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Posted (edited)
On 4/9/2019 at 8:03 PM, The Tomohawk Kid said:

I have no qualms whatsoever about the B.777-300ER, but compared to the A340, A380 and 878-100 it pales into insignificance as regards passenger comfort, even in business class it is cramped and old hat.

Surely that's down to the airline? Rather unfair to bash the airframe for what is a customer choice of fit.

 

(Sorry to continue wandering off-topic 😔)

On 4/9/2019 at 7:43 PM, Paul J said:

Sounds like Boeing and the FAA have made a big faux pas.

Regarding the 737 Max, I'm sorry to say but this is a case of chickens coming home to roost from the regulatory point of view. And don't let's kid ourselves that Airbus' relationship with EASA is any less problematic.

 

Alan

Edited by Alan P

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Apart from the MCAS system and how they got there and to compete quickly with Airbus 320 family Neos so  instead redesigning it etc.  . Fancy having a warning light that tells the crew the MCAS system is operating ,an attention grabber ,if it's important , flag it up. The industry has always been this way generally . We even had these warnings, be it audible ,visible  or both as part of our courses . It's important .

So why was it an optional extra ? Not a BMW's comfort package we're talking about with heated driver's seat. This warning tells you it's operating and  you're still going down and if you can find the kill switch on Check list page 30 ,you're crashing .

Ethiopian didn't buy the light ,did they even know about the light and if  they did ? Can an airline be that tight .Who at Boeing thought ..Yeah , we can do that ,make it an option though. Might give Airbus a clue to how out of it we are .

If it 'aint Boeing it 'aint going . Give me a break

Mind blowing

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Posted (edited)
43 minutes ago, bzn20 said:

and if you can find the kill switch on Check list page 30 ,you're crashing .

The stabilizer cutout is a memory drill item so it's not really a question of actions, but identifying the problem in the first place. The biggest regulatory issue here is how a flight control override system like the MCAS was certified without any reference to it in the AFM or type conversion/differences training for pilots.

 

Experienced Boeing operators would be aware of the runaway stabilizer item in the memory checklists, so the behaviour of the aircraft might be readily identifiable and the stab cutout drill actioned in time to save the aircraft. However, an inexperienced, newly-converted or less well trained crew might just struggle on, believing it to be a control or autopilot problem, and run out of ideas once the automatics had been disconnected. Until the official report is published, it's going to be speculation for now, but as an experienced Boeing pilot my sympathies are with the crew members concerned. Without proper documentation, it's asking a lot of an average line crew to correctly diagnose a new problem and deal with it effectively with only seconds to spare.

Edited by Alan P

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I’m curious about what stage in the design process of the MAX did Boeing feel that they needed to add the MCAS system. It feels to me like a quick and dirty solution to an unforeseen problem. After initial flight test perhaps?

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13 hours ago, Alan P said:

The stabilizer cutout is a memory drill item

I agree with you but during the Ethiopian flight emergency ..they were going through the checklist in order (caught on the CVR) , and didn't make it to the relevant instruction on the checklist ,think it said it was page  30 , had no height and time to complete the checklist or MCAS warning light .

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1 hour ago, bzn20 said:

I agree with you but during the Ethiopian flight emergency ..they were going through the checklist in order (caught on the CVR) , and didn't make it to the relevant instruction on the checklist ,think it said it was page  30 , had no height and time to complete the checklist or MCAS warning light .

Again, there was far more going on than just reading the QRH, the MCAS system may have been activated and deactivated multiple times. It's time to steer the focus away from the crew in this instance and await the final report - I suspect it may be damning for both the manufacturer and regulator.

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With regard to the tragic Ethiopian Airlines crash, there appears to be more it than what I'm reading in the papers. Here is the latest from Aviation Week:

 

https://aviationweek.com/commercial-aviation/ethiopian-crash-data-analysis-points-vane-detachment?NL=AW-05&Issue=AW-05_20190411_AW-05_553&sfvc4enews=42&cl=article_1&utm_rid=CPEN1000000985591&utm_campaign=19193&utm_medium=email&elq2=62aae782c6e845adbb1e9b2d483cbe76

 

"As the investigation continues into the causes of the Mar. 10 Ethiopian Airlines Boeing 737 MAX accident, sources close to the probe say flight data recorder (FDR) data firmly supports the supposition that the aircraft’s left angle-of-attack (AOA) sensor vane detached seconds after take-off and that, contrary to statements from the airline, suggests the crew did not follow all the steps for the correct procedure for a runaway stabilizer.

