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dragon6172
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 9:50 am

Bobbvis wrote:
Having a hard time wrapping my head around trained pilots not being able to overcome a trim system malfunction to the point that it crashes the plane. The thumb switch is right there. If it keeps working against your wishes, reach down and turn it off. The Lion plane flew relatively straight and level for several minutes doing just that and then ???????? Why did they stop correcting it? This flight, I'm not sure we know enough, other than the jackscrew report, but maybe not enough altitude to counter the trim in time? Question- what kind of dive angle does full down trim produce? It's just trim isn't it? Fine adjustment? We're not talking dive bomber here are we?

If I recall correctly, the discussion was that, based on FDR control column force plots, that there was a change in which pilot was flying. When the SIC took over he did not trim nose up enough to counter the computer nose down trims. See below. The top line is the control column trim switch. Bottom line is the computer trimming. Middle line is stab angle. You can see for the first 6 or so minutes after they reach 5000 feet every computer trim down is countered by a control column trim up input of about equal time. And stab position stays roughly around 5 degrees. Then in the last minute or so, the control column inputs are very short, and the computer inputs eventually drive the stab to near full nose down

Image
Phrogs Phorever
 
XRAYretired
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 10:21 am

seat64k wrote:
airkas1 wrote:


Nice image from that tweet. I don't know why, but for some reasons I was expecting something more clean-room like looking :D

Image

Also, a video clip talking about the process. It's in French, but the guy demonstrates so you can still mostly follow if you don't understand French.

https://www.youtube.com/watch?v=SIejrcrQboQ


This is exactly what you would expect for dealing with a LRU from a crash site. Its a very dirty business. Mangled kit potentially contaminated with all sorts of nasty stuff including human pathogens and hydrofluoric acid. The PPE is probably in the drawers under the catch all tray that the kit is placed on. Sink near at hand for washing up afterwards and not spreading it around.


My first post. Treat me gently.
 
WPvsMW
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 10:25 am

X-ray, welcome to a.nut, and a nice initial post.
 
ciaran
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 10:33 am

 
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Finn350
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 11:00 am

CO953 wrote:
Finn350 wrote:
CO953 wrote:

What you're describing is the logical endpoint of a once-vibrant American (and global) aircraft-manufacturing industry which narrowed itself, at least in the Western world, to a duopoly and - in the USA - a monopoly. Monopolies create certain efficiencies but also certain dangers. The freight train of the MAX program carried a lot of momentum. It still does. Dang good chance that a flawed aircraft, which may actually not be fixable, still gets rammed down everyone's throats, instead of actually killing the program.

I have no animus to Boeing at all. Great company, with huge historical success and legendary contribution to aviation. Boeing may be the only company that can survive flat-out scrapping an aircraft type.

Before I get crowd-attacked, let me ask this:

Can the landing gear be made longer to accommodate moving the engines backward and eliminate the drag issue underlying this whole fiasco? I don't think so, due to width of the fuselage and the spacing of the engine pylons.

Can a telescoping landing gear be designed that would accommodate the width of the fuselage and the spacing of the engine pylons.... maaaaaaaaaaaaybe.

Can the airliner be made as safe as the NG in its current configuration, even with software fixes? ......... hmmmmm

Is this fair to the pilots and crew, not to mention the traveling public, as we get forced to fly the MAX for the next 25 years? .......hmmmmmmm

Does an entire globe-full of airlines keep up 5,000 orders for a plane that strongly appears to be a safety retrogression? In our current political state of "no rules" and disrespect for the rule of law .... ????????

This is a very ugly moment, for sure.


In the short term, there will be a simple software fix to address the specific MCAS design fault. In the long term, Boeing will replace the 737 with a new clean sheet design. They had been contemplating that already before this debacle, and this is the final push for earnestly starting design work for a clean sheet. There is no point to make additional changes to the 737 frame (it would be adding lipstick over lipstick as some members here call it). Irony here is that as a consequence of these mishaps, A320neo will get a potent rival from Boeing.


I understand your point.

But let me ask you... is it OK that Boeing releases 5,000 Kludgeliners onto the flying public, and we should all just grin and bear it until they all retire due to age, and accept a raised crash rate due to the engine placement?

I'm not happy with that outcome. In all honestly, I hope that killing the program is kept in the list of options, and that the final solution is chosen with safety paramount.

If Boeing can fix the MAX and make it as safe as the NG, great! If not, are we all OK in the aviation community with allowing a 21st-century safety backslide, for the life of the MAX, so as to prevent economic harm to the manufacturer?

Again, not targeting Boeing. I'm looking at the long-term. If they think they'll push out 5,000 more aircraft that my family is flying on, this thing had better be done by the effin' book. This is the risk that Boeing incurred by donning the mantle of American monopoly.


I don't see any other option than a software fix to the current problem and then launching a new clean-sheet design, although it will probably take 6-7 years for entry into service and 2-3 years to ramp up the production after that. In practice it will mean that the last 737MAX will roll off the assembly line in 10 years, and maybe even longer if they go first with the New Midsized Airplane and use technologies from there to the New Small Airplane.
 
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SomebodyInTLS
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 11:12 am

gensys wrote:
JohnKrist wrote:
What worries me is all those who keep saying ”a pilot not knowing about this issue has been in a cave for 4 months”, ”it’s a training issue”, ”it’s because the F/o had 200 hours” etc. A plane should not fly itself into the ground, switch flicked off or not.


Such as AF 447 doing so from all the way up at cruise altitude?

IIRC the remedy for the A330 was replacing the defective part (pitot) and improved pilot training.

Are you as equally unhappy with the A330 situation?


But that plane would NOT have flown itself into the ground - data shows the airspeed disagree would have resolved itself as the pitot came back online just a few seconds later, and left alone the aircraft would have happily continued to fly straight and level on its own.
"As with most things related to aircraft design, it's all about the trade-offs and much more nuanced than A.net likes to make out."
 
wingz
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 11:30 am

PW100 wrote:
dragon6172 wrote:
Or you could use that handy electric trim switch that's right under your thumb on the control column you're pulling so hard on to return the aircraft to a normal trim state before you disable electric trim. As has been pointed out numerous times the pilot ALWAYS has authority over MCAS inputs using the control column electric trim switch.


