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Ethiopian airliner down in Africa

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Ethiopian airliner down in Africa

Old 11th Mar 2019, 01:17
  #221 (permalink)  
 
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Aerobatic, crop spraying and fighter aircraft have to be unstable to allow for rapid maneuverability. A crop sprayer pilot described flying the Ayers Turbo Thrush to me as "like balancing on a beach ball".

Some of the latest fighters are so unstable that they have to be fly by wire or control would be rapidly lost by most pilots.

The certification requirement of not needing undue "skill, alertness or strength" needs to be remembered. IF the MCAS has to be watched like a hawk and requires a couple of night club bouncers to overcome a simple failure then it has no place on a civil aircraft. Imagine two slightly built female pilots trying to overcome a runaway system.
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Old 11th Mar 2019, 01:31
  #222 (permalink)  
 
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Originally Posted by krismiler View Post
Aerobatic, crop spraying and fighter aircraft have to be unstable to allow for rapid maneuverability. A crop sprayer pilot described flying the Ayers Turbo Thrush to me as "like balancing on a beach ball".

Some of the latest fighters are so unstable that they have to be fly by wire or control would be rapidly lost by most pilots.

The certification requirement of not needing undue "skill, alertness or strength" needs to be remembered. IF the MCAS has to be watched like a hawk and requires a couple of night club bouncers to overcome a simple failure then it has no place on a civil aircraft. Imagine two slightly built female pilots trying to overcome a runaway system.
What I don't understand is that if you have an MCAS failure and recognize it and apply the AD from FAA/Boeing they don't tell you to be worried about the flight regimes it is supposed to protect you from. Why not turn the thing off all Max now if that can be done even if this occurrence was not due to an MCAS failure.
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Old 11th Mar 2019, 01:32
  #223 (permalink)  
 
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Originally Posted by jimtx View Post
What I don't understand is that if you have an MCAS failure and recognize it and apply the AD from FAA/Boeing they don't tell you to be worried about the flight regimes it is supposed to protect you from. Why not turn the thing off all Max now if that can be done even if this occurrence was not due to an MCAS failure.
The certification requires MCAS.
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Old 11th Mar 2019, 01:36
  #224 (permalink)  
 
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Often the companies have a good idea what has happened before everyone else. Would Boeing already know what happened here?
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Old 11th Mar 2019, 01:48
  #225 (permalink)  
 
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Cayman Airways Suspends Operations of Both Its 737 Max 8 Planes
2019-03-11 00:43:29.973 GMT

By Derek Wallbank, Jihye Lee and Kyunghee Park
(Bloomberg) -- Cayman Airways, the flag carrier airline of
the Cayman Islands, says it is suspending operations of both its
Boeing 737 Max 8 aircraft effective March 11 "until more
information is received."
* Southwest Airlines says it remains "confident in the safety of
our fleet" including its 34 Boeing 737 Max 8 aircraft
* Singapore Airlines in tweet says it’s closely monitoring the
situation, though at this time the 737 Max 8 flights operated by
SilkAir are operating as scheduled
* Icelandair says it has had no issues with its three 737 Max 8s
* Spokeswoman at Korean Air, which is expected to take delivery
of its first MAX late April, said the airline is monitoring the
situation
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Old 11th Mar 2019, 02:16
  #226 (permalink)  
 
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14% efficiency gains by moving the engines 8 inches?

Iím not a pilot. Just a mechanical engineer whoís an armchair quarterback.

I come here when I need facts on air incidents.

A 14% increase in fuel efficiency from a simple move like that indicates vastly different aerodynamic performance. How much does bypass ratio add? How much does adding an extra row of compressor blades increase performance?

this indicates that there are some interesting boundary layer effects happening to this aircraft. Iím curious if somehow there are vortexes being generated at higher AoAs that somehow interfere with the pitot tubes.

Bring the wrath. I know Iím just an observer.
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Old 11th Mar 2019, 02:17
  #227 (permalink)  
 
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Originally Posted by PastTense View Post
See thread:
Boeing 737 Max Software Fixes Due to Lion Air Crash Delayed
Thus Boeing hasn't implemented any fixes of the MCAS problem yet. While many airlines probably did some additional pilot instruction and other pilots learned of the problem in places like PPRuNe, many other pilots probably didn't.