 

"Detailed analysis of the FDR trace data shows that approximately six seconds after liftoff was signaled by the weight-on-wheels switch data, the data indicate the divergence in angle-of-attack (AOA) and the onset of the captain’s stick-shaker, or stall warning. Almost simultaneously, data shows the AOA sensor vane pivoted to an extreme nose-high position.

 

"This, says one source, is a clear indication that the AOA’s external vane was sheared off—most likely by a bird impact. The vane is counter-balanced by a weight located inside the AOA sensor mounting unit, and without aerodynamic forces acting on the vane, the counterweight drops down. The AOA sensor, however, interpreted the position of the alpha vane balance as being at an extreme nose-high angle-of-attack.

 

"With the stick shaker active, the trace indicates the crew pushed forward on the column to counteract what they believed were indications of potential approach to stall. The aircraft, now in level flight, also accelerated rapidly as its power setting remained at 94% N1 thrust used for take-off. This was followed by some manual trim inputs using the thumb switches on the control column.

 

"Seconds after speed advisories were heard, the crew raised the flaps. With the autopilot turned off, flaps up and erroneous AOA data being fed to the flight control computer (FCC), the stage was set for the MAX’s maneuvering characteristics augmentation system (MCAS) to activate. This is indicated by approximately 8-sec of nose-down stabilizer movement, which was followed by the use of manual trim on the control column. However, with the MCAS having moved the stabilizer trim by 2.5 units, the amount of manual nose-up trim applied to counteract the movement was around 0.5 units, or roughly only 20% of the amount required to correctly re-trim the aircraft.

 

"Because of the way the aircraft’s flight control computer P11.1 software worked, the use of manual trim also reset the MCAS timer, and 5 sec. later, its logic having not sensed any correction to an appropriate AOA, the MCAS activated again. The second input was enough to put in the full nose-down trim amount. The crew again manually counteracted with nose-up trim, this time offsetting the full amount of mis-trim applied by the latest MCAS activation.

 

"By then, some 80% of the initial MCAS-applied nose down trim was still in place, leaving the aircraft incorrectly trimmed. The crew then activated the stabilizer trim cutoff switches, a fact the flight data recorder indicates by showing that, despite the MCAS issuing a further command, there was no corresponding stabilizer motion. The aircraft was flying at about 2,000 ft. above ground level, and climbing.

 

"The crew apparently attempted to manually trim the aircraft, using the center-console mounted control trim wheels, but could not. The cut-out switches were then turned back on, and manual trim briefly applied twice in quick succession. This reset the MCAS and resulted in the triggering of a third nose-down trim activation lasting around 6 sec.

 

"The source says the residual forces from the mis-trim would be locked into the control system when the stabilizer cut-off switches were thrown. This would have resulted in column forces of up to around 50 lb. when the system was switched back on.

 

"Although this could have been reduced by manually trimming the aircraft, this did not occur, and the third MCAS activation placed the aircraft in a steep nose-down attitude. This occurred with the aircraft near its peak altitude on the flight—about 6,000 ft. The engines remained at full take-off power throughout the flight, imposing high aerodynamic loads on the elevators as the crew attempted to pull back on the columns.

 

"Vertical acceleration data also indicates momentary negative g during which the AOA sensor on the left side unwinds. This is seen as further validation of the theory that the external part of the alpha vane was detached as the apparent change in angle indication could only be explained by the effect of negative g on the counterbalance weight, forcing it to float up inside the sensor housing. In addition, the captain’s stick shaker also comes off twice in this final phase, further reinforcing the severed vane notion.

 

"The source indicates the crew appeared to be overwhelmed and, in a high workload environment, may not have followed the recommended procedures for re-trimming. Boeing’s stabilizer runaway checklist’s second step directs pilots to “control aircraft pitch attitude manually with control column and main electric trim as needed,” according to one U.S. airline’s manual reviewed by Aviation Week. If the runaway condition persists, the cut-out switches should be toggled, the checklist says."

 

 

Cheers,

Bill

 

 

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If I'm reading his correct is there is only one AOA sensor on this aircraft, which is feeding information into a computer which will then take over from the pilots to try and correct, if so who the hell at Boeing thought it didn't need a back up sensor in case the main one went down.

