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737-500 missing in Indonesia

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737-500 missing in Indonesia

Old 11th Jan 2021, 01:59
  #161 (permalink)  
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It is a 737 flap track fairing tailcone. The black "strap" is nothing more than aerodynamic sealant that had not been topcoated with paint.
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Old 11th Jan 2021, 04:37
  #162 (permalink)  
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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?
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Old 11th Jan 2021, 05:11
  #163 (permalink)  
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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.
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Old 11th Jan 2021, 05:48
  #164 (permalink)  
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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.
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Old 11th Jan 2021, 06:42
  #165 (permalink)  
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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.

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Old 11th Jan 2021, 06:53
  #166 (permalink)  
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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

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Old 11th Jan 2021, 07:02
  #167 (permalink)  
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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.
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Old 11th Jan 2021, 07:08
  #168 (permalink)  
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Banana Joe

-3C1, derated 18.5
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Old 11th Jan 2021, 07:48
  #169 (permalink)  
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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.

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Old 11th Jan 2021, 07:55
  #170 (permalink)  
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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.
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Old 11th Jan 2021, 08:22
  #171 (permalink)  
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The 737 was great design 20-30 years ago. Now itís 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, itís 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.
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Old 11th Jan 2021, 08:26
  #172 (permalink)  
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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...]..
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Old 11th Jan 2021, 08:34
  #173 (permalink)  
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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....
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Old 11th Jan 2021, 08:49
  #174 (permalink)  
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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 didnít apply. Like a push bike and a motorbike...
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Old 11th Jan 2021, 09:15
  #175 (permalink)  
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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
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Old 11th Jan 2021, 09:24
  #176 (permalink)  
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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.
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Old 11th Jan 2021, 09:32
  #177 (permalink)  
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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.
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Old 11th Jan 2021, 09:36
  #178 (permalink)  
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There was no "90 degree position movement". The aircraft performed a slow RH spiral through approximately 110į over 11 seconds during the rapid descent. See previous posts.
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Old 11th Jan 2021, 09:43
  #179 (permalink)  
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Mr @ Spotty M

The cockpit of the various models is discussed here-
Boeing 737 Flight Instruments
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Old 11th Jan 2021, 10:06
  #180 (permalink)  
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Was there perhaps another aircraft involved? The left turn driven by a TCAS warning?
TCAS doesn’t do turns, just climb or descend.
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