Air France A330 accident

[Silver Spur]

Hi All,



At this early stage, by looking at the wreckage floating on the water, is it possible to determine whether the AF A330-200 experienced an inflight Break Up or It breaks up on impact with the water?

If, it was an inflight Break Up, would that be possible to predict whether it is an excessive aerodynamic force induced Break Up, or if the Break Up was caused by - i.e. Bomb?

Specific to the A330 200 operated by Air France, does anyone knows if the ACARS also transmit excessive G force experienced by the aircraft?

I haven't flown any Airbus FBW nor have I got any appreciable knowledge of the flight control logic, according to what I gather from the media and some posts on the AF330 Thread, there have been discussion about the ACARS sending "electrical fault" message, in this case, would the fault degrade the flight control system so much as to the crew lost the flight envelope protection?

Thank you all!

SS

[Genghis the Engineer]

Hi All,



At this early stage, by looking at the wreckage floating on the water, is it possible to determine whether the AF A330-200 experienced an inflight Break Up or It breaks up on impact with the water?

No, you'd need to get the bits into a lab, and probably need a reasonably number of the metal bits into a lab. That would take some time, since most of those don't float.


If, it was an inflight Break Up, would that be possible to predict whether it is an excessive aerodynamic force induced Break Up, or if the Break Up was caused by - i.e. Bomb?

I think you meant "e.g.", but I'm just being picky. Yes, the tear marks on the fracture surface look quite different from a fuel explosion, overstress, or high explosive. Also, there's a good chance of some residues that can indicate whether an explosive was present and if so which one.


Specific to the A330 200 operated by Air France, does anyone knows if the ACARS also transmit excessive G force experienced by the aircraft?

No idea.

I haven't flown any Airbus FBW nor have I got any appreciable knowledge of the flight control logic, according to what I gather from the media and some posts on the AF330 Thread, there have been discussion about the ACARS sending "electrical fault" message, in this case, would the fault degrade the flight control system so much as to the crew lost the flight envelope protection?

We'd need a lot more information than has been released by Air France to answer that.

G

[SeenItAll]

The R&N forum on the AF 447 disaster is replete with statements by pilots contributing to the forum that flight through severe CBs is incredibly dangerous, and to be avoided at all costs. My question (as an ignorant SLF) is this. Every hurricane season, the USAF and NOAA fly planes through the middle of these storms to gauge their strength, etc. These planes are Lockheed C-130 Hercules, P-3 Orions, and even Gulfstream GIV's. See: Hurricane Hunters Association (http://www.hurricanehunters.com/plane.html) and NOAA's Hurricane Hunters (http://www.publicaffairs.noaa.gov/grounders/hurricanehunters.html) .

Clearly, these are not "certain death" missions. How do these facts square with the R&N statements about the inadvisability of commercial aviation encounters with turbulent weather. Is it: (a) hurricane hunting is extremely dangerous; (b) the aforementioned planes are more robust than commercial Airbus and Boeing products; (c) hurricane hunter crews have more refined skills for this task; (d) the turbulence found in hurricanes is less or more consistent than the turbulence found in major CBs; (e) the commercial planes and crews are quite adequate, but the PAX can't abide by the ride; or (f) none of the above?

Again, I'm not trying to point any fingers, just interested in resolving the apparent disconnect. Thanks.

[sinsin]

Have heard on "good and reliable" authority:

"Aircraft hit CB...experienced +/- 100 knot windshear. Autopilot disconnected ...Power failure to screens...Airframe breeched...Rapid decompression...Followed by flight control losss......Entire event 14 minutes"

Must have been a long 14 minutes !!

[DC-ATE]

SeenItAll -
The main difference between your hurricane hunters and commercial aircraft penetrating severe weather is.....PASSENGERS. The airframe will normally withstand much more than the pasengers can endure. And, the pilots and crew of those hurricane hunter aircraft are strapped in, not wondering about the cabin or failing to "keep their seat belt fastened" even while seated !

Also, the convective forces are far greater in a thunderstorm, I believe, than in a hurricane. And, the imbedded thunderstorms within any hurricane are avoided I'm sure by those aircraft.

[SpannerInTheWerks]

Whilst I don't want to be accused of added to unsubstantiated facts, I find it incredible that an experienced Air France Captain would knowingly fly into an area of CB activity - especially at cruising altitude.

With three pilots on board I presume one was a 'cruise pilot'.

Assuming route forecasts were obtained and that the weather radar was working the question has to arise as 'why did they enter an area of CB activity?'

Was the Captain in the flight deck or were the First and Second Officer in control at the time? If so was their relative inexperience an issue?

All speculation I'm afraid, but in common with all other pilots I can't imagine anyone knowingly flying directly into a known area of bad weather?

As for the 'bomb theory', the only possible (and wildly unsubstantiated) cause I can think of is a connection with the 'Brazilian Prince' who was aboard. Unfortunately this borders on fantasy and would prove that someone has watched too much TV (Airport 77?).

The 'reality' of the situation may be ill-advised entry into an area of CB activity.

If this is the case, then Air France will no doubt be awaiting the onslaught of claims from relatives of the victims.

Amongst all the speculation it has to be said that I can't imagine the pain and grief this accident has caused. Having flown the Atlantic as so many of us have, the prospect of a catastrophe of this nature is beyond belief.

SITW :sad:

[Gergely Varju]

Also, there's a good chance of some residues that can indicate whether an explosive was present and if so which one.


While residues are present after an explosion and often they are the best evidence, numerous past events would shows three key facts.

Water can destroy the evidence
Evidence can get tainted in rescue operations
Traces of explosives can be present on an aircraft and can be unrelated to the accident.TWA-800 investigation can show examples of all 3 claims, and for this reason I would look for other evidence first. Tear marks on fracture surface, fault tree analysis, etc. can help. Sequence of events can also help to rule out some possibilities, and for this reasons ACARS messages can be important.

Specific to the A330 200 operated by Air France, does anyone knows if the ACARS also transmit excessive G force experienced by the aircraft?


I would find it extremely unlikely to see any such ACARS messages. While ACARS messages are one of the few evidence that can be used in the accident investigation, ACARS isn't designed for this purpose.

My question (as an ignorant SLF) is this. Every hurricane season, the USAF and NOAA fly planes through the middle of these storms to gauge their strength, etc.

It is quite different to fly above the storms, and measure the pressure in the eye, if the whole staff on the plane is prepared for the worst, experience, trained, strapped in. And you can also say that the hurricane is different...

[Che Guevara]

I haven't flown any Airbus FBW nor have I got any appreciable knowledge of the flight control logic, according to what I gather from the media and some posts on the AF330 Thread, there have been discussion about the ACARS sending "electrical fault" message, in this case, would the fault degrade the flight control system so much as to the crew lost the flight envelope protection?

As Gengis said we all need more information as to the sequence of events etc. However, for your information the flight controls will reconfigure with two or more related failures, for example two ADR failures etc. would put the aircraft in Alternate law which would remove the protections.
The "electrical fault" ACARS message quoted would have more information attached which we are not privy to yet unless we have "good and reliable authority" feeding us the information....;)

[DC-ATE]

SpannerInTheWerks -

You might not be able to "imagine anyone knowingly flying directly into a known area of bad weather?".....but the fact is, it has happened before on too many occasions. As to the Captain taking his break at the time, I find THAT hard to believe if he knew they were going to be in an area of storms. Unless, that is, he told the relief crew to avoid those areas and they didn't for some reason.

About all we can do is speculate unfortunately, because the chances of recovering any meaningful data does not look good at this point.

Speculation-wise, I'd say that weather was a factor as was computerized flight controls.

[SoaringTheSkies]

does anyone have any information on what the source of the "flew too slow" message was, that was on the media today?
German national radio (Deutschlandfunk) even reported that Airbus had issued an advisory, "reminding pilots not to fly too slow when entering adverse weather" they said.
Has anyone seen that?
What are the critical speeds for a 330 at the given conditions for maximum mach number, stallspeed and turbulence penetration?
Also, if there is any creedence to be given to these report, has there been any data that would allow calculating the aircraft's speed at the time of the event? Do the acars messages contain gps location and timestamp?
Somehow, given the unfolding of events that those messages indicate, I can't quite believe that structural failing was at the beginning of the chain of events. Surely, if the aircraft structure had been damaged enough to render such vital systems inop within short time, a hull breach/decompression would have been recorded early on, not just after four minutes.

Btw, it's interesting to see how most of the "experts" talking to media seem to be retired somethings. Mechanics, pilots, just about anything, but all retired. It seems that those who still are in the business often answer the right thing: "we don't know" - which, of course, isn't acceptible if you're writing for a 1st page headline.

[Che Guevara]

The turbulence penetration speed on the 332 at that level is MACH .80 and MMO is .86

[Jetstream00]

Normally the ACMS will transmit to their operations control any exceeded limits which are normally tailored by the airlines for their operational requirements ( response to your ACARS transmissions). Something that boggles me is that in todays news they are hinting towards pilot error for stalling the airplane, which does not make sense as these airplanes have alpha floor protection ( stall Protection) which with all its PRIM's and SEC's working would not allow it to reach that situation.

[toby320]

jetstream00,

when you go after several failures to direct law you lost all protections so...

[MrFixer!!!]

How about looking at the Technical side of failures????

I posted previous comment on Composite & Lightening discussion but seems a bit lost there....

Just a few things which are bugging me from what I know about A330s and my experience on them.....

I am MORE interested in that ACARS message.....if that was sent that means there was power available in that system from the BUS2... that means there was full power supply from BUS2 feeding the other electrical buses......

ALSO....IF ACARS were still gathering and sending data about the failures then ACMS/CMC was fully functional, monitoring all the relevant systems and reporting subsequent failures....

Data Transmission

The Data Transmission system comprises:

Aircraft Communications Addressing and Reporting System (ACARS)

The ACARS management unit allows management of the data transmitted to the ground (SDAC, FWC, AIDS, CMS, FMGEC) and entered by the crew. It also allows reception, printing and display of ground messages on the MCDU.
These data are transmitted through the VHF 3 system (or through the SATCOM system if installed).

Gate Link

The system allows a connection between the Aircraft Information Network System (AINS) and the airline ground based information system.

Its description is made in the Description/Operation of the AINS (Ref. 46-11).


Air-to-ground calls
When a call is initiated by an airborne subscriber, the AES sends signals to the GES, using the Rd-Channel. When the GES receives the call request, it assigns a pair of C-Channels, for a voice call, or reserves time on a T-Channel, for long-duration data transmissions. The call can then go through.
The assigned channels are reserved for as long as the call is in progress. The sequence used to initiate the call is automatic and transparent to both the originator and the receiver of the call.


ALSO......looking at the Power distribution schematic of this a/c everything essential is always powered (thats why its called essential)......


Cutting to the chase.....I am looking at these units......


Electrical Contactor Management Unit (ECMU)

The system consists of two separate equipment called ECMU1 and ECMU2.
Their functions are similar but the ECMU1 manages only side 1 contactors and ECMU2 manages only side 2 contactors.

Each ECMU receives the following signals:
-
orders from the GCUs and the GAPCU,
status of the main AC and DC generation contactors,
voltage of the main AC and DC busbars.

The two main functions of the ECMU are:

Operational function:

control of the AC/DC main contactors,

control of the galley shedding,

on ground, control of the transfer between the various electrical power sources (IDG, APU, EXT PWR) in order to avoid any break of power (NBPT),

control of AC/DC ground service busses,

control of Inadvertent Paralleling Trip (IPT).

BITE function

monitor and test the ECMU together with its peripheral circuits,
collect the failures and store the corresponding fault code in the Non Volatile Memory (NVM),

transmit the failure message to the Central Maintenance Computer (CMC) through an ARINC 429 bus.


In addition, in case of ECMU failure, a fault warning message is generated to the Engine/Warning Display (EWD).

Transfer circuit

The Bus Transfer Contactors (BTC)s and the System Isolation Contactor (SIC) are automatically controlled by the ECMUs. They enable supply of all the aircraft electrical network or half of it.
The supply only depends on the availability of one of the five power sources: GEN1, GEN2, APU GEN, EXT PWR A and B.
The control of the BTCs also depends on the availability of these sources and the correct condition of each network.

Operation of BTC1

The BTC1 closes, if no interlock conditions exist on the GCU1:

when the GEN1 is not available, in order to supply the network 1 (AC BUS 1) from another power source (GEN2, APU GEN, EXT PWR A or EXT PWR B),

to supply the network 2 from GEN1 if the GEN2, APU GEN EXT PWR A and EXT PWR B are not available.

Operation of BTC2

The BTC2 closes if no interlock conditions exist on the GCU2:

when the GEN2 is not available in order to supply the network 2 from another power source (GEN1, APU GEN , EXT PWR A or EXT PWR B),

to supply the network 1 from the GEN2 if the GEN1, APU GEN , EXT PWR A and EXT PWR B are not available.

Latching logic of the BTCs

The BTC1 is latched open if a "GLC1 welded" failure or a short circuit not clarified by C/B tripping occurs at level of GEN1 channel.
The same latching logic is used for BTC2.

System Isolation Contactor (SIC)

The SIC closes automatically:

when the GEN2 and EXT PWR A are not available and APU GEN is available in order to supply network 2 from the APU GEN,

when the GEN1 and APU GEN are not available and EXT PWR A is available in order to supply network 1 from the EXT PWR A,

when the GEN2, APU GEN, EXT PWR A are not available and GEN1, is available in order to supply network 2 from the GEN1,

when the GEN1, APU GEN, EXT PWR A are not available and GEN2, is available in order to supply network 1 from the GEN2.

