My initial impression after reviewing the flight track last night was that the aircraft was experiencing roll control problems and finally rolled left at high speed into the water.
Although the maintenance history of Captain side pitot problems may be relevant, and there is always the possibility of maintenance action causing new problems, an airspeed indication problem of itself should not cause loss of the aircraft.
Those of you speculating on the possibility of stall warnings being triggered should remember that these warnings normally are generated from the angle of attack data which is not derived from airspeed but instead from the vanes on the sides of the cockpit.
The impact of defective air data on the aircraft feel systems needs to be discussed by someone with more 737 aircraft familiarity than myself but could potentially be a significant factor. Aircraft control appeared to be degraded early in the flight.
Speculation: Could both of the cockpit crew have been applying force to the control column and not have had a free hand for setting the power? The continued acceleration of the aircraft doesn't make good sense from a piloting perspective. They needed to set a reasonable power setting and investigate if they could not continue the climb or did not wish to continue the climb.

I'm also disturbed that this document is in the public domain, but having lived and worked in Jakarta, I am not in the least bit surprised.

Pitot cover?
 

The probability of forgetting to remove the pitot covers on a day after there was a write up for Unreliable Airspeed is identical to the probability of forgetting to remove the pitot covers on a day after there was no write-up for UAS.

Not that I'm trying to claim that pitot covers are the cause here, but neither is it a given that the crash is due to an unreliable airspeed indication. That is just one of the few pieces of information that we have, that there was a UAS write-up on the previous flight, and there is speculation how that might have caused the crash, if it were to have reoccurred, whcih isn't a given.

No, the data that is available for download from FlightAware and FR24, while it certainly requires care in interpreting, is what the aircraft was sending (with a couple of caveats that aren't relevant here) and is independent of any prediction algorithms.

One thing that sticks out from the plot is that, aside from the vertical excursions, the last five minutes or so before the plot stops consist of two minutes of dead straight flight followed by two and a half minutes of continuous small track changes. I'll leave it to other to speculate on the significance of that.

I'm currently in Jakarta and can confirm there was a very large storm last night from about 9pm-12am with considerable rainfall

So the prediction you are mentioning is only implemented for displaying live flights, but it is used because quite a few people will look up and want the planes on map to match up.
Also i would not trust the timestamping on the data, the outliers in the following plot are very likely because of one of the receivers clocks being off.

Apart from that FR24 on their blog released the raw data for the flight in much better granularity than available on their website flight history.
It's unlikely that these data, probably received by multiple receivers differ significantly from what was sent by the ADS-B sender of the aircraft in question.

Because the plots of the data on the blog website are somewhat lacking, i plotted the data below in case anyone is interested:

https://cimg3.ibsrv.net/gimg/pprune....f29dd31525.png

ADS-B Data Plot

Thank you for the expanded plot wiedehopf. The final descent appears to be almost vertical with approx 2500' lost in 3 sec.
Condolences to all involved.

OAP

Equal and opposite reactions
 

Fascinating thread, yet deeply tragic.
It seems from the graph that everything has an equal or opposite reaction!
One crumb of comfort would be that the debris field is fairly limited in shallow water and that the CVR and FDR should be recovered promptly and resolved, so that everyone can understand what happened here.
At times like this I can only think of Sir Arthur Conan Doyles' quote
"Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth."
RIP

Surely the Tech Log would have been on the aircraft?

Presumably. However, it is within the realm of possibility that someone would have photographed the relevant page at some point between blocking in on the previous flight, and blocking out on the accident flight.

Please keep in mind that this is altitude plotted against time so you can't really tell the flight path from it.

If you believe the data the aircraft had a descent rate of 31000 ft per minute during the last recorded transmission.
That is around 300 knots vertical speed. Horizontal speed at that last data point is 360 knots.
That is a total speed of around 470 knots with the flight path angle being around 40 degrees downwards.

So this calculation is kind of gruesome but as the question came up i'll post it anyway.

Salute!

Besides the air data problems on previous flight, and possibly on the accident flight, I would like to re-visit the stabilizer. Just a fast mover guy here, but the sad story is worth understanding. Never know when a pilot here might see something early enough to take action, jez saying.....

