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-   -   Indonesian aircraft missing off Jakarta (https://www.pprune.org/rumours-news/614857-indonesian-aircraft-missing-off-jakarta.html)

A Squared 29th Oct 2018 18:19


Originally Posted by gums (Post 10295947)
So for you Boeing folks, is there a jackscrew stab trim as we had on the Alaska crash?

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.

Auxtank 29th Oct 2018 18:22


Originally Posted by Smithy02 (Post 10295922)
Surely the Tech Log would have been on the aircraft?

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.

Onceapilot 29th Oct 2018 18:36


Originally Posted by wiedehopf (Post 10295931)
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.


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

Auxtank 29th Oct 2018 18:52


Originally Posted by Onceapilot (Post 10295972)
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.

LaissezPasser 29th Oct 2018 18:58

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.

vmandr 29th Oct 2018 19:09

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


Flightaware data FWIW.

LaissezPasser 29th Oct 2018 19:17

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

wiedehopf 29th Oct 2018 19:23


Originally Posted by Onceapilot (Post 10295972)
Also, the data profile would tend to indicate a powered nose-over.
OAP

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

clark y 29th Oct 2018 19:27

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).

LaissezPasser 29th Oct 2018 19:37

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.

ZAZ 29th Oct 2018 19:43

BS comment
 

Originally Posted by Birdstrike737 (Post 10295254)
To those of you admonishing your colleagues for tossing around first-impressions while “bodies are still warm,” THAT’S WHAT WE DO! WE’RE PILOTS! This thread is not a news organization, it’s a crowded pub. It’s OK to put your bets on the table about what happened before the investigation has even begun, much less ended.
Maybe someone should start a different thread titled “Indonesia 737 Max crash: FACTS ONLY.” And stay there. And wait.

Get real man, parents and relatives come to these pages.
You have no information except some radar traces.
stick to flying mate let atsb do their stuff.
MH speculation all over again!
opinions are like backsides!

nicolai 29th Oct 2018 19:43

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.

vmandr 29th Oct 2018 19:46

LNI610 Flightaware comparison 29/28 Oct 2018
 
https://cimg2.ibsrv.net/gimg/pprune....4723c12ac5.jpg

ZAZ 29th Oct 2018 19:46

from all over
 

Originally Posted by clark y (Post 10296026)
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).

comes from everywhere including home hobbyists with rasberry pi receivers and the like hooked up to jam tin aerials.
Its a conglomeration of everything as noted in the tables whether official or members receiver number.

Raffles S.A. 29th Oct 2018 19:47

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.

cjad100 29th Oct 2018 19:54


Originally Posted by A Squared (Post 10295661)
Yeah, we're not discussing an airplane whcih was flying in conditions where a 300 knot groundspeed and an EAS of 100 knots are simultaneously possible. We're discussing the Indonesian 737 which crashed a day ago. That airplane was no higher than about 5000 ft MSL Neglecting winds, a 300 knot groundspeed equates to about 275 knot IAS at that altitude. Winds in excess of 20-30 knots at 5000 ft are unlikely unless there was some fairly unusual weather going on. I haven't heard any mention of extraordinarily strong winds in this accident, have you? No? So if we assume a tailwind at the upper end of that range, we're still probably looking at an IAS greater than 245 knots, if an airplane at 5000 ft is showing a groundspeed of 300 knots.

In order to get a 300 knot groundspeed with an EAS of 100 knots you'd have to be somewhere around 40,000 ft with a 100 knot tailwind. Were you under the impression that this airplane in this accident that we're discussing here, today, in this thread, was at 40,000 ft, with a 100 knot tailwind? No? If not, what on earth is your point in even mentioning that? What relevance do you imagine that brings to this discussion?

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.

groundbum 29th Oct 2018 19:56

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

cjad100 29th Oct 2018 19:56


Originally Posted by A Squared (Post 10295459)
There is nothing unprofessional or disrespectful about taking the facts that are known, and applying knowledge of aviation to consider how an accident may have occurred. This is not a news organization presenting speculation as fact. If is a forum. Forums are for discussion. We are discussing things.

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.

7478ti 29th Oct 2018 19:59

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.

jurassicjockey 29th Oct 2018 20:01


Originally Posted by fox niner (Post 10295866)
Air France A330
AirAsia A320
Lion Air 737

WHEN can we finally expect an AOA indicator in the flight deck? We need them. MAYDAY.

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


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