Consequently, China has grounded that type of aircraft pending the investigation into the latest crash.


Also for nearby India:

Boeing jets under 'surveillance' after China crash
wrote:

India's aviation regulator has placed the country's fleet of Boeing 737 planes under "enhanced surveillance" after a jet crashed in China. It said it has sent out teams "to monitor flight procedures, air worthiness and operations"...

... Boeing's chief executive David Calhoun said: "We ... have offered the full support of our technical experts to the investigation led by the Civil Aviation Administration of China." He added that the company would do "everything we can to support our customer and the accident investigation during this difficult time, guided by our commitment to safety, transparency, and integrity at every step"...

... Cai von Rumohr, an analyst at investment bank Cowen, said: "Given Boeing's problems with the 737 MAX, there is some chance that consumers may not want to fly on [any] 737 until the cause of the China Eastern crash is determined not to be a design or manufacturing issue...

Where before have we heard such hollow words from a Boeing chief executive?

What response from the other airlines flying Boeing 737s?...

When and where next?


My own personal (uninformed uneducated) view is that there are some unsafe common mode problems there waiting to kill more people...


Stay safe folks!
Martin

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My own personal (uninformed uneducated) view is that there are some unsafe common mode problems there waiting to kill more people...

Common mode MH370 and Air France 447
https://www.youtube.com/watch?v=937cKm2ENDM

I'm sorry Martin, but I think this particular incident is very unlikely to be Boeing's fault at all.

If it was a fault of the plane itself it would've been in an uncontrolled dive (meaning that the plane should've been spiraling/spinning/twisting/tumbling in its decent with pieces coming off it). What has been shown by available footage is certainly a controlled dive with the plane fully intact so I'm in the field of 1 of the 3 in the cockpit at the time put that plane into an intentional controlled dive and held it there for as long as possible.

A jack screw or runaway trim problem would've seen the plane come apart well before hitting the ground in as it would've spiraling/spinning/twisting/tumbling uncontrollably which neither video shows happening.

My own personal (uninformed uneducated) view is that there are some unsafe common mode problems there waiting to kill more people...

Common mode MH370 and Air France 447
https://www.youtube.com/watch?v=937cKm2ENDM

Possibly...

However, that is unlikely being as there should have been three pilots in the cockpit, especially so during the descent towards the destination airport... IIRC, there was a trainee pilot in the cockpit.

There are a multitude of possibilities to be discounted yet...


Stay safe!
Martin

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... I think this particular incident is very unlikely to be Boeing's fault at all.

If it was a fault of the plane itself it would've been in an uncontrolled dive (meaning that the plane should've been spiraling/spinning/twisting/tumbling in its decent with pieces coming off it). What has been shown by available footage is certainly a controlled dive with the plane fully intact so I'm in the field of 1 of the 3 in the cockpit at the time put that plane into an intentional controlled dive and held it there for as long as possible.

A jack screw or runaway trim problem would've seen the plane come apart well before hitting the ground...

Very early days yet for any guesses.

Also, amazingly, various supposed videos of the crash have turned out to be click-bait fakes!

A trim jackscrew failure or a runaway trim would not necessarily cause a spin descent and midair breakup. The pilots can at least still keep the wings level regardless of trim, unless...


There are examples of a Boeing 747 and a Boeing 737 plummeting out of the sky due to a stall from asymmetric thrust. I believe the all-fatal Boeing crash (also in Asia) just before this latest crash is suspected to have been caused by an autothrottle fault that had a single point of failure that then caused a non-recovered stall due to asymmetric thrust...

The Boeing 737 can also suffer what is known as a "deep stall" whereby recovery is not possible using the elevators alone... The trim has to be purposefully used to regain control, by which time a lot of height is lost.


For the 747 'incident', see:

Mentour Pilot: HOW This {Boeing 747} FELL 30 000 Feet in Less Than 2.5min! | China Airlines 006

Note: That is for China Airlines 006 some years ago, NOT the latest Boeing 737 crash.



Key points that I've noticed for this latest crash are:

Very rapid loss of height at about the time that the aircraft was to start its descent from 29000' cruise to approach the destination airport;
The ADB transponder shows perfectly controlled altitude and groundspeed (on autopilot?) and then an initial loss of ground speed at about the point of height loss;
Ground speed then increases and the rate of descent reduces;
The pilots were flying in cloud or at least above an undercast into which they descended;
All at about lunchtime for their local time;
No Mayday or Pan was transmitted (as so far reported).

For some completely unfounded wild guessing personal conjecture:

My first thought is that for whatever reason, the aircraft became stalled and the pilots for whatever reason(s) failed to recover from the stall soon enough.

