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Indonesian aircraft missing off Jakarta

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Indonesian aircraft missing off Jakarta

Old 6th Nov 2018, 10:17
  #661 (permalink)  
 
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Originally Posted by B-757 View Post
..Works perfect, if you are in VMC conditions..However, it will get tricky, if you are in the clouds and your instruments are giving you false information (as in this case)..Things happen very fast going at 300+ knots..

Fly Safe
B-757
Well you got this nice little instrument often called the Artificial Horizon. If in the clouds, put the nose just above the horizon and wings level. Set a power and wahllah.
Now if that instrument is telling you porkies, combined with UAS, I'm afraid you up the creek without a paddle.
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Old 6th Nov 2018, 10:59
  #662 (permalink)  
 
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So far then it looks like an unreliable airspeed problem which wasn't handled correctly and resulted in tragedy. Even back in the 1970s D.P. Davies was complaining in "Handling the Big Jets" about pilots who had forgotten how to fly due to automation, it's far worse these days as progression onto airliners is more rapid and the level of automatics is more advanced.

Today's generation of aviators are taught to operate autopilots virtually from the start and have never developed basic skills on steam driven aircraft. It's routine to engage the A/P a few seconds after lift off and only disengage it a couple of minutes before touchdown. Setting an attitude and a power setting and making adjustments to achieve the required flight path was a basic and essential skill for an earlier generation of pilots but today's crop can largely get away without the old skills, until something goes wrong. It's a sad fact that many airline pilots today are only able to do their jobs because of the level of automation on modern aircraft, they couldn't cope with an aircraft that had to be FLOWN rather than operated.
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Old 6th Nov 2018, 12:36
  #663 (permalink)  
 
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.

Just before the flood of information and supposition starts, may I just note that the confidentiality held regarding this crash and investigation has been very good. Normally on here there is endless discussion regarding leaks and voluminous criticism of the leaks (especially when it concerns certain parts of the world). Thankfully, this time things have proceeded properly, I can only hope it continues whilst the first (and then second, hopefully) recorders are examined.

.
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Old 6th Nov 2018, 13:09
  #664 (permalink)  
 
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Originally Posted by phil gollin View Post
.

Just before the flood of information and supposition starts, may I just note that the confidentiality held regarding this crash and investigation has been very good. Normally on here there is endless discussion regarding leaks and voluminous criticism of the leaks (especially when it concerns certain parts of the world). Thankfully, this time things have proceeded properly, I can only hope it continues whilst the first (and then second, hopefully) recorders are examined.

.
You mean aside from the photos of the Aircraft logs being published all over the internet?
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Old 6th Nov 2018, 13:18
  #665 (permalink)  
 
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You mean aside from the photos of the Aircraft logs being published all over the internet?
I would have expected by now that the logs of the other 3 UAS events would have surfaced too (if they were logged)
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Old 6th Nov 2018, 13:37
  #666 (permalink)  
 
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Originally Posted by LaissezPasser
I’m curious what you all read this tea leaf in Ben Otto’s latest WSJ story:


But investigators are now focusing on reasons for a subsequent abrupt altitude drop, these people said, followed by the fatal dive. Operation of another flight-control system, called the angle of attack indicator, also is bound to be examined by the probe, according to safety experts. Such devices are critical in telling aviators how high or low an aircraft’s nose is pointing. Angle of attack sensors operate independently from airspeed sensors.
Not much, seems like stating some pretty obvious general observations for the benefit of those without the aviation background to realize that they're obvious.
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Old 6th Nov 2018, 14:26
  #667 (permalink)  
 
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Originally Posted by A Squared View Post
Not much, seems like stating some pretty obvious general observations for the benefit of those without the aviation background to realize that they're obvious.
Not obvious, and not even accurate. In a “vertical” dive, the Angle of attack can be “0”. The Nose is “-90”. AoA is NOT Pitch. (How high or low the Nose is pointing).
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Old 6th Nov 2018, 14:29
  #668 (permalink)  
 