Priority order of power supply

Each network (1 or 2) is supplied in the following priority order:

1XP = IDG1/APU GEN/EXT PWR B/EXT PWR A/IDG2,
2XP = IDG2/EXT PWR A/APU GEN/EXT PWR B/IDG1.

Isolation of the two sides

The isolation of the two sides is possible by action on the BUS TIE pushbutton switch. This control is located on the ELEC control panel 235VU, cockpit overhead panel.

No Break Power Transfer (NBPT)

This function is managed by the ECMUs. It prevents busbar power interruption due to electrical power supply source transfer on ground in normal configuration.
The ECMU receives information from the main AC contactors, each GCU and the GAPCU, to perform this function.
No break power transfer occurrences are permitted between:

any external power and the APU generator,
any IDG and any external power,
any IDG and the APU generator.

Distribution

The alternating current distribution network comprises two independent sections.

Network 1

Network 1 mainly includes the AC BUS 1, the AC ESS BUS and the AC SHED ESS BUS which are three-phase, 115 VAC/400 Hz busses.
The AC BUS 1 supplies the essential busses in parallel. The AC ESS BUS also delivers 26 VAC/400 HZ power supply through a 115/26 VAC transformer.
In the event of the AC BUS 1 loss, the AC ESS BUS and AC SHED ESS BUS are automatically restored by the direct transfer of power supply from the AC BUS 2.
In case of loss of the AC essential busses, FAULT legend on the AC ESS FEED pushbutton switch comes on : this P/BSW enables to transfer the AC essential busses supply from AC BUS 1 to AC BUS 2, in particular when the loss of the AC essential busses normal supply does not result from AC BUS 1 loss.
If there is loss of AC BUS 1 and AC BUS 2 (emergency configuration), the AC ESS BUS and AC SHED ESS BUS are restored via the CSM/G driven by the Green hydraulic power. In case of RAT operation, the AC SHED ESS BUS is automatically shed.

Network 2

Network 2 comprises the AC BUS 2 which is a three-phase, 115 VAC/400 Hz bus.
The AC BUS 2 also delivers 26 VAC/400 Hz power supply through a 115/26 VAC transformer.

I somehow do not agree with so-called assumption of "short circuit" starting this chain of failures.......I think the only way it can be done is by crew intervention (eg turning the wrong BTB p/b off) and stop the serviceable bus feeding the u/s Bus.....which in turn will start the sequence of power failures to these computers......

Still trying to figure out.........any A330/340 guys would like to add????

[john_tullamarine]

Due to the sensitivity of the matters in discussion, I would like for all of us to keep the sensational and overtly speculative things in R&N or other suitable places.

Technical-related considerations are fine here.

So far as the weather at the time ... and, for those who are interested, you might like to read Tim Vasquez' analysis of the weather (http://weathergraphics.com/) - hyperlink at the top of the home page.

Makes for very sobering reading.

As we all understand (I hope) the Design Standards and the certification process consider a very wide range of reasonably expected circumstances. However, Mother Nature can still cause a few tricks to be pulled out of Pandora's box ...

[muduckace]

Have heard on "good and reliable" authority:

"Aircraft hit CB...experienced +/- 100 knot windshear. Autopilot disconnected ...Power failure to screens...Airframe breeched...Rapid decompression...Followed by flight control losss......Entire event 14 minutes"

Must have been a long 14 minutes !!

Not really a long 14 minutes necessarily, the rapid decompression at the probable max operating altitude to fly over weather like this was probably violent enough to knock most people out rather quickly.

The distance of the debris field will suggest at what altitude the airframe breach occured giving insight into how long most were consious.

[aveng]

with all its PRIM's and SEC's working would not allow it to reach that situation

When you have lost the Prims and running on secs all bets are off (and most control law protection).

Interesting about the reported "electrical" failures, as the satcom (probably outside vhf range) and data link atsu were still working, ie. must have still had ac power.

[Capt Pit Bull]

ALSO......looking at the Power distribution schematic of this a/c everything essential is always powered (thats why its called essential)......

Caveat: About the A330 I know nothing.

OK, in general terms aircraft electrical systems are designed to fail in such a manner that the core of the system is maintained. i.e. battery for essential DC and an inverter for essential AC. Pretty much every aircraft I am familiar with has something like that sitting in the middle of the system, to give you half an hour or so to either get a gen going or land.

Then we add some emergency power generation, maybe a RAT, or a hydraulic driven Gen, to allow us to fly indefinitely, albeit substantially degraded.

Then we add an APU gen, which, depending on the flight envelope and type will be able to run a good chunk of the aircraft.

Then we have the main engine gens that run the whole shooting match when all is well.

Obviously theres lots of variations on the theme, but when you get right down to it most modern electrical systems are conceptually identical.

As such we tend to get into the habit of assuming the system will fail in a manner its designed to cope with. Like in the Sim. Ho hum... an engines failed. Better start that APU. Oh dear... the other main gen has failed... what an annoying coincidence. Good job we started the APU. except... bummer, thats failed as well. Now we're down to some scrawny Gen spinning off a hydraulic pump or something. And wouldn't you know... its failed as well, leaving us at battery power. Time to land ASAP etc etc..

But real failures aren't always as cooperative. In 25 years of flying, apart from the occaisional gen failing, the only time I've seen a really nasty electrical problem, the bit that failed was the core of the system.

The essential buses fell over, taking with them either directly, or indirectly (because those core buses supply the relays and indications for large chunks of the rest of the systems) pretty much everything on the aircraft.

I forget exactly what we were left with, but it wasn't much. The first officer's instruments were ok, and a couple of conventional navaids. But we had no hydraulics, no other flight instuments (both mine and the standbys were dead), no intercom, we had a radio each but both audio management panels were dead. Pretty much every other gauge or indicator in the flight deck was dead.

The only saving grace of the whole situation was - thank god, because it was a grobbly day and the F/O had hardly any time on type - we hadn't taken off yet. We got the tug to stick us back on stand and left it for the Engineers!

The situation we'd seen had not been covered in grounschool, the sim, and there wasn't even a checklist for it.

The point of this story? Electrical systems can fail from the inside outwards instead of the other way round. The fact that one of the main buses is still powered is no gauruntee that the really crucial stuff is healthy.

pb

[dessas]

1. Why, if ACARS was transmitting (AC power still available), there was no radio transmission on Guard?
It is a well established fact that there was at least 1 a/c (LH) within VHF range... The Germans (as opposed to pilots from some other nationalities) would definitely listen on Guard, especially in a remote area. In any emergency the PF (he takes over comms as per Airbus procedures) should make the "Mayday" call asap or if directed by ECAM (red LAND ASAP).
2. My company has some reasonably new Airbuses and even though they are not equipped with the manual ELT activation switch, I am 99% sure the AF a/c had this installed... Why didn't anybody manually activate the ELT? Monitoring stations around the World need only a few seconds of transmission to triangulate the position, and also the ELT might have (depending on model installed) transmitted it automatically... Can anybody enlighten us on the AF procedures regarding manual ELT activation from the cockpit? Please?

[Mad (Flt) Scientist]

The problem with either a MayDay or ELT activation is that they don't actually help right now while everything is going to Hell. They had their hands full (and then some, I suspect) doing the "Aviate" part of the response - "Communicate", especially where they were a long way from help, shouldn't have been anywhere on the priority list.

[Mad (Flt) Scientist]

Also, I'd note that the new, clean, thread in R&N has a good and legible version of the ACARS messages, and while I'd echo the statements made there that we don't know enough about the details (yet) I will note that not one message is ATA 24 - Electrical. Which seems to at least make the various electrical power failure scenarios less likely at this point. (Indeed, that thread has become almost TechLogish right now)

[dessas]

The problem with either a MayDay or ELT activation is that they don't actually help right now while everything is going to Hell. They had their hands full (and then some, I suspect) doing the "Aviate" part of the response - "Communicate", especially where they were a long way from help, shouldn't have been anywhere on the priority list.

I do not agree with your opinion. There are some common sense issues here.
"Avigate, Navigate, Communicate" The priority is well defined, but not in regards to a "MAYDAY" call, that is straightforward and we do it in the sim every 6 months!

To me the answers/speculation on the 2 questions I put are absolutely significant in building the total picture. I keep thinking over the last 24 h waht would prevent me from doing the MAYDAY call. What would prevent you? The PTT is on the sidestick, you know...
:sad:

[kwachon]

dessas

Whilst I agree a Mayday or ELT activation would be nice, and the PTT is right there on the sidestick, we do not know if the radios were tuned to guard, I suspect there was plenty going on around them that precluded setting up a frequency on the radio. Even tx-ing blind on whatever frequency they were on might not be heard if as is thought, they were in an area of an electrical storm.

Just my two rupees worth.

KW

[dessas]

As far as I am concerned in remote areas w/o VHF coverage VHF1 is set on Guard, VHF2 - IFB (123.45 or 126.9) and VHF3 ACARS.
So a MAYDAY call is REALLY straightforward...
VHF is not affected as much as HF by thunderstorms.
The ELT manual "on" is on the overhead panel right next to APU Fire push-button or somewhere thereabouts...
:sad:

[kwachon]

dessas

Whilst I appreciate your reasoning and the settings on the radios, as I understand it, events started to evolve shortly after the last radio contact. I suspect the flightdeck was somewhat chaotic and events overtook the norm.

KW

[ttcse]

Try to think of other accidents and recall whether there were 'Mayday' calls that weren't a request for ATC services but were a simple announcement of the situation. I can think of a couple off the top of my head where no calls were made.

I can entirely relate to 'no Mayday call' from an emergency I had in a smaller plane with just a few passengers. The scenario is you have a crisis in the cockpit, you need to hustle and solve the situation that appears to have the upper hand over you. You really can spare no thoughts or movements that don't address the situation. You realize a Mayday call brings you no benefit whatsoever and the needs an desires of prospective listeners are their problem, a lack of understanding on their part becomes no concern to yourself.

Furthermore, we're all aware of how car-drivers get distracted when using their cell-phones. Spending too much time on the radio, splitting your mind cycles between flying and talking, will tend to reduce your critical emergency handling performance.

[MrFixer!!!]

Capt PitBull,

I agree with you on the failures never seen before.....But we should never forget that here we had fully operational a/c in cruise with no reported failures.....and the chances of an Essential bus collapsing before a fully serviceable AC Bus is extremely rare,

Which Aircraft you had those failures on???

I know A320s were very susceptible initially but then Airbus came with mods to rectify those problems and in the A330s these were dealt with right from the beginning,

I have only ever seen a major electrical failure on A330 was after both engine startup the AC Bus1 and AC Bus 2 wont tie up.......fault came down to ACMU and BTB.......but still not accepting the fact that how can it just fail on its own and probing in detail led to a very interesting finding.....Aircraft on stand was powered by the Mobile GPU and not by the external power.....and just by reading the frequency meter showed that the generator on this particular unit was generating AC with frequency jumping all over the place which was the extremes of limits......and Aircraft systems however powered were put into max stress and just after engine start both computers gave in.......

There is always a reason for everything........we can only help by learning from these things!!!!!

[MrFixer!!!]

Mad (Flt) Scientist,

With no message related to ATA 24........goes back to contradicting everything which was mentioned everywhere right from the beginning....that a severe lightening strike caused a "short circuit"........wonder where all this info comes from?????? People imagining things....

[mini]

"For example, on a 747 the throttle is pushed by hand. You feel it move in turbulence. On recent Airbuses, this throttle is fixed. You look at the dials. You don't feel anything."

This is an extract from a Reuters news article. Can someone please explain why the 747 throttle levers move during turbulence?

Genuinely curious, why would turbulence effect throttle position? is it down to a pre-set thrust or speed requirement?

Cheers, mini (obviously a non driver)

[DC-ATE]

The throttles (thrust levers) on the 747 will move IF the auto-throttle is engaged. And, if you're in turbulence, the airspeed will be fluctuating quite a bit.

[wiggy]

mini

Very basically the aircraft's autothrottle is "programmed" to fly the aircraft at a certain speed..as DC-ATE has said in turbulence the aircraft's speed could be varying quite rapidy as the headwind/tailwind effecting it changes. The result is the autothrottle will be changing power to try and maintain the programmed speed. On most, if not all Boeings, that in turn means the throttle levers physically move fore and/or aft to reflect the power changes demanded by the autothrottle.

[Handy_Man_01]

A summary of the final messages from Flight 447 is as follows:

(AP) French and Brazilian officials have described a "burst" of messages
from Flight 447 just before it disappeared.

A more complete chronology was published Wednesday by Brazil's O Estado de
S. Paulo newspaper, citing an unidentified Air France source, and confirmed
to The Associated Press by an aviation industry source with knowledge of
the investigation:

_ 11 p.m. local time — The pilot sends a manual signal saying the jet was
flying through CBs — towering cumulo-nimulus thunderheads.

_ 11:10 p.m. — A cascade of automatic messages indicate trouble: The
autopilot had disengaged, stabilizing controls were damaged, flight systems
deteriorated.

_ 11:13 p.m. — Messages report more problems: The system that monitors
speed, altitude and direction failed. The main flight computer and wing
spoilers failed.

_ 11:14 p.m. — The final message indicates a loss of cabin pressure and
complete system failure — catastrophic events in a plane that was likely
already plunging toward the ocean.

[BOAC]

Handyman - a loss of cabin pressure and
complete system failure — catastrophic events in a plane that was likely
already plunging toward the ocean. - do you have some information that we do not? Where do you see the loss of cabin pressure?

[milsabords]

Hi,

Right now a BEA press conference is broadcast on France 24 TV channel.
If skilled members of this forum could watch it they might gather useful information.

Cheers !

