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MH370 - "new" news

Old 19th Dec 2022, 01:40
  #161 (permalink)  
 
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Originally Posted by Dora-9
Thanks for answering that.You're dodging another question though, namely about what's your experience of operating in this enviroment?
Sorry, one more thing... why's his experience in that specific environment so important? If he's flown jet airliners for a while and if he's switched on wrt systems and SOPs he's eminently qualified to comment on a technical scenario. I don't think you really need to have flown into Penang to have an educated opinion on it all. There is almost an infinite number of small variables which might've influenced the capt that night to make numerous decisions on one plan or another and GBO having flown to Penang or through that airspace last month or last year or never won't change anything.
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Old 19th Dec 2022, 02:44
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Eclan:

why's his experience in that specific environment so important?
Because the operating environment in SE Asia is VERY different from the Australian domestic scene. I'm not commenting on, nor criticizing, his impressive technical expertise. He doesn't have to have flown specifically into Penang to offer a valid opinion (although that might "open his eyes" somewhat) but his responses to my criticism leave me thinking he's never been in that environment. And, notably, he's never rebutted that.

I believe once SSR has lost the transponder that's it
I checked with an Air Services friend and he thought you'd just be harder to "see" - but there would be a return. I ended up entering BNE without a Xpdr once and it took them a few minutes to "find" me, but then again I did tell them I was coming!

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Old 19th Dec 2022, 03:29
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Originally Posted by GBO
...or there has been an FMC failure and software reset to the other FMC. Thus, there will be a period where the aircraft doesn’t have LNAV capability.
You made this statement previously and you were told then that your understanding is incorrect. With both FMCs operating normally, one of them is active and the other is inactive. The active FMC synchronises the inactive FMC any time there is a change to the flight plan or performance data. If the active FMC fails with the FMC selector in AUTO (ie the usual position), there will be an automatic failover to the previously inactive FMC, which already has all the data it needs to take over as the active FMC. There is no "software reset" and LNAV remains engaged.

Indeed, LNAV capability remains available even if both FMCs fail. In that case, the alternate navigation system uses the flight plan data stored in the internal memory of the CDUs; however, LNAV must be re-engaged.

Last edited by BuzzBox; 19th Dec 2022 at 04:43.
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Old 19th Dec 2022, 03:41
  #164 (permalink)  
 
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Originally Posted by Eclan
If he's flown jet airliners for a while and if he's switched on wrt systems and SOPs he's eminently qualified to comment on a technical scenario.
Of course, but is that actually the case? Some of his comments indicate that he is not very well versed in certain aspects of airline operations that should be well known to anyone with airline experience. That leads people to question the accuracy of his other claims. The question about his background has been asked several times, with no response.
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Old 19th Dec 2022, 03:49
  #165 (permalink)  
 
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Originally Posted by Dora-9
Eclan:
I checked with an Air Services friend and he thought you'd just be harder to "see" - but there would be a return. I ended up entering BNE without a Xpdr once and it took them a few minutes to "find" me, but then again I did tell them I was coming!
I think your friend meant to say that ATC can still find you on primary RADAR.

No Xponder = No SSR return.

I note this from Airline Online:
Three radar industry and ATC sources in southeast Asia consulted by AIN confirmed that air traffic controllers rely almost exclusively on SSR and receive little or no refresher training on the use of primary radar after their initial qualification. Military radar controllers also rely on SSR to identify civilian air traffic.
I suspect you were ‘found’ on the primary RADAR because they knew you were ‘there’ and where to ‘look’ to find your primary return.
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Old 19th Dec 2022, 04:27
  #166 (permalink)  
 
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Originally Posted by Dora-9
I checked with an Air Services friend and he thought you'd just be harder to "see" - but there would be a return.
In Malaysia's case the civilian long-range surveillance radars are SSR only, with a range of 200 NM; there is no primary radar. The major airports (eg KL, Kota Bharu) generally have a 60 NM primary surveillance radar collocated with a 200 NM SSR. An approach controller could see you on primary radar at short range if they knew where to look, but they'd be blind to anything outside 60 NM.
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Old 19th Dec 2022, 05:49
  #167 (permalink)  
 
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Lead Balloon and Buzzbox:

Thanks very much for the clarification. I just keep out of the way these days. In my BNE example, as I stated they did know I was coming (and they were extremely helpful too).
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Old 19th Dec 2022, 06:25
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Originally Posted by GBO
And how do you know when to descend without VNAV?
You've got to be kidding right?
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Old 19th Dec 2022, 10:12
  #169 (permalink)  
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Originally Posted by BuzzBox
With both FMCs operating normally, one of them is active and the other is inactive. The active FMC synchronises the inactive FMC any time there is a change to the flight plan or performance data. If the active FMC fails with the FMC selector in AUTO (ie the usual position), there will be an automatic failover to the previously inactive FMC, which already has all the data it needs to take over as the active FMC. There is no "software reset" and LNAV remains engaged.
There are software resets, as stated in the FCOM.

