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AF 447 Search to resume

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AF 447 Search to resume

Old 6th Feb 2011, 16:06
  #2701 (permalink)  
bearfoil
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PJ2

Hi. Sorry for the delay, and thank you for the usual brilliant post. One thing, you mention a "disconnect" of AP does not degrade flight Law. I was of the impression an involuntary (auto) drop commanded Alternate Law? If Aero and accel considerations caused the A/P to quit, that does not trigger Law Change?? I have long believed the AP dropout was caused by its inability (programmed) to keep up?

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Old 7th Feb 2011, 02:54
  #2702 (permalink)  
 
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Bearfoil

Which-ever way you look at this "chicken & egg" situation at 0210z, I am reminded of the the favorable CRM analysis made of the THY crew involved in the B738 accident at AMS. The investigation confirmed that they in fact did everything correctly in a tight ATC controlled environment, but were badly let down by an unexpected automation condition not documented nor trained for. Unfortunately their epitaph acknowledges that, "The combination of training standards and experience is not always enough to protect crews from the subtle effects of automation failures during automated, human-monitored flight", and there may well be some relevance to the events we are dealing with here.
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Old 7th Feb 2011, 15:40
  #2703 (permalink)  
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The quoted conclusion is a glaring example of the incongruity (and potentially deadly results) of a human crew flying with an automatic or fbw system they do not "understand". Inherent in this unfortunate statement by a regulator (of all things) is the mirage of safety due automation.

Pilots have been caught out with a bird's nest in air intake, a mud dauber's nest in pitot, or dual failures since the "day". There is and can be no excuse for introducing advanced control systems and then making an effort to "isolate" the crew from its operation.

What is the goal of automation? Pilotless flight? Fine. Say so. With 447, it would appear that a cascade of warnings and alerts of varying criticality deluged the dark and lumpy cockpit with distracts of almost sinister veil.

THY had alot of experience to hand, but the state of the "Art" caused a disconnect at the most critical of times, (Always the case??) It would seem that the most inopportune times are populated more heavily with the breakdown in "Awareness".

Will we find out if Captain DuBois' flight was besieged with a clumsy "reversion" in Flight Laws and Manual command?? One hopes the evidence will be found. That it is easy to entertain such a thought is worrisome. Were the PF's lulled into reliance on the AP for too long? Did they allow a dangerous drift into complete trust of the systems?? Would we use computers comparable to those aboard in our most mundane business tasks? Computers cannot think, they Act. Or Not. It is the Not part that gets people in trouble when "Novelties" are not trained. The ebb and flow of flight data and control command needs a new 'seamstress'.

Wasn't THY more a flight data reads issue? Unreliable airspeed syndrome is just that. There is no real Airspeed issue at all, only (sic) the air data displayed by the sensors. In 447's case, Pitch and Power should have saved the day. Duff airspeed read has been recovered thousands of times.

Reliance of the entire Airframe on flight controls that are operated by a system that doesn't have any idea what it is doing is regrettable, and here may be a case in point. A perfectly serviceable Aircraft and its people destroyed by Human Pride, Stubborn adherence to antiquated ideas, etc.

Ice? Upset? Mechanical Malfunction/Failure ?? Let us all hope there is a more thoughtful conclusion to this accident than the laughable and pathetic conclusion made by the authority in the case of THY Amsterdam.

regards,

bear

Last edited by bearfoil; 7th Feb 2011 at 15:56.
 
Old 7th Feb 2011, 17:14
  #2704 (permalink)  
 
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First, bearfoil, I see a lot of emotional assertions with no facts in evidence.

Second, put your money where your mouth is and design a flight control system that works your way for that airframe. It ain't that simple, McGee.

{^_^}
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Old 7th Feb 2011, 17:45
  #2705 (permalink)  
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Bearfoil;
One thing, you mention a "disconnect" of AP does not degrade flight Law. I was of the impression an involuntary (auto) drop commanded Alternate Law? If Aero and accel considerations caused the A/P to quit, that does not trigger Law Change?? I have long believed the AP dropout was caused by its inability (programmed) to keep up?
An involuntary autopilot disconnect does not in itself result in any degrading to alternate 1 or 2, or direct law.

However, some system abnormalities or failure conditions which do result in a degradation to alternate or direct law also result in an involuntary disconnection of the autopilot and autothrust systems.