[Thermal Rider]

Something that boggles me is that in todays news they are hinting towards pilot error for stalling the airplane, which does not make sense as these airplanes have alpha floor protection ( stall Protection) which with all its PRIM's and SEC's working would not allow it to reach that situation.

If Airbus flight control is in "alternate law" mode, alpha floor protection is lost.

[Thermal Rider]

ACARS Messages
A summary of the final messages from Flight 447 is as follows:

A detailed and relatively complete overview of ACARS messages and some conclusions are on the AF 447 wikipedia page in the automated messages section.

[vanHorck]

Tim Vasquez has posted a fantastic weather analysis for the AF744 flight here Air France 447 - AFR447 - A detailed meteorological analysis - Satellite and weather data (http://www.weathergraphics.com/tim/af447/) . At the same time some pilots have posted observations of temps within cells climbing with 30 degrees within seconds and on the R&N live thread this is currently being discussed.

I have asked Tim his opinion on the likelyhood of this and below is his reply. Unfortunately I am not able to post on R&N, perhaps pilots reading this thread may wish to report it there.

Sorry for the thread drift. I felt it was necessary given the circumstances.

I do not agree that a bubble of warmer air (that is, any warmer than about
5 degrees compared to the environmental air) would have made it up
to flight level. This requires exceptionally high equivalent potential temperatures at some
lower altitude. The atmosphere has a tendency to overturn bubbles of hot air as soon as they
start becoming significant because "absolutely unstable" lapse rates are unsustainable.
We do see thunderstorm heat burst phenomena on the Great Plains at night, but this occurs due to
the downward forcing of a low-level inversion, and I can't picture a mechanism for
this to occur at flight level given the conditions shown.
But in regard to the above mention of an aircraft's "coffin corner"
(<a href="http://en.wikipedia.org/wiki/Coffin_corner_(aviation)">Wikipedia</a>) it is
possible that wind values alone could greatly affected airspeed -- on Doppler radar we often
see anomalies of 40 to 80 kt at flight level within storms (Google "storm top divergence" for
some examples).

Tim

[vanHorck]

Thank you flybywife for reposting, it was at the recommendation of a mod that I asked the question

[Fly-by-Wife]

Hi Van Horck,

Yeah, I read Tim's piece and thought a lot of it, so I thought his reply to your question should get an airing on the R&N thread.

Dunno how lon it'll last though - the mods seem pretty hot on deleting stuff! :{ Gets a bit confusing sometimes when you read somthing that makes seems to make sense and when you go back it's gone!:eek:

What did you do to not be able to post on R&N?

FBW

[john_tullamarine]

R&N is subject to some control at present to keep things on an even keel. If the discussion is more technical, you might find it easier to run the information in Tech Log.

[vapilot2004]

@Handyman - cc:BOAC

The loss of cabin pressure message is incorrect.

According to a former A330 engineer, the ACARS data that was posted on French TV translates to the cabin pressure controller logging a warning/fault to the CMS of the aircraft altitude catching the cabin altitude.

[ComputerCynthia]

Quoting: Gergely Varju (http://www.pprune.org/members/274724-gergely-varju)
It is quite different to fly above the storms, and measure the pressure in the eye, I think that impression of hurricane hunters should be set right. It's incorrect to think the planes in the hurricane hunter fleet merrily "go over" the storms of a full hurricane. The planes are limited by physics like any other, even if they might have more power for their weight and so on. They're not trying to avoid the "bad" weather. They go in low to study it. But if you want an account of why only hurricane hunters fly into storms. Forgive me if it's been seen before.
Hunting Hugo : Weather Underground (http://www.wunderground.com/education/hugo1.asp) (an account of flying into Hugo)
As Seen It All said, it's not a mission where they go out to take crazy risks. It really is a mission for those pilots and they're not going to go out there to risk the plane or the people anymore than a commercial pilot would like to. (but they will get into close scrapes as per the account above.)

[Joss]

Aircraft altitude catching cabin altitude? Let's see If I understand this right: The airplane was descending so fast it went through cabin altitude before reaching the water?

Whats the max rate for the cabin press system?

I guess you see where we are going.. isn't it?

[Checkboard]

Tim Vasquez has posted a fantastic weather analysis for the AF744 flight ... At the same time some pilots have posted observations of temps within cells climbing with 30 degrees within seconds ...

"I do not agree that a bubble of warmer air (that is, any warmer than about 5 degrees compared to the environmental air) would have made it up to flight level. This requires exceptionally high equivalent potential temperatures at some..."

While I don't doubt Mr. Vasquez's credentials, and I know he is being quoted third hand here, perhaps people should read the report on the four engine rollback of VH-JJP which was investigated in 1992 in Australia:

The aircraft was on a scheduled domestic passenger service flight from Karratha to Perth at Flight Level 310 (31,000 ft). As the aircraft entered cloud while diverting around a large thunderstorm, there was a sudden and significant rise in the outside air temperature. A short time later, all four engines progressively lost power and the aircraft was unable to maintain altitude. During the next 17 minutes, numerous attempts to restore engine power were made without success until, approaching 10,000 ft altitude, normal engine operation was regained.

Appendix 1 of the report contains the Meteorological research of the warm air outflow from the top of the thunderstorm which caused the event.
The report is here:
www.atsb.gov.au/publications/investigation_reports/1992/AAIR/pdf/aair199200286_001.pdf

[BOAC]

It may be of interest to other jet pilots, so I reproduce here a relevant passage from Checkboard's and Yaw String's posts regarding 'warm air pools' - a new concept to me. It does not offer any advance on all the 'computer' glitches, I fear, but may explain the TAT changes quoted on various threads. It is from Appendix 1 to the report quoted.

The phenomenon is almost certainly the result of folding of stratospheric air back into the troposphere with concomitant warming as it descends. The most likely mechanism for this to occur is strong convection (and for the pilot, strong returns on his weather radar). It is reasonable to assume that, where there is strong thunderstorm activity, there is a fair likelihood that an area of anomalous warming will be present somewhere around the storm cell. The vertical extent of the anomaly is difficult to ascertain and is probably dependent on the strength of the outflow from the storm and its interaction with the environmental flow, but in this case, with the tropopause at 41000 feet, observations from the aircraft indicated that the warming stopped abruptly at 28000 feet. The horizontal distribution of the anomaly is most likely to be oncentrated in a zone of confluence between the environmental flow and the thunderstorm outflow, as that would be the area where maximum descent was occurring, associated with the largest perturbation of the tropopause. In this case the anomaly took place on the western flank of the main convective activity. It is unlikely that any anomalous warming would have occurred on the eastern side of the storm as there would have been no confluence and no tropopausal perturbation. The temperature anomaly was observed over a horizontal distance of approximately 60 nm. By comparison, the incident in 1979 took place within a distance of near 40 nm. It is appropriate to relate some of the pilots’ comments here. His normal practice (and it is understood that this is standard practice) when diverting around radar echoes was to ensure a buffer of 10 nm between the radar echo and the aircraft. As an extra safety margin on this occasion he diverted 30 nm from the strongest echo and in doing so encountered the phenomenon. Perhaps this is a reason why it is not encountered regularly by aircraft - most pilots (in maintaining the normal 10 nm buffer) may travel between the anomalous zone and the thunderstorm. It is estimated that in the ncident associated with tropical cyclone Kerry in Queensland, the aircraft encountered the temperature anomaly about 40 nm on the western flank of the main convection area. The BAe 146 pilot also commented that he had been flying in an area of innocuous radar returns - visible as a “green fuzz” on his radar screen. He noticed that the warming commenced as they flew along the boundary between the weak returns and the clear air. It is suggested that that boundary was an indication of the delineation between air masses of differing characteristics. Another interesting comment was that prior to the incident there had been an incredible display of St Elmo’s Fire, the best that he had ever seen. Whether this was a precursor to this type of event or merely coincidence is conjectural at this stage.

Disregarding, of course, the type involved etc etc, it is significant that the apparent rise in SAT caused a large degredation in the altitude/weight capability of the engines.

[safetypee]

Re: the serious “a sudden and significant rise in the outside air temperature” (#608 R&N) and above.
Subsequent to the Australian report, the majority, if not all of the temperature rise was shown to be an apparent rise due to a frozen TAT probe – the probe indicated the ice temperature and not that of the atmosphere.
Following several other incidents BAe/Honeywell conducted tests in and near large Cbs to investigate the engine icing problem. As a result, the affected engine variant was modified.
The initial flight tests showed that the problem did not per se occur in the tops the Cbs, instead it was the water/ice concentrations in the out flow of these large storms (in the anvil) which presented a threat over a large area. The analogy is of smoke spreading out from a chimney.

The erroneous TAT in BAe146 aircraft was not deemed a significant risk. IIRC there was only an input to the TMS takeoff mode and a temp display in some FMS variants. Thus, the problem was documented and risks agreed with certification authorities; all engines were modified by AD.
At that time the industry did note similar problems with engines and TAT/pitot probes in other aircraft types, but (at that time) the safety concerns were not significant, certainly not in the same category as the multiple engine ‘rollbacks’ with the 146.
The TAT problem persisted, but industry follow-up identified differences between probe manufacturers and probe design, i.e. aspirated / non- aspirated versions.

I suspect that TAT is used in many modern computations and hence there are multiple sensors. Assuming that individual sensors do not ice at the same time / rate then disparities in temperature or in the parameters using TAT could trigger comparator alerts or even system lockout through data disagreement.
Many of the reported ACARs messages appear to represent this type of problem.

[BOAC]

sp - "the probe indicated the ice temperature"- thus you are saying that ice that forms at -39C will be at a significantly higher temperture? I'm familiar with L Heat release at state change but cannot see how this can be? Surely also the measured TAT will decrease if the probe ices since there will be less airflow to 'halt'? We are looking to explain an overall 20deg rise or so.

Can someone remind me how/where SAT is derived on a/c? I've had a 'blank moment':)

[Checkboard]

Subsequent to the Australian report, the majority, if not all of the temperature rise was shown to be an apparent rise due to a frozen TAT probe – the probe indicated the ice temperature and not that of the atmosphere.

I wouldn't mind seeing a citation for that statement, as it's the first I have heard it applied to the 146 case. You're not interpolating the Airbus AD backwards, are you?

[purr]

any idea on how much the tops of CB's would be above the cruise lvl of the a/c
and was the wx radar collins or bendix

[BOAC]

If you've missed it, this (http://www.weathergraphics.com/tim/af447/) is as thorough as I have seen yet.

[Checkboard]

sp - "the probe indicated the ice temperature"- thus you are saying that ice that forms at -39C will be at a significantly higher temperture?
BOAC, I think that the theory is that the probe is heated, but not enough to handle the conditions. As the ice forms (at the atmospheric temperature, plus a bit of latent heat from the state change), that ice is then heated by the heating element of the probe.... or something like that.

Can someone remind me how/where SAT is derived on a/c?

The Rosemount SAT/TAS probe. (http://books.google.co.uk/books?id=KY-MBUeQoZEC&pg=PT250&lpg=PT250&dq=Rosemount+SAT/TAS+probe&source=bl&ots=cMYpXnWUWR&sig=W00w1S5MUV4y7fr2VVc8p-CdEgw&hl=en&ei=2hstSv2ZDZGUjAfqhoGACw&sa=X&oi=book_result&ct=result&resnum=5#PPT251,M1)
http://mozaic.aero.obs-mip.fr/web/features/information/overview/mainColumnParagraphs/08/image/inlet.jpg
(The lower sensor is the Rosemount probe housing - the other is an ozone detector, for the MOZAIC programme.)

[TripleBravo]

Concerning one of the last ACARS messages,
WN0906010214 213100206ADVISORY

Here's an excerpt of the A332 AMM about the Cabin Pressure System, I shortened some paragraphs:


B. Cabin Pressure Controller


(1) [...]

(2) Internal Pressure Sensor



The cabin pressure sensor within the pressure controller 311HL (312HL) is of a vibrating cylinder type. The principle is, that a physical body vibrates at its natural frequency with high stability under constant environmental conditions. The frequency of oscillation of this system is a function of materials and shape of the cylinder. The frequency depends on the environment, specifically temperature and pressure surrounding the cylinder. Therefore, the frequency can be used as a reference value of the pressure.

(3) Warnings



The cabin pressure controllers send the subsequent warnings to the System Data Acquisition Concentrators (SDACs) or the Flight Warning Computers (FWCs):
- excessive cabin altitude (EXCESS CAB ALT),
- outflow valves not open (FWD OFV NOT OPEN, AFT OFV NOT OPEN),
- low delta p (LO DIFF PR),
- safety valves open (SAFETY VALVE OPEN),
- system fault (SYS1 FAULT, SYS2 FAULT or SYS 1+2 FAULT),
- fault of the landing-field elevation selector (LDG ELEV FAULT).

(a) Excessive Cabin Altitude



If the pressure in the fuselage is less than the atmospheric pressure between 9550 ft. (2910.78 m) and 14350 ft. (4373.79 m) (depending on the airport altitude):
- the automatic circuit of the cabin pressure controllers 311HL and 312HL sends a signal to the SDACs and FWCs,
- the manual backup circuit of the cabin pressure controller 311HL also sends a signal to the SDACs and from there to the flight warning computers.

(b) Outflow Valves Not Open

[...]

(c) Low Delta P/High Descent

This shows that the aircraft will have a negative differential pressure if the descent rate is continued and that a negative pressure relief will occur. The signal is sent from the automatic part of the cabin pressure controller 311HL or 312HL 1.5 minutes before the external pressure is the same as the pressure in the fuselage.

(d) Safety Valves Open

This warning indicates that at least one of the safety valves is open. Therefore the differential pressure between cabin and atmosphere is to high and can cause damage to the aircraft structure. The cracking point of the valve (and thus the maximum differential pressure) is at approximately 610 mbar (8.84 psi) .

