking about what they do, but what about the rest out there?Great information on this thread, I like the bus a lot but quite agree with CONF iture's post. :D

[RWA]

I can undestand your feeling, and to a point -though it pains me - I could agree with you. Perhaps have we gone too far in trying to insist on how NOT different the 320 is ?

It's still this 'difference' that I can't understand. I've only flown light GA singles and the occasional twin - plus gliders, my main interest - but I still remember the occasion, on about my third lesson, when coordinating ailerons, rudder, and elevators became automatic (exactly like learning to ride a bike, coordinating handlebars and body lean, plus the 'vertical dimension') and I began 'learning to fly,' in the basic sense.

Sorry if the question appears unduly elementary, but how does this sidestick control actually work? From what I gather, to bank say right, you move the sidestick say two inches to the right, and then let go (and, being spring-loaded, the sidestick centres itself). The aeroplane then banks right.

As I understand it, to cancel the command and level out, you have to move the sidestick the same distance in the opposite direction - precisely two inches to the left - and then release it again; and the aeroplane will then level out.

My question is, lacking the 'feedback' and self-centring that aeroplanes with normal controls provide, how do you know that you have exactly cancelled the previous bank command; and not either left some bank on, or corrected too far the other way?

Seems to me that there are only two ways that you could be certain. Either by observation (if the aeroplane doesn't level out, you've either overdone or underdone the correction) or by looking at some sort of instrument on the panel that shows the 'aileron command' situation?

Maybe I'm over-simplifying - I've certainly never tried to land a 60-ton airliner in any conditions. But I HAVE done plenty of crosswind landings - and I can't readily imagine a situation where I had to wait to see what the aeroplane did, or look at anything other than the yoke, to find out whether I had actually given the aeroplane the 'command' I intended or not?

Hope someone can enlighten me - and preferably tell me that Airbus controls don't actually work like that?

[sleeper]

left or right sidestick commands rollrate.
This means that upon releasing the stick to neutral, zero rollrate is commanded and roll stops.
You do not need to stop the roll by using opposite stick. in fact if you do that the roll will be reversed.

[Lemurian]

RWA :
"...when coordinating ailerons, rudder, and elevators became automatic..."
The 320 does that *automatic* bit for you. Through the FCS.

..."From what I gather, to bank say right, you move the sidestick say two inches to the right, and then let go (and, being spring-loaded, the sidestick centres itself). The aeroplane then banks right..."
No ! Once again, the side-stick displacement commands a roll rate, or in other terms how fast you're gonna bank that airplane. leaving it in that position, the bank angle will keep on increasing at the same rate.When you move it then toward the centre, you'll slow the rate and annull it when the side-stick is centered : you have just asked the FCS to fly a new flight path with a G-demand, and it'll stay there until you cancel it. To that effect, move the stick in the opposite side and the stick will demand how fast you'll be having a bank command to that side, whether in order to reduce the rate of turn, to achieve a wings-level flight or to do a spiral in the opposite direction...within 5 degrees of wings level, it will center by itself.
There is no perceivable lag between command and aircraft response.

..."My question is, lacking the 'feedback' and self-centring that aeroplanes with normal controls provide, how do you know that you have exactly cancelled the previous bank command; and not either left some bank on, or corrected too far the other way? ..."
The true red herring...As far as I know, there is no *self centering* in any airplane I know except Airbus products : the pilot constantly moves the flight controls in any given circumstances...if not, he has achieved a damn good trim and his "stability augmenting system" is outstanding...until the next disturbance...
As for feed-back, I probably do not understand the term as it is meant by others. I will do what is necessary to get the response/state I require from the aircraft, on some, I may need some reverse aileron to maitain a given turn...on the Airbus, I get exactly what I want in the simplest way possible.

..." I HAVE done plenty of crosswind landings - and I can't readily imagine a situation where I had to wait to see what the aeroplane did, or look at anything other than the yoke, to find out whether I had actually given the aeroplane the 'command' I intended or not?..."
As I said, one moves the flight controls in order to achieve a given manoeuvre, regardless of the kind of airplane one is flying, regardless of the system one's airplane is operating on, be it even a side-slip. Piloting is about making sure that the airplane is EXACTLY placed, in the right configuration where it should be, as the pilot has decided.
In that respect, the precision of the Airbus system is peer-less, and a lot more intuitive than non-Airbus pilots would ever imagine.

Big problem is they don't imagine. Easier to criticise out of spite, prejudice, ignorance...
Their loss.

[Chris Scott]

In the light of all these illuminating exchanges more recently, I have EDITED my post on A320 side-stick [Mar04/18:07, currently Page12, #229]. These amendments have now also been added below during EDITing.***

Quote from gonebutnotforgotten [Mar12/20:46, currently #452]:
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.


Having arguably over-contributed to this Thread (20 posts at the last count...), I see that the sidestick-abuse :rolleyes: issue is still worthy of further comment. I made little attempt to describe how to handle the stick in my previous post, except to express the opinion that, with notable exceptions, inputs should be "short and often". The alarming over-control exhibited in the "instructional" (ouch!) video [see link in lamer's post of Mar06/11:49, currently Page 18 #345], is even worse than what I often observed from the detached point of view of the jump seat in about 12 years as a specialist line-checker on the A320 family.

