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AF447

Old 5th Jun 2009, 15:07
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P2J, thanks for your insights.

Here is (partly) the actual ATA chapters from the AMM A330 of AF (actually and currently valid for MSN660, April 1, 2009):

34-10 Air Data / Inertial Reference System (ADIRS)
34-11 Sensors, Power Supply and Switching
34-11-00 Sensors, Power Supply and Switching
34-11-15 Probe - Pitot
34-11-16 Probe - Static
34-11-17 ADM (Air Data Module)
34-11-18 Sensor - Total Temperature
34-11-19 Sensor - Angle of Attack
34-12 Air Data / Inertial Reference System (ADIRS)

And yes,
21 Air Conditioning
21-31 Pressure Control and Monitoring
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Old 5th Jun 2009, 15:13
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Blacksheep,
But what do clouds consist of, if not of water or ice particles? OK, the wx radar will not pick up up/downdrafts or other forms of CAT inside them, but surely it would detect dense cloud. Or am I missing something?
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Old 5th Jun 2009, 15:15
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There is a pattern to AF and ABI press releases (warnings). Without the boxes, they initially (AF) reported the cause as 'Lightning'. Then the PR was 'maintain airspeed', (this interesting because the implication is the pilots were 'behind'). Now the investigators are reporting 'no 447 debris', just other 'junk'.

It doesn't take a genius to conclude that the line is not only hoping for, but trying to lay the foundation for, pilot error.

How convenient, predictable, and deceitful.

For an aircraft that makes much of its automation, to the exclusion of the necessity for brilliant airmanship, only to see such aircraft dump the flight on the humans when it can't keep up seems, what, ironic??
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Old 5th Jun 2009, 15:19
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Engine FADEC Question

theamrad:

Question concerning Airbus FADEC:
Notwithstanding Safety Concerns warning, and given the earlier posts trying to explain the ACARS messages. I presume with no sign of degraded engine performance and no loss of engine indications, and that PFD flags concerned only airspeed (and possibly alt) – attitude reference was still available. I presume with A/TH disconnected – the throttles allow the setting of a specific n1(from the unreliable speed chart etc), subject to FADEC derived limits??
Also – do the FADEC units derive their main sensed data from their own dedicated sensors – or is some derived externally (ADIRU’s etc)?
GE CF6-80E1 - FADEC (ECU) is selfpowered by engine alternator when N2 > 12%.

As far as I know:
ADIRU input is used for N1 Limiting / Thrustsetting.
When A/THR is off,
Fuel Metering is proportional to T(hrust) L(ever) A(ngle)
with structural and thermal protections from its own ' Engine mounted' sensors.

A330 GE Engine Testrunner.
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Old 5th Jun 2009, 15:23
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Rockhound,

the radar will not show "dense clouds".

Radar reflects best of water in the liquid state, very lightly of ice (hardly detectable) and not at all off of vapour.

As stated above, you need to actively scan the sky by moving tilt up and down, to hit the part of the cloud that contains the liquid water.

And the airbus I flew had a Turbulence mode on the radar, a rather unreliable gadget that was supposed to indicate areas of turbulence (in magenta), but usually did so inside a cell. And as one doesn't fly into the cell knowing that turbulence exists inside, the information was generally useless.
Don't ask me how the technical part of that radar worked, I have forgotten and don't have access to the manuals anymore...

Nic

PS: And, Rockhound, there is no CAT inside a cloud - ever. CAT stands for CLEAR air turbulence and is the term for turbulence OUTSIDE of clouds. Everybody who flies knows it is ALWAYS turbulent inside cumuliform clouds, it's just the nature of these things, it is how they are created...
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Old 5th Jun 2009, 15:34
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Thanks, Nic. I shall now retreat back under my rock.
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Old 5th Jun 2009, 15:36
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AMF

I am struggling a little with your concept.
If the Ap disconnect was inadvertent, would the pilots not re-engage immedietly to preserve protection integrity?
If deliberate, which I am doubtful, attention scan and workload is necessarily more demanding. Not recommended and of very doubtful assistance in a very hostile environment. I am still inclined to problems with AD sensors, for whatever reason, being causative .
I am very grateful to the many informative posts which appear to be managed in a more enlightened manner. Downloaded Weather actuals for AF447 are particularly revealing together with ACARS intepretation.
Thanks to all.
Clearly we are all hopeful that search mechanisms are reliable and successful not only for possible debris but also ultimately for FDR and CVR.
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Old 5th Jun 2009, 15:48
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Boxkite Montgolfier- If your language is French, would you explain your comment re a/p 'inadvertent disconnect'. Because to me that implies 'accidental'. Please tell me you didn't mean 'accidental.'
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Old 5th Jun 2009, 15:49
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A330 vs A340 at FL350

Given the sensitivity on this forum I hesitate to ask this question (Sensitivity I don't agree with BTW, there are always idiots and you can't sanction for them)

We have much discussion about the fact the A330 was likely to have been operating out of it's comfort zone at FL350 at this point in the flight. Pretty much in Coffin corner.