Looking at thelfight path plot we have from a previous post, the end seems to happen very quickly, and not a "gradual" loss of control due to PIO chasing the altitude, attitude and speed.

So for you Boeing folks, is there a jackscrew stab trim as we had on the Alaska crash? A squak previously described unusual stab trim. If the stab "came loose" suddenly, I do not see any recovery possible. As Bach said, all crashes are the result of "loss of control". Plane comes apart, big part fails, new FBW laws act up, crew screws up, etc.

Gums asks....

Va= 260 kias at sea level
and 306 kias at 31,000 feet

So, yes you could.

As someone with very limited single engine experience long long ago I'd love to get some thoughts from those in the pointy end. Just looking at the track between 23:25 and 23:29 I'm slightly confused. My understanding is that if the correct memory items where followed you would have established pitch and power as constants...normally in a gentle climb while troubleshooting. During those 4 minutes it appears that both speed and altitude remain "relatively" stable but with clear oscillations that appear to indicate an inverse speed to altitude shift so there is clearly an issue maintaining level flight. I've always thought that at higher altitudes hand flying a swept wing plane was significantly harder than at lower levels. Under an emergency would the aircraft commander normally take the controls and rely on the FO to trouble shoot or would he be more likely to allow the FO to maintain level flight while he looked at the issues?

It would appear that there was an upset and recovery at roughly 23:29:30 and then again roughly 2 minutes later that proved unrecoverable. In both instances it appears to be a roughly 800 ft drop over roughly 20 seconds...that seems awful "ham handed" for purely pitch induced control input to me without some sort of rolling oscillation involved??? What type of flight path variation would be "normal" for an experienced airline pilot with minimal hand flying currency? Hard to imagine losing the plane at 5000 ft. in benign VFR conditions without some other issue in play???

Not a Boeing guy, but this thread caused me to wonder the same thing, so I went googling. It appears that the 737 does have a trimmable stabilizer actuated by a jackscrew.

It surely would have been.

The copy posted earlier and now gone (good move) was the pink/ purple copy which would have been for the office.

Well, you can make a deduction of ROD from alt/time. Integrated with horiz speed gives TAS, and an angle of descent, as you have done.
Of course, it is possible that some errors are present and incorrect data is involved. Unhappily, I think that your calculation is credible.
Also, the data profile would tend to indicate a powered nose-over.

OAP

Amidst the somewhat hysterical exchanges going on here about stall speeds, AOA, Pitots, etc; you point out something which I think is salient; and that is that the pilots were fighting that aircraft to gain back control. A backward glance at the FR24 seems to suggest the mayhem that was going on in that cockpit.
It was mentioned earlier in the thread about the overspeed two minutes in to the flight and flap retraction was mentioned as being possibly disregarded due to workload saturation.
It's possible that the aircraft became simply un-flyable as a result of airframe stress/ damage.

So are we all discounting the pax reports' from the previous night's Denpasar flight that the right engine was behaving erratically (as reported by Detik)? I know it isn't mentioned in the leaked aircraft flight and maintenance log, but it's an interesting data point, if true.

https://cimg5.ibsrv.net/gimg/pprune....c3fb6e9b98.jpg


Flightaware data FWIW.

flightradar24 posted more granular ADSB data on their blog, for what it's worth

This is altitude plotted over distance traveled, the graph includes the last 10 nautical miles of the flight data.
The distance vs altitude is drawn to scale.

https://cimg6.ibsrv.net/gimg/pprune....7b81fbaed0.png

Is the data on Flight aware and Flightradar Pure GPS or is it mixed with other data from the IRSs etc?
Reason for asking is because I would have thought 300ish knots at 5000' would be quite a safe speed (if flaps retracted) even allowing for winds(usually not too much around WIII).

Data on flightradar24 is ADS-B, so the navigational information is GPS and not inertially derived. FR24 also uses multilateration in some parts of Indonesia to calculate the position of older aricraft with Mode-S transponders, but I don't think that applies to this case, given how new the a/c was.

