The twitter link herein:

It is a 737 flap track fairing tailcone. The black "strap" is nothing more than aerodynamic sealant that had not been topcoated with paint.

The article linked previously that discussed the pilot's pre-flight behavior mentioned twelve crew being on board, six active and I assume six dead-heading? (Didn't say whether they were pilots or cabin crew.) Might any of the excess crew have been jumpseating? If so, could the presence of a third person have affected CRM or otherwise relate?

2 pilots and 4 flight attendants from a subsidiary NAM Air, the 2 pilots were manifested in Row 3 and the 4 flight attendants in row 20/21. I'd say highly unlikely the jumpseat was occupied.

The article that talked about the pilot apologizing to the wife and kids - I didn't see any mention of what he apologized for. It also said he left without his clothes being ironed. To me, that sounds more like "over slept, running late, need to skip breakfast/morning chores" than anything nefarious. However, he might have been somewhat off his game if he'd had a late night or hadn't slept well, which could compound a mechanical or other issue.

The event that occurred was a rapid onset issue. A couple of potential causes of a rapid lateral departure at speed are a failure of a slat track; (query Flash 604 Sharm al-Sheik) a high-speed turbulence encounter resulting in rapid alternating rudder inputs and consequent structural failure, a T/R deployment that is not recognized or responded to (Lauda 4); loss of IRU's, an attitude/erroneous attitude on one side not identified (a roll channel only failure can end badly... EGSS, B742F KAL 8509, VABB, AI855... Adam Air DHI574... (for own goals)

The B735 is quite a different autopilot architecture to the NG/MAX; a trim runaway is possible, as it is on any aircraft, but as had been discussed in depth following the Max events, a runaway in the first instance can be countered by control column input or the pickle switches and most appropriately by the trim cutout switches just behind the throttles. The aircraft has the same inherent issues if way out of trim, but it is an unlikely scenario for the plane given the events of the last 2 years.

If the mechanical reasons for a problem don't show evidence, then the human causes become of more concern. The parallels to MI185 Silkair are matched by the number of differences, and those suggest it is unlikely to be another in the sad list of intentional losses by a crew member. Simply, the time and height that the event occurred at is inconsistent with historical cases, where the pilot that causes the problem is sitting by themselves for a period of time. at 10K, both pilots will still have been in their seats. Intervention by the 2nd pilot will almost certainly occur, and that essentially is contrary to all of the historical cases.

I would be discounting a pitot-static problem in this case; while they occur with monotonous regularity, they almost invariably result in vertical deviations as well as IAS changes, but in this case, the ADSB data suggests otherwise. Dependent on setup and system selected, the ADSB data recorded may be the same or different from that shown on the MASI/ALT etc... The DFDR picks up the signal from the DFDAU which also converts the data sentence between 717 and 429 (don't have my refs with me... and its a few years since I was doing flight test on that aircraft... ) The data however will be able to be reconstructed from the known endpoint, and errors in P-S data compared to the necessary kinematics. The first glance suggests that this is a rollover event to the left, resulting in a very low nose attitude within a short period of time. That suggests attitude indicator issue/slat/T/R or unrecognized engine failure/rudder hard over or something similar. All of those have historical precedents, and all are able to be recovered from by an alert crew. COVID 19 has not left the industry in the best of shape... The CVR will give considerable information, some information will be available from the DFDR if recovered. This aircraft should have control input sensors being recorded, but limited flight control section position would be recorded in the -500 if my memory does not fail me.

Don't be too fast to blame the flight crew for active causation, this looks already like some event that was not able to be responded to effectively.

IMHO

waito

I think I covered some of that in an earlier post, but I can't find it any longer.

Of the parameters obtainable from FR24, the timing data is probably the least reliable, for the reasons of latency already described. That's easy to see from a chronological timeseries of, for example, altitude or track, and results in the jagged charts that have been posted. There are ways to mitigate that, but beyond the scope of this post.

As for the rest:
Altitude is normally baro-derived, almost always to the nearest 25', and based on a 1013.2 hPa datum (as with Flight Levels). FR24 sees exactly the same data as ATC uses.
Horizontal position (lat/lon) is nowadays almost always GPS-derived, with only a very few aircraft sending inertially-derived data. This aircraft had GPS.
Speed (for FR24 purposes) is always horizontal groundspeed, not airspeed, and is resolved by the receiving station from N-S and E-W components. It comes from the same source as track and position.
Track (not heading) is true, not magnetic, and is likewise resolved from those two components.