(e) System Fault

If there is a general fault in the CPC system, the respective warning (SYS1 FAULT, SYS2 FAULT or SYS 1+2 FAULT) comes on the ECAM.

(f) Set-LFES

[...]



The ATA2131 advisory message is not specified in detail what the problem really was. This creates some possibilities, that are (or are not) discussed up to now:
excessive altitude of cabin pressure (lead to speculation about fuselage break up)
excessive aircraft descent rate taking over cabin pressure (lead to speculation about deep dive)
safety valves open (not yet discussed)
system component fault (not yet discussed)BUT: The measurement method to the second point, excessive aircraft descent rate, is to calculate the difference of the measured values of
cabin pressure – measured by Cabin Pressure Sensor located in the e-bay below the cockpit
static outside pressure – measured by the Static Ports and gathered by the ADIRUs=> If the Air Data part of the ADIRUs is delivering erroneous data, the delta-p warning can be triggered without any physical facts behind.

=> No hard evidence of mid air break-up
=> No hard evidence of steep dive

[vanHorck]

Thanks Bert,

I have posted an update on the AF447 page clarifying my position
on the warming theory based on some new data. You may feel
free to relay this in whole if you wish. Hopefully it helps the
discussion.

Tim

On Mon, 8 Jun 2009 08:36:17 +0200, Bert van Horck wrote:
Dear Tim,


I have posted your comments on the open AF thread on the PPRUNE
forum. Several pilots have nevertheles come forward after this
posting confirming they have had temperature rises of in excess of
20 degrees C within Cb's.


Kind regards,


Bert

[BOAC]

The lower sensor is the Rosemount probe housing - I have always seen that as a TAT probe (probably aspirated) and the brain fade I am having is in remembering from 400 years ago where SAT is measured.:) In any of these supposed 'warm air' events, surely the clue would lie with the displayed SAT, not TAT? If that has increased too, then the air is warmer, if only TAT has increased.....?????

[Fly-by-Wife]

Bert -

A further mail from Tim Vasquez
You may feel free to relay this in whole if you wish. Hopefully it helps the
discussion.

Done

FBW

[safetypee]

Checkboard “…interpolating the Airbus AD backwards…” absolutely not; the BAe/Honeywell work preceded the concerns on the ‘big jets’.
Links to the science relating to the TAT probe freezing are in http://www.pprune.org/tech-log/375784-pitot-icing.html#post4963257 ; most of this relates to engine core freezing, but the mechanism and atmospheric conditions are similar if not identical, for certain TAT probes.

BOAC, et al, as the TAT probe freezes the indicated temperature increases toward zero - ice temperature in a static airflow; because the airflow is blocked. The atmosphere - ambient air temperature is still cold.
In engine rollback incidents the TAT increase was a preceding or confirming characteristic seen on the FDR in the vast majority of events. Conversely there were TAT rises without engine malfunction. ( See slide 8) (http://icingalliance.org/collaborations/documents/Strapp_Engine_Icing_Project_2007.pdf)
In the very unusual conditions associated with large Cbs (probably only those which penetrate into the troposphere), the area in and around the anvil contains large quantities of minute ice crystals and often a high super cooled water content. In these conditions the TAT probe heater is progressively overcome by the high negative heat flow – melting ice crystals and water-flow off, such that further ice crystals accumulate in the probe throat (behind the heater). The melt water acts as glue for the ice crystals until the probe becomes blocked. IIRC the effect has been demonstrated in an icing tunnel.

With respect to the AF accident, it is of interest to establish how the various sensors use ‘temperature’, and particularly where there are multiple TAT inputs, how the systems (ADC/ ADIRS, Cabin, Rudder Lim) might cope with different values.
Assuming that multiple probes do not freeze identically; there will be different TAT values.
In a dual system, comparison can provide a comparator warning (systems still operative). However, with a triple input it may be possible to vote out an erroneous value; except in this instance the odd-one-out might be the true value and the voting system may have capability to shut down a ‘good’ system i.e ADC/ADIRS, etc.

Another issue is pitot icing. If the pitot system is also susceptible to icing in the same conditions, then conventionally the pressures existing at the time of blockage will be trapped. Thus there is no change in any of the input parameters with icing – whereas TAT will change with probe icing.
However, is has been suggested that the A330 pitot systems have a small leak path (drain) which will result in a pressure reduction to ambient (decreasing or fluctuating IAS). Thereafter the issues of value comparison and shut down are as above.

[Will Fraser]

A bit premature on 447, but with the image of the complete R/VS assembly and the aerodynamic failures associated with its loss, the topic may be timely now. "Donated Failure". We have been addressing this concept for some time at my firm. Consider "crumple zone" where energy is dissipated by sequential failure of linear structural assemblies. "Ablative Cooling", where temps are dropped by sacrificing material in its melting or burning; "anomalous design" where systems have different capabilities but solve the same problems, Airbus and its "three different computers".

In Brief, if AA 587 had suffered a loss of its Rudder instead of the Rudder/Vertical Stabiliser together? Perhaps, though not demonstrable for AF447, the same?

A Rudder is a trimming device. Without it, flight is difficult but survivable. Without a VS, the game is over.

Had 587 been equipped with design limited hinges on its Rudder, well, you get the picture?

MD11 at Narita. Way too strong MLG and NLG caused the last bounce (when the NG failed to break off) and the subsequent "landing" on the mains, which broke both wings (but the gear "survived" on the right).

AF 447 may have had other issues, but if the VS separated first, instead of not at all (with a "donated failure" of the Rudder), ?? Will have to see.

[Checkboard]

as the TAT probe freezes the indicated temperature increases toward zero - ice temperature in a static airflow
A plainly incorrect statement - as it presumes that ice will be at zero (presumably Celsius) at any ambient temperature!!!

In any case - I am aware of the icing conditions and engine effects in the links you posted. You appear to think that that is the only possibility for engine rollback, and indeed dismiss high altitude temperature increases as misunderstood icing events. The science for high altitude warming is well understood - and there is no evidence that the JJP 146 event (certainly) was an icing event. Both events occur, both are rare.

[Grunf]

IMHO,

Structural failure as a cause of this accident is highly unlikely. Especially unfounded speculation(s) regarding the v/stab and rudder on Airbus articles.

A lot more then a mere picture would be needed to provide sufficient data to support this. Everything else is out of scope for the "real world" situations like fleet operations with thousands of cycles.

Cheers

[DC-ATE]

Regarding separation of the vertical fin:

The onboard computers that keep the pilot from 'overpowering' the rudder seem to get the job done while in 'Normal Law' on Airbus aircraft. But, when not in Normal Law for whatever reason, what indication does the pilot have to keep from exerting too much force through the rudder pedals to the rudder to keep it from departing the aircraft ?

[982500h]

I posted this question on another thread, but didn't get an answer. What model radar was Air France 447 using? The new digital Honeywell RDR-4000 is listed as an option on the A330, but I don't think the aircraft was new enough to have it. Does anyone know if Air France A330's are using the RDR-4000?

[982500h]

Why didn't anybody manually activate the ELT?

I didn't see a reply to this, but here's my simple take on this: The last thing you want when fighting for your life and asking for help, is to jam your radio. That is why military pilots are trained to turn off the parachute beacon ASAP. If you are transmitting on 121.5 (or 243.0), then you can't talk on it. If you can't turn it off (you're hurt or unconscious), then you want it to automatically turn on.

[Milp]

Hello everyone, this is my first post here, and i hope i got the right topic for this.

As seen recently in the news, there is a discussion about the un-overridable fly-by-wire technology in the Airbuses, compared to the overridable tech in the Boeing planes.

Now, most of you have a lot more experience in this topic than me, which is exactly why i am asking here.

Please correct me if i am wrong, but if i remember correctly, Airbus planes had (i think it was) three switches to disable all the flight support computers on board and override them manually.

Or am i really wrong on this one?

I'm just asking out of pure interest, would be glad if someone could help me with that issue :)

[dessas]

Sorry, but you are talking Vietnam war technology.
Modern a/c ELTs transmit on 406MHz which is nowhere near any voice band.
MAYDAY calls are made on 121.5MHz or any other available one. This is an ICAO approved procedure - not only a recommendation! And as stated before in post #22 in this forum, I find it utterly improbable and unacceptable that the crew didn't make it! I still believe that finding the reason for this will be a major contribution in establishing the cause for the disaster!
Pls do not mislead the uninformed...
:mad:

[ttcse]

I find it utterly improbable and unacceptable that the crew didn't make it! I still believe that finding the reason for this will be a major contribution in establishing the cause for the disaster!

Other flights where no mayday was made before they perished:
Perpignan A320
UA585 Colorado Springs
Continental Connection Flight 3407, Buffalo NY
EgyptAir Flight 990
AirFlorida flight 90, 1982
Copa Airlines Flight 201, 1992

They all had time to key the mike. No value, unaffordable, counterproductive. Perhaps if you ever have an urgent crisis you'll understand. Perhaps not.

Amoung those who did: (radio calls)
USAir 427, 1994, ("Oh [unintelligible] Oh [expletive]" and "427 emergency")
Alaska Air Flight 261, 2000, ("Mayday")

I ignored flights where they crashed just short of the runway in bad weather, and a number of others which crashed just after takeoff. It wouldn't be fair to you to add these.

[vanHorck]

Tim has posted a further update on his MET site http://www.weathergraphics.com/tim/af447/ with a specific request for assistance from the pilot community.

Could somebody report this on R&N please? I have no access to it. Thx Bert

Update / June 9, 2009:

Myself (Ed: TIM) and Scott Bachmeier at University of Wisconsin/Space Science and Engineering Center are requesting that airline pilots who observed a significant warming episode at cruise altitude within the past 10 years and know the exact date/time and approximate location please drop us an e-mail with the story and include your credentials (which will remain anonymous). Unfortunately we must have an exact date and time in order to research the event. I have received a number of anecdotes from pilots who report encountering the phenomena, and while neither of us see evidence yet which supports this occurring in the Air France 447 storm cluster we believe it's a good idea to research this further rather than just dismissing it at this point. We appreciate your help.

[DLKE]

Regarding a search for AF447 ACARS messages, i found anywhere
(do not know where), that there should be a guy that holds all
received messages complete.
Is there anyone here, that have these original, not reformated messages
and can send it via private mail and attachment ?
(Or giving a hint, where it can be downloaded...)

[Deaf]

Modern a/c ELTs transmit on 406MHz which is nowhere near any voice band.
MAYDAY calls are made on 121.5MHz or any other available one

ELT's transmit on 406 to talk to satellites for ID (and GPS if available) as per:

http://www.cospas-sarsat.org/DocumentsTSeries/T1OCT30.08_CompleteDoc.pdf

It also includes a 121.5 option

The US FCC (and a lot of others) require 121.5 transmissions as before (but at a lower power) for final homing purposes.

[PapaEcho]

Regarding a search for AF447 ACARS messages, i found anywhere
(do not know where), that there should be a guy that holds all
received messages complete.
Is there anyone here, that have these original, not reformated messages
and can send it via private mail and attachment ?
(Or giving a hint, where it can be downloaded...)

You can find a clean file in R&N thread, or you can look at my post in Italian Forum, under relevant Thread. By the way, the ACARS messages which can be found is only maintenance ACARS without position reports.

Regards,
PapaEcho

[PapaEcho]

Hi folks,
as you can see on EASA Airwothiness Directives section, under NON-MCAI, the European Authority have raised a Safety Information Bulletin (something like SAIB for FAA issue) regarding the Unreliable Airspeed Indications, where is required the operators and pilots to start assesment and recurrent training on Unreliable Airspeed Indications condition in order to identify and take corrective action as soon as experienced.

The direct link to this SIB is: EASA Airworthiness Directives Publishing Tool (http://ad.easa.europa.eu/ad/2009-17)

In my opinion this SIB is a good system to throw media and press attentions out from construcotr and, why not, authority too.
So, now, if the aircraft we fly is not equipped with a satisfactory stand-alone stanby system, the problem is the pilot not trained and the operators poor training about that. :D Thanks guys, I will log on my Logbook anytime I will experience this type of accident stating in the notes "My company not provide training good enough & I'm a dm'ass because I'm not well trainee to read indications from my completely unreliable and failed instruments" :=

PapaEcho

[FE Hoppy]

Can someone remind me how/where SAT is derived on a/c? I've had a 'blank moment'


Not sure if it's been answered as I'm just scanning the threads but SAT is calculated by the ADC as a function of TAT(measured by the TAT probe (when not iced up)) and Mach number(calculated by the ADC as a function of pressure(static and dynamic))

or at least that's what they told me when i were a lad.

[BOAC]

Thanks FE - that was what I thought, but I wondered if there was some canny little thermocouple somewhere out of the airstream.

[Blacksheep]

as the TAT probe freezes the indicated temperature increases toward zero - ice temperature in a static airflow

A plainly incorrect statement - as it presumes that ice will be at zero (presumably Celsius) at any ambient temperature!!!
You are evidently unaware of the physical construction of a Rosemount TAT Probe (http://www.freepatentsonline.com/7174782-0-display.jpg) and its heating system. The phenomenon of rising temperature is the result of the blockage of the air flow through the probe (and there is a flow - the air is not brought to a complete standstill) and subsequent heating of the detecting element by the probe's own anti-icing protection. It takes a lot of energy to raise the temperature of a probe that is air-blasted by air at -40C degrees C, to -5 degrees C, but with a blocked probe that is exactly what will happen. The ice will not penetrate into the sensor cavity and the sensor will be heated by radiant energy.