Full stick one way followed by the exact opposite a split-second later, such as in the video, could be most kindly described as nervous "occupational therapy", in my opinion, whether the air is rough or smooth.
LET THE DUTY ELAC/SEC DO THE WORK...

Last month, there was a good discussion on this Forum; "Fly by Wire questio0n" (sic):
http://www.pprune.org/forums/showthread.php?t=313926
This was my two-pence-worth on how to use the sidestick, for the uninitiated (and the habitual "stirrers") := , slightly clarified:

Re the sidestick, it's worth mentioning that there is a special armrest, adjustable in height and rake, for each pilot. The idea is to rest the flat of your forearm on it, wrist slightly raised. You do not actually touch the stick until you need to make an input.

For simple roll-rate demands, you can use your thumb for one way, and 1 - 3 fingers for the other way. For up demands, use your fingers; for down demands, your thumb. To do these different tasks, your wrist will twist to the necessary angle, but will not move up or down, or significantly sideways. Inputs are normally the most successful when small, short-duration, and frequent. The obvious exceptions are rotation on take-off, and a simple roll from one side to the other. ***

The stick can be moved in any direction, of course. ...the stick does take account of your hand's hook-action being stronger than its "slice". Although the pitch and roll-rate resistances are well harmonised, combinations of the two are the easiest to get wrong. The sticks do not move to reflect autopilot inputs. Normally the signal to the EFCS is the algebraic sum of the 2 sticks. But if one pilot wants to take control, he/she can press a red button on the stick (eliciting a 'gringo' announcement and warning lights). The red button is also used for AP disconnect.


*** [EDITING CLARIFICATION]

Pitch inputs are also best small, short-term, and often; except (1) rotation; (2) the flare, when countering the progressive forward trimming in land-mode; and (3) in recovery from a dive or steep climb.

[U]CROSSWIND LANDING
In airborne sideslip, (usually delayed until decrab) the sidestick roll-input must be released as soon as the desired bank is achieved. However, the opposite rudder will have the effect of lifting the lowered wing again, so you may need to reapply the roll command intermittently, elsewhere referred to as "bumping". [See Post #449, et al.] Once both main L/Gs have touched down firmly, the stick can be kept slightly displaced in the direction of the sideslip. 5 seconds later, the FBW will revert to roll-direct mode (stick-to-aileron), and continuous into-wind aileron can (and should) be applied - in the conventional manner - until the wing ceases to be vulnerable to side-gust.

CROSSWIND TAKE-OFF
A small amount of into-wind aileron can be selected before starting the T/O run, avoiding "cracking" the spoilers.* During rotation, the upwind wing tends to rise in the conventional manner, and can be countered by retaining into-wind aileron. As the main L/G lifts off, any downwind rudder will be eased off, yawing the aeroplane into wind. This will temporarily assist the aileron. Half a second after lift-off, however, Normal Law in roll is introduced (AND the white cross on the PFDs has disappeared). At that point, any remaining roll input needs to be released.
5 seconds after main L/G lift-off, Normal Law also becomes fully effective in pitch. Stick-to-elevator control is now removed, and pitch-attitude can be refined by small nudges of sidestick.

* Roll-spoiler deployment can be avoided by placing the PFD white-cross so that its inner edge is not noticeably to the side of the centre spot.

[DozyWannabe]

Lemurian:
Easier to criticise out of spite, prejudice, ignorance...

To be fair, in the early days Ziegler and Airbus did kind of set themselves up for that kind of backlash. Pilots tending to be a proud bunch, if you build an aircraft that you claim your maid could fly then some will definitely get sniffy. If they'd angled the promotion from the outset as "We've built an aircraft that's there to help you do your job to the best of your ability", which is pretty much what they said later, then I wonder if the kneejerk reaction would have been as prevalent. Having studied under one of the professors whose job it was to translate the pilots' requests into software I *know* that they went out of their way to make the A320 and its later sisters as pilot-friendly as possible.

It's a shame that it was so advanced that they didn't have the now ubiquitous car technologies of traction control and the like to compare it to at the time, because while not 100% accurate it is the best analogy I can think of.

[Lemurian]

Chris,
Read your updated post.
I disagree with your editing. It needs to be here.People generally don't bother to go back that far .
As for the video I haven't seen ( I'm only on pge 12) before, I AM APALLED !
That idiot went into the stops, and more than once ! to achieve what ?
Definitely an example of *what certainly not to do*. In fact, I am quite sure that in calm conditions, the airplane would be jerking a bit with no visible results in terms of achieved flight path. Talking about PIO would be charitable.
As for the flying technique, I've striven to reach that level of de-contraction for years. I do most of the time...most of the time...

Cheers

[Lemurian]

DozyWannabe,
Historically, theZiegler quote is not the one that antagonised the French pilot population but this one :
"airline pilots ? Are they anything more than taxi drivers ?"
That in response, IIRC to a query by the SNPL (main Union) -would you believe - about moving throttles.
Then it became quite ugly.