I'm basing that guess upon the incident happening at the point they attempted to begin their descent to their destination. With possibly confounding problems of:

Were they in cloud and lost all external cues? (And were not checking the flight instruments?)
Were they completely relying on the autopilot and an incorrect adjustment made (wrong units? barometer setting upset??) that then commanded the autopilot into a dive?
Autothrottle failure or upset causing a stall?
Some aspect of pilot in-flight training or some pilot test went awry?
Uncontrolled trim runaway that wasn't recovered or could not be recovered?
Decompression failure damage?
Icing causing a critical control failure?...

Further thought, was the aircraft loading and fuel use (shifted centre of load) such that they had (somehow inadvertently) flown into "coffin corner" and suffered a deep stall?...


IIRC, I believe that there is still some wiring for the 737 trim jackscrew control whereby chaffed wires or other insulation failure within a singular wiring bundle can power up the jackscrew in such a way that the crew cannot turn the thing off from the cockpit, from which there is no recovery possible. I consider that to be very dubious...


One to watch for as soon as the flight recorders are unearthed.

Stay safe folks!
Martin


Edit: The penultimate latest all-fatal Boeing 737 crash noted was:

Sriwijaya Air Flight 182
wrote:

... A preliminary report released on 10 February 2021 discovered problems with the plane's autothrottle, where the left thrust lever engine started to reduce as it climbed, while the right thrust lever engine remained the same...

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I'm sorry Martin, but I think this particular incident is very unlikely to be Boeing's fault at all.

If it was a fault of the plane itself it would've been in an uncontrolled dive (meaning that the plane should've been spiraling/spinning/twisting/tumbling in its decent with pieces coming off it). What has been shown by available footage is certainly a controlled dive with the plane fully intact so I'm in the field of 1 of the 3 in the cockpit at the time put that plane into an intentional controlled dive and held it there for as long as possible.

A jack screw or runaway trim problem would've seen the plane come apart well before hitting the ground in as it would've spiraling/spinning/twisting/tumbling uncontrollably which neither video shows happening.

Yes, CFIT. The 12000+ FPM descent rate is not something that you could program an autopilot to do, it would disconnect if you found a way.

If it was a runaway elevator trim the aircraft would pitch past vertical and be in an inverted dive and pieces would be coming off.

Don't think it would be that hard to intentionally, or unintentionally, jam say a laptop or flight bag between the seat and the yoke to prevent another pilot from pulling back to recover.

If they find the CVR and can play it, we will finally know. If they only find the FDR is playable we will only be able to guess.

Far to many fight hours on 800's (over 5000 built) for there to be an undiscovered systemic bug.

... If it was a runaway elevator trim the aircraft would pitch past vertical and be in an inverted dive and pieces would be coming off...

That may well not be possible...

As you pitch the aircraft into a dive, the airspeed increases and the wing lift increases to pitch the aircraft back up towards horizontal.

There is some dashcam footage suggesting the plane came down at an angle, wings level, and very much not perpendicular to the ground... So... What is the maximum controlled angle of descent for a 737-800?...

... Far to many fight hours on 800's (over 5000 built) for there to be an undiscovered systemic bug.

Unfortunately, that means very little other than other pilots had happened to have not flown through the same circumstances...


Stay safe folks!
Martin

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... If it was a runaway elevator trim the aircraft would pitch past vertical and be in an inverted dive and pieces would be coming off...

That may well not be possible...

As you pitch the aircraft into a dive, the airspeed increases and the wing lift increases to pitch the aircraft back up towards horizontal.

Not if you stall the elevator. Remember the elevator is an upside down wing. Down pitch trim increases the angle of attack on the elevator. Once the boundary layer separates there is going to be a extremely rapid aircraft pitch down through vertical into inverted. Now the wings themselves will stall as the relative airflow over them is near right angle to their orientation. At this point no control surface will have any authority. As the wings are larger drag surfaces than the elevators they will continue to force a nose down until the forward momentum drops and gravity builds up enough downward velocity to reattach the boundary layers. Then a recovery can be attempted.

You should understand why VG's are put on the lower side of the elevator on a STOL aircraft.

Besides there was no contact made by the plane's crew saying that there was trouble or even a mayday and that elevator control had to be manually adjusted for such a dive to happen that way as they just don't dive that way all by themselves no matter what (dynamically impossible in fact).