And of course even if a pilot was informed of something doesn't mean he will remember it in a critical situation.
What is there to fix. There are numerous failures that can cause a trim runaway. They have been happening since the first electric trim systems were installed in aircraft. The 737 more than any aircraft currently in service provides a very positive indication of a trim issue via the trim wheels. Solution, disconnect the automatic trim system and continue the fight using manual trim.
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Old 11th Mar 2019, 02:24
  #228 (permalink)  
 
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Originally Posted by PastTense View Post
While many airlines probably did some additional pilot instruction and other pilots learned of the problem in places like PPRuNe, many other pilots probably didn't.
I can't believe that there would be a MAX pilot anywhere who isn't fully aware of the MCAS implications from the Lion incident.

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Old 11th Mar 2019, 02:32
  #229 (permalink)  
 
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A cautionary tale about assuming that the correct response to a failure is obvious and straightforward:

Once upon a time, I was involved with the addition of a FADEC (Full Authority Digital Engine Control) to the turbine engine on a single-engine helicopter. I forget why but it was single channel. In the unlikely event that it failed, the pilot was obligated to control rotor rpm with the throttle twist grip on the collective just as you did when flying a helicopter powered by a reciprocating engine back in the day.
Before deliveries began, I took it upon myself to fly and land one in manual mode and even though I hadn’t twisted a throttle in some years, there was no drama involved.

Unfortunately, as subsequent events proved, many pilots had never flown a helicopter with a reciprocatiing engine, having learned to fly ones powered by turbine engines with mechanical fuel controls that kept the rotor rpm constant, and training to fly this helicopter in manual mode not as prevalent or extensive as it should have been.
What was worse, the FADEC manufacturer had a circuit-board quality-control problem, which meant that pilots were being presented with the need to manually control rotor rpm after the FADEC had packed up fairly often and at least a few were not up to it, fatally in at least a couple of cases. The quality-control issue was subsequently resolved of course and after perhaps too many early incidents, more emphasis placed on training and occasional practice in manual mode. Moreover, my understanding is that the FADEC now has dual channels.
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Old 11th Mar 2019, 02:39
  #230 (permalink)  
 
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Originally Posted by WingNut60 View Post
I can't believe that there would be a MAX pilot anywhere who isn't fully aware of the MCAS implications from the Lion incident.
Crews may be aware now, but remember- the Lion Air accident were dealing with unreliable flight instruments along with the MCAS trimming. Merely shutting off the electric stab trim does not eliminate the bad air data indications on the affected side. In itself, a bad set of PFD indications can be a handful wether or not the stab trim is cut off by the crew as recommended.

Clearly, there is no final report from the Indonesians, but unreliable airspeed, etc. was one of the problems as far as Iím aware.
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Old 11th Mar 2019, 02:48
  #231 (permalink)  
 
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Originally Posted by FIRESYSOK View Post
Crews may be aware now, but remember- the Lion Air accident were dealing with unreliable flight instruments along with the MCAS trimming. Merely shutting off the electric stab trim does not eliminate the bad air data indications on the affected side. In itself, a bad set of PFD indications can be a handful wether or not the stab trim is cut off by the crew as recommended.
Absolutely correct.

I was only commenting on the previous inference that there might be MAX crews around who until now were still blithely unaware of current conclusions about the loss of an aircraft of the type that they fly.
Either through official or unofficial channels.
That I find hard to believe.

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Old 11th Mar 2019, 02:52
  #232 (permalink)  
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Originally Posted by RickNRoll View Post
The certification requires MCAS.
True. The MMEL does not provide any relief for a MCAS system. The MMEL does however provide relief for the MLA system, which is curiously a factor itself in reduced longitudinal stability. Accepting the operational constraints of the MLA system inop would remove to an extent the necessity for MCAS.

A couple of aerodynamic effectors can be applied to alter downwash at the tail plane, one of which we trialled in 2015 on a B737. It had been trialled years back on a B742 with similar outcomes. The downside of the aero effectors is that altering the downwash is going to be undesirable from a load alleviation standpoint, and is like eating your own tail, unless sufficient increase in downwash is obtained in the near wake to reduce the downwash affecting the tailplane.

Control system counter weights exist to an extent at every bell crank, and that is the simplest means to alter control response during manoeuver.

Any control system or aerodynamic alteration would be a major PITA for alteration of the product, whereas taking MLA out of he equation may remove the necessity for the MCAS to a great extent and remove the issue until resolved.

ET's loss has too many similarities to 610's to be discounted as a system-crew problem.