[Lemurian]

As a conclusion to what we've been talking about for quite some time, I'd submit this paper by Capt John Bent, ex Cathay Pacific Training Manager.
It was written in 1994 when CPA received the new Airbuses, after a long experience with Boeing and Lockheed products. At CPA, they sensed that the whole training philosophy had to be re-thought and this is what he wrote for a CRM symposium :
Training for New Technology (http://www.crm-devel.org/resources/paper/bent.htm)
It is about training philosophy, new concepts and flight safety, mainly.
John Bent later set-up with a colleague two TRTOs in order to cope with the need of new pilots for China and was involved (still is ?) with the GEcat school in Hong Kong.
If anyone could be credible on the subject, he certainly is one of them. (Chris, need your input soon on the subject, too)

[DozyWannabe]

Lemurian - probably so. I've never heard that one myself - but the whole attitude seemed counter-productive to me, admittedly looking at it with 20-20 hindsight nearly 10 years after the fact (which was when I was at University studying Software Engineering).

But we live and learn - it's just a shame that all this negativity had a chance to take hold in the interim.

[CONF iture]

Chris, if I can add some precision to your post 229 (http://www.pprune.org/forums/showpost.php?p=3956007&postcount=229)

Stick-to-elevator control does not trigger the Sidestick Position Indicator (white cross) which is only visible on the ground and disappears as soon as the main L/G lifts-off.

Also the different transitions between Normal Law and Direct Law during landing and takeoff phases are more progressive. I would say it is not after 5 seconds but during 5 seconds: “The system blends in ...” in a way that’s almost unnoticeable.

That’s why I pretend Airbus could (and should !) re-introduce the Roll in Direct Law for the flare, and get rid of that undesirable roll rate.
Decrab landing would be ... classic !

The training *makes* it instinctive - it's the whole point of training
I would be interested if PJ2 could publish some figures from the Flight Data Monitoring regarding “Dual input” ... That would not surprise me if “Dual input” warnings largely overshadow “Priority left or right” advisories.

A procedure which request specific training, by definition, is NOT instinctive.

If, during a flare, a sudden situation erupt and PNF, by sauvegarde, intervenes, his probable first action will be, in an instinctive way, to simply move his sidestick. Only if he’s properly trained the next move will be to push the Sidestick Takeover Pushbutton, but as we saw in the video, a lot can happen in one single sec.
Data from HAM would say a lot ... Let’s hope we’ll see them ?

Boeing didn't consider changing their flight control input method for financial, not technical reasons
WHAT !???
Money was the culprit ? ... for BOEING ?
Well ... before taking decisions for the 777 I’ve heard some B guys did properly flight test the FBW 320.
Later, for the 787 conception, Boeing widely surveyed pilots, and had many questions specifically aimed to Airbus pilots ...
... 787 will still fly with old yokes.
If they thought sidestick was the way to go, by now they would have gone for it. With present and future fuel cost I’m afraid 757 67 47 will take a rest sooner than later, FBW 737NNG should follow 787 ...

A crew should not consider landing above any demonstrated value
I can see your point, but my view is that xwind has a lot to see with pilot experience, and therefore should not be restricted in a rigid way. If an airplane, a few feet over runway, in a subtle combination of limited but approved crab + low wing, is able to maintain the center line, then he lands, and if not, he just goes around.

For LH044 Wind readings (http://www.pprune.org/forums/showpost.php?p=3962486&postcount=388) (if information is reliable ...) were in the limits (Gust included)
Even the last windcheck 32G37 was OK for the demonstrated 320 limitation 33G38

There are logical restrictions regarding tailwind.
There are also restrictions regarding xwind for ETOPS alternates (planning purpose)
There are also recommendations regarding xwind on contaminated runways.

[Chris Scott]

By request, I have just expanded post #474 [Yesterday, 20:52] to incorporate the amendments I made yesterday to a much earlier post on sidestick handling. These amendments owe a great deal to the contributions of everyone on this topic. Please do not hesitate to criticise the new content, as you will. It would be good to reach a broad consensus here.

Quote from CONFiture:
(1) Stick-to-elevator control does not trigger the Sidestick Position Indicator (white cross) which is only visible on the ground and disappears as soon as the main L/G lifts-off.
(2) Also the different transitions between Normal Law and Direct Law during landing and takeoff phases are more progressive. I would say it is not after 5 seconds but during 5 seconds: “The system blends in ...” in a way that’s almost unnoticeable.
(3) That’s why I pretend Airbus could (and should !) re-introduce the Roll in Direct Law for the flare, and get rid of that undesirable roll rate.
Decrab landing would be ... classic !
[Unquote]

(1) Thanks for setting me straight. I trust your manuals are fresher than my memory, and have incorporated this information in my EDITED post #474 [yesterday's posting at 20;52], above.

(2) Yes, it cannot be instantaneous.

(3) Can see some theoretical logic in your argument. Would this happen at 50'R, or 30'R, perhaps, or at L/G extension? Whatever value you choose, I would not like to be the first pilot to try this on the line in windshear and a crosswind gusting to limits or beyond.

[Lemurian]

Conf iture :
"Stick-to-elevator control does not trigger the Sidestick Position Indicator (white cross) which is only visible on the ground and disappears as soon as the main L/G lifts-off."
Wrong. On the ground, the displacement of the white cross reflects truthfully the movement of the side-stick, in pitch as well as in roll. Part of the flight control check we perform during taxi-out.