Do we know that for fact? Could the Max have some logic (for instance, when stickshaker is active), where MCAS overrules control column electric trim switch?

If so, then it's vital to flick Stab Cut Switch immediately. Now the crew have to revert back to manual trim wheel. What's the normal rate your average pilot can obtain using the wheel?
From previous posts in this thread:
* MCAS rate: 0.27 deg/sec
* Control Column Electric Trim Switch: 1 deg/sec
* Manual Trim Wheel: ?? deg/sec.

Can a pilot spin the wheel fast enough to raise the nose, and at the same time maintain enough pulling force on the control column? Probably that would require one pilot pulling hard, and the other one spinning the wheel. Requires very good CRM - and quick, as time is definitely on their side.


To me this last point about time to manually retrim is the most pertinent question, at least for the Lion Air case but maybe also for the Ethiopian crash. It looks like autotrim simply gets on with its job of retrimming the aircraft in response to whatever pitch condition is demanded. If this is severely nose down from MCAS then we have the situation where the pilot uses the thumb switch to correct the trim, only for the process to repeat a few seconds later. That might be sustainable for a while. But lets say finally, after figuring out the problem, the decision to disconnect is made, and the pilot flips one of the 2 switches described by PW100 at #2593 and dragon6172 at #2596. If it is (mistakenly?) the one that disables electric trim then the pilot's thumbswitch does nothing, and the trim wheel has to be used to retrim. If it was a mistake with the disconnect switch, it will take time to figure out why the thumbswitch is inactive. And what if the switch was thrown when the aircraft was in the extreme nose down trim state as a result of MCAS. Thats a lot of work to do to recover a flyable trim state as the plane nose dives.

Another point. It does seem from various posts that MCAS has this connection with autotrim, but I wondered why. Ordinarily if an aircraft is approaching stall with nose up trim, surely a large down elevator movement (from pilot or MCAS) would be sufficient to recover? If that were the case then MCAS would simply be a stall prevention system. The "pitch-up" tendency is much talked about as problem with the MAX, and that this is what MCAS corrects. That suggests stall recovery without MCAS could be a problem, made worse by any nose up trim state. Maybe this is why MCAS has to engage with the trim system - elevator alone is not enough. Also, It is surprising if a lot of nose down trim is allowed for this purpose. I would have hoped that a minimal reduction of nose up trim would be enough to allow elevator to counter the pitch up, and maybe then avoid any extreme node down pitch to follow. Obviously it would be good to know the exact workings of the system.
 
LupineChemist
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 11:58 am

XRAYretired wrote:
seat64k wrote:
airkas1 wrote:


Nice image from that tweet. I don't know why, but for some reasons I was expecting something more clean-room like looking :D

Image

Also, a video clip talking about the process. It's in French, but the guy demonstrates so you can still mostly follow if you don't understand French.

https://www.youtube.com/watch?v=SIejrcrQboQ


This is exactly what you would expect for dealing with a LRU from a crash site. Its a very dirty business. Mangled kit potentially contaminated with all sorts of nasty stuff including human pathogens and hydrofluoric acid. The PPE is probably in the drawers under the catch all tray that the kit is placed on. Sink near at hand for washing up afterwards and not spreading it around.


My first post. Treat me gently.


Welcome. And my French is very rusty but I mostly got that the video focused on the pre preparations for checking the integrity of the electronics prior to reading to see what would have to be repaired if there was any need to worry about damage from powering the cards themselves after an impact.
 
Interested
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 12:03 pm

For those of you who are interested

In the other 737max grounded thread ive been able to post the actual reports from 6 US pilots complaining about issues on these planes. I'm not going to post here as well but thought I would point you guys that way.

They make interesting and very worrying reading at the same time

Most worrying bit for me is that experienced US 737 pilots don't feel adequately trained to be flying these planes in the first place. Plus there are even new switches on the plane not even explained in the manual!!

It's scary to read the reports to be honest
 
Interested
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 12:12 pm

By the way these two threads should be merged again

The only reason they split was when people started debating if the planes should be grounded. They are grounded now and it's one discussion again?
 
dragon6172
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 1:13 pm

wingz wrote:
But lets say finally, after figuring out the problem, the decision to disconnect is made, and the pilot flips one of the 2 switches described by PW100 at #2593 and dragon6172 at #2596. If it is (mistakenly?) the one that disables electric trim then the pilot's thumbswitch does nothing, and the trim wheel has to be used to retrim. If it was a mistake with the disconnect switch, it will take time to figure out why the thumbswitch is inactive. And what if the switch was thrown when the aircraft was in the extreme nose down trim state as a result of MCAS. Thats a lot of work to do to recover a flyable trim state as the plane nose dives.

The procedure is to turn off BOTH switches. It also says to use control column trim switches to relieve control forces before turning trim switches off if need be.
Initially, higher control forces may be needed to overcome any stabilizer nose down trim already applied. Electric stabilizer trim can be used to neutralize control column pitch forces before moving the STAB TRIM CUTOUT switches to CUTOUT. Manual stabilizer trim can be used before and after the STAB TRIM CUTOUT switches are moved to CUTOUT.
Phrogs Phorever
 
XRAYretired
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 1:14 pm

No, I'm not a pilot, but I have looked at many scenarios in my time and at this point in an investigation it is useful to hypothesise possible scenarios that fit reasonably with what is known (and what can be assumed), at this point, throughout the event timeline. Its only with verified 'facts' that these can be confirmed or discarded or refined but give you something to look for (e.g. the investigators likely looked for (and found, and inspected) the stabiliser assys at the ET crash site specifically because of the previous LionAir event). In any case, a stand back view point is desired rather than getting obsessed with minutia (like 200hr pilot, which is exactly that is at this stage).

