Re asking for Airspeed
...does that imply that the FC could not determine reliable airspeed from their 3 indicators....? |
Gold contacts on circuit boards
Originally Posted by AlexGG
(Post 10299841)
I wonder, considering there are not that many contacts, why aren't they made of gold or something which does not corrode? Sure that can't be overly expensive? That's assuming the recorder is built around memory chips (not tape or wire).
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Originally Posted by flash8
(Post 10299990)
In some cases would the QAR (assuming it has one, think it is an option) yield useful information (assuming also intact) and if the FDR were damaged or as a supplementary sources?
However the current generation of FDR contain a wealth of information - far beyond the minimum requirements of the regulations. The only real shortcoming of the FDR vs. the QAR or ONS is the update rate for some parameters (e.g. engine and FADEC stuff - once per second FDR, much higher update for QAR/ONS). |
Originally Posted by FullWings
(Post 10300004)
I find it interesting that the pilot asks for “airspeed” from ATC. Unless there was a EHS compatible transponder/receiver pair, then the answer is going to be groundspeed - which should be in the top left corner of the NAV display in front of him. It does seem to indicate that at least one of the problems they are facing is UAS...
However, based on previous news coverage of international accidents, often things get garbled in translation of ATC dialog in English to the local vernacular language and back to English again. Has the claimed JT610 ATC transcript been published somewhere other than the gist given in the tempo.co article?
Originally Posted by tdracer
(Post 10300061)
Unlikely that the QAR (or ONS server) would survive a high speed impact and subsequent extended immersion in salt water - they are simply not designed for it.
Is it likely as the ABC News article suggests that significant data may be recovered from the Boeing servers back home from the ONS? Even twenty years ago I was surprised how much operational and maintenance information was spit out in the clear over VHF ACARS by so-called modern airliners. Engine readings, fluid levels, EFIS alerts, crew lists with employee numbers (and in some cases SSN's :eek:) plus the usual mundane text messages to call the chief pilot's office on arrival. Even if Lion Air didn't buy the upgraded subscription to Boeing's inflight data services, would some of the information be transmitted anyway? |
Originally Posted by Airbubba
(Post 10300080)
I would think a brand new 737 MAX would have EHS capability. If so and if ATC did as well, maybe the 332 knot reading was indeed indicated airspeed and transmitted with the Mode S data.
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Unlikely that the QAR (or ONS server) would survive a high speed impact and subsequent extended immersion in salt water Or maybe not - there are a lot of variables. I have known several business cases where data has been recovered from both flooded and fire damaged systems by specialist data recovery companies, they are very good at their job. If a fire gets into the server room the machines are usually wrecked and then drowned by the fire brigade but data is usually recoverable. Indeed, the opposite case of securely destroying sensitive data is very difficult and expensive. |
So, are we looking at a UAS event causing false inputs into the STS? This puts in a nose down trim, the pilots counteract with nose up elevator. Without any throttle reduction the aircraft accelerates to high speed until something snaps. As no other separate floating debris field has been found, and a near vertical dive, I suspect it was the stab trim screw jack that gave way at the end. |
Originally Posted by Airbubba
(Post 10300080)
I
Is it likely as the ABC News article suggests that significant data may be recovered from the Boeing servers back home from the ONS? Even twenty years ago I was surprised how much operational and maintenance information was spit out in the clear over VHF ACARS by so-called modern airliners. Engine readings, fluid levels, EFIS alerts, crew lists with employee numbers (and in some cases SSN's :eek:) plus the usual mundane text messages to call the chief pilot's office on arrival. Even if Lion Air didn't buy the upgraded subscription to Boeing's inflight data services, would some of the information be transmitted anyway? Many operators only do downloads when they are at a suitably equipped (e.g. wifi) airport. It's simply a matter of what Lion Air has signed up for (which I can't speak to - I honestly have no idea). |
Salute!
With all due respect, you can compare all the gauges and indicators with what you expect they should read and then add what the plane is doing that you do not expect, and then you have to take action or wait just second or two. 'Hal' will not be your friend. Unless in a 'bus, your plane most likely has traditional aerodynamic stability and power characteristics. You know. The thing tries to get back to your trim AoA, and pushing up power raises or lowers the nose, especially with motors below the wing. The 'bus has great aero, but it does not show itself until the flight control computers are back to the lowest possible functional capability. You never have complete manual control of that plane. The 'bus is 100% +/- computer with tiny bit of manual reversion for something or other, but not significant. It has a myriad of reversion control laws, but at least you know you are dealing with a full FBW system. The stab trim implementation on this beast seems to be a hybrid, and I am not sure what one should do if we have unreliable air data or maybe some hydraulic/electric malfunction involving the stab. So we now have a plane with some type of "trim"/ speed stability feature that depends upon air data and weight on wheels and autopilot status and time after takeoff and so on. What does it do when the airdata is unreliable? How could it determine that? And what did it do a flight or two before if something mechanical is beginning to fail ( can't get Air Alaska outta my mind)? The recorders should really help us see what happened from the human aspect as well as the mechanical/computer aspect and we can then improve the STS function and crew procedures, ya think? Gums sends... |
ake this news report with a grain of salt . . . which indicates Indonesia’s transport ministry found faults in two other Boeing 737-MAX 8 jets, including a cockpit indicator display problem . . . https://www.perthnow.com.au/travel/l...6c4a47f53d21e6 If if it was a wider Boeing problem you would be looking at global groundings until rectified. |
Originally Posted by tdracer
(Post 10300115)
The operator needs to sign up for the service - the hardware is baseline on the aircraft, but not the download service. Boeing (and GE/CFM) will store the data, but only if it gets sent -and that costs money. And the more data is sent out, the more it costs - shortly after the EIS of the 747-8, we started getting complains that we were sending out too much engine health data and it was costing too much for the data transmission services. So when we revised the EHM software we reduced the baseline reports.
