|Steve Hargreaves - Moderator||29/04/2012 17:52:39|
6742 forum posts
Interesting article here about the Air France Airbus crash.....seems like the pilot was holding back stick for ages.....most of the decent of 38,000 feet apparently & the plane simply decended in a very nose high "stalled" attitude.....
|ken anderson.||29/04/2012 18:37:39|
8549 forum posts
programme i saw on the tv...mentioned that the pitot tubes had iced up and that the onboard computers were feeding the crew with rubbish info-which they were trying to interperate and adjust the aircraft etc......then a massive stall which most airline pilots have no training as how to recover from........
ken anderson...ne..1 ..it was on tv/so must be true dept.
|Steve W-O||29/04/2012 19:37:13|
|2775 forum posts|
It seems that it was a maintenance issue, but you still can't help wondering if the indicated airspeed added up with the RPM, or if the altitude change made sense, or the control responsiveness etc etc.
Did they have GPS? So many questions which we will never get answers to.
They are trained to follow procedures, but many times in the past the procedures do not apply to the real situation.
When the engine went on the 380, initial interviews reported that the onboard systems took more than 40 minutes to calculate the landing procedure/distance due to so many errors and checks during the process. This report disappeared later, with the pilots stating all went well with the onboard systems, I doubt if the Air France plane had time for all the input needed to the systems to give a meaningful output..
It is unfortunate that we rarely hear what really happened, either the answer is not known, or they don't want us to know.
|Martin Harris||29/04/2012 20:29:57|
9159 forum posts
All major accidents that are investigated by the CAA AIB have full reports published which are in the public domain although they may take several years to complete and publish. The level of detail they go into is mind boggling but there is always a precis of the findings so I'd find it difficult to agree with your last statement, Steve.
|29 forum posts|
Pilots these days reley too much on computers these days instead of proper flying, basically baby sitting the computers.
|Steve W-O||29/04/2012 20:49:58|
|2775 forum posts|
Yes, sorry I meant that it is not made known in the same way as the original event, rare are the times we read about the findings, the feeling is left that it is often preferred the public not know.
This goes for any kind of accident, and I suppose the reason is really the media, the findings don't sell, but I still get the feeling that the airlines/manufacturers are rather pleased that the causes don't become widely known.
I have read several reports where the cause has not been positively identified, but sometimes shorcomings were found which may have played a part.
|Martin Harris||29/04/2012 21:55:41|
9159 forum posts
I'd certainly agree that the press don't seem to be bothered with reporting the facts of past accidents when there are so many current happenings to speculate and mis-inform readers about!
|Area 51||29/04/2012 21:57:36|
|653 forum posts|
If it isnt Boeing I ain't going......
|Rob Lewis||29/04/2012 22:55:25|
228 forum posts
As a professional pilot myself, i think this statement is a bit harsh. Yes our lives are made easier by the automatics, and they do make flying so much safer. Does this lead to a degradation of hand flying skills, quite probably, but..... A 100T airliner is a bit different to your cessna 150 and so needs to be flown in a different way. We have simulator sessions every 6 months and in my outfit we are allowed to practice hand flying the aircraft to keep skills up. Babysitting the computers is definately not in my job role. Yes the computers are controlling the aircraft 90% of the time but we are telling the computer what to do and watching it like a hawk to make sure its doing what its meant to. Anyway rant over, hard hat on.
My take on the Air France crash from what i've seen / heard.
Whan they flew into the storm the pitot tubes froze, hence the loss of IAS data. The First officer decided to try and climb out of the storm (mistake #1). AFAIK its a known problem with some airbus' with the pitot tubes freezing up but with proper handling it is nothing but an inconvenience.
When the tubes freeze the computers change from Normal Law to Direct Law. Normal Law is when every pilot control input goes to the computers which decide what to do with the control surfaces. With a loss of data (tubes freezing), the computer realises that it cannot perform properly and so the control system reverts to Direct Law. This means that whatever inputs are input by the pilot is what happens to the control surfaces. The tubes subsequently unfroze but i believe that without pilot action the aircraft will continue to use direct law.
I do not fly an Airbus so cannot say for sure, but i would guess that normally pulling the stick back would put the aircraft into a climb with the computer knowing what AOA to aim for to keep the aircraft flying safely. The pilot didn't know / realise that the aircraft was in direct law (mistake #2) and so whan he pulled back on the stick that is exactly what the elevators did.
When they got the stall warning they should have performed a full stall recovery, pointing the nose down applying full power and recovering airspeed. They seem to partially do this but then resume a steep nose up attitude (mistake #3).
Basically they then stalled and lost 38000'.
In my opinion the main reason for the crash, was obviously mishandling by the pilot and not understanding the aircraft systems. But CRM (crew resource management) also plays a big part. This is basically a posh meaning for teamwork and is big in aviation. If the guy with the stick right back had stated this earlier than the whole disaster would have been avoided.
258 forum posts
With the pitot tubes playing such a crucial role in feeding the computers with information, surely they should be heated just as carburettors are on piston engined aircraft?
why is this not the case?
|Rob Lewis||30/04/2012 00:01:19|
228 forum posts
Pitot tubes are indeed heated. I'm not sure on how / why the ones on the airbus can freeze up.
|Josip Vrandecic -Mes||30/04/2012 14:05:32|
2993 forum posts
" The difenders of Airbus put it thus: “When you drive you don’t look at the pedals to judge your speed, you look at the speedometer. It’s the same when flying: you don’t look at the stick, you look at the instruments.There is a problem with that analogy. Drivers is usually the only instrument a motorist needs to monitor. .....etc"
Of course there is a contradiction !.........The human senses will never be replaced by technology............. successfully..... because, a human factor is the weakest link anywhere and anytime.
