AF447 wreckage found

[wallybird7]

No Evidence of Thunderstorms???

SATURNV

No evidence of thunderstorms?????

Please read "Air France Flt 447: A Detailed Meteorological Analysis"
By Tim Vasquez

Every scrap of information on this flight shows a line of thunderstorms directly in line of their flight path.

Every advisory from NASA, to the FAA, advises avoidance by a large margin.

Every professional is aware of thunderstorms and the hazards they pose.

Weather Avoidance Radar is required on every airliner. Why?

[MATELO]

Both main manufacturers and the airlines are leaning more and more towards a situation where the 'systems' hold sway and the pilots are virtually forbidden to fly manually

What chances did these guys have if they were trained to "understand the aircraft will never stall" and they never knew the stall warning would silence itself under 60kts.

Plummeting towards the ocean with no stall warning might lead someone to think they were heading "nosedown" into oblivion, especially in the middle of the ocean at night.

[RWA]

Quoting One Outsider:-

"Then you don't know very far. The 'first duty' of any crew is to fly the aircraft. Any other actions are secondary and are to be performed when not interfering with flying the aircraft."

I didn't say they should or would stop flying the aircraft, One Outsider. That's why there are two of them! But it is the duty of the PNF to read off the ECAM messages, one by one, cancelling each once the PF has absorbed it and then moving on to quote the next.

There's a video here that shows that procedure being carried out. Only a 'sterilised' mockup in the simulator, but it will give you the idea.......

‪Airbus emergency descend after cabin pressure failure‬‏ - YouTube

"Being a mere amateur you are perhaps excused, but with the amount of nonsense already posted there is no need to add more."

I hope (without much hope) that you will now withdraw the word 'nonsense' .........

[SaturnV]

Wallybird7,

I have read Vasquez, both his 2009 and 2011 analyses. I have read the BEA Meteo France analysis in the first BEA report (an appendix in French only). I have read NASA's re-analysis of the Wx. I have noted AF dispatch's message to the crew alerting them that satellite imagery indicated Cb along their route in the vicinity of TASIL.

In the earlier 'conversation' in this forum on whether they flew into a Cb or not, I believe there is agreement that:
> nobody publicly knows what the gain and tilt of their radar was set at, and what they likely saw.
> nobody can yet accurately characterize the nature of the turbulence experienced earlier, other than the cockpit indicating to the cabin crew that the turbulence they were anticipating at 0208-0210 would probably be greater than the previous episode.
> they were using their radar, and made a slight deviation off the track before the pitots iced.
> nobody publicly knows what the CVR transcript may say about any conversation in the cockpit about the weather.
> that the weather in the ITCZ is dynamic, with conditions that can change rapidly.

As I noted earlier, there is agreement that they flew into a cloud with sufficient ice crystals to clog the pitots.

Satellite data has confirmed that areas of very small ice crystals in high concentrations exist within and in the vicinity of large scale convective weather systems. This is especially true in tropical latitudes where these systems are at their most extensive and can produce cloud tops as high as 50,000 feet because sea surface temperatures are at their highest and so more water is absorbed into the developing system. These ice crystals can remain long after the active convection which produced them has begun to decay. They are extremely small - probably only about 40 microns in diameter - and even at high concentrations, are unlikely to be evident visually even by day. With a radar reflectivity of only about 5% of that of average-sized raindrops, they will not appear on airborne weather radar displays either.
.....
The areas of abnormally high crystal concentration are believed to originate from columnar ascent in cumulonimbus cloud and can be expected to drift downwind from the main area of cloud tops. They are an entirely different phenomenon to the more ‘normal‘ occurrence of the ice crystals which give rise to high level Cirrus, Cirrostratus and Cirrocumulus cloud which are at much lower concentrations and do not represent a similar hazard.

SKYbrary - High Level Ice Crystal Icing

[wallybird7]

cloud vs thunderstorms

SaturnV

"There has been a back and forth conversation on this forum about whether they flew into a Cb.

