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-   -   AF 447 Search to resume (part2) (http://www.pprune.org/tech-log/449639-af-447-search-resume-part2.html)

gums 23rd Apr 2011 19:05

AF 447 Search to resume (part2)
 
Part 1 of this thread can be found Here


Need some of you "bus" drivers to clue me in re: autopilot authority and inputs.

If the pitot-static inputs go tits up, what happens? The B-2 crash was a result of several sensors being filled with water and the jet tried to climb like hell just after WOW. Seems like an "attitude" control law would have helped those two guys.

So my theory all along is the pitot-static system went south and the crew didn't react properly and/or the autopilot didn't revert to an "attitude" mode. Sheesh. All of us that have flown into CB's or had a pitot-static ice problem and simply held attitude and didn't chase speed or altitude until we figured out our problem. Keep wings level and a semblance of level attitude.

In several instances I was glad that the Viper control laws were gee- command and roll rate. Let go of the stick and the jet would try to keep trim gee and zero roll rate. I have a hard time with all the "control laws" for the "bus". Glad I am not/ was not a pilot of the beast.

HazelNuts39 23rd Apr 2011 19:19

Quote:

Did all Tx (ACARS) arrivee via FIN??
The BEA report #1, 1.16.2.4 states that after 2:10 all ACARS messages passed through the same satellite:
Quote:

The messages received on 1st June after 2 h 10 all transited via the same satellite (Atlantic Ocean West, operated by the Inmarsat Company) and SITA’s ACARS network.

bearfoil 23rd Apr 2011 19:42

Hazelnuts39

Yes, of course, the ACARS that were released to the public. That is not demonstrably untrue, it merely would mean that the repeated ACARS stream broadcast after the antenna interruption by the SATCOM antenna/System had restarted with the first of the ACARS stream we have. (The "Overlap").

I have wondered why we see no activity of ACARS prior to those we have in the public domain. Weren't these released by a whistleblower, and if AF had those streamed by the Fin (VHF) that weren't released, why would they release those? I was given to undertsand that ACARs tx of preference is VHF (cost??). Golly, that is complicated, though, surely if they existed, BEA would release all the ACARS from this flight?

This of course means that 447 was airborne and Txable SATCOM if there was a repeat Tx by the flight. It would certainly allow that the pilots may have taken a breath prior to re-engaging the A/P?? Well, I am certainly beyond my expertise here.

JD-EE 23rd Apr 2011 19:59

HN39, just a short note, when I was developing some software for Inmarsat-M SatCom terminals I communicated regularly with AOW from Torrance through the ground station in Goonhilly. That gives you some notion of the theoretical coverage range. (My antenna was aimed below the horizon for the typical ACARS antenna though.)

bearfoil 23rd Apr 2011 20:00

I have wondered since the outset why there are no ACARS alerts via Satellite between the last two on the ramp at RIO, and the ones beginning at 0210.

Wouldn't there be at least a few? 447 was no virgin, and she must have had reportable defects prior to "The Sky is falling" at 0210. Or is radio abandoned at the intervals I would question?? Irrespective of antenna issues, what explains the dearth of ACARS coms??

JD-EE 23rd Apr 2011 20:05

Bearfoil, you are reaching way too far. You are presuming the airline is so cheap they'd send messages via HF rather than SatCom when the plane is SatCom equipped. And I am not at all sure HF would be even pennies a message cheaper. It would certainly be less reliable without some serious Automatic Link Establishment sort of technology. HF propagation is not necessarily a hands off operation without such technology.

You have a habit if making unsupported and too often unsupportable assertions. And you are back to your mantra that you said you never discuss, "the VS er Fin came off the plane and caused the accident." This gets REALLY tiresome, sir.

I'd also like to note that there was a previous trouble message included in the logs - one of the potties had a problem.

HazelNuts39 23rd Apr 2011 20:05

Quote:

Originally Posted by bearfoil
if AF had those streamed by the Fin (VHF)

The fin has HF1/2, whereas VHF1/2/3 are on the fuselage.

mm43 23rd Apr 2011 20:08

Quote:

Originally posted by bearfoil ..

I have wondered since the outset why there are no ACARS alerts via Satellite between the last two on the ramp at RIO, and the ones beginning at 0210.
There was a LAV fault reported, and don't forget the AOC position reports were every 10 minutes via ACARS.

JD-EE 23rd Apr 2011 20:08

HN39, I'd also note that you ain't gonna stream via VHF out where the plane was no matter WHERE its antenna is. 100nm is about it for VHF give or take a factor of two. (I'm not going to bother to go look it up on the nomographs I have.)

bearfoil 23rd Apr 2011 20:25

For goodness sake. This thread is 100 percent conjecture and partial repetition of BEA regurgitatae...... The Potty pressure valve bollux and the Audio panel glitch were rampside, if I'm not mistaken, and frankly what is tiresome are people who eat mush blindfolded, without palpating it at least.