[kijangnim]

Greetings,
May the Crew and Passengers of this Flight Rest In Peace.
Why must we assume that it was ice that did provoque an unreliable Airpseed situation.
pitots and sensors are just calibrated tubes or holes, transmitting to the computors whatever is going through.
I think we could focus on the "whatever is going through"
If the recommandation to change the pitot tube had a sense of urgency, it would have been done OVERNIGHT :ouch:
Very often the Radar attracts Lightning, and is not the first time nor the last that the Radom will simply be blown away leaving a flat surface, which highly distrubs the Airflow to the pitots and probes, along with a big drag increase.
Severe turbulence CAN trigger flight controls to revert to DIRECT LAW (shake the controls in the simulator, and watch it happen) and all this happening in a giant storm.
It is easier to blame the technology and probably send the lawyers to try to get some juicy compensations :E, rather than looking at the reality and blame a Giant Thunderstorm. :=

[Graybeard]

"Very often the Radar attracts Lightning..."

Yeah, sure.

Like I told a line pilot once, "Oh, this is low power radar; it can't attract lightning." And that's the truth..

[kijangnim]

Greetings,
IONISATION is the attracting factor, not power.
:}

[patrickal]

SLF questions here. I am not a pilot, but have over 30 years in the IT industry, most of that focused on user interface. My questions are;

On the 330, when the autopilot disengages, how is that communicated to the crew? Also, from the same perspective, how is the transition from Normal Law to Alternate or Direct Law communicated? Is it possible that when the flight, possibly unexpectedly, entered severe turbulence, that one or more of those cues may have been missed?

[boeing75705]

audio warning, if it was disabled with a system fault. I agree with what you say but it still rises alot of questions but all answer at the moment are hitting a :ugh: because we can only base these issue on facts.

[Blacksheep]

Why must we assume that it was ice that did provoque an unreliable Airpseed situation.Because it has happened before. Try checking the reason behind the 2002 Airworthiness Directive and the more recent focus on upgraded Pitot Probes that had not yet been fitted to the accident aircraft.

Lightning damage to radomes is very, very common and the results are not dramatic. Just a series of small holes in the paintwork.

[gh0strider]

Lets not forget about the bright red Master Warning light flashing in front of your eyes...

[safetypee]

Re; “ Why must we assume that it was ice that did provoque an unreliable Airpseed situation ”

Supporting Blacksheep’s answer (#73, #79), see the presentation Instrument External Probes (www.sae.org/events/icing/presentations/2007s30duvivier.pdf).
For ref, the certification Appx C for icing is on page 126 of CS 25 Large Aircraft (www.easa.eu.int/ws_prod/g/doc/Agency_Mesures/Certification_Spec/CS-25%20Amdt%205.pdf), also see Fig 5 (page 182) and compare the events (outside the cert envelope) with the information on The Ice Particle Threat to Engines in Flight (http://airs-icing.org/AIRS_II/AIAAReno2006/AIAA-2006-206-739.pdf) and other similar references to engine problems which involved TAT anomalies.

The relevance of TAT freezing is as an indicator of the ambient conditions (temp/ice/water near large Cbs), also that the displayed temperature will always change (increasing temp).
Whereas with pitot icing the indications may not change unless altitude is changed (trapped pressure) or there could be fluctuating indications as shown in the first link. Thus there could have been many more pitot icing events which went unnoticed – and involve a range of aircraft types depending on the type of pitot probe and how the data is ‘managed’ before being displayed.

Also see The Ice Crystal Weather Threat to Engines (www.sae.org/events/icing/presentations/2007sopenmason.pdf) slides 7 & 19 - TAT anomalies & Appx C.

[falconer1]

well aware of the ice crystal - engine compressor icing debate..

would like to throw the following into the debate..

the weather has not changed that much in the last 50 years..

let's assume the atmospheric conditions described in these phenomena have been around for a long while..

Question: Could it be that we all are too cozy with all the new technology nowadays and fly closer to storms more often than in earlier times..???!!!

[safetypee]

falconer1 – “…we all are too cozy with all the new technology nowadays and fly closer to storms more often than in earlier times…”

Absolutely, Yes !
Investigations of several of the engine incidents (pre 2000) indicated that the fight crews, who had moved up from commuter / older aircraft, were using the ‘new’ digital radars without appropriate conversion training. Thus they flew in the ‘green areas’ closer to storm centres than they would have done previously.
Other crews, brought up on the new equipment showed some complacency. Avoiding a clearly defined storm edge on the WXR could be finessed; crews did not question if they had generated the picture correctly, nor that some storms are much more severe than others – ‘they forgot to be afraid’ (James Reason).
More recently the trend is reversing with the focus on turbulence, but even this is challenged with the economics of operation and airspace constraints.
IMHO crews lack deep knowledge of systems operation and limitations, particularly in relationship to the threat of weather – we all lack time for additional learning, and suffer to some extent from commercial pressure.

The atmosphere hasn’t change, except that perhaps we are flying higher and thus experiencing a different set of conditions (a little bit colder, a little thinner air, ‘just small changes’, etc).
Also, other aspects of technology have changed. Many of the ‘supercritical’ technologies have been applied to engine components and possibly probes; modern systems use smaller, fine tolerance parts, which proportionately might suffer ice (or other particle) contamination more readily. They may require higher standards of maintenance.

Like many aspects of safety, hazards originate from change, particularly when we don’t notice the changes.
What is disappointing in this accident is that it appears that many of the probe problems were known and the hazard severity identified even by the regulator, but the safety activities were not applied proportionately or in time.
No blame, just seeking an understanding from which we might learn.

[falconer1]

lest somebody thinks I get carried away with a very subjective view of the subject ( aren't we all??) let's not forget for our statistics guys...

we also fly A LOT MORE.. more planes more flights..

and all in all we are tons safer now..

maybe just a lot more critical if something happens..

so let's stay real..

a lot of superb guys & gals out there flying superb airplanes..

with a safety record, nobody would have believed possible a couple of decades ago...

[lomapaseo]

More and more our accident causal chains are containing man and machine interface issues.

We have less and less all machine or all crew issues as the primary cause (in spite of some folks that use probable cause in reports)

Yes the overall accident rate is decreasing since the paper I presented in 1992 but we still have a lot to learn about to how to live with the systems that we create.

As always we need to not only identify the causal factors but decide as an industry where and how to address those that are most common today

Do we improve the machine or the man since neither will achieve perfection?

[Putt]

Lomapaseo
Now you're talking. We will continue to improve the machines...but the interface to a human is THE critical component in the total performance picture.
I had this discussion with Al Smith at MDC years ago (around the time of the DC-9-50). The man/machine interface has to be intuitive!! And, here is the crux, it has to be intuitive to the pilot...not the engineer who designed it!!
When I was at Bendix, the RDR 1E and 1F Pilot's Guides were written by engineers. Most pilots didn't read them.
I rode a lot of jumpseat with CO, WA, FR, MX. AW, HA, AN, AV, and Air Mic, talking with crew about the use of WXR. A colleague did the same with other airlines. We agreed that most pilots are non technical!! WXR is also subjective. That drove the development of color and Doppler, both attempts to make the radar less subjective. It's better but not perfect.
I have always been concerned with the automation in the aircraft failing and handing the aircraft off to the pilot at the worst possible moment. Not sure how we prevent that scenario, but if I were flying the airplane I'd want to have some hands on, in a sim or benign conditions, practice, to prepare for that contingency. I think that training is most important.

[jurassicjockey]

Falconer 1
let's assume the atmospheric conditions described in these phenomena have been around for a long while..Actually I recall reading a study that was trying to quantify why the size of super-cooled water droplets was increasing. Speculation was that it was due to several things, one of them being the decrease in particulate matter in the atmosphere due to lower levels of certain types of pollution. The end result from our perspective was that the icing models that had been used to certify a/c deicing systems were no longer valid and would have to be reevaluated. A link to the study when I can locate it again.

[lomapaseo]

Pilot's Guides were written by engineers. Most pilots didn't read them

Or didn't understand what they meant.

Yes indeed, the line rides were good for both sides. The trouble is we don't always think with the same side of our brains, but we have to get over this hurdle!!

It's good to knock heads even if it's only in forum words with guys like PJ2 and Safety Pee etc. etc. We're going to get there if only because we care.:ok:

[Graybeard]

I must know you, Putt, and you can't be Stan Lipnicki. I knew Al Smith at DAC also.

The avionics manufacturers wrote Pilots' Guides, and few of them reached the pilots. They were too expensive to just hand out, after all. Besides, how many pilots would have read them?

Today, it's so easy to put a PG on a site, with unlimited access.

I did get to provide limited pilot training during re-currents. One Capt. said, "Don't use it in Wx; it attracts lightning." I was caught flatfooted by that, but recovered, saying, "Your old radar transmitter was 60,000 watts peak. This new radar transmitter is only 100 watts; it won't attract lightning.

GB

[Data Guy]

For Gerunf at Post 59, and all in this thread

Okay so structural failure of the vertical stabilizer is hardly likely.

Has anyone any thoughts on engine structural failures ?

Would not engine vibes tell the tale ?

Does the ACARS on this specific accident broadcast vibes data ?

Does the ACARS transmit in intervals ? One pilot forum commented it may be 10 minutes ?

[BOAC]

I'd like to bring this thread BTTT with a question generated by comments on the R&N thread. I am surprised to discover that there is not just 'Alternate Law', but AL2 as well. Can someone explain SIMPLY what this does? I THOUGHT I understood the AB philosophy (a bit!) and that unless in 'Direct Law' you could not stall the a/c - in other words, despite bungling the hand flying, the FCC 'took care' of you and limited/adjusted your pitch. I read now on R&N (takata #2440) that this is not so and that AL2 has no such protection.

Q2: Is it correct that while (handflying) in AL(1) the FCC would adjust pitch (nose-down) if it sensed a large drop in airspeed towards the stall, or is AoA the over-riding trigger?

I suspect I'm going to get different answers to these questions from different folk - which would put me straight back on my 'bandwagon' about training not keeping up with systems.

[h3dxb]

BOAC

Acc. to AMM:

-
The control law level which is:

No. 1: normal laws,

No. 2: alternate laws,

No. 3: direct laws, from the highest to the lowest level.


The law is such that:
-
each computer establishes the highest level of law (normal, alternate or direct) it can engage, taking into account the results of the internal monitorings and the availability:

. of the ADIRUs,

. of the control components,

. of the control surfaces, THS and slats and flaps.


-
among the computers which can engage the highest level of law , the computer having top priority is chosen (if only one computer is capable of the highest level of law , this computer is selected, whatever its priority level).



In FCOM is mentioned that ALTN LAW has 2 categories. ALT 2 would happen when U have an ADR DISAGREE>

With 2 ADR lost U have no HIGH AOA prot. anymore
with 3 ADR lost U have no HIGH SPEED prot. anymore

hope this helps :ok:

[h3dxb]

BOAC

Q2: Is it correct that while (handflying) in AL(1) the FCC would adjust pitch (nose-down) if it sensed a large drop in airspeed towards the stall, or is AoA the over-riding trigger?



In ALT 1:

PITCH ATT is lost, HIGH AOA on ALT, but lost at loss of weight or slat/flap pos. failure.


Hope this helps as well :ok:

[BOAC]

I don't think it has answered the questions? Let me try another way.

Does the FCC still have 'over-ride' on the control DEMANDS in Alt 1 and 2, and would either 1 or 2 command a pitch down if an impending stall was sensed, or, conversely, a pitch up with high speed?

Tyro - where are you?:)

[h3dxb]

BOAC

The answer is YES/NO. like written before:

in ALTN1 the AOA protection is there (till you lost weight or slat flap pos informations) and the EFCS protects and takes over.
in ALTN2 AOA PROT is gone when U have 2 ADR's faulty, HIGH SPEED at 3 ADR's faulty and the direct stick to surface so called direct LAW is working.

Old Boeing champ with yr FCC's:}

[BOAC]

That's clearer, thanks. So in the AF crash, as we understand it, they would have been at Alt2 with no high speed prot? What, then, is the difference between THAT Alt2 and DL? EG Are there still pitch and bank or some other limits?

[h3dxb]

I knew this question would come :}

Before U lost the AOA/HIGH SPEED etc. due to this ADR failure U have still the LOAD FACTOR LIMITATION to +2.5g and -1.0g which is also lost in direct law.

[h3dxb]

SmartCockpit - Airline training guides, Aviation, Operations, Safety (http://www.smartcockpit.com/pdf/plane/airbus/A330/systems/0010/)


Check 1.27.30 pg1

rgds

[BOAC]

Great link - thanks.

[Dani]

Well, in fact, there are two different AL's. But alternate in the correct sense doesn't exist at all! Funny to here that after so much squak?

AL is just a transitionary phase from normal to direct law. Actually, when you are in AL, you are direct law in roll and some (un)protected condition in pitch. To make it easier, AI called this mode AL. But generally speaking, there are only 2 laws, normal and direct. Which is completly logical: Eighter the computer does it, or you!

To make it even more complicated, there are two different AL! If you are still with me, continue to read: There is AL with protections and AL without. Pretty simple, when your computers still can deliver protections, they do, if they cannot, they don't. So it goes back again to the "AL doesn't exist" from above.

So, your question is: Do you have over- and underspeed protection in alternate law? Well, it depends. If you are in AL with reduced protection (that's what you mean by AL1 I guess), you still have low and high speed stability, and you have load factor stability. So in other words, you have it all (pitch-wise). In AL without proctection, you only have only load factor stability.

Or, in other words: In AL1 you still have all. Well, nearly all. In fact, you don't have anything. The trap is in the word "reduced" protection. As soon as you are in AL, the nice little green double bars at the speed tapes disappear, and amber X's are painted. This is a clear sign that you are not protected against high or low speed conditions. So you have to live with it.