I would hypothesise that the unreliable airspeed with or without unreliable AOA is the key. In that initiates the event and puts both a/c in the position where an undesirable nose down command is unrecoverable. (NB unreliable airspeed can be low as well as high and both in a short period).

Both A/C appear to have completed a T/O roll and initial climb reasonably well albeit the stick shaker may or may not have active throughout or periodically. It is likely that that flaps would have been retracted and Auto Pilot may or may not have been initiated as well. In any cases it is possible, and both A/C did, experience a nose down command. viz. Flaps Up/AP OFF MCAS initiated nose down due to unreliable airspeed/AOA high OR Flaps Up/AP on AP initiated nose down due to airspeed low.

Pilots in both cases did exactly what you would expect them to do. Get into straight and level flight (although levelled out at considerably different AGLs), 'fly the plane', assure you in as much control as possible, trouble shoot, plan return to runway. It is unlikely that either crew would have retarded throttles an athema to pilots still worried about about stalling. Flaps Up and AP OFF most likely status for both and hence unrelable airspeed/AOA is not in play excepting that stick shaker may still be active throughout or periodically.

Both A/C initiate a high speed turn to return to runway with Flaps Up/AP off. (NB it appears that the ET flight may have made a climb to get some height and lose some speed before or during the turn).

MCAS wakes up in the turn (by design is my understanding) drives stabilisers to nose down. Even if the pilots noticed trim change, they may have expected some sink rate in the turn and unlikely would have had enough time to respond effectively anyway.

MCAS applies the coup de gras - per Pluto007 earlier.

It remains for investigation conclusions to support or refute the hypothesis.

Time for lunch.
 
wingz
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 1:30 pm

dragon6172 wrote:
The procedure is to turn off BOTH switches. It also says to use control column trim switches to relieve control forces before turning trim switches off if need be.


Agreed, but this is the ideal handling of the problem. There has been a lot of talk about flight manual changes - was this procedure in the manual before the Lion Air crash? I my post I was thinking of how pilots possibly unfamiliar with MCAS, and finding themselves in an extremely dangerous situation, may respond. ie disable the system in panic without realizing the trim problem to come.
 
HaulSudson
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 1:32 pm

ciaran wrote:


That's why the company prefers to use every cash dollar available not for improving their airplanes but for buying back stock: it lets their net worth take off.
 
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qf789
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 1:35 pm

Interested wrote:
By the way these two threads should be merged again

The only reason they split was when people started debating if the planes should be grounded. They are grounded now and it's one discussion again?


No they are not going to merged, lets be realistic there are already 6100 posts between the 2 threads and counting (note this number is what I can see as I can see the deleted posts, the number you can see will be different). Furthermore neither of these topics are going to slow down for a while, we may even have to open second threads for both of these if they continue like they are. This thread is about the crash, so lets keep it about the crash, there will be future developments to discuss in this thread just like there will be future developments in the grounding thread so they can co exist together
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Lrockeagle
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 1:41 pm

Elementalism wrote:
Finn350 wrote:
MD80Ttail wrote:
My point about the FOs 200hr Total time is not about weather he or she did anything wrong or not. Even IF he or she did everything right my point is a 200hr total time pilot does not provide for the best possible outcomes for the fight and passenger. Most likely he or she didn’t do anything wrong. I have never once said that. My concern, and I believe it’s very valid, is at 200hrs total time it’s impossible to bring anything more than standard normal operations experience to the flight deck. A pilot with more hours would have a bigger “tool bag” from which to draw experience from in problem solving. Why everyone has so much vitriol for what to me is extremely obvious I have no idea.

Put another way I just checked my car computer and in the last 10,000 miles I’ve averaged a speed of 36 mph. I’m guessing that’s pretty avaerge for most folks in my area with a mix of Highway and city driving. 36mph multipled by 200hrs is 7,200 miles driven. So it’s ok for a pilot that has the equivalent of 7,200 miles in their entire lifetime of “driving” experience to be considered safe and fully vetted to fly a mainline pax aircraft wide or narrow body, domestic or international and is equally as good and expeienced as someone with 8,000hrs??? I don’t think you can even get a license to drive a school bus in most places with 50 kids on board with a lifetime experience of 7,200 miles behind the wheel. This is a huge issue.


Let's put it this way: MCAS implementation will likely be at least a contributing factor if not the root cause of this accident based on the similarities between this flight and Lion air flight. What about the pilot experience then? If Boeing 737MAX is such a complex machine to fly that 200 flying hours is not adequate experience to fly it safely, then Boeing should have had for example 2,500 flying hours experience as a requirement for the 737 MAX pilots. In that case contributing cause to the accident would be inadequate pilot requirements as stated by the manufacturer.


It isnt up to Boeing to set the rules for each countries flight requirements. Common sense prevails and sub 200 hour pilots in mainline aircraft is not commonsense. Anyways that policy is set by respective govts\aviation authority. If the govts are going to be so irresponsible they will allow a sub 200 hours FO in a mainline craft. Then the people in that country need to voice their complaints to change the policy. I am really surprised the EU allows an airline to fly into their space with pilots with so little experience.

I am now interested in knowing how many hours this FO had when he first started flying mainline aircraft. If he is at 200 now. That means he started with even lower flight time. I have dabbled in GA and have about 75 hours in single engine piston. Hard to believe I nearly have half the hours of a pilot sitting right seat in a mainline aircraft.

I have a little over 300 with some king air 200 experience and don’t feel in any way that I should be near a 737 flight deck. Crazy
Lrockeagle
14 years ago

I got $20 says AA takes their 787's with GE powerplants. Just a hunch. Any takers?
 
Np2019
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 1:50 pm

Why can't Boeing simply retrofit two mcas switches one for the pilot and one for the first officer. Both switches physical or touchscreen must be engaged to enable or disable the system at the same time. In doing so the mcas is 100% enabled or 100% disabled and the pilots have complete control of the flight and all other controls manually.
 
