Go Back  PPRuNe Forums > Flight Deck Forums > Tech Log
Reload this Page >

AF447 wreckage found

Tech Log The very best in practical technical discussion on the web

AF447 wreckage found

Old 1st Jun 2011, 08:36
  #1221 (permalink)  
 
Join Date: Sep 2009
Location: Europe
Age: 75
Posts: 48
HundredPercentPlease wrote:
"I too shall declare my interest: A320 Captain.

I really don't know where to start with this thread. So much noise, so little signal. The number of red herrings and long irrelevant side tracks is so great that no one can even start to address them.

The PF quickly and correctly diagnosed the situation. Loss of airspeed indication, resulting in AP/AT off and Alternate Law. He then incorrectly pitched up to 10 until the AoA was just 2 from the stall.

In this perilous position, the AoA increased again to 6 and the aircraft stalled. The response was incorrect with TOGA + pitch up.

So, two apparent errors. So much has been said about the wrong procedure being used (TOGA + pitch up is used in many other procedures) and a lack of training that I won't bother. But here is something frightening:

Most older Airbus pilots have done their time in cranky old jets and turboprops, where you fly by pitch. Everything is done by pitch settings - choosing, setting, adjusting, waiting and so on. However, in the world of the safety committee it is fine to pluck young lads straight from a Seneca and place them into an Airbus. To mitigate the risk, the flight director must be on at all times. Now all the cadet has to do is put the square in the centre of the cross. Never has a pitch been noticed nor noted.

I asked 5 first officers in the cruise to look me in the eye and tell me what pitch we were at (2.5). 4 cadets answered between 5 and 10 , and one ex TP guy answered correctly at 3. Not much of a sample, but indicative I suspect.

The Airbus is a fine aircraft. It is conventional, and simple. On top is a thick layer of cotton wool, that should protect us from our silly mistakes.

Once the cotton wool is removed, we are back into a simple jet. The snag is that with the current drive to train/recruit people as quickly and cheaply as possible, not one of the recent arrivals has ever flown in "simple jet mode" (by pitch and thrust). Incredibly in our airline it is now even prohibited to take off with the flight directors off.

I feel sorry for the two FOs on the flight deck. Without the FD they will have been in new territory. Without the airspeed, it is no time to have to guess pitch settings and develop a strategy to keep the thing in the air.

I hope the airlines have a good think about this. I imagine the safety departments will, but nothing will happen due to the cost of recruiting people with experience on conventional types.

PS: Below 60 knots I imagine the stall warning is inhibited because there is not enough airflow over the AoA vane to make it accurate and trustworthy.

PPS: Has any Airbus pilot here ever actually heard the stall warning in the sim? "

My interest: 36 years flying militarily and commercially, 90 aircraft types as PIC, expertise in flight instruction, experimental flight test and more. Management degree in air transportation.
You are essentially right on the money! I do however think that the layer of cotton shouldn't be there at all, assuming the pilot in command is qualified, by my standards. FD is an aid only at pilot discretion, pencil pushers should be kept out of such decisions. From what I read here and other threads, and my study of NTSB accident reports, it is risky to fly as passenger nowadays, without a solution in the horizon. Until people like us both with our qualifications make the call on how to run an airline.
opherben is offline  
Old 1st Jun 2011, 09:09
  #1222 (permalink)  
 
Join Date: Aug 2009
Location: Germany
Age: 63
Posts: 1,809
Cool

Hi,

In most of the reports of accidents involving Airbus aircraft there is a constant:
Whenever it appears that some actions of either system (resulting themselves by actions of the pilot) have not been seen or understood by the pilot
It also appears that some informations (which could be very useful to the pilot) concerning malfunctioning or status of certain commands or automation are not show evidently to the pilot
This does not mean that Airbus is not a good aircraft (other reports about other planes were also reveals flaws) .. but he is cautious about this to become a constant
jcjeant is offline  
Old 1st Jun 2011, 09:20
  #1223 (permalink)  
 
Join Date: Aug 2005
Location: Cloudbase
Posts: 149
TheShadow

from what I can judge, you seem to have a fairly consistent story there.
If, and it's of course all still speculation, but if you're right, then there's a number of things to be addressed in the aftermath.