Frustratingly, there are a bunch of other Mode S EHS (not ADS-B) parameters that ATC can interrogate but which FR24 doesn't seem to have captured on this occasion, including TAS, IAS, magnetic heading, roll angle and track angle rate

HTH

Easy Street

The fairing there is an outer flap element inner flap track fairing. The outer fairing has a landing light incorporated, so it is the inner fairing. The inboard flap in the Yehudi area between the engine strut and the fuselage has a quite different fairing, that was a redesign of the JT8D engine pylon which incorporated the flap track on its sides. On the NG and Max, this was redesigned and the vestigial -100/200 inner flap track was changed to a similar system to the outer flap tracks. Peter Randolph wrote an excellent report on je transport high lift devices which IIRC covers in part the design changes. He also indicates the inherent design problems on the T/E flap tracks which cause so much irritation to owners of B737's by a poor choice of design by the OEM which results in unnecessarily high loads on the track/carriages.

Banana Joe

-3C1, derated 18.5

The man on the left of post #147 photo is holding what appears to be a section of the HP Turbine nozzle guide vane assembly. The damage is not what would be expected if the impact was the primary cause. More consistent with a major engine event.

infrequentflyer789

XL888T, the A320 event into the water south of Perpignan had more to do with attempting to conduct a flight test data point without following a test flight plan. The test point was missed in the upper air work and was added ad hoc without proper setup for system monitoring, which precluded the flight crew from detecting the faulty AOA probes. Had the test been conducted IAW the test plan, the error would have been detected early. With the decision taken hastily to complete the test point at a low level, and without reference to the procedure in the test plan, then the crew were left with just their wits to ascertain that the system was not behaving correctly. As it was, they slowed down and went straight through multiple conditions that were displaying incorrect system behavior. In the end, the stall event, roll instability, and thrust increase related THS trim error (THS did not stop trimming at the correct point in decel due to the AOA fault, failure to recognize that (checklist response to be noted....) oversight of "USE MANUAL TRIM" when the ELACs finally gave up the ghost... Not monitoring the AOA on the maint page.... etc.

It is human nature to shortcut processes and procedures, but any time that is done in an aircraft that is near an operational boundary, or thereafter can approach an absolute limit, it is necessary to ensure that the process is well thought out beforehand, and a full safety analysis conducted of each aspect of the plan. There is an assumption of goodness in functional check flights FCF's conducted for maintenance purposes, that they are just box-ticking, and that anyone can go do that, particularly if they are.... a training captain, an examiner, a manager, a [choose your position]. The hard truth is that FCFs have a disproportionately high catastrophic loss rate, and often that is the result of a lack of preparedness of the crew for what they are about to do. If the crew has not considered every test point as a unique hazard, then they are just filling the seats and not managing risk. You don't have to be Yaeger, or an NTPS, EPNER, ETPS, USNTPS, or USAFTPS graduate, but the crew need to know what steps are necessary to conduct a test flight appropriately, be able to read, and to know that when they deviate from the plan, they are potentially in a bad place, and better be on top of their Chuck Yaeger zen side on the day. Even then, the competent, well-trained crew can still mess up, where the task is considered inadequately, as in a Challenger loss, a GeeWhiz loss, an A330 loss, where on reflection the test points were not thought out fully.

FWIW, the baby Boeing is not a. bad little airplane and is generally honest. The rudder single control valve was not pretty, the wing was a cost-effective compromise to get enough CL out of it, but, it is generally honest. It stalls nicely enough, and the high-speed characteristics are OK, although watching the ailerons buzz between MMO and MD is not a pleasant part of its envelope. Boeing made an OK aircraft, and the majority of the losses speak to crew loss of SA up to the Max debacle. The type is over-represented in overruns of airports and as the methods to radically improve V speeds and reduce the risk are established, that should someday be resolved. It is not one of my favorite Boeings, but then dealing as an owner with TBC is enough to affect impressions of the type.

The 737 was great design 20-30 years ago. Now it’s just not up to scratch. The NG was about the limit of what the design could take. The Max is not just a step too far, it’s a huge leap too far.

Boeing may not have the money, and they may say there are not the cost savings available in a new design at the moment. But the 737 has long outlived its design, and the more Boeing push that out dated design, the more we will see issues.