If someone is still able to follow me, you are an Airbus pilot :ok:

Dani

[BOAC]

If someone is still able to follow me, you are an Airbus pilot- the thing that bothers some of us 'old-timers' is that probably even a lot of those won't be able to either!

[Dani]

that was one of my goals :E

No, really, jokes aside. It's pretty easy and everyone understands it, if you do a serie of sim sessions. I don't really know a lot of Airbus pilots who do not get it or do not like it. Even some B afficionados.

Dani

[411A]

Synopsis;
Tuesday 23 June, 2009 10am enroute HKG to NRT. Entering Japan airspace.

FL390 mostly clear with occasional isolated areas of rain, clouds tops about FL410.
Outside air temperature was -50C TAT -21C (your not supposed to get liquid water at these temps). We did.

As we were following other aircraft along our route. We approached a large area of rain below us. Tilting the weather radar down we could see the heavy rain below, displayed in red. At our altitude the radar indicated green or light precipitation, most likely ice crystals we thought.

Entering the cloud tops we experienced just light to moderate turbulence. (The winds were around 30kts at altitude.) After about 15 sec. we encountered moderate rain. We thought it odd to have rain streaming up the windshield at this altitude and the sound of the plane getting pelted like an aluminum garage door. It got very warm and humid in the cockpit all of a sudden.
Five seconds later the Captains, First Officers, and standby airspeed indicators rolled back to 60kts. The auto pilot and auto throttles disengaged. The Master Warning and Master Caution flashed, and the sounds of chirps and clicks letting us know these things were happening.
The Captain hand flew the plane on the shortest vector out of the rain. The airspeed indicators briefly came back but failed again. The failure lasted for THREE minutes. We flew the recommended 83%N1 power setting. When the airspeed indicators came back. we were within 5 knots of our desired speed. Everything returned to normal except for the computer logic controlling the plane. (We were in alternate law for the rest of the flight.)

We had good conditions for the failure; daylight, we were rested, relatively small area, and light turbulence. I think it could have been much worse. The Captain did a great job flying and staying cool. We did our procedures called dispatch and maintenance on the SAT COM and landed in Narita. That's it.



Email direct from the NWA pilot concerned.
The A-330 clearly has some problems that need to be corrected, poste haste.

PS:
Crew members names removed to protect confidentiality.

[lomapaseo]

The A-330 clearly has some problems that need to be corrected, poste haste.


This being a technical forum you need to substantiate that with some technical points like why the A330 is a unique problem. Otherwise with just an opinion there is no room for discussion :)

[411A]

This being a technical forum you need to substantiate that with some technical points like why the A330 is a unique problem.

How many other aircraft types, lomapaseo, have repeated problems with pitot probes icing up (or indeed, any other indicated airspeed difficulties) at altitude that you have heard about recently?

The latest incident with the referenced NWA A-330 has gotten the rapt attention of the FAA, you can be sure.
I would expect an emergency airworthiness directive to follow shortly.

[lomapaseo]

The latest incident with the referenced NWA A-330 has gotten the rapt attention of the FAA, you can be sure.
I would expect an emergency airworthiness directive to follow shortly.

No doubt that EASA and the FAA are looking at the design assumptions. But with all the sucesses of the various aircraft designs Boeings, Airbus etc. to accomodate this single system failure there's not a clear conclusion of a violation of the original certificate.

Now on the other hand if there is yet another combination that is at work here we do need to understand that and perhaps work that into our continued airworthiness fix.

[Flyinheavy]

@411A

How many other aircraft types, lomapaseo, have repeated problems with pitot probes icing up (or indeed, any other indicated airspeed difficulties) at altitude that you have heard about recently?Last week a Polnish B767 experienced some related problems. But I think that many incidents passed unrecognized, right now the industry sure is sensitized about 'pitots'. Seems to me also that the very achitecture of the A330 in respect of its FCC might have to do with it, as it is the most advanced.

Anybody to comment on the switching logic of the Antiicing System. I learned that the Ice Sensor is switching Pitot Heat to ~200°C inflight with the Antiicing Switch in 'Auto'? Switch to 'ON' would keep it at that value?

[bobrun]

After about 15 sec. we encountered moderate rain. We thought it odd to have rain streaming up the windshield at this altitude and the sound of the plane getting pelted like an aluminum garage door. It got very warm and humid in the cockpit all of a sudden.

What would explain that the air became warm and humid all of a sudden?
There's no outside fresh air being blown directly in the flight deck obviously, so would the icing have also affected the packs operation? Could the heat exchangers have taken ice?

[bobrun]

Anybody to comment on the switching logic of the Antiicing System. I learned that the Ice Sensor is switching Pitot Heat to ~200°C inflight with the Antiicing Switch in 'Auto'? Switch to 'ON' would keep it at that value?

On the airbus, the probe heat computers manage the level of heating. Inflight, the pitots are heated to the high value. The position of the push button has no effect.

[Bullethead]

G'day bobrun,

What would explain that the air became warm and humid all of a sudden?
There's no outside fresh air being blown directly in the flight deck obviously, so would the icing have also affected the packs operation? Could the heat exchangers have taken ice?

I've experienced a marked OAT rise crossing the ITCZ many times, and in clear air occasionally, and sometimes the first indication is a sudden warming and stuffiness in the cabin. I don't believe it is the packs icing up just that they are not capable of the rapid response needed to counter such a quick OAT increase.

Regards,
BH.

[411A]

I've experienced a marked OAT rise crossing the ITCZ many times, and in clear air occasionally, and sometimes the first indication is a sudden warming and stuffiness in the cabin.

Likewise....not at all unusual.

[Dani]

Rain with -21° ist not possible.

[BOAC]

Time for some Met revision, Dani?

Surface crystallization of supercooled water in clouds ? PNAS (http://www.pnas.org/content/99/25/15873.abstract)

Supercooling Water - Video (http://www.metacafe.com/watch/854309/supercooling_water/)

Freeze Water in Seconds Supercooling - Video (http://www.metacafe.com/watch/1149234/freeze_water_in_seconds_supercooling/) NB That was 5hrs at-18C

Mind you, not too many plastic bottles around (outside) at 35k.:)

It is worth remembering that water is one of the strangest substances known to man.

[Dani]

Thanks for the revision, Boac :ok:

Still I think it quite unlikely to see rain "streaming" around the windshield. Characteristical for supercooled water is that it freezes immediatly when it touches an object (the seed). Hence you cannot see if you have supercooled precipitation around you.

Anyway, all these incidents and one accident makes me think that with the change of earth's climate, we encounter stronger and different weather effects. I also count the BA 038 accident to these series, because they had unusual cold temperatures over Russia and the Scandies. Maybe we as pilots have to modify the way we look at weather.

Dani

[safetypee]

The type of icing most likely in this/these incident(s) involved ice particle icing or glaciated/mixed phase icing. These relatively rare conditions are described in the report The Ice Particle Threat to Engines in Flight (http://airs-icing.org/AIRS_II/AIAAReno2006/AIAA-2006-206-739.pdf) (page 13).

Reports of rain streaming around the windshield are discussed and clearly answered as being due to the ice particles melting on the anti-iced surfaces. The conditions are outside of the conventional airframe icing boundaries, thus no airframe icing is seen. Also, note that the conditions are near, or above large Cb build-ups; the aircraft are not necessarily in Cbs.
I have encountered these conditions during test flights in 1997 (tests preceding those referenced in the report - USA 1998). On occasion small ice build-ups could be seen at the windshield edge or on the windscreen wipers - the windscreen was very wet.
Also, the IMC described in the report is often very thin cirrus cloud, which many pilots would declare as VMC due to the apparent good visibility.

The mechanism of pitot icing (AF447) is probably similar to TAT probe icing, or where the pitot is considered to be a very small scale engine. Ice particles, slowed by bends in airflow ducts, melt when in contact with heated surfaces, and the water acts as the glue for more ice particles to accumulate and freeze, which in time exceeds the heat-flow capability of the anti-icing structure; the report gives details – I urge all pilots to read the details.

Re “What would explain that the air became warm and humid all of a sudden?”.
As a hypothesis, perhaps encountering an ice particle cloud (high ice water content) where the melting ice and changes in heat flow are beyond the instantaneous dynamics of the Air Cond packs. The report cites the possibility of very high Ice Water Content, as a guide, a mid value of 4gm/M^3 would require a stout umbrella at ground level if transformed to rain.

Re “Maybe we as pilots have to modify the way we look at weather”. I agree.
Other sections of the report (page 17) discuss the shortcomings of radar in detecting ice particles and hence the inability to see the high altitude structures of Cbs, or new, emerging build-ups in the general cloud mass or anvil.
Defensive strategies include avoiding the core of large storms by a very wide margin, remaining upwind to avoid the anvil region, and being aware of new build-ups.
We must reconsider the way we look at very large storms; the judgment of size might be subjective, similarly ‘a very wide margin’ involves judgement and decision making processes.
My experiences indicate that the risk of encountering conditions favourable to malfunctions are present up to at least 30nm from a detectable Cb core, thus with a margin of safety, 50 nm should be considered – this consideration should also include turbulence. We need to focus more on planning ahead - rerouting, use of satellite pictures, and reasoned judgement of met forecasts – know before you go.
On two occasions during test flights, super, ‘super’ cells were seen – so large (area, height), so black, and so menacing, that ‘evil’ was a worthy term. These storms were not investigated during the tests and were avoided by 100 nm.

[Dani]

safetypee, thanks for that very enlightening post.

[Desert Dawg]

Having kept a close eye on a.net forums, I have noticed that two pilots who regularly post sane comment about this issue have done a lot of work to try and figure out what may have happened.


One poster (Mandala499) who is probably the most sane guy there, has done a good job of trying to figure out the timeline of the ACARS messages and re-order them according to their respective time stamps.

I have shamelessly (sorry Mandala) copied his good work here in order that someone on PPRuNe may make more sense (or gain a better insight) as to what went on at the time these messages were sent?

This is the list reordered...

0209 START
0210 34-11-15-0 FLR EFCS2
EFCS1, AFS - PROBE PITOT 1+2/2+3/1+3 (9DA)
9DA=HEATING ELEMENT PITOT 1 (6DA1/PHC1)
Heating Element Pitot 1 suspected failed.

0210 27-93-34-0 FLR EFCS1
EFCS2-FCPC2(2CE2) WRG:ADIRU1 BUS ADR1-2 TO FCPC2
No Data from ADIRU 1, ADR 1 & 2 no sending signal to FCPC2
No ADR Data from ADIRU 1 to PRIM2.

0210 27-90-45-5 WRN MXSTAT
EFCS1
ERROR NOTICED - Air Data Fluctuation/Inconsistency

0210 27-90-45-0 WRN MXSTAT
EFCS2
ERROR NOTICED - Air Data Fluctuation/Inconsistency

0210 22-10-00-0 WRN AUTO FLT
AP OFF
Autopilot Shut off for safety, result loss of 2 Valid Air Data Channels.
This prevents faulty Air Data from affecting autopilot into making the wrong actions.
Commence AP/FD FAULT ISOLATION PROCEDURE
System Filter & Check:
- DISAGREE AOA Sensor Data in FCPCs
- DISAGREE PITOT PROBE Data in FCPCs
- FAIL ADIRU 1 and 2
- FAIL ADIRU 1 and 3
- FAIL ADIRU 2 and 3
- FAIL ADIRUs

0210 22-62-01-0 WRN AUTO FLT
REAC W/S DET FAULT
Loss of 2 ADRs, autopilot cannot provide Windshear Protection.

0210 27-91-00-5 WRN F/CTL
ALTN LAW
2 ADR REJECTED, NAV DISAGREE NOT YET CONCLUDED - FAULT ISOLATION IN PROGRESS

0210 22-83-00-2 WRN FLAG
LEFT PFD LIMIT
Rejected ADR still feeding data to PFD
If there is valid ADR, it's not being selected for LEFT seat.

0210 22-83-01-2 WRN FLAG
RIGHT PFD SPD LIMIT
Rejected ADR still feeding data to PFD
If there is valid ADR, it's not being selected for RIGHT seat.

0210 22-30-02-5 WRN AUTO FLT
A/THR OFF
Autothrust Shut off for safety, result loss of 2 Valid Air Data Channels.
This prevents faulty Air Data from affecting Autothrust into making the wrong actions.

0210 34-43-00-5 WRN NAV
TCAS FAULT
Loss of ADR1 to Transponder 1 (if selected) or Loss of ADR2 to Transponder2 (if selected)
Loss of Mode C.
This is downstream of loss of ADR.

0210 22-83-00-1 WRN FLAG
LEFT PFD NO F/D
Automatic Flight System (AFS/FMGC) loss of 2 ADR sources.
Safety mechanism, prevents erroneous F/D for pilot to follow

0210 22-83-01-1 WRN FLAG
RIGHT PFD NO F/D
Automatic Flight System (AFS/FMGC) loss of 2 ADR sources.
Safety mechanism, prevents erroneous F/D for pilot to follow

0210 27-23-02-0 WRN F/CTL
RUD TRV LIM FAULT
Loss valid of ADR Data (require 2 ADRs) for FMGC/AFS
FMGC Flight Envelope Module locks in Rudder Travel for safety.