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Grrr

Originally Posted by krismiler View Post
So far then it looks like an unreliable airspeed problem which wasn't handled correctly and resulted in tragedy. Even back in the 1970s D.P. Davies was complaining in "Handling the Big Jets" about pilots who had forgotten how to fly due to automation,
You mean the Sperry SP77 was "automation"? Methinks the dear Capt. Davies exaggerated a bit.
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Old 6th Nov 2018, 14:44
  #669 (permalink)  
 
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Originally Posted by Concours77 View Post


Not obvious, and not even accurate. In a “vertical” dive, the Angle of attack can be “0”. The Nose is “-90”. AoA is NOT Pitch. (How high or low the Nose is pointing).
Really ... you're claiming that at no time during the course of an investigation into an airline accident involving a loss of control and strong evidence of Airspeed Unreliability and possible malfunction of an automated flight stability system, would investigators think to take a look at AoA data? That is an interesting opinion. Fascinating, really.
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Old 6th Nov 2018, 14:51
  #670 (permalink)  
 
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Originally Posted by A Squared View Post
Really ... you're claiming that at no time during the course of an investigation into an airline accident involving a loss of control and strong evidence of Airspeed Unreliability and possible malfunction of an automated flight stability system, would investigators think to take a look at AoA data? That is an interesting opinion. Fascinating, really.
With respect, I don't think he claimed that at all.

He was simply pointing out that the journo had conflated two terms - AoA and attitude - that in an upset may not bear any relation to each other.

In fact I was typing a similar post at the same time, but I was too slow.
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Old 6th Nov 2018, 14:59
  #671 (permalink)  
 
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Originally Posted by double_barrel View Post
What am I missing here? These guys called V1 and V2 on the take-off run. Similarly with the infamous Brisbane take-off with pitot covers on.

How is this possible? Can the tape or covers on the pitots stretch enough to compress the air in the pitot to give accurate and consistent speed readings at ground level? That seems very unlikely.
Well, it should be pointed out again, that the speculation that pitot tube covers might have been left on in the current accident is just that, purely speculative. It hasn't been ruled out, but there's no reason to suggest this was the problem. So, given that, it is entirely possible that in the current accident, the airspeed indication was normal during the takeoff run, and the airspeed unreliability occurred later. It should also be pointed out that we don't know that they called V1 and V2. The CVR has not yet been recovered.
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Old 6th Nov 2018, 15:06
  #672 (permalink)  
 
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Originally Posted by DaveReidUK View Post
With respect, I don't think he claimed that at all.

He was simply pointing out that the journo had conflated two terms - AoA and attitude - that in an upset may not bear any relation to each other.

In fact I was typing a similar post at the same time, but I was too slow.
Well, yeah Journalist has a "not quite right" idea of what AoA means, I noted that and moved on, I guess if we want to attach a lot of significance to that, we can. I'm not sure what, exactly though. My take on the question to which I was responding was that the poster was asking "what do you think of the announcement that the investigators will investigate the sudden unplanned descent and the AoA data? " Not: "what do you think about the Journalist's ability to accurately describe Angle of Attack"
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Old 6th Nov 2018, 15:17
  #673 (permalink)  
 
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Originally Posted by A Squared View Post
Well, it should be pointed out again, that the speculation that pitot tube covers might have been left on in the current accident is just that, purely speculative..
I was referring to the CVR from the Aeroperu 603 accident which was shown to be due to the static ports being covered. To add complication to this tangle of links and posts, I had misread that report and taken it to say that the pitots were covered. But my comments do also apply to the BNE MAS takeoff with pitot covers on. I remain unclear about how an apparently accurate 100kn speed call was made there.
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Old 6th Nov 2018, 15:24
  #674 (permalink)  
 
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Originally Posted by A Squared View Post
Well, it should be pointed out again, that the speculation that pitot tube covers might have been left on in the current accident is just that, purely speculative. It hasn't been ruled out, but there's no reason to suggest this was the problem. So, given that, it is entirely possible that in the current accident, the airspeed indication was normal during the takeoff run, and the airspeed unreliability occurred later. It should also be pointed out that we don't know that they called V1 and V2. The CVR has not yet been recovered.
And if the reported previous occurrences of UAS (alleged to be on 4 previous flights...) are correct, then I think all would agree that covered pitots for multiple flights seems completely implausible.