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QuarkFly
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 2:17 pm

This whole process of completely turning off electric trim with the cutout switches lays bare the flawed MAX flight controls.. So a trim system working perfectly well gets disabled and you revert to an archaic manual trim wheel because of an FCS that does not use redundant AOA or air data.

The MCAS was patch to cover for an engine too big for the 737 wing. Now B is going to provide a software patch to the original patch. That is not the way engineering should be done.

The MAX should have never been certified. Shame on the FAA and Boeing. MCAS type functionality should only be on FBW aircraft. If necessary, B should provide a hz-stab and elevators with enough authority so MCAS is not needed. Also AOA and air data sensors should be handled together...no more single input to FCS.

Perhaps this all leads to a modernized, at least partial FBW system...so be it. The MAX should stay on the ground for a long time, until it is fixed.

Non-US certification authorities should also sign off before it flies again...sadly the compomised FAA can't be the sole approver.

Maybe NMA should become NSA sooner. Time for the over-patched 737 to fly into the sunset.
Always take the Red Eye if possible
 
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qf789
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 2:31 pm

BEA has just released pictures of the CVR

Image

Image

https://twitter.com/BEA_Aero/status/110 ... 60134?s=20
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mm320cap
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 2:40 pm

sgrow787 wrote:
mm320cap wrote:
Well, we still don’t know if the Ethiopian accident was even an MCAS event.


Recovered jackscrew shows stabilizer leading edge up, hence nose down (we know that MCAS response to a stall is to put the nose down)
Vertical speed variation from FR24 is similar to Lion Air - the time between peaks is 20 sec. (we know from the Lion Air crash FDR data that MCAS response to a continued stall detection is to cycle the nose-down commands every 15 seconds indefinitely - 10 sec nose down, 5 sec rest, repeat again)
We know the primary cause of Lion Air crash is a badly designed MCAS system.
We know that because Boeing hadn't yet delivered a software patch for that system, the same system exists in the Ethiopian crash.
Common sense: both crashes involve same aircraft model, same high speed dive to earth, during climb out, same call to ATC to return back, both had erroneous airspeed and/or AOA indications


I understand all that. But the nose of the airplane apparently lifted off the ground below 90knots on the takeoff roll. That has nothing to do with MCAS. There is more to this story.

*if that data is true, I’m not exactly sure why they didn’t reject the takeoff, but I’m guessing the CVR will hold that clue.
 
musicrab
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 2:44 pm

qf789 wrote:
BEA has just released pictures of the CVR

Doesn't look too bad. Don't think we seen anything of the FDR yet?
 
BHM
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 2:52 pm

I understand all that. But the nose of the airplane apparently lifted off the ground below 90knots on the takeoff roll.



Where did this information come from?
 
Interested
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 3:18 pm

qf789 wrote:
Interested wrote:
By the way these two threads should be merged again

The only reason they split was when people started debating if the planes should be grounded. They are grounded now and it's one discussion again?


No they are not going to merged, lets be realistic there are already 6100 posts between the 2 threads and counting (note this number is what I can see as I can see the deleted posts, the number you can see will be different). Furthermore neither of these topics are going to slow down for a while, we may even have to open second threads for both of these if they continue like they are. This thread is about the crash, so lets keep it about the crash, there will be future developments to discuss in this thread just like there will be future developments in the grounding thread so they can co exist together


No prob. I can't see any difference between the 2 threads anymore myself?
 
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flyingturtle
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 3:20 pm

Np2019 wrote:
Why can't Boeing simply retrofit two mcas switches one for the pilot and one for the first officer. Both switches physical or touchscreen must be engaged to enable or disable the system at the same time. In doing so the mcas is 100% enabled or 100% disabled and the pilots have complete control of the flight and all other controls manually.


...so it's up to the crew to decide when MCAS is necessary and when not? Uh-oh. That's not sensible for a system that maintains flight stability.

It's the philosophy behind MCAS that still bothers me.
Reading accident reports is what calms me down
 
Planetalk
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 3:27 pm

BHM wrote:
I understand all that. But the nose of the airplane apparently lifted off the ground below 90knots on the takeoff roll.



Where did this information come from?


It was discussed earlier based on FR24 data but the person who suggested it themselves retracted it; it appears most likely it was caused by the runway profile which shows considerable elevation changes.

The thread is moving so fast unfortunately things keep being brought up that were long ago shown as untrue, so such as people still saying it only reached 1000'.
 
flybucky
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 3:34 pm

But the nose of the airplane apparently lifted off the ground below 90knots on the takeoff roll.


BHM wrote:
Where did this information come from?


The FR24 data showed that at 93 knots, 23 seconds and ~1900 ft (~15% down the runway) after takeoff roll, the aircraft was "airborne". Vertical speed was +128 ft/min (vspeed resolution is 64 ft/min).

The question is whether the plane was truly airborne or not. I had discounted it because the runway elevation profile does rise in the middle, causing the altitude to rise. Others said that the ADS-B airborne/ground data comes from a sensor in the nose gear, which could have been triggered if the nose gear was light enough, even without the plane actually lifting off.

That brings another question though. If it came from the nose gear sensor was just a temporary lightening of the nose gear (due to runway profile, bump, etc), shouldn't it have went back to Ground later in the takeoff roll?
 
hivue
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 3:58 pm

Np2019 wrote:
Why can't Boeing simply retrofit two mcas switches one for the pilot and one for the first officer. Both switches physical or touchscreen must be engaged to enable or disable the system at the same time. In doing so the mcas is 100% enabled or 100% disabled and the pilots have complete control of the flight and all other controls manually.


A lot of posters talking about just turning of the bloody thing off if it's acting up (or even if you're just not comfortable with it always lurking there) seem to be missing the point that MCAS was implemented to make the airplane certifiable. An important part of MCAS is that it operates in the background. I would suspect that if Boeing told operators, hey it's OK for the pilot to decide whether MCAS is available or not and installed MCAS-dedicated cutoff switches, the airplane would lose its certification.
"You're sitting. In a chair. In the SKY!!" ~ Louis C.K.
 
hivue
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 4:02 pm

flybucky wrote:
The FR24 data showed that at 93 knots, 23 seconds and ~1900 ft (~15% down the runway) after takeoff roll, the aircraft was "airborne". Vertical speed was +128 ft/min (vspeed resolution is 64 ft/min).