 

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15 hours ago, EwenS said:

I’m curious about what stage in the design process of the MAX did Boeing feel that they needed to add the MCAS system. It feels to me like a quick and dirty solution to an unforeseen problem. After initial flight test perhaps?

The stage when the realised the aerodynamic  handling characteristics were changing enough to require a complete re-certification and additional pilots’ Type Rating (which, coincidentally, isn’t required for the A320neo).

 

not very attractive to current 737 operators if they’d needed to get all their 737 pilots Type Rated on a separate one for the Max.

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9 hours ago, colin said:

If I'm reading his correct is there is only one AOA sensor on this aircraft, which is feeding information into a computer which will then take over from the pilots to try and correct, if so who the hell at Boeing thought it didn't need a back up sensor in case the main one went down.

 

There are two AOA sensors on the MAX, but MCAS only gets data from one. The fix Boeing is proposing would now compare data between the two.

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16 hours ago, EwenS said:

I’m curious about what stage in the design process of the MAX did Boeing feel that they needed to add the MCAS system. It feels to me like a quick and dirty solution to an unforeseen problem. After initial flight test perhaps?

The issue almost certainly was identified from computer simulations of the aircraft before it ever took to the air. But remember that MCAS was implemented to correct a control "feel" issue, which is how Boeing justified only connecting it to one AOA sensor. Somehow, Boeing's analysis of possible failure modes seems to have been hopelessly inadequate. 

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On 12/04/2019 at 20:07, Alan P said:

Surely that's down to the airline? Rather unfair to bash the airframe for what is a customer choice of fit.

Alan

 

I have flown on the B.777-300ER with three different airlines, other than the branding they were ostensibly the same. Of course there will be different fits but I don't think they are that widespread. After all there is only so much an airline can do with a fit without impinging on their profitibility.

 

Its a decent enough airliner, but in my opinion as far as the pax experience is concerned there are better out there.

 

Tommo

 

 

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Posted (edited)
8 hours ago, The Tomohawk Kid said:

It's a decent enough airliner, but in my opinion as far as the pax experience is concerned there are better out there

This is how ours (BA) look when Boeing delivers them to us. It's not the manufacturer's decision to put 3-4-3 across economy with a 29in seat pitch.

 

DSC0229.jpg

One aircraft-specific thing I would definitely agree from the passenger comfort point of view: the 777 has the driest cabin atmosphere I've ever experienced. Sit in one for more than ten hours and you wonder if you'll ever be able to blink or swallow again 😂

Edited by Alan P

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12 hours ago, VMA131Marine said:

The issue almost certainly was identified from computer simulations of the aircraft before it ever took to the air. But remember that MCAS was implemented to correct a control "feel" issue, which is how Boeing justified only connecting it to one AOA sensor. Somehow, Boeing's analysis of possible failure modes seems to have been hopelessly inadequate. 

 

For a system which is designed to aggressively retrim and nose-down an aircraft and do this repeatedly, fighting the pilots, and all from a single sensor to be implemented quietly is absolutely shocking and speaks of multi-level incompetences and procedural failures at Boeing.

 

Anything which affects control or safety should have been design reviewed by node against a comprehensive suite of guidewords with someone experienced and competent from outwith the immediate design team critiquing the design, its causes, effects, failure modes and effects of those failures and thus define actions to mitigate against it happening. Then again I've only got a strong interest in aviation but a professional background in oil and gas which most other industries will admit is somewhat superior in technical safety engineering. Be that as it may, this "feature" should never have survived a design review if there even was one.

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I'm guessing that with glass cockpits & fly by wire, the old style of instrumentation with gyros driving turn & bank indicators, altimeters etc is no more, I wonder if the pilots on these two aircraft could have done more had there been this sort of back up. Maybe its time for a rethink.

Steve.

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5 hours ago, stevehnz said:

I'm guessing that with glass cockpits & fly by wire, the old style of instrumentation with gyros driving turn & bank indicators, altimeters etc is no more, I wonder if the pilots on these two aircraft could have done more had there been this sort of back up. Maybe its time for a rethink.

Steve.

 

I doubt it in this case Steve - I get the impression the pilots were fully aware of what the aircraft was doing situationally - it's more the alarmingly high control forces that a drastically out-of-trim aircraft will generate which is something I have experienced. They knew it was aggressively pitching nose-down and they were fighting it with fly-by-bicep hauling back on the yoke, probably one of them groaning at it with the other desperately flicking through pages of a checklist trying to work out why the aircraft kept retrimming nose-heavy. From the above it sounds as those the MCAS retrimmed it so aggressively as to bunt the aircraft.