- GY
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Old 6th Nov 2018, 15:33
  #675 (permalink)  
 
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What if the pitot/static system is not the root cause?

The engineers investigated UAS three times and would surely have discovered blocked or disconnected sensors. What is the next most likely cause? How many AoA sensors does the A/C have?
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Old 6th Nov 2018, 15:36
  #676 (permalink)  
 
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Originally Posted by double_barrel View Post
I was referring to the CVR from the Aeroperu 603 accident which was shown to be due to the static ports being covered. To add complication to this tangle of links and posts, I had misread that report and taken it to say that the pitots were covered. But my comments do also apply to the BNE MAS takeoff with pitot covers on. I remain unclear about how an apparently accurate 100kn speed call was made there.
Ahhh, OK, obviously I though you were speaking of the current LionAir accident. I too am unclear on the BNE MAS incident. Did the PM make the call based on GS? Where is GS displayed on a A330? On the airplane I fly, it's displayed in a location that you're really have to work at it to mistake it for IAS. Or did he make the call based on GS intentionally, because he didn't have an IAS displayed? The preliminary report states that they observed IAS error flags, was that before or after the 100 knot call? It will be interesting to read the final report on that incident.
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Old 6th Nov 2018, 15:51
  #677 (permalink)  
 
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Originally Posted by mross View Post
The engineers investigated UAS three times and would surely have discovered blocked or disconnected sensors.
One would have thought/hoped so.

But then again, one would have thought/hoped that the engineering response to a warning of a discrepancy between the inputs (either pitot or hydraulic) to the Elevator Feel Computer would have been to investigate those inputs, rather than just cleaning an electrical connector on an 11-week-old aircraft (!) and then confirming that there was no fault in the EFC itself, before signing off the aircraft as fit for flight.
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Old 6th Nov 2018, 16:56
  #678 (permalink)  
 
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Originally Posted by mross View Post
The engineers investigated UAS three times and would surely have discovered blocked or disconnected sensors. What is the next most likely cause? How many AoA sensors does the A/C have?
I don't think we know exactly what is stated here.We 'know' from statements apparently based on initial FDR data (?) that three (immediately?) previous flights showed URA (UAS) tendencies. We don't know that they were investigated as each occurred. The infamous leaked MX log only showed a single write-up. It is surely possible that nothing was written up until the final flight of the day, so MX really only had one (overnight) troubleshooting attempt?
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Old 6th Nov 2018, 17:45
  #679 (permalink)  
 
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Originally Posted by Mad (Flt) Scientist View Post
It is surely possible that nothing was written up until the final flight of the day, so MX really only had one (overnight) troubleshooting attempt?
No.

Leaving aside the many other implications of that suggestion, the aircraft in question only flew two sectors on the day preceding the accident (MDS-DPS-CGK), so it had nightstopped at least twice since the first of the three previous reported UAS events.
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Old 6th Nov 2018, 18:01
  #680 (permalink)  
 
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Originally Posted by DaveReidUK View Post
No.

Leaving aside the many other implications of that suggestion, the aircraft in question only flew two sectors on the day preceding the accident (MDS-DPS-CGK), so it had nightstopped at least twice since the first of the three previous reported UAS events.
Thanks, I'm not even remotely able to keep up with the info.

Has it been definitively stated that is was the three immediately preceding flights? if it were intermittent over a longer period that's even more insidious.
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