FR24 reports GS. What IAS does 93 kts translate to at that field elevation?
"You're sitting. In a chair. In the SKY!!" ~ Louis C.K.
 
flybucky
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 4:45 pm

Bobbvis wrote:
The Lion plane flew relatively straight and level for several minutes doing just that and then ???????? Why did they stop correcting it?

Seems that the JT610 Captain was using the electric trim to successfully counteract 21 times. Then he gave control to First Officer, perhaps to do troubleshooting, or he was tired of the stick shaker (only the Captain's stick was shaking). Apparently, the FO did not use the electric trim, which led to unrecoverable situation.

"When the MCAS system pushed the nose down, the captain repeatedly pulled it back up, probably by using thumb switches on the control column. But each time, the MCAS system, as designed, kicked in to swivel the horizontal tail and push the nose back down again. The data shows that after this cycle repeated 21 times, the captain ceded control to the first officer and MCAS then pushed the nose down twice more, this time without a pilot response. After a few more cycles of this struggle, with the horizontal tail now close to the limit of its movement, the captain resumed control and pulled back on the control column with high force. It was too late. The plane dived into the sea at more than 500 miles per hour." https://www.seattletimes.com/business/b ... ol-system/
 
giopan1975
Posts: 57
Joined: Wed Jun 03, 2009 7:55 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 4:49 pm

QuarkFly wrote:
The MCAS was patch to cover for an engine too big for the 737 wing. Now B is going to provide a software patch to the original patch. That is not the way engineering should be done.

The MAX should have never been certified.

Time for the over-patched 737 to fly into the sunset.


:checkmark: Cannot agree more.

HOWEVER......
The captain of the ET flight should have been fully aware of the mcas issue following the Lionair disaster. A seasoned captain doesnt need a Boeing seminar to become alert for such important issues in his type.
Therefore, responsibility in the Lionair accident lies almost 100% upon the manufacturer, whereas in the recent tragedy part of responsibility should burden the crew.

Only trying to use my small mind (i am not a pilot) and on the basis of pure speculation:
1) Stall warnings immediately after rotation should have been identified as false in a clear day only by looking out of the window with following action be no sweat pitch and thrust.
2) mcas kicks in after relatively early flaps retraction, he should have been prepared and within miliseconds hit the bloody stab cut off switch.
 
max999
Posts: 1218
Joined: Fri Dec 09, 2005 11:05 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 4:58 pm

Here's a good explanation from the LA Times about how 737's 50 year old design is causing Boeing problems. https://www.latimes.com/local/californi ... story.html

Quotes from the article.

But the decision to continue modernizing the jet, rather than starting at some point with a clean design, resulted in engineering challenges that created unforeseen risks.

“Boeing has to sit down and ask itself how long they can keep updating this airplane," said Douglas Moss, an instructor at USC's Viterbi Aviation Safety and Security Program, a former United Airlines captain, an attorney and a former Air Force test pilot. "We are getting to the point where legacy features are such a drag on the airplane that we have to go to a clean-sheet airplane."

Over the years, the FAA has implemented new and tougher design requirements, but a derivative gets many of the designs grandfathered in, Moss said.

“It is cheaper and easier to do a derivative than a new aircraft,” said Robert Ditchey, an engineer, aviation safety consultant and founder of America West Airlines, which purchased some of the early 737 models. “It is easier to certificate it.”

But some aspects of the legacy 737 design are vintage headaches, such as the ground clearance designed to allow a staircase that’s now obsolete. “They wanted it close to the ground for boarding,” Ditchey said.

Andrew Skow, founder of Tiger Century Aircraft, which develops cockpit safety systems, and a former Northrop Grumman chief engineer, said Boeing has had a good record modernizing the 737. But he said, “They may have pushed it too far.”

To handle a longer fuselage and more passengers, Boeing added larger, more powerful engines, but that required it to reposition them to maintain ground clearance. As a result, the 737 can pitch up under certain circumstances. Software, known as the Maneuvering Characteristics Augmentation System, was added to counteract that tendency.
All the things I really like to do are either immoral, illegal, or fattening.
 
1010101
Posts: 15
Joined: Tue Nov 14, 2006 12:13 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 5:12 pm

MCAS does not seem to be the root problem. There is something wrong in the AoA sensor path that is causing unreliable readings. This is potentially leading to faulty MCAS operation, but also unteliable air speed and additional control column forced due to the yoke feel system. And some of the anecdotal reports are problems in configurations where MCAS would be inhibited. So I think MCAS alone is just a red herring. Clearly unchecked it can make a bad situation worse.
 
PlanesNTrains
Posts: 9524
Joined: Tue Feb 01, 2005 4:19 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 5:17 pm

Interested wrote:
No prob. I can't see any difference between the 2 threads anymore myself?


Therein lies the problem. This thread should be about the crash, while that thread should discuss a grounding. There will of course be discussion about the crash in that thread but it should really be focused on the various aspects and ramifications of grounding the MAX. I’ve stopped going in that thread since the final US grounding because it’s done - I don’t want to have to come into this ET crash thread and sift through 2600 more posts just to find something from this thread. Who has time for that?
-Dave


MAX’d out on MAX threads. If you are starting a thread, and it’s about the MAX - stop. There’s already a thread that covers it.
 
Zed6550
Posts: 1
Joined: Tue Mar 12, 2019 7:32 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 7:12 pm

First of all hello. I’ve been lurking around here since AF447 and have really enjoyed the frank and sometimes lively discussions. Also I have learned a lot by reading here.