“A software reset may occur while in single FMC operation. The active route becomes inactive, the performance data is erased, and LNAV and VNAV (if engaged) modes fail.”

It is not possible for an active FMC to synchronise to the inactive FMC if the link is severed.

If the active FMC always changes automatically, then there wouldn’t be a need to install a FMC selector switch for Left, Auto, or Right.
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Old 19th Dec 2022, 10:22
  #170 (permalink)  
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flightleader,

Refer to table 2.5A of the Safety Information Report for information on the Flight ID change status at the 1825 SATCOM logon.
Manually clearing the Flight ID via the MCDU with power interrupt is not possible.
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Old 19th Dec 2022, 11:00
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Originally Posted by GBO
There are software resets, as stated in the FCOM.

“A software reset may occur while in single FMC operation. The active route becomes inactive, the performance data is erased, and LNAV and VNAV (if engaged) modes fail.”
Yes, a software reset MAY OCCUR WHILE IN SINGLE FMC OPERATION because there is no redundancy in single FMC operation. That is NOT the case while in dual FMC operation; if one fails, the other automatically takes over.

It is not possible for an active FMC to synchronise to the inactive FMC if the link is severed.
You missed the point. The active FMC synchronises the inactive FMC any time a change is made to the active flight plan or the performance data. When the active FMC fails, the inactive FMC IS ALREADY SYNCHRONISED and ready to assume operation; further synchronisation is not necessary.

If the active FMC always changes automatically, then there wouldn’t be a need to install a FMC selector switch for Left, Auto, or Right.
So what? The inactive FMC still has the data that was synchronised from the active FMC before the failure occurred. If the automatic failover does not occur, all the pilot needs to do is switch to the operative FMC and re-engage LNAV. Your claim that LNAV is not available is bollocks.

Last edited by BuzzBox; 19th Dec 2022 at 11:43.
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Old 19th Dec 2022, 13:56
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All this talk about whether LNAV is engaged, is all a bit irrelevant if as I suspect the autopilot has failed, due to the flight controls degrading to secondary.

As GBO correctly concludes, the analysis of the primary returns coming back to Penang show no straight line portions… after the turn at Penang and after 18:01z we have no radar returns to work from. Therefore, we don’t know if LNAV was engaged or not.

I see no reason to make the claim the autopilot was ever engaged again and connected to an active route….

GBO is correct in his initial failure scenario, it’s just the aftermath of that failure that need to be ironed out.
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Old 19th Dec 2022, 18:35
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The question about his background has been asked several times, with no response.
And still deafening silence from GBO about this.
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Old 19th Dec 2022, 21:52
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Sorry, one more thing... why's his experience in that specific environment so important?
Because he is making a lot of noise about what he thinks might have happened to MH370 so he should state his credentials. All he has stated is that he is a pilot, so what. A pilot of a trike, an ultralight or a 172 has no credibility to discuss on an open forum how an airline pilot responds, reacts or manages an inflight emergency. In this case the inflight emergency he has proposed is just a theory based on a multi-level series of failures to explain a flight path that took an airliner to the far reaches of the Indian Ocean.
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Old 20th Dec 2022, 01:15
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Originally Posted by GBO View Post
And how do you know when to descend without VNAV?
How would you do it in the jet you fly GBO?
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Old 20th Dec 2022, 04:03
  #176 (permalink)  
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Originally Posted by BuzzBox
The active FMC synchronises the inactive FMC any time a change is made to the active flight plan or the performance data. When the active FMC fails, the inactive FMC IS ALREADY SYNCHRONISED and ready to assume operation; further synchronisation is not necessary .
Actually, “The active FMCF sends its flightplan data to the inactive FMCF for these conditions:
- Long term power ups
- BITE induced restart
- Flight plan entries and performance data changes.
When the active FMCF fails, a resynchronization (resync) occurs. Resyncs take about 1 second for an entire flight plan update. The active FMCF always resyncs the inactive FMCF. The active FMCF selection is a function of the FMC selector position and FMF partition health.” 777 Training Manual 34-61-00 p106

If the link between both FMCFs in the respective Left and Right AIMS Cabinet is severed, and the active Left FMCF has failed, a resync is not possible. An auto fail switch is not possible.
A software reset is a function of BITE/fault monitoring. If a software reset should occur, the active route becomes inactive, the performance data is erased, and LNAV and VNAV (if engaged) modes fail. At this time, the crew cannot be using LNAV because it has failed eg diverting to Penang in a chaotic cockpit. The Flight ID has been erased. To regain FMC operation, manually selecting the FMC selector to the right, will make the right FMCF as the active. The crew need to activate and execute the flight plan, enter the necessary performance data, and engage LNAV and VNAV. Now LNAV is available eg tracking west from Penang.