0211 34-12-34-0 FLR IR2
EFCS1X,IR1,IR3, ADIRU2 (1FP2)
ADIRU2(1FP2) - ADR2 self monitoring & PHC rejects own data
Loss of discrete data from ADR2 = PITOT 2, STATIC 2L, STATIC 2R, TAT 2, AOA 2.
NAV DISAGREE CONCLUSION DELAYED - ADDITIONAL FAILURES - RECOMMENCE FAULT ISOL

0211 34-12-00-0 FLR ISIS
ISIS (22FN-10FC) SPEED OR MACH FUNCTION
SUSPECT LOSS OF ADIRU1 AND/OR ADIRU3 FOR ISIS MACH
Suspect Loss of ADIRU3
NAV DISAGREE CONCLUSION DELAYED - ADDITIONAL FAILURES - RECOMMENCE FAULT ISOL

0211 34-12-00-1 WRN FLAG
LEFT PFD NO FPV

0211 34-12-01-1 WRN FLAG
RIGHT PFD NO FPV

0212 34-10-40-0 WRN NAV
ADR DISAGREE
NAV DISAGREE DISCOVERED - FAULT ISOLATION COMPLETED
Due to no further ADR faults occuring.

0213 27-90-02-5 WRN F/CTL
PRIM1 FAULT

0213 27-90-04-0 WRN F/CTL
SEC1 FAULT

0213 22-83-34-9 FLR AFS
FMGEC1(1CA1)

0214 34-10-36-0 WRN MXSTAT
ADR2
RESULT OF 32-12-34-0

0214 21-31-00-2 WRN ADVSRY
CABIN VERTICAL SPEED
LOSS OF ADR DATA

Open to comments?

[Towhee]

How many other aircraft types, lomapaseo, have repeated problems with pitot probes icing up (or indeed, any other indicated airspeed difficulties) at altitude that you have heard about recently?



there's this:

Aviation Week & Space Technology, 3/5/2007, Vol. 166 Issue 10, p62-62, 1p; Abstract The article reports on the adoption of an airworthiness directive by the U.S. Federal Aviation Administration.

The directive requires Embraer 170 and 190 operators to inspect pitot drain holes of certain air data smart probes for blockage and remove accumulated moisture from the probes' pneumatic passages. The move is a result of reports of incorrect airspeed indications caused by frozen moisture in the passages that blocked the pitot sensors.;

[Svarin]

Desert Dawg citing Mandala499

Impressive work !

Following this reading, there is a question I have been wondering about for weeks, and now is the time to ask :

what is the precise difference between a NAV ADR DISAGREE (which we have in the AF447) and a F/CTL ADR DISAGREE (which we have in all the other instances) ?

Thanks for your help.

[Desert Dawg]

@Svarin,

I hope Mandala reads PPRuNe as he may be the person to answer this?

[PK-KAR]

I have noticed that two pilots who regularly post sane comment about this issue have done a lot of work to try and figure out what may have happened.

One poster (Mandala499) who is probably the most sane guy there, has done a good job of trying to figure out the timeline of the ACARS messages and re-order them according to their respective time stamps.
Me, (aka Mandala499) am not a pilot (although some have refused to believe it *sigh*) := . I just have a "deep interest" in the accident... but hundreds of pages of printouts etc, and that list, amongst with my other partner in crime there, still has a LOOOONG way to go...

I didn't get involved in the other AF447 topic because despite the heavy moderation, it appeared to be going in circles most of the time... and missed the one here.

That list still needs revision... it's been revised hundreds of times already.

I do need help on those just to see what happened based on the ACARS (to the limit of what the ACARS can give). How I think (personal theory) the plane went up to 0210 is on the works too but I keep coming back to the ACARS... although I need to match it up with the last position and where it was in terms of the weather (which sadly, indicates they made it (or almost) out of the weather, only to be hit by something such as icing). This doesn't rule out the occurence of intermitten errors/failures which would not have been picked out by the CMC... but that would be guessing too much. So pardon the inaccuracy if you find one, and help improve it.

I still need to know the details of 2CE2, and 22FN-10FC... (the part coding convention does give clues, but not much)
I find it interesting that Pitot 1 PHC came up, but ADR2 data downstream of the PHC2, failed.

As to difference between F/CTL ADR DISAGREE and NAV ADR DISAGREE??? No answer for the moment... it's equally baffling. However, it seems that the FCOMs I read have NAV ADR DISAGREE but not F/CTL DISAGREE. It might have something to do on where/how the disgreement happened... I was hoping that you guys over here can help.

[Dani]

My guess is that F/CTL ADR DISAGREE is showing when the FCCs have problems with ADR data, while NAV ADR DISAGREE comes on when the FMGC has problems with it.

You have to understand, that those modern planes take their data from all kind of sources and route them to all different aircraft subsystems. FCC needs the ADR data for computation of stearing commands while the FMGC needs it to compute navigational data.

Makes sense?

Anyway, as mentioned elsewhere, I do not think that we will get important information about the cause of the crash from the well known ACARS signals.

hth,
Dani

[Svarin]

Nice to 'meet' you PK :)

I will try to elaborate some constructive criticism. I am aware that it might bump into some serious hard work, please take it as I intend it to be, positive thinking to improve general knowledge.

Starting from your work, which I take is based upon the famous maintenance messages, two things strike me :

is the 34-11-15 fault to be taken as all 3 probes failed together, or as n°1 heating failed ? Finally, how many probes are deemed failed as we can deduce from this message ?

The devil hides in the details :

in the second message, 0210Z 27-93-34-0, I would like your thoughts on the tiny detail here : ADIRU1 BUS ADR1-2 TO FCPC2
Is the translation "ADR 1 & 2 no signal to FCPC2" correct ? Could it be instead that this BUS ADR1-2 TO FCPC2 refers to the part that connects ADR1 to n°2 parts of the system, here FCPC2 ? Wouldn't a dual ADR failure be named ADR1+2 instead ?

This hypothesis from the fact that ADRs are connected crossways to various parts of the system, and not only n°1 parts. And the fact that multiple failures are usually labelled with a + sign.

Best regards.

[Svarin]

To Dani and PK-KAR,

please humor my insistence on this point : we need to seriously evaluate the difference between NAV ADR DISAGREE and F/CTL ADR DISAGREE.

From various documents I have read (and believe me, I have read quite a lot in a month, and I need to stop else I won't pass my medical because of eyesight), all instances of speed indication failures in the known incidents I could put my hands on were of the following nature : a quick determination of a F/CTL ADR DISAGREE. This failure is well documented, have a look at eurocockpit.

On the AF447, we have a slow-in-coming NAV ADR DISAGREE.

It might be minor, but I doubt it. AB shows pretty consistent wording throughout their 'namespace'. Since we are oriented towards a similarity between previous incidents and this dreadful crash, we might miss the exact difference which spelled death for so many people. I think we should try to find these differences, and surely some of them are inside the aircraft computations. This NAV / FCTL discrepancy definitely looks like one.

Of course, it 'very likely' means that the system which slaps the ADRs out is different in the instances. However, it also means that the overall reaction of various systems throughout the aircraft will be different on the AF447.

How different ?

[augustusjeremy]

I still need to know the details of 2CE2, and 22FN-10FC... (the part coding convention does give clues, but not much)
I find it interesting that Pitot 1 PHC came up, but ADR2 data downstream of the PHC2, failed.How did you get to the relationship between air & phc data and the IR2 fault reported by disagreement with IR1 and IR3 ?

I think Inertial Data is independent from air data - and that the opposite is not true - so an IR fault would only be detected by comparison with inertial data...

Am I Wrong ?

P.S.: I know AOA differs from pitch attitude - it relates to the relatively motion of the airflow to the wing - but is there any inertial component in the AOA calculation ? This question is related to the qantas incident...

[PK-KAR]

FCC needs the ADR data for computation of stearing commands while the FMGC needs it to compute navigational data.

My guess is that F/CTL ADR DISAGREE is showing when the FCCs have problems with ADR data, while NAV ADR DISAGREE comes on when the FMGC has problems with it.
I looked at 1 QRH from 1 airline, and 1 FCOM3 from a different airline... one has F/CTL ADR DISAGREE, the other has NAV ADR DISAGREE.

NAV ADR DISAGREE
This caution is triggered by the PRIMs, when they only use 2 ADRs, and these 2 ADRs disagree. This may occur when:
- One ADR has already been selected OFF by the pilot, or
- One ADR has been eliminated by the PRIM, without any caution, because it deviated from the others.

F/CTL ADR DISAGREE unfortunately has no descripton.
The procedures are identical (both versions are roughly from the same period)..

AIR SPD... XCHECK
- IF NO SPD DISAGREE
AOA Discrepancy

- IF SPD DISAGREE
ADR CHECK PROC...APPLY

F/CTL ALTN LAW (PROT LOST)
Note: Following an ADR disagree detected by the PRIMs, the ALTN LAW is latched. Resetting the PRIMs using the pushbutton will not allow recovery of normal law.

- MAX SPEED... 330/.82

STATUS
- MAX SPEED... 330/.82
CAT 3 SINGLE ONLY
RISK OF UNDUE STALL WARNING
RUD WITH CARE ABV 160 KT

INOP SYS
RUD TRV LIM
CAT 3 DUAL

Where one has NAV ADR DISAGREE, it doesn't have F/CTL ADR DISAGREE and vv.

Both are caused by the PRIMs rejecting 1 ADR and the other 2 disagree with each other... but are they identical? I guess this depends on the airline on where it wants the ADR DISAGREE to appear... coz, I looked at an Airbus document, and it just says "ADR DISAGREE"... *shaking head even more in confusion*. Perhaps it depends on the FWC standard one is using.





is the 34-11-15 fault to be taken as all 3 probes failed together, or as n°1 heating failed ? Finally, how many probes are deemed failed as we can deduce from this message ?
To be honest, I am not sure it means 3 of them failing together...
EFCS1, AFS - PROBE PITOT 1+2/2+3/1+3 (9DA)... AFS senses fluctuation or rejects an ADR, asks EFCS1 to compare the rest, 9DA as problem's suspect. I have a separate list showing 34-11-00, failures of inputs... most of the list is sensor power supply and switching... 34-11-15 is something else... (and different airlines may have different numbers).

ADIRU1 BUS ADR1-2 TO FCPC2 yes ADIRU1 BUS ADR1+2 TO FCPC2 makes more sense...
The thing is, I don't know the databus layout... ADR 1+2 Failure I think would occur if PRIM1 or none of the PRIMs receive the data... unless PRIM2 was the Master Prim at the time...
The "-" instead of the "+" could have just been a typo...


The devil hides in the details :
:yuk:
INDEED !!!!!

we need to seriously evaluate the difference between NAV ADR DISAGREE and F/CTL ADR DISAGREE.
Svarin, read the above... and I need new glasses now because of the same thing! Still no satisfactory answer though...

How did you get to the relationship between air & phc data and the IR2 fault reported by disagreement with IR1 and IR3 ?
I'm just reading what I got...

I think Inertial Data is independent from air data - and that the opposite is not true - so an IR fault would only be detected by comparison with inertial data...
That's what we all believe in... but somehow there's a relationship somewhere... be it just a crosscheck/diagnose function, or a relational function... The thing that caught me was that the FPV would disappear... FPV would largely be a result of all things IR and the only ADR part is barometric... but that's a downstream relationship... the other thing that caught my eye is the report from the VH-QPH upset (26Sep2006) and VH-QPG ADR/IR fault (27Dec08), where it too found a relationship between ADR and IR when one of them of the same ADIRU was faulty and/or switched off (unless my eyes deceive me)... But the wording from the manuals seems to say that they both perform their computations independently from another... But if they need data relationship, surely the loss of one function over the other should just mean degradation and not failure...

Still got a lot of reading to do (and repeat readings)...

PK-KAR

[PK-KAR]

I know AOA differs from pitch attitude - it relates to the relatively motion of the airflow to the wing - but is there any inertial component in the AOA calculation ? This question is related to the qantas incident...
If it has an AoA estimator, there could be a link... where a PRIM takes the speed from an ADR and computes a theoretical AoA, which is then compared to the voted AoA... to see if it fits... How it comes up with the theoretical AoA can come from several sources... but I don't have details of this yet... so this could be a wild guess...

[celtic mech]

the data available (ACARS
messages) at this stage:
-Does not suggest any loss of electrical power
-Does not suggest loss of cockpit display units

The majority of the messages are linked with unreliable airspeed
measurement
• Some additional messages are also consistent with unreliable
airspeed measurement but require further analysis (hopefully we can all try piece together some info from this)
• Others resulted from crew action

02:10 UTC Maintenance message
“PROBE-PITOT 1+2/2+3/1+3(9DA)”

2 different sources of trigger:
The EFCS detected a speed decrease greater than 30kts in 1s on 2 or 3 airspeed measurements.
The AFS detected that each airspeed information compared to the 2 others showed at least transiently a difference greater than 20kts

The Above Message, as per its design, triggered the following messages:
“FCTL ALTN LAW”
“AUTO FLT REAC W/S DET FAULT”
“FLAG ON CAPT PFD SPD LIMIT” and “FLAG ON F/O PFD SPD LIMIT”
-Indicates that characteristic speeds information
(VLS, VMAX….) were no more displayed on PFD
-Information displayed on both PFD speed scales
* current airspeed, selected airspeed
* SPD LIM flag on bottom of airspeed scales
“AUTO FLT AP OFF” - Auto disconnect of AP
“AUTO FTL ATHR OFF” - Again auto disconnect of ATHR as above
“FLAG ON CAPT PFD FD” and “FLAG ON F/O PFD FD” A red flag FD was displayed on both PFD (attitude area) to indicate that FD were disengaged but selected ON

At 2:10 UTC message “F/CTL RUD TRV LIM FAULT”
Indicates that the FCPC detected a speed variation higher than 50kts in 10s on 2 or 3 airspeed indications
Indicates that the rudder travel limit is locked at the position corresponding to the speed immediately before the detected speed variation


02:12 UTC “NAV ADR DISAGREE”
-The Flight Control System had already rejected one ADR AND
-Out of the 2 remaining ADR’s, the Flight Control System detected a discrepancy on one ADR parameter

Other maintenance messages and cockpit effects pointing at
ADR system:
02:10 UTC
–“FCPC2 (2CE) WRG: ADIRU 1 BUS ADR1-2 TO FCPC2”
–“MAINTENANCE STATUS EFCS1”
–“MAINTENANCE STATUS EFCS2”
02:11 UTC
–“ISIS (22FN-10FC) SPEED OR MACH FUNCTION”
–“ADIRU2 (1FP2)”
02:14 UTC
–“MAINTENANCE STATUS ADR2"

In Relation to other messages triggered:
02:13 UTC
–“F/CTL PRIM1 FAULT” and “F/CTL SEC1 FAULT” - SHows PRIM 1 and SEC 1 were either both switched to off or Reset.
"FMGEC1 (1CA1)”
02:14 UTC
–“ADVISORY CABIN VERTICAL SPEED” - This indicated Cab Vertical Speed was greather than plus or minus 1800ft/min


All pieced together from a prelim round up and also trying to shed some light on this

[Svarin]

ADIRU1 BUS ADR1-2 TO FCPC2 yes ADIRU1 BUS ADR1+2 TO FCPC2 makes more sense...
The thing is, I don't know the databus layout... ADR 1+2 Failure I think would occur if PRIM1 or none of the PRIMs receive the data... unless PRIM2 was the Master Prim at the time...
The "-" instead of the "+" could have just been a typo...