BTW I’ve read this topic since the beginning, however not the grounding thread. I remember some time ago reading an account on Avherald about a 73G, stab trim cutout, a 21,000 fpm descent, caused partially by misadjusted elevator trim tabs. Started at FL410 and was eventually recovered at about five thousand feet. I’m definitely not saying this is the cause here, but it’s at least probable that MCAS combined with some other fault may have made this a/c very hard to control. That fault may or may not be restricted to this particular aircraft.

The interesting part of this report starts in the second section.


https://avherald.com/h?article=4135efab/0002&opt=0
 
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airkas1
Posts: 7904
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 7:36 pm

03/10 accident to the #Boeing737Max @BoeingAirplanes ET-AVJ operated by @flyethiopian / Data from the CVR has been successfully downloaded and transfered to the Ethiopian investigation team / communication on their behalf. / @BEA_Aero did not listen to the audio files.

https://twitter.com/bea_aero/status/110 ... 91361?s=21

They also mentioned that work on the FDR will continue tomorrow.
 
GalaxyFlyer
Posts: 5645
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 7:57 pm

hivue wrote:
flybucky wrote:
The FR24 data showed that at 93 knots, 23 seconds and ~1900 ft (~15% down the runway) after takeoff roll, the aircraft was "airborne". Vertical speed was +128 ft/min (vspeed resolution is 64 ft/min).


FR24 reports GS. What IAS does 93 kts translate to at that field elevation?


93 knots of ground speed is 93 knots at all altitudes. If it was indicated airspeed, it’d be about 107 knots TAS. Again ADS-B data in NOT always representative of exactly what the plane is doing, it’s taken off the indicated airspeed.

GF
 
vfw614
Posts: 3840
Joined: Mon Dec 10, 2001 12:34 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 8:06 pm

Lrockeagle wrote:
I have a little over 300 with some king air 200 experience and don’t feel in any way that I should be near a 737 flight deck. Crazy


You do not have airline-style ab initio training, that's the difference. As many have pointed out, ab initio training of ailrine pilots is not the exception, but the norm outside the US. And still we don't have aircraft crashing every other day outside the US.
 
SC430
Posts: 190
Joined: Tue Dec 26, 2017 11:45 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 8:12 pm

One thing is becoming obvious to me. Design flaws aside - there needs to be more consistent and stringent global pilot training and experience requirements. A good pilot can make all the difference in a malfunctioning aircraft. The global shortage of pilots will lead to more younger and less experienced crews. Ground crew certifications have to be monitored and enforced as well.
 
smartplane
Posts: 1473
Joined: Fri Aug 03, 2018 9:23 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 8:35 pm

OEM's are building structurally stronger and more resilient air frames, highly dependent on software.

The early demise of 777 models using Honeywell AIMS with thousands of unused hours and cycles shows the future.

MAX life will be less than 20 years, because Boeing will be unwilling (and possibly unable) to support the software.
 
flipdewaf
Posts: 3510
Joined: Thu Jul 20, 2006 6:28 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 9:05 pm

SC430 wrote:
One thing is becoming obvious to me. Design flaws aside - there needs to be more consistent and stringent global pilot training and experience requirements. A good pilot can make all the difference in a malfunctioning aircraft. The global shortage of pilots will lead to more younger and less experienced crews. Ground crew certifications have to be monitored and enforced as well.

A problem the world over, need a job to get experience, no experience without a job.
(I’m not having a go at you)

How would one get a thousand hours experience on suitable frames? Are we expecting students to pay for this time on complex multiengine types themselves?

Should an airline hire a new pilot then put them on phantom flights costing several hundred thousand dollars? Would the rate of incidents go up simply due to there being more flights? Is 200 hrs as good as 2000hrs? Probably not but it seems that having a 200hr f/o sat next to a 2000hr mentor is a pretty good compromise.

Fred




Sent from my iPhone using Tapatalk
Image
 
NIKV69
Posts: 13422
Joined: Wed Jan 28, 2004 4:27 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 9:31 pm

trnswrld wrote:
I asked this exact question many pages ago. It got pretty much no response. Big problems in IMC is one thing, but to not be able to fly an airplane in clear blue VMC daylight conditions just baffles me....computer issues or not. How does this happen? Look out the window.....fly the airplane FIRST, then figure what the heck is going on. I know easier said than done.


You won't get an answer because the pilots have not been scrutinized as the kneejerk reaction was something is wrong with the aircraft.
I am the Googlizer!!!
 
sadiqutp
Posts: 290
Joined: Thu Sep 08, 2016 5:05 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 10:01 pm

There is a new article in reuters with few new details about the last moments of the doomed aircraft ..

After one or two minutes, the voice on the air traffic control recording requested to remain on the same path as the runway and to climb to 14,000 feet, the source said.
The aircraft’s ground speed after departure was unusually high, the Reuters source said, reaching around 400 knots (460 miles per hour) rather than the 200 to 250 knots that is more typical minutes after departure.

..
After starting the turn, the plane disappeared from radar at an altitude of 10,800 feet above sea level, the highest it reached during the six-minute flight. Addis Ababa’s runway is at a high elevation of around 7,600 feet, suggesting the doomed jet made it about 3,000 feet into the sky.

...


https://uk.reuters.com/article/uk-ethio ... KKCN1QX0MT
 
osiris30
Posts: 2681
Joined: Sat Sep 30, 2006 10:16 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 10:27 pm

Interested wrote:
osiris30 wrote:
DeltaMD90 wrote:
How do you think AP works? There is no "disable MCAS" switch. The stab cutout will disable MCAS but it also disables your electric trim (talking about the electric trim operated by the pilots with their thumb on the yoke) and AP itself.

You would be taking off and flying the entire flight without AP and without electric trim, only the manual wheel


As I understand it, stab cut does not disable all AP functionality. I may be wrong, but I am pretty sure the rest (speed hold, nav hold, AT, etc) all still function if you hit the stab cut switched located beneath .. well beside and beneath the trim wheel. Happy to be corrected, but my understanding is it is not all or nothing.


I would have to have more context before commenting, and hey, I could be wrong, yes. But I'd be surprised if this is a normal occurrence by crews on passenger flights day after day condoned by the airline. My AA 737 NG/MAX friend didn't indicate he was doing much different, but that is an anecdote and I didn't really ask too many details

Look it up, it was very interesting.