If you go over other cases of trim or elevator failure over the decades you'll see that in cases from that height the plane actually tears itself apart well before it hits the ground because the decent isn't controlled allowing the air resistance and G-forces to pull it apart (and the same also happens to a plane when all hydraulic assistance is lost). They fall, not dive (unless you're in a 737-MAX with no MCAS updates done of cause).

What puzzles me is that the plane's air speed was not increasing rapidly during the near vertical decent but fairly constant which implies some degree of control was being applied, I suspect it was human, but have no proof of that.
From the two videos of the crash I've seen one is from a point more or less along the flight path, while the other is off to one side. In the first a very steep decent will appear to be vertical, while in the second you will see that it is not actually vertical, but at a very steep angle. The maximum normal decent angle for airliners is somewhere in the 15-20 degree region, normally the long decent from cruise is at something like 3 degrees.
Number of pilots? Well, in the US and Europe on airliners it is mandatory for a minimum of two people (pilot plus "nominated person" is the absolute minimum), and if there are more than two pilots on board and on duty for them to be all in the cockpit during take-off and landing. I don't know if this rule applies for internal flights in China, but I would assume it does. Two pilots plus a very junior trainee - I would guess that two minimum rule applies, but there could be some interesting shuffles past the jump seat should one of the pilots at the controls need a comfort break as 737 cockpits are quite small.

---

Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

There was a trainee in the cockpit at the time making 3 up front according to all reports Rob.

What puzzles me is that the plane's air speed was not increasing rapidly during the near vertical decent but fairly constant which implies some degree of control was being applied, I suspect it was human, but have no proof of that.

But we don't have airspeed data, we only have ground speed data. Ground speed should decrease as the vertical speed increases. If it does not, you would not expect the wings to still be attached as you would have passed Vne. Ballistic descent.

Both videos show the wings etc. are (more or less) in the right places so unless it broke up in the last few moments it was intact.

---

Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

Latest word being reported here this morning is that the black boxes may have likely been obliterated in the crash so we may never know the true cause.

The cockpit voice recorder has been found:

YouTube: Black box recovered from China Eastern plane crash is cockpit recorder: officials



Stay safe folks!
Martin

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Yes 1 of the black boxed has been found, but it's so damaged that they can't tell whether it's the cockpit voice recorder or the data recorder and getting info from what little is left of it maybe still impossible.

Reports just coming in now from an analysis of radar tracking have estimated that the plane hit the ground at between 1,000-1,100km/h, black boxes are only designed to survive an impact of 499km/h.

Reports just coming in now from an analysis of radar tracking have estimated that the plane hit the ground at between 1,000-1,100km/h, black boxes are only designed to survive an impact of 499km/h.

540knots.

You might think Vne could be found on the web, secret number. Vmo is 340knots IAS. The radar data would be TAS +/- wind. To convert pressure altitude and temperature are needed.
As the altitude wasn't that high, the airplane was well above Vmo and likely well above Vne. Very well built as it appeared to be largely in one piece.

Latest update:

China plane crash...
wrote:

... It is hoped the cockpit voice recorder, recovered intact, will yield clues. It was damaged on the outside but its internal records appeared to be fine, officials said. It has been sent to Beijing for its data to be analysed...

... aviation officials said there hadn't been any weather or other hazards endured by the flight on its route path. China Eastern said the Boeing 737-800 plane, less than seven years old, had also passed all pre-flight checks.

There had been three pilots, China Eastern officials disclosed. The captain had 6,709 hours flying experience, and the first and second officers had 31,769 hours and 556 hours respectively. "From what we know, the performance of the three pilots had been good and their family life relatively harmonious," the airline representative said.

Air traffic control had also been in regular communication with the pilots on board right until it entered its near nosedive descent from a cruising height...

The ADSB tracking plot in that article from FlightRadar24 is suggestive:



Does that show a recovery from a drastic first stall, to then stall again for a second time?


That looks very much like a profile that I've flown for a demonstration failed stall recovery (and to show off how stable the aircraft was). For my example, the control stick was pulled back and continuously held back against the endstop. You then get to experience some stomach sickening roller coaster type swoops until you either release the control stick or otherwise do something useful! My example was very definitely a demonstration with a very experienced instructor and we lost a mere 1000' for two swoops. (Good test for being properly strapped in!) ((NB: That was in a semi-acrobatic aircraft. Care needed to stay within spec!...))

For the 737 example... Was their deadly swoop caused by extreme (runaway?) trim for which the very experienced pilots couldn't recover?


Stay safe folks!
Martin

---

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The data storage section of the 2nd black box has been recovered out of the ground, but whether either will be any good is yet to be determined.

Second 'black box' found in China Eastern plane crash.