The difference is illustrated below - the following summarizes both crew-actioned autopilot disconnections and involuntary disconnections which would not be associated with any degradation of flight control laws:

AP DISENGAGEMENT
AP1 or 2 disengages when :
– The pilot presses the takeover pushbutton on the sidestick.
– The pilot presses the corresponding AP pushbutton on the FCU.
– The pilot pushes on the sidestick harder than a certain threshold. (Disengagement through rudder
pedals is only active on ground).
– The other AP is engaged, except when localizer/glideslope modes are armed or engaged, or rollout or go-around mode is engaged.
– Both thrust levers are set above the MCT detent and the aircraft is on ground.
– In a non-precision approach, with FINAL APP mode engaged, the aircraft reaches :
• The MDA/MDH minus 50 feet (if entered), or 400 feet AGL (if no MDA/MDH is entered), or
• The Missed Approach Point (MAP), depending on which one comes first.
– One of the engagement conditions is lost.
– Furthermore, in normal law with all protections available, the AP will disconnect if :
• High speed protection is active.
• Angle-of-attack protection is active (α prot + 1° is reached).
• Pitch attitude exceeds 25° up, or 13° down, or bank angle exceeds 45°.
The standard way for the flight crew to disengage the AP is to press the takeover pushbutton on the sidestick.
When AP is OFF, the associated FCU pushbutton goes off, and the “AP1” (or AP2) is removed from the PFD's FMA.

The following is a table of results/outcomes from various system degradations which result in alternate laws 1 or 2 or direct law, and an involuntary disconnection of the autopilot & autothrust systems:

Depending on the type of failures affecting the flight control system, or peripherals, there are 3 possible reconfiguration levels :
– Alternate law (ALT 1 or ALT 2)
– Direct law, or
– Mechanical.

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Old 9th Feb 2011, 15:06
  #2706 (permalink)  
 
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Thank you PJ2 for these tables.

One can notice that ADR DISAGREE does not entail A/P LOST condition.

Which means that under ADR DISAGREE conditions, A/P can be reengaged, presumably when the problem is over... Or almost over... See again the AD previously mentioned...
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Old 9th Feb 2011, 16:16
  #2707 (permalink)  
 
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AP Reconnect and Prim And Sec Faults

I am having a hard time reconciling the AD scenario of an AP reconnect with the Prim1 and Sec1 faults.

1. It appears that the Prim1 and Sec1 faults would not cause a second disconnect?

2. Would it be a reasonable action to attempt a AP reconnect and command a Prim 1 and Sec 1 Shutdown?

3. If commanded, in what order would the FCPC and FCSC's be shut down, eg. Prim 1 then Sec 1 or Prim 1 then Prim 2, etc.?

Last edited by thermalsniffer; 9th Feb 2011 at 17:22. Reason: clarification
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Old 10th Feb 2011, 19:13
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Search Update

The dive support vessel "Alucia" departed Harbor Island, Seattle, WA at 10/1430z for Port Suape, Brazil via the Panama Canal. The Puget Sound pilot disembarked off Port Angeles at 10/2010z and the transit time to Balboa, Panama is 13 days 19 hours at 12 knots (3,975NM).
A long time ago nautical charts labelled unexplored regions with the phrase, ‘Here be Dragons’. That’s what MV Alucia is all about. We want to visit the dragons.
Edit :: Vessel anchored / slow maneuvers in Freshwater Bay, west of Port Angeles at 10/2112z. Why? Possibly testing dynamic positioning (DP) mode. Your guess is as good as mine!

Last edited by mm43; 10th Feb 2011 at 20:44.
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Old 10th Feb 2011, 21:51
  #2709 (permalink)  
 
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Alucia is currently en route

mm43

Possibly testing dynamic positioning (DP) mode. Your guess is as good as mine!
Its seems to me that tests have been conducted previously between North Bay/Blue Ridge and Richmond Beach.

But now, what's the matter? What is succeeding in Freshwater Bay?
The vessel seems to be currently (Speed 0.3 kn, heading 130˚) coming back to Eliot Bay.
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Old 10th Feb 2011, 23:11
  #2710 (permalink)  
 
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The vessel seems to be currently (Speed 0.3 kn, heading 130˚) coming back to Eliot Bay.
From the Deep Ocean Quest website:
In 2010, after a profound redesign and rebuild......
Alucia just got out of a overhaul/refit, didn't it? Maybe they had an equipment casualty. It can take some time to bring a ship up to fully seaworthy condition after major rework.
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Old 11th Feb 2011, 02:27
  #2711 (permalink)  
 
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Alucia

The video attached to this report says that they planned tests in Puget Sound prior to departure, and then expected to head for Brazil at 10PM (local 2011/2/9).

Seattle-Based Ship Sets Out To Find Air France Flight 447 - News Story - KIRO Seattle

If they are still in the Seattle area, then either they found something to fix, or the reporter got the details wrong (has that ever happened? )
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Old 11th Feb 2011, 03:46
  #2712 (permalink)  
 
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Alucia

If they are still in the Seattle area, then either they found something to fix, or the reporter got the details wrong..
They are anchored in Freshwater Bay, and I suspect they are waiting for something "essential".

