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AF447 wreckage found

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AF447 wreckage found

Old 2nd Jun 2011, 02:15
  #1281 (permalink)  
 
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You have to balance Stall Warnings in extremely rare events with far more common nuisance stall warnings, in order to maintain confidence in the system.
True. But where that balance point is located is a matter of opinion (i.e, professional judgement). People can and do disagree. We tend to fixate on the needs of the moment and forget there is two sides to the story. Then it just becomes a game of ping-pong where we respond to one crisis by going too far to the left and another crisis by going too far to the right. It seems to me that the better course of action over the long haul is to pick a point of balance, any point, and then train around it.

I'm not sympathetic to the cacophony that wants to tweak software systems in response to every accident. The human being with their hand on the stick has to bear some responsibility, as does the entire safety systems in the corporation. Who trained this crew? Who gave them their line checks? Who oversaw the sim sessions and designed the syllabuses.

Edit:

The aviation industry may have just found their spokesperson. Notice his emphasis on proper training and having AoA displayed . We should all be grateful he landed that plane safely on the Hudson and became a hero. It seems his time has come....
I think his time has been and gone. Everything he says sounds good in theory but he fails to mention the critical factor of money. Sims are not cheap, sim sessions are not cheap, practice lessons in the plane are not cheap. How much money is a society supposed to spend in order to save 200-300 lives. Naturally, if it's your life at stake you want them to spend a lot of money. But when it's the other guy, maybe not so much. Whether it is explicit or implicit there is always a cost/benefit analysis going on. Always.

Last edited by MountainBear; 2nd Jun 2011 at 02:29.
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Old 2nd Jun 2011, 02:16
  #1282 (permalink)  
 
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Gents,
a question - without intending to minimise the difficulty of dealing with a situation like this - espec when the EFIS appears to have been giving very confusing readings, in strong turbulence and a confused flight deck environment - and without intending to insult anyone's intelligence.
Does this model of Airbus have a standby analog artificial horizon on or near the centre of the panel as I have seen in some airliners?
In what would appear to have been a jetupset situation like this, could any experienced airline pilots viewing this thread comment on how feasible it would have been to simply set cruise power and then maintain a wings level, nose level attitude using an analog AH alone?
I know it's aviaition 101 if you go IMC in a light aircraft, but perhaps not in a heavy jet...
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Old 2nd Jun 2011, 02:29
  #1283 (permalink)  
bearfoil
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Artificial Horizon is an available selection, at extra cost, and was not optioned by AF for this a/c, as I understand it. I think it occupies the LHS of panel, top and left in P1's scan.
 
Old 2nd Jun 2011, 03:54
  #1284 (permalink)  
 
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AVIATE

Razoray,

Part of AVIATE means don't fly through CBs when you are close to the "coffin corner". Had they deviated, all this talk of this law and that law and how to handle a stall would not be taking place. That's the real cause of this crash, nothing else. If they were already close to the CC at 35,00 ft, think of what would happen when they went to 38,000 ft.
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Old 2nd Jun 2011, 04:11
  #1285 (permalink)  
 
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Fuel stop

Soaring the Skies,

The embarrassment of making a fuel stop should never get in the way of safety. Divert if necessary then stop somewhere for fuel. That's the Captains prerogative. The Captain is totally responsible for the safety of the aircraft and it's contents. They could have stopped in the Canaries or Lisbon for fuel.
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Old 2nd Jun 2011, 04:11
  #1286 (permalink)  
 
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Tartare

The pressure side of the EFIS was giving erroneous information the ATTITUDE part of the PFD was still working so they had a large Artificial Horizon to enable attitude to be flown.

Bearfoil

They had a standby AH it is called the ISIS, basically a smaller version of the PFD.
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Old 2nd Jun 2011, 04:43
  #1287 (permalink)  
 
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So - a hypothetical question - Bearing in mind the idiosyncrasies of swept wing aircraft in stalls... if such a jet is in a fully developed stall, applying power and then using the AH/EFIS to obtain a wings level, nose level attitude would arrest the stall?
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Old 2nd Jun 2011, 05:24
  #1288 (permalink)  
 
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So - a hypothetical question - Bearing in mind the idiosyncrasies of swept wing aircraft in stalls... if such a jet is in a fully developed stall, applying power and then using the AH/EFIS to obtain a wings level, nose level attitude would arrest the stall?
Not without a big afterburner.

Too much induced drag. Reduce AOA first, accelerate, and fly happily ever after.