[Note: AOT is an acronym most famous for the Apollo Lunar Lander's Alignment Optical Telescope... the CM also had one, but it was known as a sextant and part of the PGNCS. ]
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Old 11th Mar 2019, 02:53
  #233 (permalink)  
 
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Originally Posted by FIRESYSOK View Post


Crews may be aware now, but remember- the Lion Air accident were dealing with unreliable flight instruments along with the MCAS trimming. Merely shutting off the electric stab trim does not eliminate the bad air data indications on the affected side. In itself, a bad set of PFD indications can be a handful wether or not the stab trim is cut off by the crew as recommended.

Clearly, there is no final report from the Indonesians, but unreliable airspeed, etc. was one of the problems as far as I’m aware.
Originally Posted by Sailvi767 View Post


What is there to fix. There are numerous failures that can cause a trim runaway. They have been happening since the first electric trim systems were installed in aircraft. The 737 more than any aircraft currently in service provides a very positive indication of a trim issue via the trim wheels. Solution, disconnect the automatic trim system and continue the fight using manual trim.

Originally Posted by canyonblue737 View Post


it is not dissimilar from a trim runway though, MCAS can be disabled in seconds using the standard trim runway procedure that has you flip two switches on the center pedestal.
Yes, sounds easy if you're 100% confident that MCAS is wrong. But, MCAS is reacting to sensor data- the same data that the instruments in front of your eyes are relaying to you. If your AOA indicator goes haywire, or your ASI is showing lower than stall speed, then you'll have a difficult situation. What MCAS does... it controls flight surfaces to prevent a stall that is likely to occur given the sensor inputs that it's receiving. If you're flying you'll usually trust the instruments- the same instruments as MCAS. Maybe other MCAS interventions haven't been noticed or reported because the rest of the time it's actually functioned the exact same way as the pilots have operated anyway.

If you've just taken off on most other aircraft, if you get a low reading from ASI, or even stick shaker, your first priority is to try to control the aircraft, stabilize flight, level off if at a safe altitude, call a pan and go through the checklists... whereby you eventually should discover that the ASI sensor is bad, Air speed is fine and switch to the alternate input and go on your merry way. Why MCAS is scary is that it 100% relies on sensor data- you're now in the exact same situation as described above, with the exception being that your aircraft has just trimmed nose down by itself, any breathing space you had to troubleshoot has been eroded by MCAS nose down, and any time you could have used to figure out the problem is now spent trying to pull back on the yoke as hard as you can.

It's very easy to say "just pull a couple of CBs, disconnect trim switch, everything will be fine", but in those circumstances, you're on climb out of airport XYZ, suddenly the stick-shaker goes, the ASI in front of your eyes IS showing a reading that's abnormally 'low', the aircraft just trimmed itself nose down to prevent stall, before you have any chance to diagnose the problem you're fighting against the MCAS nose down attitude, your right hand man has 200 hrs all-in and is panicking.

Again, like I said earlier, absolutely not jumping to conclusions as to what caused this tragedy. Again, just re-examining the MCAS issue that has been brought up. Again, stating that MCAS in and of itself should not be a problem- providing the inputs are 100% reliable the software goes unnoticed and may even act as a safety net in the manner it was designed to be. Again, the problem that I see that I haven't seen highlighted previously is the hardware! MCAS relies on data, sensors are the source of the data, why are the sensors so fallible?? Why can't they spend more money on the hardware- ensuring sensors are foolproof with adequate redundancies that can always be relied upon?

Again, Southwest knew the problem and had a quick fix for their own 738 MAX orders, providing an additional AOA indicator for crew to easily cross-check if needed. Note that their statement on 738 MAX listed above is qualified- they're happy with 'their fleet' Possibly their quick & simple solution might be sought by other 738 MAX operators, or even demanded of Boeing to retrofit.

Last edited by positiverate20; 11th Mar 2019 at 03:11.
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Old 11th Mar 2019, 02:55
  #234 (permalink)  
 
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Originally Posted by RickNRoll View Post
The certification requires MCAS.
That just might turn out to be the Oxymoron of the Century!
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Old 11th Mar 2019, 03:08
  #235 (permalink)  
 