I don't want to appear that I am targeting you, I merely jumped into the discussion around where your post was. I take issue with 1: how certain you sounded in your post, considering how unlikely your scenario sounded based off my, admittedly, light 737 NG piloting (just short of 1000 hours) and 2: the whole notion that we currently need an explanation. Wording like "if you have a better explanation" kinda proves my point... whether or not I have an explanation, a better one, lack of one, educated or non-educated guess, etc is irrelevant to whether yours makes sense. It's perfectly valid of me to sit back without a formed opinion and poke holes in the opinion's of others. If I make a claim, then I'll be required to back it up


Fair enough re not targetting me. Appreciate your insight even if I disagree with some of your assumptions. My comment on 'if you have a better explanation' was genuine. That is why I bolded the PLEASE. I am all for alternate theories, but there are a lot of bits and pieces of the data we have so far that does not fit any of the popular narratives.

Also I am not (nor is anyone here AFAIK) part of the investigation, so we don't need to quite as judicious with what we say. Lord knows there are probably 35 pages of it being MCAS, when that doesn't begin to describe the first 3 minutes of the flight, which is arguably where the AC got into trouble.


For what it's worth to both of you:

I'm purely an outsider with zero plane knowledge looking in. And I find your debate very interesting. Of course it's all speculation. . It's great to hear a pilot point of view Delta. Osiris clearly you know an awful lot about how these planes work. Do you work in the airline industry as well or is it just your interest etc?


Sorry for the delay. My background is engineering (primary computer, a little electrical and a dollop of mech eng.). A lot of embedded stuff and big corporate 5 9s type stuff (and more recently security/mgmt). That said I have been an aircraft nerd for years, have built my own fluid dynamics simulators and all sorts of stuff just to see how things work. I have also had a lot (sadly too much) exposure to UI/UX design and RCA work. I will always respect and usual defer to our in industry folks here on most things. But I do reserve the right to be crusty every once in a while where I feel there is enough cross over that by experience has value. Seeing as I have done a lot of complicated RCA on very complex systems that involve both technical and human failures, accident investiations naturally picque my interest.
I don't care what you think of my opinion. It's my opinion, so have a nice day :)
 
flybucky
Posts: 376
Joined: Tue Apr 17, 2018 7:44 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 10:30 pm

[Edit: sorry, this was already posted earlier]

Data from the CVR has been successfully downloaded by BEA and transferred to the Ethiopian investigation team. BEA did not listen to the audio files.

https://twitter.com/BEA_Aero/status/1107002307542159361
 
ikramerica
Posts: 15090
Joined: Mon May 23, 2005 9:33 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 10:41 pm

sadiqutp wrote:
There is a new article in reuters with few new details about the last moments of the doomed aircraft ..

After one or two minutes, the voice on the air traffic control recording requested to remain on the same path as the runway and to climb to 14,000 feet, the source said.
The aircraft’s ground speed after departure was unusually high, the Reuters source said, reaching around 400 knots (460 miles per hour) rather than the 200 to 250 knots that is more typical minutes after departure.

..
After starting the turn, the plane disappeared from radar at an altitude of 10,800 feet above sea level, the highest it reached during the six-minute flight. Addis Ababa’s runway is at a high elevation of around 7,600 feet, suggesting the doomed jet made it about 3,000 feet into the sky.

...


https://uk.reuters.com/article/uk-ethio ... KKCN1QX0MT

Just because another source retells some details doesnt make it new

1. The first was in the NYT already
2. The plane didnt crash on the runway. Terrain changes, and airports arent usually in the highest spot, just the flattest, most open spot closest to the population base without too many obstructions. From what I understand, the elevation nearer to crash was closer to 9000 ft.
Of all the things to worry about... the Wookie has no pants.
 
iamtom
Posts: 12
Joined: Mon May 22, 2017 5:36 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Mar 16, 2019 10:56 pm

giopan1975 wrote:
QuarkFly wrote:
The MCAS was patch to cover for an engine too big for the 737 wing. Now B is going to provide a software patch to the original patch. That is not the way engineering should be done.

The MAX should have never been certified.

Time for the over-patched 737 to fly into the sunset.


:checkmark: Cannot agree more.

HOWEVER......
The captain of the ET flight should have been fully aware of the mcas issue following the Lionair disaster. A seasoned captain doesnt need a Boeing seminar to become alert for such important issues in his type.
Therefore, responsibility in the Lionair accident lies almost 100% upon the manufacturer, whereas in the recent tragedy part of responsibility should burden the crew.

Only trying to use my small mind (i am not a pilot) and on the basis of pure speculation:
1) Stall warnings immediately after rotation should have been identified as false in a clear day only by looking out of the window with following action be no sweat pitch and thrust.
2) mcas kicks in after relatively early flaps retraction, he should have been prepared and within miliseconds hit the bloody stab cut off switch.


Your assumption is that the ET crew were at fault because they must have known about the MCAS issue from the Lion Air crash.

I’d agree, but my assumption is they would also must know, and surely this couldn’t have been the problem. The captain had 8000+ hours, probably most of those on “type” (read:737). He had recently completed the MCAS update training and I’m sure well prepared for an MCAS issue.

Hearing about those reports from other pilots via the NASA reporting system, there have been notes of several uncommanded nose downs WITH autopilot activated, which suggests some MAX planes have a whole other issue. MCAS should only be active in manual flight, so we need to wait for more information.

I’d fully expect the data from the ET crash to show something other than MCAS as being the primary issue, which might well have been misdiagnosed as MCAS and even something that happened after they tried a manoeuvre with MCAS already disabled and lost control of the plane.
 
flybucky
Posts: 376
Joined: Tue Apr 17, 2018 7:44 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 17, 2019 12:02 am

ikramerica wrote:
Just because another source retells some details doesnt make it new

1. The first was in the NYT already
2. The plane didnt crash on the runway. Terrain changes, and airports arent usually in the highest spot, just the flattest, most open spot closest to the population base without too many obstructions. From what I understand, the elevation nearer to crash was closer to 9000 ft.