Try to power out of it and everyone will be shaking their head at your airmanship as they attend the funeral.
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Old 2nd Jun 2011, 05:29
  #1289 (permalink)  
 
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Alternate destinations

xcitation:

The BEA Interim Report stated:

1.17.1.3 Preparation of flight AF447 on 31 May 2009
Preparation of the flight by the central flight study service
The flight was prepared between 15 h 28 and 18 h 59. Paris Orly was given as the alternate airport at destination. Given the estimated load of 37.8 t, the dossier included a main flight plan at a standard Mach of M 0.82 with an ETF at Bordeaux Mérignac with alternate at Toulouse Blagnac as well as two additional direct flight plans, one at Mach 0.82 and the other at a "slower Mach", i.e. M 0.81. A summary table of the loads offered enabled the crew to make the choice of the definitive flight plan from among these three options.

The full report is at http://www.bea.aero/docspa/2009/f-cp...90601e1.en.pdf
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Old 2nd Jun 2011, 05:55
  #1290 (permalink)  
 
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Lack of Stall Warning

To have a design where blockage of the pitots not only loses airspeed data but also (because it now shows speed is less than 60kts regardless of the truth) disables the stall warning strikes me as unwise.
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Old 2nd Jun 2011, 05:59
  #1291 (permalink)  
 
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Flight Plan

xcitation:

The BEA Interim Report stated:

1.17.1.3 Preparation of flight AF447 on 31 May 2009
Preparation of the flight by the central flight study service
The flight was prepared between 15 h 28 and 18 h 59. Paris Orly was given as the alternate airport at destination. Given the estimated load of 37.8 t, the dossier included a main flight plan at a standard Mach of M 0.82 with an ETF at Bordeaux Mérignac with alternate at Toulouse Blagnac as well as two additional direct flight plans, one at Mach 0.82 and the other at a "slower Mach", i.e. M 0.81. A summary table of the loads offered enabled the crew to make the choice of the definitive flight plan from among these three options.

The report is available at: http://www.bea.aero/docspa/2009/f-cp...90601e1.en.pdf
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Old 2nd Jun 2011, 06:30
  #1292 (permalink)  
BRE
 
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Two questions I could not find the answer to in this thread (bear with me if I overlooked them):

1. auto-trim moved the THS to up 13° while the PF was pulling up -- was the auto-trim movement a consequence of the PF's pulling up?

2. would a full down sidestick have had the authority to overcome the full up THS later on?
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Old 2nd Jun 2011, 06:38
  #1293 (permalink)  
 
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MountainBear wrote
,"I think his time has been and gone. Everything he says sounds good in theory but he fails to mention the critical factor of money. Sims are not cheap, sim sessions are not cheap, practice lessons in the plane are not cheap. How much money is a society supposed to spend in order to save 200-300 lives. Naturally, if it's your life at stake you want them to spend a lot of money. But when it's the other guy, maybe not so much. Whether it is explicit or implicit there is always a cost/benefit analysis going on. Always. "
I beg to differ:
a. Sully landed on the Hudson with his USAF training and experience background dominating, not airline training.
b. The way for cost effective and inexpensive training starts with proper pilot selection, syllabus and training. My son following a few weeks in class then simulator sessions along one week, got his B737NG type rating and is now flying with that top notch airline. Contributors are, again: proper candidate selection, syllabus and training. Decision makers need to understand flight, airline management, and wrap-up this prohibitive cost bull.

Regarding who to spend money on, the study of ethics teaches us that the best way to get life quality is to pursue smart egotism, in which people benefit by donating private resources to their community.

Last edited by opherben; 2nd Jun 2011 at 07:00.
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Old 2nd Jun 2011, 06:46
  #1294 (permalink)  
 
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Cool

Hi,

Two questions I could not find the answer to in this thread (bear with me if I overlooked them):

1. auto-trim moved the THS to up 13° while the PF was pulling up -- was the auto-trim movement a consequence of the PF's pulling up?

2. would a full down sidestick have had the authority to overcome the full up THS later on?
Those questions were already answered
It's YES for the 2 questions if the airplane was acting like it must be in alternate law
Pull up and the THS will go up
Pull down and the THS will go down
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Old 2nd Jun 2011, 07:25
  #1295 (permalink)  
 
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"You have to balance Stall Warnings in extremely rare events with far more common nuisance stall warnings, in order to maintain confidence in the system"

With an AOA probe/indicators system set up to alarm CONTINUOUSLY anytime AOA reaches predetermined level before critical AOA and BEYOND (...sorry sound like Buzz Lightyear) with the addition of a weight on wheels breaker.

Can you envisage any scenario which would lead to a "Nuisance stall warning"?


PS.-- One interesting post few pages back was from a captain who made the point that sometimes having an alarm going of continuously can detract from an individuals ability to deal with a problem. I suspect there is a balance that has to be struck and I suspect / hope that the engineers, psychologists, pilots involved in cockpit design have already thought it through.
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Old 2nd Jun 2011, 07:51
  #1296 (permalink)  
 
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I apologise in advance if this has been covered already, but in the absence of any trustworthy data, two buttons on the FMGC would have led them to the GPS altitude and groundspeed.