Edit ::
11/1918z 48.1479N 123.5933W (anchored - Freshwater Bay)
12/1754z 48.1480N 123.5933W

Last edited by mm43; 12th Feb 2011 at 18:03. Reason: update position
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Old 12th Feb 2011, 23:40
  #2713 (permalink)  
 
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Ship Tracker

Alucia seems to be not showing on the Seattle tracking site.
Try this link to see where it is.
Alucia ? HO3651 ? position and weather
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Old 13th Feb 2011, 04:07
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Alucia

Machinbird;

Thanks for the alternative link. AIS positions were being received intermittently while the vessel was anchored in Freshwater Bay, and that was probably to do with terrain shadowing.

She got underway at 13/0300z and crossed to the northern side of the Juan De Fuca Strait to get into the outbound traffic lane. Is now proceeding west at 10.5KTS

Edit :: WX prognosis is not good - SW 10/15KT becoming S 20/30KTS. Mod to heavy W swell, and by Monday (PST) the wind will be S 30/40KT.

Last edited by mm43; 13th Feb 2011 at 04:29.
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Old 13th Feb 2011, 08:57
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Hello,

She seems to be currently en route (11kts / 213°)
48.4188
-125.0979
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Old 13th Feb 2011, 10:55
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oil slick and initiation event

Whatever happened to the oilsick ? Was it ever taken seriously in choosing the search area ? Not saying it should have been but just wondering.

On a separate point, whats the current view on the condition of the aircraft at the time the first ACARS message went out: was this the start of the event or some point down the chain ? Can't recall the opinions about the possibility that the systems had previously been misled by erroneous (but consistent) inputs and the aircraft was suddenly left in a poor trim condition at the time the AP gave up.
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Old 13th Feb 2011, 18:54
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Mr Optimistic;
Whatever happened to the oilsick ?
It vanished, i.e. evaporated or dispersed.
Was it ever taken seriously in choosing the search area ?
It was discounted due to it being well outside the area of probability calculated by the Drift Group. Though it does fall within the statistical probability area defined in the Metron Report, and the area will be covered in the current Phase 4 search.
On a separate point, whats the current view on the condition of the aircraft at the time the first ACARS message went out: was this the start of the event or some point down the chain ?
Ops not normal, and 7 thousand or more posts on this and the AF447 thread later, the only satisfactory answer will (possibly) be revealed on recovery of the CVR and DFDR.
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Old 13th Feb 2011, 19:24
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MM43

Thanks as always.
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Old 13th Feb 2011, 20:03
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mm43

the only satisfactory answer will (possibly) be revealed on recovery of the CVR and DFDR
Yes, of course... but CVR/DFR solid state memory cards data are granted only thirty days at 16,000 feet deep water.

More than tweny months after the wreckage, how many probability % to recover recorded data?
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Old 13th Feb 2011, 21:58
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A/P disengagement

Originally Posted by Svarin #2706
One can notice that ADR DISAGREE does not entail A/P LOST condition.
It seems to me that the distinction between "DOUBLE ADR FAULT" and "ADR DISAGREE" is rather subtle, as both conditions usually occur together. As I understand it, the former results from two ADR's internally faulting (each ADR faults itself when it sees a sudden change in its output), and the latter from the PRIMs comparison of one ADR against the other(s).

Air Caraibes recorded the following explanation for A/P OFF from 'Airbus engineers' (my translation):
<q>The warning "AUTO FLT AP OFF" appears on the first line of the ECAM. The AUTO FLIGHT system compares continuously the values it receives from the three ADR's. If this cross-check is no longer possible after loss of two ADR's, it results in disconnect of FD and automatic pilot. As the AUTO FLIGHT system is conceived, any sudden variation of CAS, Mach, or altitude implies the rejection of one ADR. Thus, due to icing of PITOT and TAT probes, one sees on the two PFD, i.e. the ADR's 1 & 2, a very rapid reduction of these parameters which change respectively from 273 kt to 85 kt, M0.80 to M0.26 and from 35000 ft to 34700 ft within 1m25s. NOTE: thresholds for reject of one ADR: CAS 20 kt during 0.45s, Mach 0.04 during 0.45s, altitude 400 ft during 0.45s. <u/q>

See also Paragraph 1.6.11.2 in BEA's 2nd Interim Report on AF447.

EDIT:: Both explanations don't quite line up with the diagram posted by PJ2. If ADR DISAGREE does not cause A/P disengagement, then it was probably caused by DOUBLE ADR FAULT due to a rapid change of CAS and Mach in at least two ADR's.

regards,
HN39

Last edited by HazelNuts39; 14th Feb 2011 at 14:30.
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