Steve, thanks for article from "The Telegraph"....reading ,I felt weakness and frustration...but anyway thanks.
Jo. (former member of the Air Force)
Edited By Josip Vrandecic -Mes on 30/04/2012 14:10:47
|Keith Simmons||30/04/2012 14:27:32|
|450 forum posts|
I do not know about Airbus systems, but what I read that the action on the side joystick was not duplicated to the other pilots position. Is the joystick pressure activated with a minimal movement, like a F16? According to the news, Boeing has a different approach which gives the action taken (on the joystick) giving to the other pilot input information, that's how I read it.
I am sad that it happened and hope we can move on with improvements, and a clearer picture of what is going on during the flight and maybe a flight logger giving speed and height via GPS of the last few minutes of the flight shown in the cockpit. (it happened during a storm at night with no outside references) I believe a quick look at that would give vital clues of what's going on. Perhaps that information already exists, I don't know.
|Steve W-O||30/04/2012 14:40:23|
|2775 forum posts|
Not so sure about that.
When I drive, if the speed does not match the position of the accelerator, I need to know why. Hill? Engine losing power? Accelerator stuck? Same as the direction of travel and the position of the wheel, it must match, otherwise sometning unintended is going to happen!
|Area 51||30/04/2012 16:24:21|
|653 forum posts|
The overriding sensation of speed within an aircraft is from the noise, wind noise! Even when a reference is lost with the ground or at night. I find it very odd the report suggests the control column (side stick) was being held back with the a/c at around 60knts.. This suggests chaos in the Flt Deck as one would be aware if the wind noise had decayed from 450knts to 60knts.. in the Flt deck the loudest noise is the wind noise.. I appreciate these gentleman had warning bells/pull up and no external point of reference.
Comments they could also smell St Elmo’s Fire makes me wonder just what any of us would do in such circumstances!
If indeed pitots were frozen as suggested (frozen rail / super cooling due to the storm had taken place) motion across the earth is also judge by satellite comms and this would be shown on the flight guidance systems. A number of backups are the built in redundancy most modern airliners come with.. Check your gps or phone sat nav and it will tell you if you move, even a few feet..! at altitude and speed these numbers (your ground speed and lat long co ords) are moving swiftly!
Flying intuition tells us.. If a stall is suspect, stick forward, speed is your only friend.. Once you have speed and are under control, speed of course is converted to height, your other friend! With both speed and height you have control and are safe..
Given this, some data must have been available to allow confirmation the airliners progress had slowed from 450knts to 60knts.... However in typing this.. I was not there! It is wrong to comment what was going through the minds of the cockpit crew as they fought to identify and overcome these circumstances...
A dear friend is a training Capt on B767/B757 and heavily involved in SIM work, plus he is an inspector of airline instructors for the CAA! Within this training environment, it is suggested the reliance on the Airbus systems has become too heavily dependant and automated, removing the basic instinct (desire?) of a crew to override an issue and return the a/c and flight to safe parameters.. this all said, the stall of the Trident in Staines, albeit at a lower altitude.. was not helped by crew misunderstanding of the information available… that was some years ago…
My friend is at pains to ensure that “systems” are frequently switched off during line flying, training and SIM sessions; returning the a/c and pilot in command to raw data flying…. Chiefly to ensure those who are now growing up within “glass cockpits” era do not respond on day with … “Computer says no!”…..
Human factors….. dodgy things.... Playstation generation with 300,000kgs of a/c ouch.
|Stephen Grigg||01/05/2012 10:42:46|
8691 forum posts
Worrying reading from a potential passengers point of view.The pilots didnt seem to communicate with each other very well,surely instrtuments arent relying on 1 hole that froze up.They didnt know speed or altitude,why not,surely there is back up.
|Piers Bowlan||01/05/2012 22:49:40|
2041 forum posts
There were known 'issues' concerning the pitot tubes performance in severe icing conditions going back to 1990. I believe there had been no less than 13 incidents where they had iced up causing erroneous airspeed information and subsequent loss of auto-pilot and auto-thrust systems as well as spurious stall warnings in nine incidents. An airworthiness directive was eventually issued involving replacement of the pitot tubes with an alternative design, however the ill fated AF447 had not been modified by Air France.
Following this tragic accident Boeing revised their 'stall recovery manoeuvre' and I would guess that Airbus did too.
|Biggles' Elder Brother - Moderator||01/05/2012 23:47:09|
15748 forum posts
Regarding airline and manufacturers' views on wide dissemination of crash investigation findings - remember, this is an industry that in safety briefings still uses the phrase...
"In the event of a landing on water..."
Landing? Who do they think they are kidding?
|Allan Bennett||02/05/2012 08:37:43|
|1603 forum posts|
The Black Box says the pilot held the stick back, but how can you be sure? Perhaps a fault was causing a "full up" signal to be sent from the stick to the elevator (and black box) without the stick having been moved from neutral.
I seem to remember reading in the print edition that the joysticks in Airbus are different from other "traditional" controls in that they only need a brief touch to initiate a command, and they then continue that command while the stick is centered, until an opposite command is given. So, even the pilot who's made the command can't see what it was by looking at the stick, let alone his colleague in the other seat.
|Steve Hargreaves - Moderator||02/05/2012 09:55:29|
6742 forum posts
I think thats the point Allan.....with an Airbus you only need to initiate the control & the stick returns to centre rather than have to hold the stick in position. From what I understand if it had been a "conventional" control column the fact that the PIC was holding it back into his stomach would have aletred the other crew members that maybe the wrong control was being applied in time for them to do something about it.....
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