It seems that automation, albeit no doubt helpful and safe in most cases, was a factor here, or rather: the way the automation behaves when pushed outside the anticipated envelope (Stall warning silenced / reappearing)

Another factor is the question what parameters are available to the pilots in those extreme situations. I wonder what the rationale is not to have an AoA display, even in situations when the AoA is clearly way out of the normal. (btw, how many AoA vanes are there on a 330? I know I've seen three on Boeing types)

Training of extreme situations is yet another area that will have to be revisited. Have airlines become overly confident that automation will keep the plane inside it's operatinal envelope at all times? After all, the most important function of the guys and gals up front is to save the day in the (unlikely) event of the automation "losing situational awareness" and handing the whole mess over to the humans.

Lastly, I still think that Airbus might have gone too far in removing tactile clues such as coupled movement of the side sticks (how does the PNF know what the PF is doing on the stick in extreme situations like this?) and, albeit not relevant in this case, tactile feedback on the thrust levers. Eyes and ears are limited bandwidth channels and to forego the additional, very direct, tactile channel does seem to be a less than smart engineering decision.

[edit]
so I just found that the A330 has three AoA vanes just as any other self respecting jet. Makes me wonder even more why it's not displayed everywhere since traditional logic would say "one for the CPT, one for the FO and one for the backup instruments". Oh well.
SoaringTheSkies is offline  
Old 1st Jun 2011, 09:35
  #1224 (permalink)  
 
Join Date: Apr 2008
Location: Paris
Age: 70
Posts: 275
Corporate myopia

Everyone here agrees the pitots were flawed.
Everyone agrees AF process was flawed in not enforcing substitution.
Everyone here agrees the Airbus automation is flawed in the way it handles bad sensor input.
No one here will admit that the pilot training may be deficient too.

Corporate myopia?
edmundronald is offline  
Old 1st Jun 2011, 09:41
  #1225 (permalink)  
 
Join Date: Aug 2005
Location: Cloudbase
Posts: 149
edmundronald

I beg to differ. Every single one of the statements you made there seems wrong.

Last edited by SoaringTheSkies; 1st Jun 2011 at 09:42. Reason: missed name
SoaringTheSkies is offline  
Old 1st Jun 2011, 09:48
  #1226 (permalink)  
 
Join Date: Jun 2009
Location: Bangkok,Thailand
Posts: 106
Aviate, navigate, communicate. They hadn't got past the first which is why you see no discussion of the third.
Mountain Bear,

Thanks...makes sense.
Razoray is offline  
Old 1st Jun 2011, 09:53
  #1227 (permalink)  
 
Join Date: Apr 2005
Location: Australia
Posts: 1,414
FD is an aid only at pilot discretion,
Agree. But I would guess that 99 percent of airline pilots - especially cadets - are lost without the crutch of a flight director. The training departments (simulator instructors) are at fault because they fail to understand that pilots should be taught that stick and rudder stills are the most important priorities in a pilot and the automatic goodies need to seen as aids - not the be all and end all of flying. As a simulator instructor I cannot ignore what I see and that is if the FD is deliberately switched off as part of hands on training, the usual result is significant out of tolerance instrument flying by the pilot.
A37575 is offline  
Old 1st Jun 2011, 10:57
  #1228 (permalink)  
 
Join Date: Mar 2001
Location: us
Posts: 694
Delta T, the Lufthansa at 350 that preceded AF447 by 20 minutes on UN873 deviated 10 NM to the west. The Iberia following AF447 by 12 minutes was at 370 and deviated by 30 NM to the east. AF459 (an A330-203) following the Iberia by 25 minutes deviated first by 20 NM to the west, and then 70 to 80 NM to the east of the track, and was given permission to climb to 370. Neither the Lufthansa or Iberia deviations would have significantly affected fuel consumption.