The audio panel was mel, I don't think the lav was important enough to make the list. The radio selects were of no small concern.

This entire exercise is nothing more than an intriguing diversion. To think any real results are to be found here is absurd. The reality of the exercise is what is elusive. The pilots knew. They knew. The a/c and ground support failed them, and by extension, all those in their loving and skilled care.

What is beyond tiresome is most here taking themselves far too seriously.

There are a few here for whom I have utmost respect, and frankly more for their grace than their respective expertise, inspiring though that be.

If anyone here thinks I am serious beyond an informed speculation and earnest question or two, please read me with tongue in cheek, as intended.

Christ on a freaking crutch.

ACLS65 23rd Apr 2011 20:35

JD-EE

"HN39, I'd also note that you ain't gonna stream via VHF out where the plane was no matter WHERE its antenna is. 100nm is about it for VHF give or take a factor of two. (I'm not going to bother to go look it up on the nomographs I have.)"

Where AF447 was it was out of range of VHF and ADS-B, and didn't have HF ACARS. It doesn't look like their is much amateur monitoring of ADS-B in that area.

In terms of previous ACARS messages I suspect there would have been VACARS transmitted via VHF3 prior to SATCOM.

The A330 Comm manual says that "ACARS normally transmits via VHF3. It automatically switches to SATCOM when VHF3 is not available."

Not quite sure if that means ACARS switches automatically when it is no longer receiving ACARS msgs via VHF3, or if by unavailable they mean something else.

mm43 23rd Apr 2011 21:25

Mr Optimistic posted a message at #9 in this thread, but has subsequently withdrawn it. The question posed was, "Is Svarin's analysis of the ACARS messages accepted?"

With the thread otherwise engaged, potty/lav included, I think the substance of what Svarin had to say in post #3858 and post #3863 in Part 1 of this thread has been overlooked.

In essence, the A/P and A/THR disconnected due to UAS. Cockpit activity is evidenced by -

2:12:10 WRN/WN0906010211 341200106FLAG ON CAPT PFD FPV
2:12:16 WRN/WN0906010211 341201106FLAG ON F/O PFD FPV

Two pages not normally selected in the cruise.

Secondly, the A/P was reconnected 3 minutes after the UAS in what was apparently an unstable situation -

2:14:20 FLR/FR0906010213 22833406AFS 1,,,,,,,FMGEC1(1CA1),INTERMITTENT

possibly causing a pitch up command, a situation around which an Airworthiness Directive was issued this (northern) winter regarding A/P reengagement after an UAS condition.

I think that Svarin is probably correct, and I know that he has meticulously examined each of the ACARS messages and sought rational explanations for all. The answer was found in the "detail".

The CVR will be necessary to confirm what was going on prior to 0210.

Machaca 23rd Apr 2011 21:49

From EASA AD No.: 2010-0271 (22 December 2010):

REASON
http://i337.photobucket.com/albums/n...271_Reason.jpg

http://i337.photobucket.com/albums/n..._Prodedure.jpg

Khashoggi 23rd Apr 2011 22:02

Assuming AF447 was intact on hitting the Ocean surface, could you explain the disparate condition of the floating wreckage by considering that the Ocean surface was not flat but instead had large wave action?

The BEA thinks there was low forward velocity, but a fuselage hitting a line of waves could cause multiple impacts, and various breaks and ejection of components under varying impact loads.

There was wx in the area, so presumably the Ocean wasn't smooth as silk that night??

Mr Optimistic 23rd Apr 2011 22:05

mm43
 
Sorry, thought my post was contentious (not a pilot so cautious). Svarin's post seemed informative but don't understand why after nearly 2 years anything new is coming from the ACRAS messages and if it is new why so little attention is given to it.

HazelNuts39 23rd Apr 2011 22:21

Maybe there is a difference between AP disengaged, AP lost, and AP off?

broadreach 23rd Apr 2011 22:30

Machaca,

Note the date of that!

EASA AD No.: 2010-0271 (22 December 2010)

Would there have been an AD along similar lines available prior to the accident?

Machaca 23rd Apr 2011 22:33

khashoggi - A very good point and quite correct. Yes, the irregular surface of the ocean did indeed play a large part in how the airframe and its contents were damaged and to what level.

It was discussed many moons ago in an earlier thread. Sadly, many have forgotten or disregarded much of the valuable and substantiated input that has been provided over the last 22+ months. Yet some proffer curious scenarios as if they were never contemplated beforehand. :ugh:

I don't know why it is so difficult for some to envision how a galley can be ejected relatively undamaged in such an impact with the sea.

Machaca 23rd Apr 2011 22:45

broadreach - AD 2010-0271 does not supersede any previous AD's.

jcjeant 23rd Apr 2011 22:55

Hi,

Quote:

It has been identified that after such an event,if two airspeed sourcesbecome similar while still erroneous,the flight guidance computer will:
Do any one know the date and what event ... when this was identified ?


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