[Chris Scott]

Hi Lemurian,

You and CONFiture are not really in disagreement, methinks. The context of his remark (that you quoted) was that he correctly noticed that I had suggested the presence of the white cross coincides with stick-to-surface control. This, he argues, is not strictly correct; and I am prepared to take his word for it. So I've adjusted the wording of my (Edited) Posts #229 and #474 to reflect this. Perhaps you could confirm from your up-to-date FCOM?

In haste,

Chris

[Milan N]

http://cdn-www.airliners.net/aviation-photos/small/4/6/4/1344464.jpg (http://www.airliners.net/open.file/1344464/M/)

[Interflug]

http://www.bfu-web.de/nn_41542/DE/Publikationen/Bulletins/2008/Bulletin2008-03,templateId=raw,property=publicationFile.pdf/Bulletin2008-03.pdf

Only in German so far, but some interesting graphs of the stick inputs and resulting roll in the addendum.

They were using both sticks before touchdown simultaneously. He was countering her, whenever she rolled the plane to the left.

Seconds before touchdown she commanded roll to the left, left spoiler was deployed, then she also kicked in the rudder fully to the left...

Also noteworthy: Lufthansa's internal recommended A320 max. crosswind component for manual landing is 30 kt, 3 kt less than Airbus demonstrated max. for a not contaminated runway...

The actual wind (2min. average) at the time of incident was 33 kt from 300.

[Alien117]

F4F, I'm not a pilot, but judging from videos like this one:

http://www.flightlevel350.com/Aircraft_Various_Aircraft-Airline_Various_Airlines_Aviation_Video-9689.html

what you say in post #21

Flying in blustery weather the bus is a scary beast, either you let itself to sort it out (good luck!) or you try and give some correcting inputs. Then, depending on the concerted decision of at least 3 computers you might get some form of control from your sidestick inputs... or not :ouch:

Thanks Airbus, you really gave us a fantastic machine :cool: doesn't seem entirely correct.

[cb6]

Google leaves me thinking the official report into this hasn't yet been produced, is that right?

[Denti]

Incident/accident reports are published from the BFU, you can find their webpage at BFU Bundesstelle für Flugunfalluntersuchung BFU - Homepage (http://www.bfu-web.de), you can switch to english there, click on publications, incident reports and you'll get a list of published reports. However the report to that incident is apparently not published yet.

It seems further that not all reports are published in english, probably only those where one participant of the incident is not german.

[Baron737]

There is no final report on this incident, because Airbus still can´t answer the question,
why the ailerons didn´t react to both pilots full right input. (check the graph of the BFU
report at 12:33:35)

Maybe the computer was ´stuck´ in the transition between flare mode and direct law.

[Baron737]

Yokes are old. They are on their way out. Yesterday's technology. Get used to it.You just don´t get the point. It´s not the question of yoke or joystick, it´s just what there is behind. You could build a feedback-sidestick and direct law behind. And you can build a non-feedback sidestick with 4 different laws behind (with no indication of change)
Get used to it ? Why ? Because of AI ? As far as i know there are more than one hundred airplane manufacturer, which do it another way. Perhaps they know why :).

[CONF iture]

Baron737,

I agree with you on your last post.
For the C serie, Bombardier is going for the sidestick but I don't know which philosophy they will apply to it ... ?
Hope they won't repeat the Airbus mistake.

I disagree on your previous post :
why the ailerons didn´t react to both pilots full right input. (check the graph of the BFU report at 12:33:35)
Ailerons did react but roll rate limitation probably did apply as well.

[Baron737]

Ailerons did react but roll rate limitation probably did apply as well. You are right, the roll rate limitation could have been the cause as well. But the ailerons did not react as the pilots expected them to do. In such a thrilling second you expect full aileron, if you give full input. There is just no time left to think about internal flightcomputer modechanges or envelope protections and how you can counteract them. There was no time for pulling CB´s in Hamburg either :)

[ZAGORFLY]

Looking at the video I had the following comment:

the left wing sink was in my opinion the result of the combination of:
1) strong left rudder application generating a lift wings asymmetry higer on the fasted wing (the right one)
2) the wind shadows area over the Left wing caused by the interference of the Airplane body decreasing lift
3) the cross wind over limit (10 kt?)

in addition ,becasue the control jokes are not mechanically linked I suspect that both pilots were flying the same plane in different way. The controls are electronically algebra corrected by the FBW system . I'm sure that in such extreme condition "dual Imput" is not what keep the plane more stable . But this is my own comment (non pilot) I comment this becausue I do not see any right spoilers command up even in the extreme left bank position.

[CONF iture]

Actually full right input on both sidesticks came up after initial damage was done.
That incident is a consequence of improper applied technique for cross wind, important rudder input but with no aileron to counteract ...
But everybody has to learn at some point.

But mainly, no way for a Pilot Monitoring to monitor what kind of input the Pilot Flying is applying on its sidestick ... and to me it is ridiculous Airbus early on took that turn !?

[Gargleblaster]

As far as i know there are more than one hundred airplane manufacturer, which do it another way. Perhaps they know why...

OK, but probably around 95 of them don't make aircraft that are relvant to the discussion, e.g. the Husky Aviat Aircraft: The Husky A-1C (http://www.aviataircraft.com/husky.html), I doubt there's been many discussions on how the joystick is going to behave (or not) :-)

[Jerry B.]

Below is a rough translation of an article that appeared in today's Der Spiegel online.