I think perhaps the minimum level of agreement by parties engaged in this conversation is that AF 447, at night with the moon aft, flew into a cloud that had sufficient ice crystals at FL 350 to quickly clog the pitots."

A "cloud" that rises to 50,000 is not merely a cloud -- it is a thunderstorm.
It can contain severe up and down drafts and severe turbulence.
The FAA advises avoiding it.
When AF 447 entered this area a multitude of failures occurred.

And yet you are saying it was merely a coincidence. It had nothing to do with all that followed.
I think you need to do some more research on the subject of thunderstorm flying and the hazard it represents.

[DL-EDI]

RWA:

Is the "first duty" nowadays to listen to the systems or is the "first duty" still to fly the aircraft and use the systems as tools to achieve that end? Hasn't the latter been the general philosophy since the first instrument was added to an aircraft? I can't say with any authority.

[Henri737]

SatrunV

Lets not confuse cause and consequences.

what radar system was installed? not seen an answer yet.

[SaturnV]

Henri 737.

The radar system in use was identified much earlier in one of the previous, now-closed threads on this accident. I am not going to search for the posts describing it. It was the same radar system used by AF459, which followed AF447 along the same track by about 35 minutes, but which after ORARO, deviated to the left by about 20 NM and then to the right by 70-80 NM, and did so after adjusting the tilt and gain on the radar.

Wallybird7,

Regarding the 'conversation' earlier in this thread, I do not believe anyone is asserting that the crew deliberately flew into a Cb whose top was subsequently described as being at 520 (Meteo France) or 560 (Vasquez). AF459 began adjusting its radar after unexpected turbulence at 350 in the vicinity of NATAL, in weather described as cumulus congestus. The crew of AF447 may not have been prudent, but I don't believe there is any indication from the CVR excerpts that they were reckless.

As we don't yet have a full CVR transcript, we don't know what, if anything, was said about what they saw on their radar (except for a reference to the anticipated turbulence and a reference to deviating a bit off the track). We don't know if they adjusted the settings on their radar.

As there was no lightning, and the moon was behind them, there was little illumination of the clouds ahead. We do know that a Lufthansa 744 flying 20 minutes ahead at 325 reported it was in the clouds at the time it deviated. The only weather-related comment by the AF 447 crew in the CVR excerpts released by the BEA references the outside air temperature.

No one disputes that the crews of the LH ahead, and the IB and AF459 following, deviated based on what they saw on their radars. The unanswered question is what did AF447 see on its radar that led them to continue on the track, and only attempt a slight deviation when they were in the middle of the 'cloud'.

[wallybird7]

SaturnV
"No one disputes that the crews of the LH ahead, and the IB and AF459 following, deviated based on what they saw on their radars. The unanswered question is what did AF447 see on its radar that led them to continue on the track, and only attempt a slight deviation when they were in the middle of the 'cloud'."

No one knows what they saw or what they understood it to mean.
My concern is why they didn't deviate sooner, and raises the question to me, that there is sort of a cultural issue regarding minimizing the potential hazard a thunderstorm poses. It exists also on this web site whereby the automation and it's "Protections" will save the day.
If a pilot is forbidden to "hand-fly" the plane at altitude in clear weather conditions, and then in a turbulent circumstance is forced to do it, with very limited resources, no airspeed etc, I think it is literally impossible.
This airplane is very fragile having 32 plus adventures with loss of pitot info and subsequent auto failures, and to venture anywhere near major storms is irresponsible.

[Turbine D]

AF447 Weather Radar

SaturnV,

Here is a post from Thread 2 in the Tech Forum by Graybeard. It notes the onboard radar type. Hope this helps your discussion with wallybird7.

Wx Radar Factor
RR_NDB
Quote:
Ok, let´s look at each point:

1) Crew decided to keep course going through WX.
2) Entered an unexpected WX condition.
...