 

I doubt mechanical instruments would have told them anything they didn't already know which was that the aircraft was trying to kill them. What nothing told them was that this was something the MCAS would do if it got confused with a dicky sensor and how to switched the damned thing off.

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Posted (edited)
16 hours ago, Jamie @ Sovereign Hobbies said:

What nothing told them was that this was something the MCAS would do if it got confused with a dicky sensor and how to switched the damned thing off.

This is really the heart of the problem, leaving some tough questions for the manufacturer but more importantly the regulator. 

 

Here's an interesting take on the competitive environment that rushed the Max through certification.

 

Edited by Alan P
Video link added

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I may be being naive, but I would have thought that the FAA would have been well aware of the necessity for redundancy in flight-critical systems after the loss of an Alaskan Airlines MD-80 and everyone aboard after the one and only screw jack controlling the tailplane failed due to inadequate maintenance.  It’s also not unreasonable to expect Boeing to be aware of the need for visible (and aural) warnings for aircrew of potentially unsafe conditions after the loss, admittedly a long time before, of a Lufthansa 747 at Nairobi because the crew had no warning that they had not extended the slats for take-off.

 

Let us hope that the lessons from the Ethiopian Airlines and Lion Air 737 Max tragedies are heeded and remembered so that the deaths of nearly 350 people will not have been in vain.

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15 hours ago, Alan P said:

leaving some tough questions for the manufacturer but more importantly the regulator

So if both the manufacturer and the regulator are "in the Dock", so to speak, who is going to be asking the questions?? 

 

I'm reminded of the inquisition into the Space Shuttle disaster, and fortunately the maths & physics genius Richard Feynman was put in charge. 

I was reading his biography quite recently, and this episode was dealt with. 

Feynman got to the bottom of it eventually, but it took some doing. 

A less able mind could well have been stopped by the "stonewall"! 

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On 4/14/2019 at 6:15 PM, stevehnz said:

I'm guessing that with glass cockpits & fly by wire, the old style of instrumentation with gyros driving turn & bank indicators, altimeters etc is no more,

Nope. The mechanical instruments remain even on glass cockpits.

Have a look at the panel and there are three dials for A/h, Airspeed and Altitude, one above the other in the centre of the panel (or slightly offset to port - due to the central MFD screen).

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Steve, unless the photo you provided link to shows a 737 MAX cockpit mock-up you are probably right! Hairystick's comment is certainly valid for 737 NG cockpit but, as far as I can tell, the only mechanical thing in 737 MAC cockpit seems to be a compass on the top of the windshield frame. However, that central mini LCD or MFD looks more like a pro forma addition than a functional back up to me. The display is small, not very conveniently placed and reading it must be quite a task, especially in emergency situation. Cheers

Jure

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13 hours ago, hairystick said:

Nope. The mechanical instruments remain even on glass cockpits.

Have a look at the panel and there are three dials for A/h, Airspeed and Altitude, one above the other in the centre of the panel (or slightly offset to port - due to the central MFD screen).

Sadly, they're not mechanical either. They run from a standby flight instrument system which uses a separate air data source and inertial reference unit. The only mechanical instrument you're likely to find these days is the E2 compass (central windshield pillar) and that's not a given!

 

Alan

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On 4/22/2019 at 3:39 AM, stevehnz said:

@hairystick Thanks for that, I had found this photo of a Max instrument panel but nothing I recognised as old style back up instruments, does the square blue thing between the glass displays do all those functions you mentioned, a new style back up instrument. :unsure:

Steve.

That seems to be a flight sim and yes that item seems to be an electronic version of the instruments.

I looked over a few photos and specifically avoided cgi images. If what Alan is saying is correct, then I'd be concerned about the lack of backup instrumentation! Perhaps we'll see a return to the "duck and cat" in the cockpit for flight reference?

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15 minutes ago, hairystick said:

That seems to be a flight sim and yes that item seems to be an electronic version of the instruments.

I looked over a few photos and specifically avoided cgi images. If what Alan is saying is correct, then I'd be concerned about the lack of backup instrumentation! Perhaps we'll see a return to the "duck and cat" in the cockpit for flight reference?

More like the dog and pilot 😄 

 

(For those unfamiliar with the reference, the pilot is there to watch the computer fly the aircraft. The dog is there to bite the pilot if they touch anything 😉)

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