Link Landeanflug im Orkan: Ließ Computerproblem Lufthansa-Maschine beinahe verunglücken? - SPIEGEL ONLINE - Nachrichten - Wissenschaft (http://www.spiegel.de/wissenschaft/mensch/0,1518,638211,00.html)

"Did computer problem Lufthansa plane almost crash?

In investigating the near-crash of a Lufthansa Airbus on 1st March 2008 in Hamburg, there is a surprising turn: the air accident investigators examined after SPIEGEL information the dangerous role the flight computer played in the landing during a hurricane.

Hamburg - First, it was assumed that wind alone or carelessness of the A320 pilots were the cause of the scaping of the wingtip on the runway which was captured by a hobby cameraman. "Now the matter is complex," said Johann Reuss, investigators at the Federal Bureau of Aircraft Accident Investigation (BFU) for the MIRROR.

"We obviously investigate the role of the aircraft itself has played." According to hitherto secret investigation, results showed the A320 during the hurricane landing apparently unexpected behavior.

The most likely explanation: Because of a tire briefly touching the ground, the computer shifted from the "landing mode" to the "ground mode". The latter mode limited the deflection of the aileron, much less than the pilots commanded due to the extremly gusty conditions. The computer took over and limited the aileron deflection - and the wing tip made contact with the runway.

"Such a behavior of the machine was not documented in any manual," criticized a pilot to the Spiegel - and it is still not in there, because Airbus keeps things close to their chest until the completion of the investigation. This landing could have ended in a terrible catastrophe.

For almost three seconds the computer stayed in command. Only through the decisive and courageous action by the pilot the plane, traveling at over 200 kilometers per hour, was pulled back into the air and stabilised thus preventing a crash."

Hmm, interesting isn't it?

[Dani]

Well, another Airbus-FBW-conspiracy theory. Of course the aircraft has other characteristics in the ground mode. But if you use the wrong landing technique (and wrong runway), you get at your limits, in any aircraft.

As soon as you apply TOGA, the aircraft knows in which mode it is, problem solved.

Dani

[TvB]

It has nothing to do with "conspiracy", dear Dani and others. It is simple that AI's design philosophy has sometimes a few "hidden" (from the pilot and others) features incorporated that make sense under normal operation, but may lead into problems in others.

The remarkable thing is that AI keeps these things as a secret to pilots. I always recall a senior member of the management, telling me in regards to their reduced V1 calculation: "We (AI) did not make any publicity about this fact as we are safety minded and we would like the pilots to ignore that they have a more safety margin."

Well, keep the pilots in the dark is not a good idea, as this case proves again.


So in regards to design of flight controls and protection features I prefer the conventional approach, where I am and I stay in command and the aircraft doesn't "think" for itself. Aircrafts and specially the ones from AI are not so very good thinkers and what is even more a problem: those who designed certain features do not see the entire picture of the operation under sometimes very special conditions (gusts and x -wind just being one). It is not okay, and has never been, when I as PiC have to start thinking in such a special situation how I could get around the computers. There is no time for that, specially not in turbulence or x-wind conditions with gusts.

So I wonder if AI birds now will get a more stringent gust and x-wind limitation. Probably not, and as usual they may shift the responsibility to the pilots...

[CaptainProp]

Well spoken Dani.

5 years of flying airbus and never had any system "hick-ups". Whenever I, or my colleagues at the time, had some problems I always found out in the end that the problem was myself and my inability to program the FMS, manage the FCU etc etc.

Looks to me that the almighty LH pilots/flt department are having some responsibility issues here and are desperately reaching for something to blame....

CP

[falconer1]

WOW circuits can aggravate tight situations very close to the ground in 50+ KTS gusting winds...

"Such a behavior of the machine was not documented in any manual," criticized a pilot to the Spiegel - and it is still not in there, because Airbus keeps things close to their chest until the completion of the investigation. This landing could have ended in a terrible catastrophe.

how about hurricane mods in all new aircraft??????

hope that pilot who gave that interview with "Der Spiegel" is not entrusted in a command position to fly SLFs...

can it get more ridiculous than that????

[CaptainProp]

TvB - I respect your opinion and you preferring "the conventional approach". Having said that, all systems and how they operate are explained in great detail in the FCOM. Problem is, not saying that this applies to you in person, that a lot of pilots are simply too lazy to really dig in to the manuals and really, I mean really, learning how the systems work... I don't know how many times I have heard from colleagues that "ah, that's not something that's important to fly the airplane, just a bunch of engineering BS".

CP

[CaptainProp]

falconer1 - could not agree more.

CP

[Dani]

isn't it amazing that it's always the non-pilots and non-Airbus-pilots blame the craft? Is there an actual rated Airbus pilot out there who has similar allegiations against the system?

Except the LH captain in the incident maybe...

[Cacophonix]

One has to ask how many Airbus aircraft of this type, using this system have landed at, near or over their cross wind limits. Out of these landings how many resulted in one of the following outcomes: had an incident, crashed, landed safely.

I suspect you will find that the negative outcomes constitute an extremely small percentage of the total possible outcomes.

It appears that this landing attempt was made in unfavourable crosswind conditons in an unfavourable runway direction. What is more likey to have caused this incident, some unique Airbus flaw or the other factors pertaining on that day?