BS comment
 

Compare KAL 8509 at Stansted in 1999
 

This discussion of unreliable Captain's instruments, possibly badly diagnosed and rectified, reminds me of the crash of a Korean 747-200F near Stansted airport in the UK in 1999. AAIB Report 3/2003

Notably elements:
Carrier from a place with high authority gradients - no arguing with the Captain and his instruments,
Disorganised troubleshooting and rectification of the reported defect,
Airline with poor maintenance and operations reputation (at the time, KAL's rep was not good),
Failure to follow QRH procedure and use good CRM to resolve the issue before hitting the ground.

The comparison of the reports, if the Indonesians publish one, will be interesting.

LNI610 Flightaware comparison 29/28 Oct 2018
 

from all over
 

Hopefully they release facts as they are determined.
Many strange things here. For instance, if it was simply static sources blocked/partially blocked it shouldn't affect the attitude information and controlled flight in VMC would be quite achievable.
IIRC an elevator feel computer/computation fail shouldn't lead to loss of control at this altitude.
An autopilot failure in the pitch mode resulting in pitch oscillations should also be controllable at that altitude, just disconnect the autopilot and fly manually.

Some crashes with similarities:
Both Birgenair and Aeroperu accidents happened at night.
An A320 had a bad joint on a circuit board which then failed, causing a crash, but it was at high altitude and A320 is vastly different.
The CRJ-200 in Norway had an instrument failure only on the captain side, but it was on a pitch dark night.



The tech log image could be a top copy or carbon copy retained after the previous flight.

Sorry, I'm with A squared on this one. You guys barking on about the fact that it's theoretically possible there is a 200 knot difference between groundspeed and TAS at 5,000ft on departure into calm whether are keyboard warrior idiots, frankly.

As to the guy with the "NOT theoretical, actual" - NO. Theoretical. In this context that means "pretty unlikely but possible in theory". And that's exactly what it is. To say something is "actually" possible or "literally" possible is no different from saying it's theoretically possible. Theoretically possible doesn't mean it's NOT possible, it means it's possible. In theory. But most likely not in practice in the circumstances in which the plane found itself.

Honestly, I pray to god I never have to fly with argumentative morons like the pair of you. A squared has been pretty restrained.

does the Boeing MAX generate ACARS maintenance messages back to base that will therefore be available pretty much immediately? As in the assorted Airbus incidents these give a pretty good idea of the timeline of system failures...

G

Completely right. What kind of moron logs on to a private forum for the discussion of potential aviation safety matters and complains that it's discussing the same. To say nothing of the fact it's an EXCELLENT mental exercise to try and process, from limited information, what might have happened to a flight which has had an incident. Good pilots are constantly considering whether they've experienced something similar, how they handled it, what the accident cause might be, etc. I'll fly with pilots who consider the possible causes any day - their brains are active, considering the problem and working it.

Not sitting back spouting nonsense about "respecting the dead" and "waiting for facts". This isn't the newspapers or live television. Go away.

Sounds like it's time to wait for the CVR and FDR data... ?

and perhaps some well informed maintenance statements,

Witness statements (albeit often unreliable), might be helpful, and maybe even some video of the final descent?

"Stall" (very unlikely),... "pitot covers" (very unlikely)... "birds" or OEI (still possible, but it doesn't readily fit the data so far to this point),... "inappropriate crew response to a QRH addressed airspeed fault" (very unlikely),...

"STS going the wrong way" (could be a significant)

Further, there are lots of other scenarios still possible, not yet even raised in this thread yet... e.g., involving stabilizer or elevator control issues, ..."speed trim".. damage to the stabilizer leading to a consequent "pitch tuck",...

Dozens more than those could be responsibly posed, far beyond the scope of the above speculation earlier in this thread...

So now,... is it perhaps time to honor the memory of the lost flight crew, give them the benefit of the doubt, support their families, send in a technically qualified team, and wait for some real data???

Crew and Pax... RIP.

Available on the HUD on the 787 within 5 degrees of stick shaker. I would have assumed that the MAX would have the same if equipped with the HUD