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Originally Posted by meleagertoo
(Post 11206108)
Well, we got shouted down asking that question of the two MAX accidents as it somehow implied the pilots hadn't done their job properly and was taking some of the heat off the anti Boeing witchunt that was the only politically acceptable cause in town..
What's different here? But of course you're right, with a runaway trim you do the drills and circumvent it. Easily. |
Originally Posted by finestkind
(Post 11206241)
Tend to agree especially if someone states this is the reason. Maybe I missed that but most appear to have indicated along the lines of this "may have happened".
. In respect to offering an opinion, "Causative Factors: Absolutely no idea. How could I offer an opinion before the data is in?. An opinion is "a view or judgement formed about something not necessarily based on fact or knowledge". So by all means offer your opinion and if outside the bounds of reasonability standby to receive. |
Originally Posted by henra
(Post 11206388)
While I do agree from a technical perspective, historically in past accidents the ADS-B data rarely if ever painted a really different picture regarding trajectory/flight path and velocities than were leater determined by the proper tools.
FR24 began in 2009, so there was nothing available from AF447 at the time, but we did use the ACARS messages to read the tea leaves in the AF447 accident and got quite a bit from that source until the recorders were located two years later. But until we had the side-stick parameters, the stall-warning parameter plus pitch/roll, it was not possible to say where the problem originated and why; from the AF447 thread in Tech Log on ACARS: https://www.pprune.org/tech-log/3764...ml#post4975184 Data is not opinion, nor is validated data stochastic. That's really my only argument. There can be a form of equivalence between FR24 information and the eventual results from the recorders but the former cannot be turned into action nor legitmately be included as part of any final report / recommendations. |
Originally Posted by henra
(Post 11206388)
While I do agree from a technical perspective, historically in past accidents the ADS-B data rarely if ever painted a really different picture regarding trajectory/flight path and velocities than were later determined by the proper tools.
But there is an important caveat: ADS-B data (as transmitted by the aircraft) and an FR24 download (however granular) are not the same thing. The latter will be subject to asynchronicity, hysteresis and latency - though many (but not all) of those issues can be mitigated with some work and patience. So, while I have no sympathy for the knee-jerk "ADS-B is rubbish" view sometimes expressed in these columns, nor do I agree with the "ADS-B is gospel" view when applied to FR24 data. |
Originally Posted by PJ2
(Post 11206422)
Data is not opinion, nor is validated data stochastic. That's really my only argument. There can be a form of equivalence between FR24 information and the eventual results from the recorders but the former cannot be turned into action nor legitmately be included as part of any final report / recommendations.
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I know this is pure speculation but one report says "One possibility is that this 737 may have previously been involved in a tail strike incident on landing or take-off and the damage done to the rear pressure bulkhead was not noticed or not repaired properly causing it to fail, damaging the tail."
Has there been any evidence to support this or are they just making noise? https://www.airlineratings.com/news/...und-10km-away/ |
Originally Posted by PJ2
(Post 11206074)
The reliance upon FR24 data as an investigative, diagnostic or even theorizing tool is significantly beyond its design, conception and utility.
While "realistic" results may obtain on occasion, its equivalence to reality is largely stochastic. The process of building a theory and then going to data to find support is essentially what is occurring through the use of FR24 data. The method is faulty simply because the data isn't good enough to do so. FR24 data is not validated through testing to the same precise standards & legal requirements that DFDR data is. It has its uses, but not in the manner being sought here. The only tools registered and recognized for such work are the SSCVR & SSFDR, and even then, as we have seen, from such a point there can still be a number of valid theories & interpretations, some ultimately critical to understanding what actually occurred. If scientists had gone about validating MRNA vaccines in the same manner, we would not be as eager to use them and the FDA would have trouble justifying their wide public use. The principle here and elsewhere in other investigative endeavours is the same. Respect for the data and for accuracy is paramount as many lives have been affected. PJ2 How much should we respect the data? data? Since Traditional and Internet news outlets routinely raid forums like this one, maybe we should scientifically assess the information that comes out here. I won't even ask to be principal author. |
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Originally Posted by fdr
(Post 11205931)
....
Planes fly nicely unless they are either -
Your list of conditions does suggest something "permanent", IE mechanics, though the issue with fundamental toy stability can also be something intermittent. Where mechanical items either work or break, electrical/electronic/software items can easily show intermittent behavior. IE, upset, working again, upset, working again, etc. For MU5735, the FR24 data does show a severe upset, a temporary recovery and again a severe upset, suggesting an intermittent issue with the aircraft. Of course, FR24 data is not perfect, though it was good enough to determine on PP, what potentially happened with SJ182. |
I posted a paragraph from a Chinese site discussing the crew. Everything was deleted for reasons I don’t know.