Used in conjunction with the unreliable airspeed drill, I could envisage a successful outcome to their predicament with a minimum of fuss.

On an antecedent note, don't mess with the ITCZ.
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Old 2nd Jun 2011, 08:28
  #1297 (permalink)  
 
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As I remember, the Air Caraibes pilots used GPS altitude to confirm that they were in stable flight using the pitch + power settings
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Old 2nd Jun 2011, 10:00
  #1298 (permalink)  
 
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Concerning fuel on board. Please read BEA's report appendix 7 page 116/117.
http://www.bea.aero/docspa/2009/f-cp...90601e1.en.pdf
At T/O, they had :
- 900 kg EXTRA fuel over the minimum M .82 DIRECT flight plan to CDG (alternate ORY) ;
- 1.900 kg EXTRA fuel over the minimum M .81 DIRECT flight plan to CDG (alternate ORY) ;
- 2.000 kg extra fuel over the minimum M .82 "subject to RIF to CDG" ("ETF" in BEA's wording) flight plan to BOD (alternate TLS).

At any given time, if fuel becomes an issue, the crew can decide to fly at M .81 (iso M .82) or to land at LIS/BOD/NTE without too much "embarrassment".

Concerning ITCZ crossing. Please read Tim Vasquez conclusion :
Air France 447 - AFR447 - A detailed meteorological analysis - Satellite and weather data
Air France Flight 447 crossed through an area of tropical showers and/or weak thunderstorms with weak to moderate updrafts and a high likelihood of turbulence. The flight penetrated one cell at about 0150 UTC and then entered a cluster of cells beginning at 0158 UTC. The suspected zone of strongest cells was reached at 0208 UTC, which corresponds with the beginning of a track deviation, and another cell appeared to be reached at 0210 UTC, which corresponded with the time of autopilot disconnect. The flight was suspected to be within areas of showers and precipitation up until the time of impact, and the descent below FL250 into the critical -10 to -20 deg C zone probably involved some degree of clear icing on control surfaces, though it is uncertain whether this affected recovery of the aircraft, especially due to the short accumulation time that would be involved.

Tropical storm complexes identical to or stronger than this one have probably been crossed hundreds or thousands of times over the years by other flights without serious incident, including ascents and descents through critical icing zones in tropical showers. My original conclusion from June 2011 is still unchanged: turbulence and possibly icing creating an initial problem that led to a failure cascade. Whether that final weak link was human or machine error is beyond my area of expertise and is best left for the experts at BEA.
If CB/turbulence was a factor, why did they start to deviate at 02:08 and not during the 01:50/02:08 period (when they went through an equally "bad" area according to figure 5b shown above) ?

Concerning captain behavior : he went to rest only 10 minutes before things went bad.
Who on earth would go to rest if the 160 Nm radar picture showed some "extra-ordinary" weather ahead

Last edited by GerardC; 2nd Jun 2011 at 17:38. Reason: typo
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Old 2nd Jun 2011, 11:27
  #1299 (permalink)  
 
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Re AOA Probe balancing

Static Balance
Every AOA sensor I've seen on ground has been full stop down (neg AOA), which indicates no static balance. Don't believe I've ever seen one in flight.

I don't know a lot about AOA vanes, which I why I asked for someone really knowledgeable to speak up. You can peruse pix on airliners.net to get a good sample.

The F4 had an AOA probe without the need for balancing. During groundcheck we checked the free movement of the probe and it stayed where you put it.
AOA Probe

AOA value was displayed on the AOA gauge. The AOA also triggered an aural AOA tone in the headset, starting with a low frequency low repetitive tone at 15 units (if i remember correctly), becoming a steady medium frequency tone when optimum AOA was reached for landig (19.2 AOA) increasing to a high repetitive high frequency tone when AOA limits where exceeded. That was our stall warning and nothing else was needed.

Advantage over the betty bitch thing is IMHO, that you are aware over the trend the AOA is developing, whether it is increasing or decreasing.

I´m not saying that this would be the ideal system, just to make a point that the balancing problem should not lead to shutting off any kind of stallwarning below a predetermined speed. The technology is available since 1960!

Last edited by RetiredF4; 2nd Jun 2011 at 11:45.
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Old 2nd Jun 2011, 11:47
  #1300 (permalink)  
 
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Further to jcjeart's response (#1302) can someone tell me why trim is automatically triggered by nose-up or nose-down side stick commands in an Airbus? When flying my C152 I might wind in a bit of trim to ease the control loads when establishing a lengthy climb or descent but it's my decision. Once I've trimmed the aircraft for level flight I usually leave it alone regardless of altitude changes.
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