Occam might be a good guide here.

[bsieker]

It has nothing to do with "conspiracy"

[...] where I am and I stay in command and the aircraft doesn't "think" for itself.

Saying that the aircraft "thinks for itself" is the conspiracy theory.

It doesn't.

Let's looks at some stuff in the FCOM: 3 seconds after main gear touchdown the control configuration in Normal Law blends into ground mode, which is a direct stick-to-surface relation. (Flare mode is standard roll-rate demand.)

So, if anything, during the period in which the Spiegel says "the computer was in command", the pilots were actually in more direct control than before, directly commanding aileron/roll spoiler surface deflection.

I have also looked through the FDR graphs from the prelim report (it is very well hidden on the BFU website, in one of the bulletins: not even its search function turns it up, but google is your friend) and there are only two transient transitions to ground mode, during which aileron deflection does not reduce.

[20milesout]

Final report (English) (http://www.bfu-web.de/cln_005/nn_223936/EN/Publications/Investigation_20Report/2008/Report__08__5X003__A320__Hamburg-Crosswindlanding,templateId=raw,property=publicationFile.pdf/Report_08_5X003_A320_Hamburg-Crosswindlanding.pdf)

Abschlussbericht der BFU (http://www.bfu-web.de/cln_005/nn_223936/DE/Publikationen/Untersuchungsberichte/2008/Bericht__08__5X003__A320__Hamburg-Seitenwindlandung,templateId=raw,property=publicationFile.pd f/Bericht_08_5X003_A320_Hamburg-Seitenwindlandung.pdf) (Deutsch)

[XPMorten]

Right, no gust, it was yaw induced roll - as expected :ok:

XPM

[Starbear]

20milesout: Thanks for posting the links, a very interesting report.

I am always amazed at what we each seem to take from such reports. XP Morten says for example:
Right, no gust, it was yaw induced roll - as expectedWhereas I got: Flight to Ground Law changes with just one gear on ground; Ground Law limits surface deflection by about 50%; Crosswind limits imprecise; Contradictions in both Airbus manuals and also Company manuals; Airbus write a more precise technique for strong crosswind and much much more

It is probably correct that the approach should have been discontinued earlier (but not mandatory) but that aside this low exeperinced but able young co-pilot did a very good job but used a technique (published) which guaranteed a drift downwind and when it went awry there was insuficient aerodynamic control via ailerons/spoilers (and rudder) to correct the situation quickly.

I hope this post is elevated back to the main rumour/news page as its worthy of a read by all Airbus pilots, especially trainers.

SB

[XPMorten]

Whereas I got: Flight to Ground Law changes with just one gear on ground;

:rolleyes: Yaw Induced Roll got them INTO the situation;

"Rudder inputs were in the case at hand of importance because the aircraft manufacturer had determined
during their analysis that the rudder inputs had been too fierce and abrupt."

"The aircraft yawed towards the left, thereby increasing the lift from the right wing and decreasing that
from the left wing. In spite of the co-pilot's right sidestick correction, this resulted in unintended contact
between the downwind main landing gear and the runway."

"After touchdown the aircraft yawed a further 5° to the left."

"It is in the opinion of the aircraft manufacturer, that contact between the left wingtip and runway could
have been avoided if there had been an earlier, coordinated sidestick roll input, combined with less left
rudder deflection"

In other words, Airbus says the pilots created a yaw induced roll by
applying too much rudder and too little aileron BEFORE touchdown
(which will give you a Yaw Induced Roll)

The flightlaw change prevented them from getting OUT of the situation sooner,
but it was not the cause of the incident.

The BETA angle was much higher than it should have been
after touchdown which requires ALOT of rollpower.

XPM

[tildeleb]

Many thanks to 20milesout for posting this. I've been waiting for the final on LH44.

Starbear: I too am amazed at the different take aways from the report.

Section 2.1.1 of the BFU Final Report"The exemplary account of the aircraft manufacturer that, if the co-pilot's sidestick input had been delayed by 1.5 seconds the result would have been a maximum of 10 deg left wing down -- and would thus have avoided wingtip contact with the ground -- is theoretically understandable. However from a practical point of view of a pilot, this assessment can be queried [questioned]. With the aircraft under manual control, a time period of 1.5 seconds would have been difficult to coordinate precisely. Further it should be noted that in this specific case a reduction of the wind-down angle to a maximum of 10 deg would have prevented wingtip contact with the ground but also that pilots are enjoined to avoid unintended changes in the attitude just prior to touchdown."

From the OM/B and 1.18.2.2 of the BFU Final Report
"In strong crosswind conditions, small amounts of lateral control may be used to maintain the wings level. This lateral stick input must be reduced to zero at first main landing gear touchdown. Even during an approach of considerable turbulence, the control system resists the disturbances quite well without pilot inputs. In fact, the pilot should try to limit his control inputs to those necessary to correct he flight trajectory path and leave the task of countering air disturbances to the flight control system."

From 2.2.1 of the BFU Final Report
"Up until 20 ft above ground the approach was stabil[e] and exhibited aeronautically no reason for a go-around procedure."