When the SATCOM logged on at 1825:27, the Flight ID was missing.
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Old 20th Dec 2022, 05:25
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Originally Posted by birdspeed
GBO is correct in his initial failure scenario, it’s just the aftermath of that failure that need to be ironed out.
How can you possibly know that he is correct?

Sometimes people just need to take a step back and look at the big picture. There’s very little hard facts that can be established with this incident. Any theories on hypoxia or smoke inhalation or massive avionics failure are speculation. There’s no way they can be proven correct. Even if/when the data recorders may be recovered it still probably won’t be conclusive enough to end speculation.

Maybe this will be unsolved forever.
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Old 20th Dec 2022, 07:05
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Originally Posted by GBO
Actually, “The active FMCF sends its flightplan data to the inactive FMCF for these conditions:
- Long term power ups
- BITE induced restart
- Flight plan entries and performance data changes.
When the active FMCF fails, a resynchronization (resync) occurs. Resyncs take about 1 second for an entire flight plan update. The active FMCF always resyncs the inactive FMCF. The active FMCF selection is a function of the FMC selector position and FMF partition health.” 777 Training Manual 34-61-00 p106

If the link between both FMCFs in the respective Left and Right AIMS Cabinet is severed, and the active Left FMCF has failed, a resync is not possible. An auto fail switch is not possible.
A software reset is a function of BITE/fault monitoring. If a software reset should occur, the active route becomes inactive, the performance data is erased, and LNAV and VNAV (if engaged) modes fail. At this time, the crew cannot be using LNAV because it has failed eg diverting to Penang in a chaotic cockpit. The Flight ID has been erased. To regain FMC operation, manually selecting the FMC selector to the right, will make the right FMCF as the active. The crew need to activate and execute the flight plan, enter the necessary performance data, and engage LNAV and VNAV. Now LNAV is available eg tracking west from Penang.

When the SATCOM logged on at 1825:27, the Flight ID was missing.

You've made two assumptions: First, that an auto failover is not possible; and second, that a software reset will occur. The manual does not state either of those things. You also conveniently ignored the first part of that paragraph you quoted from the manual:
​​​​​​FMC synchronization monitoring occurs at power-up and during normal operation. The active FMCF sends flight plan data to the inactive FMCF. This occurs so the inactive FMCF can take over if the active FMCF fails.
As I said previously (and as described in the manual), during normal operation the active FMC synchronises the inactive FMC any time there is a change to the flight plan or performance data. If a resync did not occur in your scenario, the inactive FMC is already synchronised with the active FMC that has failed.

Now, how about answering the questions you were asked, which you have not answered?
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Old 20th Dec 2022, 11:36
  #179 (permalink)  
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Originally Posted by Icarus2001
How would you do it in the jet you fly GBO?
Since dr dre didn’t respond to the original question, my response would be to use old school methods if VNAV was not available. You can approximate the descent point based on the 3-in-1 method or the metres button. eg From FL340 to sea level, 3x34=102NM, or FL340=10363m (103.63NM).

But if VNAV was available, what distance from Penang do you predict for the VNAV Top Of Descent Point into Penang if:
Cruise at FL340/294CAS,
Descent speed 268CAS,
Nil wind,
No STAR or approach loaded.
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Old 20th Dec 2022, 20:05
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The disappearance of MH370 is a somewhat complicated but straightforward story. It is not a mystery. Very few people today will take the time to research anything Google has not already done for them, and the reason you don’t find this there or anywhere else is because this story has every one of the buttons we dare not push for fear of offending someone. For anyone truly interested in what happened, and especially why it happened, all you need is a case of real curiosity, patience and persistence.

Genuine failures of transponders tend to happen very close to the scene of the accident and valuable things that deliberately disappear at sea do so for one reason and one reason only. Also, professional pilots with good reputations and no apparent deficits would have to be highly motivated to do what this one did. The events surrounding this man’s life prior to his final flight are well documented and very helpful.

Most of those with any need have known the facts and the true story since the event.
For the mildly curious and most of the world however, it will remain the greatest aviation mystery of all time.
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