Many operators only do downloads when they are at a suitably equipped (e.g. wifi) airport. It's simply a matter of what Lion Air has signed up for (which I can't speak to - I honestly have no idea). |
"FEEL DIFF PRESS LT ILL"
If confirmed, the preceding flight reported "IAS & ALT DISAGREE SHOWN AFTER TAKE OFF" and "FEEL DIFF PRESS LT ILL". Assuming that despite overnight maintenance actions both issues re-occured on the accident flight, these combination may be quite significant, not only in terms of their cause, but for the sad outcome of this flight mainly in terms of their effect, in particular of the second message.
As concerns the cause, it would seem to me relatively rare for several pitot systems to fail simultaneously. To note that the ias/alt pitot system is separate from the elevator pitot system, the first being located at the front of the A/C, the second on each side of the front base of the V/S. (Repeated) Simultaneous failure of both systems would IMO indicate something more structural then the pitots themselves. As to the effect, in particular the "FEEL DIFF PRESS LT ILL" could be of particular relevance. The elevator feel computer provides simulated aerodynamic forces using airspeed (from the said elevator pitot system) and stabilizer position. Feel is transmitted to the control columns by the elevator feel and centering unit. To operate the feel system the elevator feel computer uses either hydraulic system A or B pressure, whichever is higher. When either hydraulic system or elevator feel pitot system fails, excessive differential hydraulic pressure is sensed in the elevator feel computer and the FEEL DIFF PRESS light illuminates. I stand to be corrected, but if (barring hydraulic problems) the elevator feel and centering unit enters into a condition that triggers the FEEL DIFF PRESS annunciation (for whatever reason, either pitots or a more systemic failure, since in this case also the "main" pitot system could have been affected simultaneously), it would mean that particularly in manual flight the elevator inputs through the control columns could have a much different (greater) effect than normal. It would be interesting to know whether such inputs with a "dysfunctional" feel and centering unit could lead to upsets with an ultimate loss of control, which at relatively low altitude would be difficult to recover from in time. https://cimg9.ibsrv.net/gimg/pprune....4ebd86043c.png |
The Maintenance Release shows the time 12:40 UTC. The aircraft landed at 15:55 UTC (22:55 local time). Maybe the airworthy release was signed at 00:40 local time on 29th, but still only 1h45min to fix two malfunctions.
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Lots been said about pilots who can't hand fly. So a Virgin Australia 777 driver would get more hand flying or a 737 driver doing island hopping with different terrain, airports and 3-4 sectors a day? Poor pilots are not those who cannot fly manual but those who do not have sufficient understanding of the increasingly complex aircraft systems. In particular, the flow on effects and consequences when a part of that system fails.
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Originally Posted by birdspeed
(Post 10300114)
So, are we looking at a UAS event causing false inputs into the STS? This puts in a nose down trim, the pilots counteract with nose up elevator. Without any throttle reduction the aircraft accelerates to high speed until something snaps. As no other separate floating debris field has been found, and a near vertical dive, I suspect it was the stab trim screw jack that gave way at the end. given the so called speeds probable a impact - it is unlikely a major structural failure was involved- but until data is released, such speculation is just that - and besides it was not a dc9 . . with a totally different isssue re screw jack |
Originally Posted by FL11967
(Post 10300180)
Poor pilots are not those who cannot fly manual but those who do not have sufficient understanding of the increasingly complex aircraft systems. In particular, the flow on effects and consequences when a part of that system fails.
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but those who do not have sufficient understanding of the increasingly complex aircraft systems. In particular, the flow on effects and consequences when a part of that system fails. |
Originally Posted by FL11967
(Post 10300180)
Lots been said about pilots who can't hand fly. So a Virgin Australia 777 driver would get more hand flying or a 737 driver doing island hopping with different terrain, airports and 3-4 sectors a day? Poor pilots are not those who cannot fly manual but those who do not have sufficient understanding of the increasingly complex aircraft systems. In particular, the flow on effects and consequences when a part of that system fails.
A Virgin 777 pilot has most likely been on the 737 for a number of years before moving up. |
Originally Posted by FL11967
Poor pilots are not those who cannot fly manual but those who do not have sufficient understanding of the increasingly complex aircraft systems. In particular, the flow on effects and consequences when a part of that system fails.
Keep/get the aeroplane wings level, in level(ish) flight, with a reasonable power setting/GPS speed, then do your diagnosing. And as Iccy says, if we can identify what the issue/warning is, we have to do what the QRH says. This isn't some gathering of engineers in a room pondering what to do next. Do what the QRH says. If some weird crazy thing happens that isn't covered, then by all means use your systems knowledge to get yourself out of it, but to my knowledge there hasn't been a recent prang caused by lack of knowledge of an aircraft system. Of course, it's much easier to test systems knowledge at a computer screen than it is to give pilots initial/continued training in stick and rudder skills... |
Have not seen any mention of CCTV from JKT ground ops/control of a 737 with streamers on the side of it taxiing/departing?
Pitot covers would surely have have red 'Remove before flight' streamers - new A/C standard equipment? |
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