AF459 at the time of its deviation would have been unaware that various centers were trying to contact AF447. (DAKAR contacted AF459 at 0411 asking it to try and contact AF447.)
SaturnV is offline  
Old 1st Jun 2011, 11:02
  #1229 (permalink)  
 
Join Date: Aug 2007
Location: inmysuitcase
Posts: 199
for opherben!
testpanel is offline  
Old 1st Jun 2011, 11:43
  #1230 (permalink)  
 
Join Date: Jun 2009
Location: Bangkok,Thailand
Posts: 106
From what I read here and other threads, and my study of NTSB accident reports, it is risky to fly as passenger nowadays, without a solution in the horizon. Until people like us both with our qualifications make the call on how to run an airline.
Statistically speaking it is no more risky to fly nowadays as it was 20 yrs ago. In fact it is probably safer now.

Having said that....
I agree 100% that people with your experience, should be a voice in the aviation industry. The issue I see is a over-reliance on the "cotton". Automation and pilots must find the "comfortable" interface that advance the industry to even higher safety records. If you and your colleagues can help....than you should.
Razoray is offline  
Old 1st Jun 2011, 11:54
  #1231 (permalink)  
 
Join Date: Mar 2002
Location: Seat 0A
Posts: 7,983
Originally Posted by Edmund
No one here will admit that the pilot training may be deficient too.
If you read the post directly above yours, you will find:

Training of extreme situations is yet another area that will have to be revisited.
And there are plenty of other negative comments about training through this or the other thread IIRC.
Capn Bloggs is offline  
Old 1st Jun 2011, 12:06
  #1232 (permalink)  
 
Join Date: Jan 2008
Location: UK
Age: 65
Posts: 294
opherben -- We are getting to the stage where electronic instrumentation and control will be more reliable than humans. We are not there yet...too many things that can go wrong. Mechanicals, electricals, electronics, passengers(!) and GPS which is only available to us at Uncle Sam's pleasure. It will happen in time even if none of us reading this are alive to see it happen. So might we not expect this to be introduced by evolution while de-skilling pilots?
Lemain is offline  
Old 1st Jun 2011, 12:15
  #1233 (permalink)  
 
Join Date: Jul 2000
Location: Nirvana..HAHA..just kidding but,if you can tell me where it is!
Posts: 344
Regarding other traffic on the Atlantic that night, I wonder how much useful weather info was being passed on 123.45, by the earlier flights, in order to help fellow crews, on the same route as AF447. Many years of Atlantic crossings taught me that AF and LH seem to be the two airlines hesitant at giving, or receiving such info,or at least, they never replied!!!
We need to look after each other in this industry with all the pitfalls!...Monitoring Data and 121.5 does use up spare radios however!
Yaw String is offline  
Old 1st Jun 2011, 13:00
  #1234 (permalink)  
 
Join Date: May 2010
Location: Germany
Posts: 73
AutoTrim?

Hi there,

german news outlet "Der Spiegel" has an interesting story about a german aerospace engineer (Professor, that is...) who experienced some strange (disturbing) behaviour in the simulator. Read yourself (english version):

Air France*Catastrophe: Victims' Families Propose Grounding All*A330s - SPIEGEL ONLINE - News - International
iwrbf is offline  
Old 1st Jun 2011, 13:00
  #1235 (permalink)  
 
Join Date: Oct 2003
Location: Hampshire, UK
Posts: 207
According to flight global, automatic stab trim should have been inhibited when alpha > 30 degrees - Stalled AF447 did not switch to abnormal attitude law but it was not.

So is this saying that the flight control system continued to do what was asked of it - trim for attitude / 1g and therefore trimmed in the stall - when it should have dropped out?


Edit: Isn't 30 degrees AOA..rather high?
JamesT73J is offline  
Old 1st Jun 2011, 13:24
  #1236 (permalink)  
 
Join Date: Sep 2004
Location: SLF, living somewhere East in the West
Posts: 235
As per the SPIEGEL article the relatives are basically demanding from a french judge to ground all A 330 and 340 worldwide until software issues regarding the trim of the elevator are resolved and to prevent further accidents.