Janner200

You may well be correct on its location, it doesn't look like early-stage compressor GV's and it isn't LPT size. That part coming off the engine is consistent with a high energy impact, such as with ET302, which exhibits similar levels of fragmentation. IF the failure was airborne, as an uncontained failure, for a 737 there is not that much of interest there to cause loss of control; an engine failure associated with ruptures of the cowling and even wing surface is not itself a control problem, even with a loss of hydraulics, the plane is quite flyable, however, a loss of both A & B system, along with a failure of the standby system with an engine failure will be challenging and may need a reduction to idle on the live engine to control, but it is extremely unlikely to occur with any uncontained turbine failure [not impossible...]..

The 737-500’s I flew had glass.......300/400/500 all the same. 600/700/800 900 have bigger fancy screens, the Max even fancier....

I flew the -200 and -400, sometimes both on the same day. They were different enough in most respects (steam/glass, turbojet/turbofan, VOR+NDB/FMC, etc.) that confusion about which variant you were on didn’t apply. Like a push bike and a motorbike...

Regarding FR24 speed, as this is ground speed derived from GPS position could GPS data been lost during abnormal attitudes, FR would still receive altitude but position would not be moving, then position data returns towards the end which causes FR24 to play catch-up showing an excessive untrue ground speed? Hence the 90 degree position movement

Reading the pompous and sometimes ghoulish ruminations of the armchair experts, who evidently think they're really clever, reminds me once again why I rarely come here anymore.
People have died. Trained people will find out the cause. Trying to impress each other with your ill- informed speculations is not going to fix anything. Putting IMHO in your comments does nothing except highlight your pomposity. Why is it that every accident is used as an excuse for people on here to show off how clever they think they are? Personally, I find it distasteful, and extremely disrespectful to the people who lost their lives, especially when you start speculating on human error, or worse, possible suicide. If you're doing it on a private chat, that's one thing, but the posts here are all public.
You're no better than rubber-neckers driving past a car crash.

With regards to the instrument layouts previous pictured.
I know that early -300 had an instrument panel similar to the -200 series.
Later versions had the P2 Centre Panel as a digital layout.
My guess would be that -400 and -500 would have the later layout, but l might be wrong.

FlightSpanner

There was no "90 degree position movement". The aircraft performed a slow RH spiral through approximately 110° over 11 seconds during the rapid descent. See previous posts.

Mr @ Spotty M

The cockpit of the various models is discussed here-
Boeing 737 Flight Instruments

TCAS doesn’t do turns, just climb or descend.

Although broadly useful FR24 data is wildly inaccurate at the detail level. I've observed my own flights on FR24 in real time out of curiosity and some of the manouevres it showed would have broken up my aircraft and had me busting controlled airspace.

DaveReidUK

Just like the China Airlines Flight 006, 19 Feb 1985. In this case the aircraft was at 41000ft. It fell 30000ft in 2 and a half minutes. The pilot managed to recover his bearings and pulled out just in time.
https://admiralcloudberg.medium.com/...6-e8bbc6683018

CAT1

Well said. I consult these forums far less regularly for same reasons. Although I have worked in aviation industry many years, including previously some accident investigation, I would like these forums to help share confirmed news and, where possible, some credible expert opinions. Sadly far too many people just offering speculation based on no credible experience and believing without any limitations some flight-radar data.

Pitch up moment
 

NWA SLF

The whole discussion about pitch-up tendency on B737's stems from why MCAS is needed on the MAX.

It has NOTHING to do with engine thrust. Is has to do with the position of the engines. Since the engines have moved forward on the MAX, (because they are to big to stay under the wing), they generate lift and thus pitch-up tendency at extremely high angles of attack. This is beyond certification limits for passenger aircraft (pre-stall behaviour), hence MCAS for the MAX. Absolutely no issue on the -500.

Hadley Rille

"Although broadly useful FR24 data is wildly inaccurate at the detail level. I've observed my own flights on FR24 in real time out of curiosity and some of the manouevres it showed would have broken up my aircraft and had me busting controlled airspace."

If you're seeing erratic tracks for your own flights on FR24 then, assuming you're flying any commercial jet built in the last 30-odd years, you really need to be having a chat with your airline's Engineering department.

DaveReidUK

Do you work for FR24, Dave? You are defending them and their data every chance you get.
Weird data from FR24? I have seen this many times, even near major airports. I have seen aircraft flying below safe altitude right into mountains. Never happened. I have seen aircraft hanging in the air, then plunge down to the runway. Never happened. I have seen aircraft overshooting runways by miles.. Never happened. Aircraft backing in the air. Never happened. Aircraft suddenly gone. Never happened.