It was deleted because you started your post with: I don’t place much validity to the following info but it was translated from a Chinese site. I suspect it can be debunked quite quickly by the China hands on here Not only a negative post, but already discussed in earlier contributions. Senior Pilot |
With the report that wreckage has been found 8km away reinforces the observation that the airframe breakup was at medium to high level. The multiple negative results of explosives residue negates any suggestion of a bomb.
On the one hand the Chinese are being uncharacteristically open with their press conferences but may still be guarded in their admissions of the possibility of a mid-air collision with an errant mil-jet. Everything outside of airways in China is mil-controlled. Consequently getting co-ordination for wx avoidance is downright impossible. Equally an errant military jet may have infringed civil airspace resulting in a mid-air, survivable for one party but not the other. Without some force-majeure intervening towards the end of a perfectly stable cruise, the likelihood of the tail simply falling off seems very unlikely indeed. |
Originally Posted by DaveReidUK
(Post 11206429)
That has certainly been true - up to a point - for the dozens of accidents/incidents that have featured in these columns over the years and where FDR traces have subsequently been published in the investigation report (including the two Max accidents).
But there is an important caveat: ADS-B data (as transmitted by the aircraft) and an FR24 download (however granular) are not the same thing. The latter will be subject to asynchronicity, hysteresis and latency - though many (but not all) of those issues can be mitigated with some work and patience. So, while I have no sympathy for the knee-jerk "ADS-B is rubbish" view sometimes expressed in these columns, nor do I agree with the "ADS-B is gospel" view when applied to FR24 data. This aircraft started the departure from stable flight with a roll to the left, and this roll got more and more like a barrel roll from about inverted. Probably due to a about 1G postitive load during the roll. The aircraft seem to have performed at least one complete roll, completed about when the aircraft briefly gained altitude again. There is a possibility that the aircraft continued to roll after the first barrel roll. Sriwijaya 182 had a A/T failure that put #1 Engine to idle. It made a similar left barrel roll. Maybe something similar A/T or engine failure or a rudder hardover( I know they aren't supposed to happen these days but…) |
I have had a catastrophic engine failure in cruise flight in a 767-300 ER. Instant loss of all thrust. In cruise flight it’s actually a very benign maneuver. You would have to be dead asleep to let it rollover. It’s also unlikely a rudder hard over would cause a upset as rudder travel is limited by dynamic pressure at cruise speeds. Rudder hardcovers normally are a problem at low speeds where full throw is available.
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Originally Posted by Sailvi767
(Post 11206622)
It’s also unlikely a rudder hard over would cause a upset as rudder travel is limited by dynamic pressure at cruise speeds. Rudder hardcovers normally are a problem at low speeds where full throw is available.
There were also some incidents with the rudder PCU that happened in cruise flight. They were recoverable. |
Originally Posted by Sailvi767
It’s also unlikely a rudder hard over would cause a upset as rudder travel is limited by dynamic pressure at cruise speeds.
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Originally Posted by Sailvi767
(Post 11205815)
The trim system in the 737 is very obvious if not annoying when running. That includes when the autopilot trims. If in fact they ignored the spinning trim wheels and noise as soon as the autopilot moved the elevator to counter the incorrect trim input the trim brake would engage and stop the runaway.
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[pax] I think any proposed cause has to account for the timing of the event ie at or about start of descent. A random occurrence, eg collision or mechanical failure could otherwise have occurred with equal probability at any earlier time in the cruise. More likely to be associated with a circumstance specific to that phase of flight surely.
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Originally Posted by Mr Optimistic
(Post 11206783)
[pax] I think any proposed cause has to account for the timing of the event ie at or about start of descent. A random occurrence, eg collision or mechanical failure could otherwise have occurred with equal probability at any earlier time in the cruise. More likely to be associated with a circumstance specific to that phase of flight surely.
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Could this be similar to Southwest B737-700 flight 1380 in 2018 whose incident report can be found at
Uncontained engine failure with a sudden left roll of a 41° bank angle leading to decompression of the aircraft, emergency descent and damage to, amongst other parts of the aircraft, wing tip and horizontal stabilizer? |
Originally Posted by N600JJ
(Post 11206871)
Could this be similar to Southwest B737-700 flight 1380 in 2016 whose incident report can be found at https://data.ntsb.gov/carol-repgen/a...ort/93897/pdf?
Uncontained engine failure with a sudden left roll of a 41° bank angle leading to decompression of the aircraft, emergency descent and damage to, amongst other parts of the aircraft, wing tip and horizontal stabilizer? However that post have since been deleted by the mods. I was surpriced by the number of cracked fan blades found acording the the report you are linking. That another fan blade could depart an 737NG engine can hardly come as a surprise, however I do not say with any certainty that an engine malfunction did actually happen in this accident, only that such a failure is one of the more likely reasons for this accident. |
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