From 2.2.3.1 of the BFU Final Report
"The BFU is of the opinion that, the captain as pilot-in-command did not reach his decision [about landing] using thus reasoning, because he did not regard the value maximum crosswind demonstrated for landing as an operational limit for the aircraft."
...
"Given this unusual weather situation, there was no company operational management support for the crew in their decision taking [making] process prior to or during the flight"

"Recommendation 01/2010 of the BFU Report
The aircraft manufacturer should initiate an assessment for the Aircraft Type A320 and Series with the aim that the transition logic Flight Mode/Ground Mode of the lateral control system switches into Ground Mode only if the aircraft is indeed on the ground." ...

My takeaways:

1. Given the wind conditions it isn't clear that anyone should have been taking off or landing that day. A 50% GA rate over the last 10 minutes is very high. If you are going to try to land in a 30 kt crosswind with gusts of 45-55 kt, you are hoping you don't get a black swan. LH management and Hamburg airport management let planes take off and land in conditions which were highly questionable.

There is kind a peer pressure situation where it is hard for a captain to say we are not going to fly when everyone else is. This is why the company needs to step in. The basic approach (no pun intended) seems to be lets fly to the destination, try for landing, and see how it goes.

2. This was complex worst case scenario, that happens only when there are hurricanes or other severe weather depressions present in the area. Wind gusts this high happen only 7 times/yr at this airport on average. In addition the specific wind gusts for this landing were worst case.

3. Airbus had to work very hard to find a way that the landing could be accomplished. Even though they found it, it is completely unclear to me that most pilots could fly it without practicing it first. Airbus doesn't want to have to make another update to 20 years old FCS for the A320 series.

4. If the FCS hadn't transitioned into Ground Law on a 1 wheel touchdown, the max right sidestick inputs that both pilots gave probably would have prevented a wingtip touchdown. In my opinion a fix is called for.

5. Documentation issues with the FM with respect to limits for cross wind landing limits and use of sidestick when landing.

On a personal note. In my opinion I believe the young FO did a great job, given her training and experience level. I believe she was criticized in the German press and the Captain was praised as a hero, which I think was very unfortunate. The Captain made the final decision to land, picked the runway, and declined runway 33, not the FO. I look forward to shaking her hand some day.

Questions:

A. How come the approximately 10 kt gust between just before wing touch which is clearly visible in diag 16 page 41/46 (the vector just before the red box for "wing touch") wasn't mentioned in the report? Didn't this contribute to the roll and wing touch?

B. I would love to know if this approach will be added to the simulator training for all LH/A320 pilots?

C. I would have liked to seen a CVR transcript?

FYI I am not a pilot but I am an engineer.

[rak64]

1 remark,

usually gusts are in additions to the regular wind, because of its convectional nature.
But in heavy wind condition is normaly no convection available, because the energy getting distributed.
In fact that means wind a number and gusts are negative, pehaps wind 60 knots in gusts 40 knots.
I wasw flying that night, i did a go around a uneventfull landing, than i was watching closly the wind indications.
That was what i discovered.

[tildeleb]

But in heavy wind condition is normaly no convection available, because the energy getting distributed. In fact that means wind a number and gusts are negative, pehaps wind 60 knots in gusts 40 knots.

It's an interesting comment and I appreciate it. A negative gust can really have the same effect as a positive one, there is really no difference. Thanks.

[Meikleour]

Whilst all the issues about control laws etc. have been most interesting - after my 39 years in the airline business why has not more been made of the human factors issues with this incident?

Clearly the captain has at all times a `duty of care` to the passengers which requires a matching of the best skills available on the flight-deck to handling of the more critical situations. Thus, given the experience disparity within the crew, why did the captain even think it was a good idea to have the F/O flying what was obviously a very critical approach. Leave aside company policies of encouraging skill development for F/O `s this has to be seen as a severe lapse in judgement or at worst an overconfident belief in his personal skill to `retrieve` situations?

My second concern was why did the crew not consider the more into wind non-precision runway from the outset? I believe the weather allowed successful approaches to both runways. This is especially relevant given that any gusts would have veered and increased the crosswind component on the ILS runway. Was this point really not considered by the captain?

All in all, to be discussing obscure aspects of the control laws when the incident could so easily have been avoided by the application of common airmanship is premature.

[A-3TWENTY]

Actually , there are two discrepancies in the airbus manuals , and one of them was never mencioned in the final report.

In the FCOM 3.01 -Limitations , it states that the max.demonstrated xwind is 38Kts. Gusts included. This is the value mentioned in the report.

But ..... I f you go to FCOM 2.04.10.Pag11 it says that thE max. x wind component for landing is 33 kts for landing in dry ,damp or wet rwy and also says that Airbus does not recommend to take off or land above this limits.

Some of you will say that this is in the contaminated runway chapter , but since I don`t know a dry contaminated rwy or a wet(less than 3mm) contaminated runway , this is a limit for me.

One other point is:

When Airbus states "max demonstrated" ,they don`t explain why it was the max. value.
Maybe it could be because either they never found an xwind higher than 38 kts, or the test pilot tought wouldn`t be safe beyond that value,or,or, etc. I don`t know and they don`t tell me.

So , my questios is:

Should I make experiences with an airplane full os passengers without the expertise of a test pilot ?
Should I push up an airplane full of pax to the unknown? I think that , as a Captain , I am just a Captain , (not a test pilot), our pax are not test paxs and my work is to take them A to B as safe as posible.