- or +
This reasonably cannot be a typo, I have it as a scan of a computer-generated document. How did you go about translating the message into plain English ?

[Svarin]

The thing that caught me was that the FPV would disappear... FPV would largely be a result of all things IR and the only ADR part is barometric...In pure theory, there are at least two ways to come up with an FPV : either take pure inertial reference and point a vector using IR, or compute the -almost- same vector by subtracting AoA from pitch. The second method needs air data.

What you end up with is either a ground-related FPV (inertial) or an air-related FPV.

Which theory was used in the A330 ?

Well, answers, answers : from QRHs, on the B777 side we have an inertial FPV, which the QRH states is reliable and to be used in airspeed indications loss situation (unreliable airspeed ind.), on all A320/330/340 the QRH states FPV unavailable... Draw your own conclusions.

[PK-KAR]

Svarin,
You mean this?
http://www.eurocockpit.com/images/PFR447.png ???
From Eurocockpit - Archives (http://www.eurocockpit.com/archives/indiv/E009445.php)
One last important thing that we must do : in order to let you compare the events experienced by the flight AF447 with those described in the technical note mentioned above, we would like to expose the actual list of the contents of the famous ACARS messages sent by the plane. In order to keep our sources secret, we have transformed the appearance of the original file, but the content has remained exactly the same.
That is why I thought a typo was possible.. how did they transform the original file? Some editing? Or? Hence the possibility. If you're the author or person who transformed it, then I have to take your word for it (but then, should have the answer)... but anyways...

How did you go about translating the message into plain English ?
The comments mentioned below the headers are just my take on what it could mean... They're not translations into plain English...

As to the FPV... yes, it needs air data on the 330... it is something I don't get as to if they can get the BUSS (works off pure IR), why not just make the FPV all inertial? Surely air pressure gradients aren't "that" steep? *that one was picked out of the air*...

PK-KAR

[Towhee]

icing:

FR Doc E8-20702 (http://edocket.access.gpo.gov/2008/E8-20702.htm)


cracks:

Docket No. FAA-2009-0005; Directorate Identifier 2008-NM-164-AD]

"This proposal would require operators to inspect the pitot tubes. If cracks are found in the tubes, they would need to be replaced, per the instructions of CASA Service Bulletin SB-212-34-11, Rev. 1 (dated Feb. 27, 2008).

This proposed AD, which resulted from an MCAI originated by the European Aviation Safety Agency, was prompted by the discovery of cracked pitot tubes on Britten-Norman BN-2 aircraft, which use the same Thales Optronics pitot tubes as are found on CASA C-212s.

Cracked pitot tubes could result in incorrect readings on the pressure instrumentation (e.g., altimeters, vertical speed indicators and airspeed indicators), potentially leading to navigational errors. FAA estimates that this proposed AD would affect 32 aircraft on the U.S. Registry and cost U.S. operators a total of $2,560, or $80 per airplane. Comments on this proposal, which are due March 25, should be sent to the DOT Docket Web site:"

http://dms.dot.gov (http://dms.dot.gov/);


overheating:

"AIRLINE INDUSTRY INFORMATION

July 29, 2002
United Airlines aircraft aborts flight due to faulty airspeed indicator

A United Airlines aircraft flying from Los Angeles to Washington DC was forced to abort its flight after was smoke was detected in the cockpit.

The aircraft - an Airbus A320, carrying 122 passengers - had been in flight for about 40 minutes when smoke began entering the cockpit. The flight returned to Los Angeles International Airport, where the passengers safely disembarked from the aircraft.
According to officials, the smoke occurred after a Pitot tube (which indicates airspeed) mounted on the fuselage overheated. The aircraft was expected to return to service once the faulty part was replaced, reported Reuters."

[JuggleDan]

A few more pitot incidents may be found in the article below:
Airbus crash: can a triple-redundant system give false readings? (Tony Collins's IT Projects Blog) (http://www.computerweekly.com/blogs/tony_collins/2009/06/in-articles-earlier-this-month.html)

[PETERJ]

Hi
Cam any of you guys help me out here (susbseuent to my post on this topic being deleted from R&N ( I am not a pilot nor a journalist, just a curious sort of person)

The crashed aircraft was invoved in a taxying incident in 2006 during which it suffered wing damge described as "minimal." The other aircraft involved suffered "substantial" tail damage ( see []www.jadec.de/years/all2006.txt)

are there any international regs regarding post repair inspections for this specific type of incident or are they company-specific ?
Any help would be much appreciated

peter

[NARVAL]

Celtic Mech, thank you for your very clear explanation
Coming a little late, and about the Nav ADR disagree message, the BEA (French investigation preliminary report) explains it thus:
Signification : ce message indique que les EFCS ont rejeté une ADR, puis
identifié une incohérence entre les deux ADR restantes sur l’un des paramètres
surveillés.
That is: this message tells that the EFCS have rejected one ADR, then has identified a discrepancy between the two remaining ADRs concerning one of the parameters.
For what it is worth...but as they work closely with Airbus I think we can trust them on that.

[h3dxb]

@Svarin

in the second message, 0210Z 27-93-34-0, I would like your thoughts on the tiny detail here : ADIRU1 BUS ADR1-2 TO FCPC2
Is the translation "ADR 1 & 2 no signal to FCPC2" correct ? Could it be instead that this BUS ADR1-2 TO FCPC2 refers to the part that connects ADR1 to n°2 parts of the system, here FCPC2 ? Wouldn't a dual ADR failure be named ADR1+2 instead ?



Only a class 1 failure is triggering a cockpit effect. Class 2 failures are not indicated during flight and have no operational impact.

Quote TSM :


Faults triggering an ECAM MAINTENANCE STATUS

These faults have no consequence on the system operating conditions. They are always GO without any restriction.




Anyhow yr translation is wrong. FCPC2 detected a malfunction in it's crosstalk between commanding part and self monitoring part, regarding ADR 2 inputs. But this type of failure will not cause a rejection of the FCPC.

Quote TSM:

Loss of the ADIRU1 ADR Bus 2 Input in the FCPC
1.
Possible Causes

-
FCPC-2 (2CE2)



-
FCPC-3 (2CE3)



-
wiring of the DGI 10 Bus from the related FCPC COM side to the first terminal block



-
wiring of the DGI 10 Bus from the related FCPC MON side to the first terminal block







Hope to shed some light :)

[kijangnim]

Greetings
SVARIN FPV uses Ground Speed over Rate of Descent, both data are inertial (earth related)

[FAERGUS]

I have been studying the ice particle icing issue and would like to communicate with the pilot and others regarding the conditions experienced, especially the sound characteristic reported during the apparent rain event at -51C. He reports a "sound of the plane getting pelted like an aluminum garage door". It would be interesting to characterize the sound quality to better identify the conditions. There are also a number of other questions that he or others may have observed that may be meaningful.

I believe I understand the "ice particle icing" issue and would like to wrap it up. If the pilot you quoted wishes anonymity, that is certainly alright. I would simply like to receive his observations. As a point of reference, I am a chemist and a pilot.

[Backoffice]

Just diverging slightly, I haven’t spotted any discussion in the 3 threads running on this accident to possible icing/blockage of the static vents (they are all in close proximity to each-other) and the effect thereof.
I find it slightly bewildering why, when the altitude was obviously bleeding off and the wings were level the crew appears not to have initiated a nose down pitch for stall recovery. Or can we possibly conclude that the controls were compromised i.e. jammed horizontal stabaliser, preventing this.

[TyroPicard]

Backoffice
when the altitude was obviously bleeding off and the wings were level the crew appears not to have initiated a nose down pitch for stall recovery.
How do you know this? Have you found the DFDR?

[BOAC]

That's it, TP, enquiry over - pilot error:ugh:

[mm43]

Seeing this thread has been resurrected, its worth adding that in addition to the BEA's Interim Report No.2, they have also published a Technical Document with the title "Flight Data Recovery Working Group Report" which can be download from:-

http://www.bea.aero/en/enquetes/flight.af.447/flight.data.recovery.working.group.final.report.pdf

[Backoffice]

TyroPichard said "How do you know this? Have you found the DFDR?"

No, the fact the aircraft entered the ocean in basically a wings level state at a high rate of descent and lowish forward speed is from the BEA interime report. I assume, perhaps incorrectly the aircraft was probably in a stalled state at that time.

What I'm really trying to understand and this is perhaps backed up by the lack of life-jackets on passengers - so I presume no message back to cabin to prepare for crash landind in sea, is whether the crew had accurate or any altitude information.

i.e. Perhaps it wasn't just the pitots that iced up, but so did the statics but there just happened to be no acars which pointed to it.

[mm43]

@Backoffice

Perhaps it wasn't just the pitots that iced up, but so did the statics but there just happened to be no acars which pointed to itWell, yes there was, but everyone has suspected the pitots were the problem. Whether the static ports were also involved, we will never know. Ice reverts to water and all traces that could lead to your static port theory have gone forever - subject to the CVR revealing that the pilots had no meaningful info from the standby altimeter.

[Backoffice]

@mm43

Agree with all you're saying.

Question though, as the static port/vent is part of the ASI circuit and is necessary for both VSI and ALT why have we assumed from day one that the pitots are the culprit ?

[TyroPicard]

Backoffice
What I'm really trying to understand is whether the crew had accurate or any altitude information.
The point I am really trying to make is that nobody knows what happened between cruise altitude and the ocean. Until we do all is conjecture.

[mm43]

@Backoffice

.. why have we assumed from day one that the pitots are the culprit ?Something to do with the pitot bore size and facing the direction of travel, as opposed to the static ports, very large bore in comparison and open to the side.

Nothing is impossible, and maybe the Thales pitot probes are not the problem after-all. They just happened to be fitted to a/c that happened to be in the wrong place at the wrong time.;)

[Backoffice]

@TyroPicard & mm43

Yep, we'll never know until those boxes are recovered.

For those analyzing the acars messages just ask yourself what if it's not the pitots feed but the static feed that has gone u/s, how would that effect your analysis of the acars messages ?

[Backoffice]

This one won’t go away in my head so have to post this theory here to be shot down.

Aircraft encounters cb cells, becomes covered in super cooled water droplets, temperature changes or encounter with ice crystals turn this to ice over much of the fuselage…ice blocks static vents, pitots may be unaffected.
Crew aware of an airspeed problem but altitude and vertical speed appear stable.
No mayday sent, no cabin announcement.:sad:

[mm43]

@Backoffice

I think it would be worthwhile to go to http://www.pprune.org/tech-log/376433-af447-222.html (http://www.pprune.org/tech-log/376433-af447-222.html)and read pages 222 through 225. A lot of what you are inferring has been raised before.:ok:

[Backoffice]

@mm43
Re-read and yes agree it has been touched on - like your graphics by the way.

Without going into many of the complex issues raised on those pages and of course the question we will have to await while the naval experts try to find the proverbial needle is, did the crew have any idea where they were in space (altitude) - I for one don't think they did.

[CorkStudentPilot]

I agree with everyone that posted about the Pitot!!

I think this crash is going to be something along the lines of Aeroperu 603
and Birgenair 301. The biggest culprit is darkness!

let say the pitot was blocked the aircraft on board computer would have picked up on the problem, when it noticed the difference in airspeed and altitude between the two sets of instruments!! that then triggered the ACARS message!!

both pilots would have gotten confused by the different readdings and flown the aircraft into the ocean!!!

Just my opinion (Sorry if thats what like everyone said, i didnt read the other posts)

[usanxb]

I know of the seriousness of this accident and the loss of life on the part of all passengers and Air France crew so this a very sad thread. My heart goes out for all of those involved. However when flying as a passenger I shall never stop flying with AF.

My comments are more related to the automated computer systems involved in modern airbus aircraft. For example one theory is that when the ASI's shut down, then also so did the onboard computer. Since us pilots know it's even possible to fly without ASI using the standard operating procedures to avoid an alleged high altitude stall I would like to pose the following question to fellow pilots:

Would we prefer the onboard computer to reset the flight controls into the mode of standard operating procedures giving us time to take over?

Or would we prefer the onboard computer to simply shut down and give us a 100 error messages while we try to figure things out?

[john_tullamarine]

We probably don't need two similar threads on this topic. I'll lock this one but include a link at the start of the other so that this doesn't disappear into the swamp.