So the question is "Given the same route and passenger/freight loading would the A340-300 be operating with a greater speed margin at FL350"?.
I sort of expect it would, being a longer range aircraft, but hard information has been surprisingly hard to find.
(This question is prompted by the IB flight going through at FL370)

regards
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Old 5th Jun 2009, 15:49
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It seems as though Airbus is suggesting, through their "airspeed" warning to pilots, that they think one of the links in the chain of events that led to the loss of AF447 is the pilots flying in severe/extreme turb. with the autothrottles engaged instead of flying the recommended turbulence power setting with the A/T off?
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Old 5th Jun 2009, 15:51
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Dysag

If you know for sure that events on ACARS are timestamped and transmitted with the message, then that answers my question nicely.
If you just quote what others have heard, said or posted, then your remark is not really helpful. I am might be getting older, yes, however a career in computer engineering has left me to take nothing for granted, most certainly not a sequence of fault messages created by a cluster of dying computers and then transmitted serially through a small bandwith expensive communication line.
cheers, oldie

Last edited by clearedtocross; 6th Jun 2009 at 09:54.
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Old 5th Jun 2009, 15:51
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The reports regarding debris seem to be completely contradicting each other. The Brazilian Air Force has been quoted as saying they have not collected anything which belonged to AF447, yet the French Air Force are quoted as saying that life vests and chunks of the plane and baggage containers have been collected.
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Old 5th Jun 2009, 15:52
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Futura Rider- This is a blunder by ABI. In attempting to finger the crew, they forget that the a/p was flying the a/c, and that after the disengage, the pilots goofed by not maintaining proper speeds. AS IF. Any release by AF or ABI will have this complexion: 'Airbus cupable? mais non'


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Old 5th Jun 2009, 15:54
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Nuclear sub to join hunt for jet

Hopefully, this might be the first bit of good news. Just surprised it hadn't been mentioned or suggested by authorities before now. BBC

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Old 5th Jun 2009, 15:55
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Originally Posted by CaptJ


(This question is prompted by the IB flight going through at FL370)
Aircraft flying at higher altitudes can simply mean they are carrying fewer passengers and cargo.
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Old 5th Jun 2009, 16:01
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WXR Operation

The weather radar system will collect returns from precipitation to activate and acquire a paint the precipitation has to be moving and measurable by Doppler Effect. The higher the Doppler Effect the faster the precip is moving allowing the different colours to be displayed.

It will not pick up hail very well as it is a 'stealthy' circular shape allowing only a single point on the spherical hail to provide a return.

The radar range is affected by the time the radar beam travels out to target & returns so for the same measurable display the radar gain has to be increased as the returning signal is weaker. (STC Sensitivity Time Control)

IF the beam is entirely reflected by Extreme precipitation the backside display of the weather Can look clear (Black) the crew temptation would be to cut across the thin line of 'bad' weather to reach the calm beyond.

What is actually beyond is Hell.
Updated radars detect this as A PAC alert (Path attenuation Compensation) Along with The TURB Mode & PWS these are calculated figures within the radar.

They are best guess logic only but best guess based on years of experience and engineering & meteorological calculation.

The radar pic presented to the crew Has to be interpreted; the same display in Iowa has to be treated differently than in Hong Kong.

As a side note this is the second Airbus down with what pre investigation appears to be erroneous sensor data (ANZ A320 AOA - admittedly with apparent crew contribution)
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Old 5th Jun 2009, 16:01
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Incontrol6 and A33ZAB - thanks for confirming/clarifying that point

Although I don't to speculate in AF447's case specifically - wouldn't failure of a FADEC sensed value, from an AD source for example, causing 'reversion' to an alternate/backup mode generate an ECAM and/or ACARS message. (Such as 744 ÉICAS message ENG 1 EEC MODE, for example).
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Old 5th Jun 2009, 16:01
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Boxkite Montgolfier AMF

I am struggling a little with your concept.
If the Ap disconnect was inadvertent, would the pilots not re-engage immedietly to preserve protection integrity?
Boxkite,

Among other ways, most autopilots will disengage themselves if the aircraft begins rolling or pitching due to outside forces to outside pre-defined limit built into the autopilot itself.

The same is true if it's set to hold a particular altitude but outside forces or decaying airspeed/high AOA approaching a stall exceeds the autopilot's ability to maintain that altitude. Therefore, it's set to disengage by design, accompanied by a warning to the pilots that essentially tells them "you're flying the airplane now".

It should also be mentioned that most generic procedures for inadvertent CB penetration call for de-selecting the Altitude Hold function of the Autopilot even if it remains engaged to allow variations in altitude occur due to extreme updrafts and downdrafts. This is so the AP doesn't keep running pitch control/trim servos to max limits in the futile attempt of trying to maintain a selected altitude which could result in overstress and/or far out-of-trim situations. Perhaps someone here could post what the A330 QRH/AFM procedure calls for with regard to Alt Hold if encountering a CB/Severe Turb?

These limits are designed into autopilots so it doesn't try and overstress the aircraft or keep trying to fly it when the wing stops flying, so through engineering they limit how far it can respond with control surface deflections. In the closed thread, others have posted what those particular pitch, roll, etc. limits are for the Airbus 330-200 aircraft. In severe or extreme turbulence, it's very possible the aircraft was pitching or rolling up to, and beyond, one or more of these internal trip points.

And an autopilot will lock-out engagement (or re-engagement) if you're handflying flying outside of these built-in parameters. So if violent pitching or rolling was/is occuring, you can select engagement as many times as you want but it won't because it needs to see all the parameters met for its engagement first.

Hope that clears up your question, and explains my line of thinking as to why it's the big, red flag of this event.

Last edited by AMF; 5th Jun 2009 at 21:09.
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Old 5th Jun 2009, 16:05
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G- Switch or manually activated 121.5/243/406 MHZ type
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Old 5th Jun 2009, 16:06
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Originally Posted by zekettledrum
The reports regarding debris seem to be completely contradicting each other. The Brazilian Air Force has been quoted as saying they have not collected anything which belonged to AF447, yet the French Air Force are quoted as saying that life vests and chunks of the plane and baggage containers have been collected.
I believe it was the Brazilians who found life vests and a WOODEN cargo pallet. Two things that boats usually carry. They are now saying that they don't belong to AF447.

Unless you can provide an official press release from The French Air Force saying otherwise, it appears that nothing has been found yet.
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