1) Several possible reasons:
a) Radar in auto mode. The best is to adjust manually the antenna elevation to characterize better the pattern ahead.
b) Shadow from first CB area (as PBS suggested)
1 a) The Wx radar on 447 did not have auto tilt. They had the Collins WXR-700, not the newer WXR-2100.

b) As I explained in detail above, it was not possible for the major line to be shadowed by the intervening cell. In this case, PBS "expert" was a ground radar guy. Rockwell Collins, the maker of 447's radar, was not listed in the credits. If RC didn't want to get involved, they surely could have referred Nova to a knowledgable source.

Here are some possibilities:

1. The storm did not look bad enough to deviate around.
2. The line of storms was so long and uniform, it would not seem to matter where they penetrated.
3. The pilots did not have enough training in Wx radar ops.
. a. Nobody was looking at the radar returns.

[SaturnV]

Thank you Turbine D.

Wallybird7, nearly three weeks ago there was a rather robust discussion in this forum on what they flew into. Rather than my continuing to try to synopsize and synthesize the various views expressed, perhaps the better reply would be to give you links to many of the relevant posts.

http://www.pprune.org/6537291-post1849.html

http://www.pprune.org/6538283-post1865.html

http://www.pprune.org/6538679-post1870.html

http://www.pprune.org/6538743-post1871.html

http://www.pprune.org/6538901-post1875.html

http://www.pprune.org/6538911-post1876.html

http://www.pprune.org/6539033-post1878.html

http://www.pprune.org/6539051-post1880.html

http://www.pprune.org/6539466-post1885.html

http://www.pprune.org/6539692-post1889.html

You may view the failure of the crew in not deviating sooner to be irresponsible, but I think most/all of the earlier posters on the subject of a track through an ITCZ meso-convective system would agree there still is far too little information to form judgments with regard to culpability.

As Vasquez summarized last month,

Tropical storm complexes identical to or stronger than this one [the MCS on June 1] 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.

[jcjeant]

Hi,

Tropical storm complexes identical to or stronger than this one [the MCS on June 1] 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.

This is what is called "Russian roulette"
A game can not be a winner ..you always lose .. it's just a matter of time.
To be sure not to lose (or sure to win) should not play "Russian roulette" (do not go in these areas)

[TioPablo]

Next report of BEA is planned to be published end this month... I´m sure we all are planning to do our best! Fly safe!

[bubbers44]

I hope the final report comes out soon from BEA so we don't have to listen to Russian Roulette stories of how they iced up.

[lomapaseo]

Tropical storm complexes identical to or stronger than this one [the MCS on June 1] 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.

This is what is called "Russian roulette"
A game can not be a winner ..you always lose .. it's just a matter of time.
To be sure not to lose (or sure to win) should not play "Russian roulette" (do not go in these areas)

This leads to the same circular argument as volcanic ash. The air we fly through always has some degree of ash, water and turbulence. You can't just say don't fly in them because it's like how high is high.
The pilot can be given guidance but can not be given orders that are black and white without the means to measure. Thus the investigation needs to ask about the guidance and the means as well as the performance of the crew. As far as I know the investigation has not made a conclusion in this regard so why should we?
Weather is dynamic so what another flight did a half hour before or after is only a hint, towards their guidance and means of measurment and not a conclusive finding for the accident flight

[RWA]

Quoting DL-EDI:-

"Is the "first duty" nowadays to listen to the systems or is the "first duty" still to fly the aircraft and use the systems as tools to achieve that end? Hasn't the latter been the general philosophy since the first instrument was added to an aircraft?"

The professionals on here can advise you better, DL-EDI - but my understanding is that in this sort of situation (autopilot/autothrust 'sign off,' 'unreliable speed indications,' etc.) the PF should 'fly pitch and power' (basically keep the pitch attitude at an appropriate level to maintain altitude and (given that one of the few things we can be certain of is that the speed indications had gone haywire) manually apply the correct throttle setting to maintain flying speed). The duty of the PNF, as shown above, is to work through the warnings/messages so as to inform the PF as thoroughly as possible on what has gone wrong. So it's a mixture, with the emphasis on keeping the aircraft at a correct attitude and at a safe speed until (hopefully) the instruments come right (in this case, first and foremost, that the ice in the pitots and ports hopefully melted).