Yet, every time an accident happens, FR24 data is taken as 100% accurate. It can be wlldly inaccurate.

Then there is the possibility that the engine fell off on its own as the aircraft spiraled down, ala PA and TWA events. This typically results in flat impacts on non-running engines. Let's see what else turns up in the investigation.

I totally agree with CAT1 , but every accident it is the same here : I call it "trial by FR24" and it is even worse when a spotter leaks the R/T ATC frequency then inevitably the "experts" prime interest is looking to blame individuals , preferably the crew or the controllers. .. Human nature I guess. When the first Investigation reports comes out their wild theories are debunked but that does not deter them to start again at the next accident . The Ted Cruz of PPRuNe...
For info, Jakarta ACC has a relatively new radar , and together with the APP one have already a very accurate track and Altitude read outs. No need of FR24.

There is a report that the black boxes have been located. They have not yet, it seems, been retrieved.

I think you've answered that question yourself:

I've seen the same at times on the (few) occasions that I've needed to use FR24 in realtime (something I normally try to avoid). I've never seen any such issues to date in downloaded data. If you want to know the reason for the difference, go ask FR24 (I'll be interested in the answer, too and, no, I don't work for them!).

No, I'm saying that typical issues with the data, which I've already acknowledged on a number of occasions (out-of-sequence messages, wrongly combined position/velocity data, unadjusted altitudes, etc) can usually be mitigated so that you end up with something that turns out to be pretty close to the relevant bits of the FDR trace once that's published. The only FR24 issues I've come across that can't be mitigated are where aircraft don't have GPS, or those that don't have ADS-B at all, where FR24 attempts to use crowd-sourced multilateration, with dire results (which may be what our northern friend is describing).

Dear Posters:
We have had sufficient digression, in terms of post count, into the reliabilty of FR24 (both pro and con).
While this will provide some useful information to novices reading through the discussion here, any further digression is no longer welcome in this thread.
FR24's quality is not this thread's topic.

Getting back to the topic of the thread, I can only think of four prior instances in the past 15 years where a large jet airliner fell out of the sky without any communication from the crew and the cause was not ultimately linked to third party interference. In all four cases icing or some recoverable technical fault led to a complete loss of control due to a lack of basic airmanship. Two of these happened in Indonesia... (and NO, I'm not speaking of Lionair). Just saying...

andrasz

Can you define what you mean by "third party interference" ? There is one other obvious instance not included in your four icing/technical cases, but which also didn't involve a third party.

No suggestion that there were any similarities to this latest event, just interested in your definition.

Ethiopean 737-800 fell out of the skies after climb out from BEY. They lost control most likely due to CB activity. Happened around 8000 ft.
West Air Sweden nose dived into the ground (CRJ 200) from cruise level because of IRS failure that messed up the captains PFD.
Loss of control is not that unusual and why a lot of training has focused on this recently.

DaveReidUK

Bomb, missile, etc. Indeed I did miss ET at BEY, that makes it five.I have purposefully excluded the instances where the pilot willfully flew into the ground, those were in full control. In case of the West Air Sweden CRJ the pilots did communicate.

It’s a theory, but loading-related accidents pretty reliably happen within seconds of attempting to fly (see 747 at Bagram as an example), as that’s when the greatest body angles occur and where you are most vulnerable to shifting/wrong cargo, mis-set trim, etc. Also, I suspect manufacturers take fuel movement into account when designing loading limits; manual and automatic load sheets certainly take account of CG movement during fuel usage to make sure it doesn’t cause problems at any stage of flight.

From our local paper,Some one living in the tropics saying it was heavy rain would indicate, to me at least, it was HEAVY.

As many have said, it's too early to speculate. There's clearly been a loss of control that could be mechanically related, weather related, crew related or a combination of all three, or some other completely different cause, but none of us know at this point in time. Having said that, the extract below has always stayed with me as an example of how easily control can be lost when there is a break down in crew coordination. Not saying that's happened here, but sometimes the ease with which a major accident occurs following a minor problem is quite unbelievable & AF447 is the classic example of that...

Not questioning the basic premise of your post but the quoted excerpt doesn’t sound like the AF447 scenario at all. Is it?
Thought it was stalled all the way into the sea.