I also think that the companies should state clear limits ,since airbus don`t.

My company has no limits as well , so my limits are the ones in the FCOM 2.04.10 Pag11

A-3TWENTY

[Starbear]

Actually , there are two discrepancies in the airbus manuals , and one of them was never mencioned in the final report.

In the FCOM 3.01 -Limitations , it states that the max.demonstrated xwind is 38Kts. Gusts included. This is the value mentioned in the report.I think you will find that this is an amendment, subsequent to and almost certainly because of the Hamburg incident, which occurred two years ago when the other figures applied.

[alf5071h]

Re #509, I would agree that HF is not the main theme of the report, but re-reading it, there is a reasonable balance between the ‘technical’ and human issues. Perhaps the BFU sensed (correctly) that HF dominant reports don’t get much action, particularly in EASA.

The technical issues are relatively insignificant – they represent ‘how the aircraft is’ and that pilots are expected to have the necessary skills to fly it. How and where they get these skills is another issue.
The comments on manufacturer’s manuals may be pedantic; manuals can always be criticized as they represent an author’s viewpoint at the time of writing and may only consider the foreseeable circumstances.
If an item is not in the AFM limitations section then it is not a limit, only advice, but by using the FCOM in lieu of an AFM (EU-OPS) the point is overlooked, – a problem of regulation.

Many aspects of piloting skill have to be assumed, thus they are open to interpretation, judgement, etc; even after a successful check we can still have a bad day. Unfortunately, in the current litigious climate, making assumptions is increasingly unacceptable and most issues to be written down as SOPs etc.

In general, the report avoids judging the Captain’s decision. We must beware of hindsight, there’s often a better way to do something when all of the ‘facts’ are known.
Decisions taken at the time are ‘correct’; they are made on the information available. Errors can only be allocated after the event – the outcome was not as expected. The pilot’s task is to avoid an unexpected outcome by thinking ahead.
In this incident the decison outcome may have resulted from either a poor situation assessment or the choice of inappropriate action, most of which is driven by the depth of knowledge and controlled thinking – the use of knowledge.
The report discusses ‘thinking’ (decision making) and judges the processes as adequate in circumstances. The weakness appears to be in the information which supported the situational assessment, both the physical situation and the background knowledge.

A major problem for the industry is that crosswind operations are poorly defined.
The discussion on maximum demonstrated crosswind (MDCw) perhaps misses some points.
The method of wind measurement for the tests may not be the same as for operations, although in this instance there were. However, when using ATC averaged wind data (over the preceding 2 min and ‘gusts’ recorded as a maximum value in the preceding 10 min), the MDCw value could actually be achieved in relatively benign conditions yet reported as more severe. Landings in each direction and multiple landings should reduce the error.

Also in operations, the reported wind may not represent the actual conditions (most times). Furthermore, gusts are not predictable so perhaps pilots need to allow for this; but the regulations don’t provide any margin.
Thus, perhaps the operator’s limit should include gusts and have a margin for reporting error (10%); so a 38 kt MDCw would be a 34 kt operating limit including gusts.
The incident crew appears to have lacked guidance in these issues, and particularly having made a well considered judgement, the attempted landing was justified.

Whether the First Officer or the Captain should have flown the landing is debatable.
With hindsight (the report), if the Captain has more experience in the conditions and in the aircraft then the safest option would be with him, but then how do FOs ever gain experience.
It could be feasible that a new Captain had never experienced high crosswinds, thus this Captain has to ‘learn’ during the first crosswind encounter – the same situation that the FO was in, but in this instance with overseeing support.
This point is similar to the problems arising from assumptions about skill and piloting capability, and may also argue for a safety margin in the crosswind limit.
Perhaps a lower crosswind limit would have triggered the Captain to consider the other runway, but then if there was a similar result, hindsight bias could have criticized poor CRM, lack of ALAR awareness, choice of NPA, etc.
No plan (or decision) survives contact with the enemy.

The manufacturer can always be cited for mis-judging the ‘average skill’ requirements when certificating crosswind operations.
How is average skill defined? CS 25 defines aircraft design standards, where (how) are the equivalent human standards defined. There is little or no harmonization in worldwide skills training or even in daily operation – we do have bad days; and then we probably all judge ourselves as above average.

I agree that airmanship is critical in these situations, but my definition of airmanship includes knowledge, which in this instance requires understanding of how MDCw is obtained, the lack of margin in MDCw values, the meteorological variability of wind / gusts, and the range of error in reporting wind speed and direction. If it is unrealistic to expect retention / recall of this knowledge then the crew need a safety margin, either self applied or a hard limit. The latter is more practical.

Perhaps this incident is a reflection of the modern industry with increasing litigious and commercially pressurized operations. The more we are driven by these aspects, the more difficult it becomes to provide an equivalent level of safety and to use beneficial human attributes.
As current operations increasingly require airmanship intervention, the more difficult it becomes to gain and apply airmanship due to so-called safety interventions and regulations.
Does our future lay with an automaton, constrained by ‘impossible’ laws and inadequate SOPs, striving to prevent reoccurrence of a minor scrape; or are we to maximize our use of human flexibility and adaptability, both for safety (avoiding the big dings) and maintaining commercial advantage?
I suspect that reality is somewhere in between, but who defines the compromise?