That's the way the AF447 pilots reacted; and it looks as if the PF did in fact manage to keep the aeroplane level and maintain airspeed for some 18 seconds; in other words, 'fly pitch and power' in accordance with the recommended procedure. I've no doubt that, if and when we ever get details of the CVR recording, the two pilots will have been going through the procedure illustrated above - checking each message/warning in turn, trying to find out what had happened/was happening.

What we DON'T know, of course, is what other instruments may have been misbehaving, in addition to the Air Speed Indicators.

Then came the (so far unexplained) zoom-climb, with no evidence of any sidestick input from the PF. Again, the PF appears to have 'done the right thing,' countered the zoom-climb with forward stick and pretty well levelled the aeroplane out again. Further, at some point during this period (the BEA 'neglects' to inform us when this process started and finished) the "Trimmable Horizontal Stabiliser' (what used to be called the 'tailplane' in my day) unaccountably went to 'full up.'

Finally, the stall warning sounded - and once again the PF appears to have 'gone by the book' as it applied at the time, carrying out the recommended procedure at the time - full Take- Off/Go Around power and try to maintain level flight.

At some point during this phase the "Trimmable Horizontal Stabiliser' (what used to be called the 'tailplane' in my day) went to 'full-up'; which would have made it just about impossible to maintain level flight. There have been several accidents due to that happening; Perpignan was one (though pilot error was definitely involved in that accident as well). Another was an MD80, Alaska Airlines Flight 261 - this accident was put down to lack of maintenance, the un-lubricated jackscrew operating the THS first of all jammed with the THS at a 'nosedown' setting, and then broke off altogether. For the record, the Alaska pilots had both to haul their columns back with all their strength just to maintain some sort of level flight, just from the 'down' THS attitude, even before the THS actually broke).

Alaska Airlines Flight 261 - Wikipedia, the free encyclopedia

TV dramatisation here too if you fancy watching it - though I warn you, it's long.........

‪Air Crash Investigation - Cutting Corners / Fatal Error - Alaska Airlines Flight 261‬‏ - YouTube

Trouble is, due to what I will politely describe as the BEA's 'reticence' on the contents of the FDR and the CVR, we can form no opinions on what caused the zoom-climb. That brings us to the main difference between modern airliners (particularly Airbus, though Boeing are moving in the same direction); that older aircraft types always left the pilot with the final word; whereas modern 'systems' are designed to overrule them if the systems 'conclude' that the pilots' actions are in some way endangering the airframe or doing other things that (in the opinion of the designers) are dangerous.

Both Boeing and Airbus modified their 'stall avoidance' procedures soon after AF447 went in; the drill now is 'adjust power but don't necessarily use full power, concentrate first on getting the nose down.'

Hope some of that helps.......

[Zorin_75]

That's the way the AF447 pilots reacted; and it looks as if the PF did in fact manage to keep the aeroplane level and maintain airspeed for some 18 seconds;

According to the note more like 11 seconds. Anyway, is that supposed to be a good thing? Orville Wright managed 12 seconds on his first try...

What we DON'T know, of course, is what other instruments may have been misbehaving, in addition to the Air Speed Indicators.

At this point we have nothing indicating that they lost anything other than the airspeed derived data either.

Then came the (so far unexplained) zoom-climb, with no evidence of any sidestick input from the PF.

While I agree that we don't know how strong it was, it's somewhat hard to ignore the "left nose-up input" made just before the climb...

Finally, the stall warning sounded - and once again the PF appears to have 'gone by the book' as it applied at the time, carrying out the recommended procedure at the time - full Take- Off/Go Around power and try to maintain level flight.

Whatever book they were going by, I'd hazard a guess nose-up inputs resulting in 16 deg pitch attitude weren't in it.

At some point during this phase the "Trimmable Horizontal Stabiliser' (what used to be called the 'tailplane' in my day) went to 'full-up'; which would have made it just about impossible to maintain level flight.

It went up because the pilot wanted nose up (that that was probably for a good reason from his perspective is a different story, we will have to wait and see...).