That was my initial reaction too, that the NYT already reported this. However, I believe the radar altitude is new information (which I'm interpreting came from the airport radar, not ADS-B/transponder):

"After starting the turn, the plane disappeared from radar at an altitude of 10,800 feet above sea level, the highest it reached during the six-minute flight. Addis Ababa’s runway is at a high elevation of around 7,600 feet, suggesting the doomed jet made it about 3,000 feet into the sky."

Previously, the highest known altitude for the flight was ~9000 ft ASML.

The last data point for FR24 was 05:41:02Z, which was 8600 ft Pressure Altitude (9027 ft ASML)

AVHerald reported the last transponder data was at 05:43:57Z, 9027 ASML. (I'm guessing that is from the satellite ADS-B data, because FR24 ended almost 3 minutes before that).

Everyone was saying that we didn't know what happened in the last 3 minutes of flight after the FR24 data ended, like what the max altitude was achieved. Well, this seems to tell us that the max altitude was 10,800 ft, which means the plane gained +3175 ft from the airport.

The ground elevation at the crash site (8.8772, 39.2512 according to AVHerald) is 7864 ft. So the plane could have fallen ~2936 ft to its crash.
 
User avatar
SuseJ772
Posts: 982
Joined: Wed Aug 10, 2005 11:13 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 17, 2019 12:22 am

PW100 wrote:
dragon6172 wrote:
Or you could use that handy electric trim switch that's right under your thumb on the control column you're pulling so hard on to return the aircraft to a normal trim state before you disable electric trim. As has been pointed out numerous times the pilot ALWAYS has authority over MCAS inputs using the control column electric trim switch.


Do we know that for fact? Could the Max have some logic (for instance, when stickshaker is active), where MCAS overrules control column electric trim switch?

If so, then it's vital to flick Stab Cut Switch immediately. Now the crew have to revert back to manual trim wheel. What's the normal rate your average pilot can obtain using the wheel?
From previous posts in this thread:
* MCAS rate: 0.27 deg/sec
* Control Column Electric Trim Switch: 1 deg/sec
* Manual Trim Wheel: ?? deg/sec.

Can a pilot spin the wheel fast enough to raise the nose, and at the same time maintain enough pulling force on the control column? Probably that would require one pilot pulling hard, and the other one spinning the wheel. Requires very good CRM - and quick, as time is definitely on their side.

This was my question as well. I think a plausable theory at this point - especially in light of this crash after the JT crash - is that the computer software code is not reacting as one might expect it to. Which would only lead more to the confusion. If the MCAS kicks in, and the belief is to counteract with the electric trim, and that doesn't stop it, then the plane is going to fly straight into the ground.


1010101 wrote:
MCAS does not seem to be the root problem. There is something wrong in the AoA sensor path that is causing unreliable readings. This is potentially leading to faulty MCAS operation, but also unteliable air speed and additional control column forced due to the yoke feel system. And some of the anecdotal reports are problems in configurations where MCAS would be inhibited. So I think MCAS alone is just a red herring. Clearly unchecked it can make a bad situation worse.

Agree, but the AoA sensor, while the initial issue, isn't what drives it into the ground. The MCAS does.
Currently at PIE, requesting FWA >> >>
 
Trin
Posts: 167
Joined: Mon May 02, 2011 4:45 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 17, 2019 12:34 am

SuseJ772 wrote:
1010101 wrote:
MCAS does not seem to be the root problem. There is something wrong in the AoA sensor path that is causing unreliable readings. This is potentially leading to faulty MCAS operation, but also unteliable air speed and additional control column forced due to the yoke feel system. And some of the anecdotal reports are problems in configurations where MCAS would be inhibited. So I think MCAS alone is just a red herring. Clearly unchecked it can make a bad situation worse.

Agree, but the AoA sensor, while the initial issue, isn't what drives it into the ground. The MCAS does.


Completely agree. In either of the Lion Air or Ethiopian incident cases, removing MCAS from the equation would result in a completely recoverable flight with no loss of life, regardless of whatever else is wrong with the equipment.

I do agree that the AOA sensor issue is starting to look more like something downstream of the actual vane itself. Which would also explain why Lion Air was repeatedly unable to rectify the issue despite replacing it in between flights. It is far too early to be casting aspersions about their mx crews' competency - this could very well end up being a previously unheard of error located somewhere along the sensor path. And when it occurs, and MCAS is relying on that one sensor input, well......then we have a terrible terrible situation.
 
ikramerica
Posts: 15090
Joined: Mon May 23, 2005 9:33 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sun Mar 17, 2019 2:03 am

Trin wrote:
SuseJ772 wrote:
1010101 wrote:
MCAS does not seem to be the root problem. There is something wrong in the AoA sensor path that is causing unreliable readings. This is potentially leading to faulty MCAS operation, but also unteliable air speed and additional control column forced due to the yoke feel system. And some of the anecdotal reports are problems in configurations where MCAS would be inhibited. So I think MCAS alone is just a red herring. Clearly unchecked it can make a bad situation worse.

Agree, but the AoA sensor, while the initial issue, isn't what drives it into the ground. The MCAS does.


Completely agree. In either of the Lion Air or Ethiopian incident cases, removing MCAS from the equation would result in a completely recoverable flight with no loss of life, regardless of whatever else is wrong with the equipment.

I do agree that the AOA sensor issue is starting to look more like something downstream of the actual vane itself. Which would also explain why Lion Air was repeatedly unable to rectify the issue despite replacing it in between flights. It is far too early to be casting aspersions about their mx crews' competency - this could very well end up being a previously unheard of error located somewhere along the sensor path. And when it occurs, and MCAS is relying on that one sensor input, well......then we have a terrible terrible situation.

Its good that you have finished the investigation. Saved everyone a lot of time.
Of all the things to worry about... the Wookie has no pants.

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