As a SLF I find that somewhat mind boggling. I never had issues flying with the Airbusses but I am getting a bit more skeptical... I would like to know if any of the major carriers (BA, AF, LH, KLM, USAir, UA Delta) are analyzing the issue at hand...?
grimmrad is offline  
Old 1st Jun 2011, 13:44
  #1237 (permalink)  
 
Join Date: May 2009
Location: UK
Age: 37
Posts: 39
AoA at less than 60knots

Guys maybe a stupid question:

How does the computer know that airspeed is less than 60knots so as to sound off the stall alarm if the airspeed is unreliable?

What if the plane is stalled at 80knots airspeed and the airspeed is unreliable 'showing' 50 knots. Will the stall alarm sound off?

AoA sensor is a small flap exposed in the airstream, how does the output of it in the cockpit (stall sound) is conected to an airspeed instrument that can be unreliable?

Can anybody expalin why AoA is not available under 60knots? If for some reason speed (reliable or not) is less than 60knots then there is no AoA input for the computers?

I'm obviously not a pilot, but I haven't understood the AoA unavailability under 60knots.
Dimitris is offline  
Old 1st Jun 2011, 13:59
  #1238 (permalink)  
 
Join Date: Aug 2009
Location: Germany
Age: 63
Posts: 1,809
Cool

Hi,

Can anybody expalin why AoA is not available under 60knots?
Cause Airbus decided it will not be available cause their planes never go (in air) at this slow speed ............
jcjeant is offline  
Old 1st Jun 2011, 14:25
  #1239 (permalink)  
 
Join Date: Oct 2006
Location: Gone Flying...
Age: 59
Posts: 274
I loved your post, "The Shadow". I agree with you.
As I have wrote a number of pages back, there are a number of questions waiting to be answered:

- What kind of information was being "shown" on Pilot Flying's #2 PFD/ND (yes I know it is not registered but, are there any conversation clues(?), other than the ones selected by the BEA to be transcripted to the report). Was he first responding to an overspeed indication,(2h10m16s) and only after he has reached 37500ft, (2h10m51s) he has triggered TO/GA in response to another "Stall, Stall" warning?
- What was the role played by the 13 Trimmable Horizontal Stabilizer (THS) plus the 4.9Ton of fuel stuck on the Trim Tank?
- What was the role of the "systems invalidations" design that below 60kts and 30kts, cancelled the "Stall, Stall" Automatic Call-Out Warning, and may have lead the pilots think they were out of it during precious seconds?
- We know that the Captain was able to reach the cockpit. It seems that by that time the speed read-outs were so low that the Stall Warning was out...but, what was his assumption of what was going on? By then, the aircraft was at about 35000ft, Pitch at about 15 and thrust 100%. Did he tell anything? Did he try to help? Didn't he notice the high pitch? Didn't he notice, the wings bouncing and the PF saying (only a minute after his entrance in the cockpit), that they were reaching FL100?
- Was the PNF so occupied, handling the ECAM, that he didn't notice the vertical speed rate, until FL100 was called off?
Why did BEA apparently decided to disclose, only a part of the information?
aguadalte is offline  
Old 1st Jun 2011, 14:30
  #1240 (permalink)  
 
Join Date: Nov 2006
Location: SoCalif
Posts: 898
Barnyard Logic

Go outside, farmer, and look at the weather vane on your barn. Note, it aligns into the wind because its tail has more area than its point, which is only needed for static nose/tail balance. Note that it also has a lightning rod above it.

Angle of Attack is vertical measure of relative wind. The AOA sensor is just a high priced vertical weathervane, as seen previously on this thread. It's high priced because it has to be reliable in all imaginable weather and flight conditions, including direct lightning strikes or sweeps. It has some inertia and frictional damping to prevent flutter in all possible conditions.

Therefore, just as your barn's weathervane can be erroneious below about 10 knots wind, the AOA sensor cannot be trusted below about 60 knots.

You got a better AOA sensor? If not, why are you criticizing lack of Stall Warning below 60 knots?

If you don't understand this, maybe your time would be better spent shoveling out the barn.
Graybeard is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.