For the record, the Alaska pilots had both to haul their columns back with all their strength just to maintain some sort of level flight, just from the 'down' THS attitude, even before the THS actually broke).

I'm not sure where you see the relevance of that incident, but as you note there the pilots fought with all their strength against the failed THS, which from what we know so far seems not to have been the case at all here...

That brings us to the main difference between modern airliners (particularly Airbus, though Boeing are moving in the same direction); that older aircraft types always left the pilot with the final word; whereas modern 'systems' are designed to overrule them if the systems 'conclude' that the pilots' actions are in some way endangering the airframe or doing other things that (in the opinion of the designers) are dangerous.

So, general anti FBW ranting aside, at which point do you suppose the FCS overrode the pilot's input, causing or contributing to the accident?

[DL-EDI]

That's quite an extensive reply to my simple question, RWA. However, I still don't see that nowadays "listening to the systems" is the crews' "first duty" over flying the aircraft.

So, general anti FBW ranting aside, at which point do you suppose the FCS overrode the pilot's input, causing or contributing to the accident?

As a mere armchair enthusiast, I'm also curious about the answer to this recurring question.

[iceman50]

So, general anti FBW ranting aside, at which point do you suppose the FCS overrode the pilot's input, causing or contributing to the accident?

As the A/C was supposedly in Alt Law (ADR Disagree) there would have been NO FCS inputs to cause the pitch up, they are inhibited.

RWA

Both Boeing and Airbus modified their 'stall avoidance' procedures soon after AF447 went in; the drill now is 'adjust power but don't necessarily use full power, concentrate first on getting the nose down.'

The manufacturers and regulators re-emphasized the Stall Recovery Procedure not because of AF 447 but because of various other stalls on both Airbus / Boeing and other types. Too much emphasis had been put on minimum height loss with some "instructors"/ schools actually saying use "back" stick to reduce height loss!!!! The UK CAA have just issued a Safety Notice to that effect on the 13th July 2011.

Again, the PF appears to have 'done the right thing,' countered the zoom-climb with forward stick and pretty well levelled the aeroplane out again.

BEA report

The airplane’s pitch attitude increased progressively beyond 10 degrees and the plane started to climb. The PF made nose-down control inputs and alternately left and right roll inputs. The vertical speed, which had reached 7,000 ft/min, dropped to 700 ft/min and the roll varied
between 12 degrees right and 10 degrees left. The speed displayed on the left side increased sharply to 215 kt (Mach 0.68). The airplane was then at an altitude of about 37,500 ft and the recorded angle of attack was around 4 degrees.

However, if you read the BEA report quoted, the inputs made were then nose up and more than likely caused the THS to move, then when the AOA increased above 30 degrees or the speed dropped below 60 kts - no more autotrim.

At 2 h 10 min 51 , the stall warning was triggered again. The thrust levers were positioned in the TO/GA detent and the PF maintained nose-up inputs. The recorded angle of attack, of around 6 degrees at the triggering of the stall warning, continued to increase. The trimmable horizontal stabilizer (THS) passed from 3 to 13 degrees nose-up in about 1 minute and remained in the latter position until the end of the flight. Around fifteen seconds later, the speed displayed on the ISIS increased sharply towards 185 kt; it was then consistent with the other recorded speed. The PF continued to make nose-up inputs. The airplane’s altitude reached its maximum of about 38,000 ft, its pitch attitude and angle of attack being 16 degrees.The altitude was then about 35,000 ft, the angle of attack exceeded 40 degrees and the vertical speed was about -10,000 ft/min. The airplane’s pitch attitude did not exceed 15 degrees and the engines’ N1’s were close to 100%. The airplane was subject to roll oscillations that sometimes reached 40 degrees. The PF made an input on the sidestick to the left and nose-up stops, which lasted about 30 seconds.

[jcjeant]

Hi,

As we have many technical documentations about the A330 systems and how they are working in the case of the AF447 event .. and pilots actions (thank's to takata and al and BEA interim reports and note) can some ones with same knowledge about the Boeing 777 .. propose a scenario about how will work the B777 systems if confronted at similar event ?