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SHANGHAI (Reuters) - China's aviation regulator has ordered domestic airlines to suspend their Boeing 737 Max aircraft, Chinese media outlet Caijing reported on Monday, following a deadly crash on Sunday of a 737 MAX 8 operated by Ethiopian Airlines.
Citing industry sources familiar with the matter, Caijing said domestic airlines, which operate some 60 such airplanes, had received orders from the Civil Aviation Administration of China (CAAC) and halted their use on Sunday.
A Boeing spokesman declined to comment. The CAAC could not be immediately reached for comment.
An Ethiopian Airlines 737 Max 8 bound for Nairobi crashed minutes after take-off on Sunday, killing all 157 people on board.
This is the second crash of the 737 MAX, the latest version of Boeing’s workhorse narrowbody jet that first entered service in 2017.
In October, a 737 MAX flown by Indonesian budget carrier Lion Air flying from Jakarta on a domestic flight crashed 13 minutes after take-off, killing all 189 passengers and crew on board.
The cause of that crash is still being investigated. A preliminary report issued in November, before the cockpit voice recorder was recovered, focused on airline maintenance and training and the response of a Boeing anti-stall system to a recently replaced sensor but did not give a reason for the crash.
Caijing, a state-run news outlet that covers finance and economics, said many flights scheduled to use 737 Max planes would instead use the 737-800 models.
China Business News also reported on its website the 737 Max suspension, saying the regulators' order had been issued orally.
According to flight tracking website FlightRadar24 there were no Boeing 737 Max 8 planes flying over China as of 0043 GMT on Monday.
Most of Air China's 737 MAX fleet of 15 jets landed on Sunday evening, with the exception of two that landed on Monday morning from international destinations, according to FlightRadar24.
It did not list any upcoming scheduled flights for the planes.
China Eastern’s four 737 MAX jets landed on Sunday evening and no further flights were scheduled until Tuesday, FlightRadar24 data showed.
Cayman Airways has grounded both of its new 737 MAX 8 jets until more information was received, the Cayman Islands airline said in a statement on its website.
Fiji Airways said it had followed a comprehensive induction process for its new Boeing 737 MAX 8 aircraft and it had full confidence in the airworthiness of its fleet.
"We continue to ensure that our maintenance and training programme for pilots and engineers meets the highest safety standards," the airline said.
(Reporting by Josh Horwitz and John Ruwitch; Editing by Richard Pullin)



-- © Copyright Reuters 2019-03-11
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Old 11th Mar 2019, 03:08
  #236 (permalink)  
 
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Originally Posted by RickNRoll View Post
The certification requires MCAS.
So when it fails you are flying an uncertified aircraft and you are not told to do anything different.
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Old 11th Mar 2019, 03:41
  #237 (permalink)  
 
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Simple question - WHO and WHY did anyone allow a SINGLE flight critical sensor to override all previous methods of recognizing and controlling the aircraft and NOT document it ??

Shades of HAL !
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Old 11th Mar 2019, 03:58
  #238 (permalink)  
 
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Originally Posted by The AvgasDinosaur View Post
Learned Contributors,
please excuse if this is considered thread drift. If this Ethiopian crash and the Indonesian previously covered on here are proved to be linked. Is
not it odd that out of the total number of B.738M departures since entry to service, no one has been subject to this upset and caught it without loss of life ? Especially since Indonesia as I expect all B.738 Max crews are looking out for a recurrence?
Your time and trouble much appreciated,
Be lucky
David
Even after knowing the DC10 had a design fault wrt to the cargo door, it didnt stop the ground crew of TK981 to not lock the damn cargo door that killed 300 odd people. There must have been tens of thousands of t/os and landings on the DC10 without incidents between AA96 and TK981.
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Old 11th Mar 2019, 04:08
  #239 (permalink)  
 
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Originally Posted by CONSO View Post
Simple question - WHO and WHY did anyone allow a SINGLE flight critical sensor to override all previous methods of recognizing and controlling the aircraft and NOT document it ??

Shades of HAL !
It is shocking how this system was introduced- only being documented and publicised following the death of 189 people.

I can see the logic as to why they'd build it in- if it was 100% operational and reliable it would act as a safety measure. AF447 for example would have been saved by a nose down attitude to recover stall. The junior PF of AF447 continued nose up throughout a 40,000 ft flop. However, in that case it was faulty sensors too- frozen pitot tubes from memory, so the input data was bad anyway. Nose down however could have been useful for stall recovery in any case.
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Old 11th Mar 2019, 04:23
  #240 (permalink)  
 
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Just a general reminder - MCAS and "autopilot" are mutually exclusive. MCAS is only active during manual flight.

While I'm in general agreement with comments to the effect that the MAX8 MCAS is an engineering kludge, poorly thought-out, and as such dangerous (in combination with insufficient redundancy in AoA sensors) - there are other ways to put a 737 into the ground after take-off. So I'm looking for a few more dots to be connected before jumping one way or the other - in this event.

I'm also not convinced that all pilots - robot-like - fly every takeoff to such an exact profile that, for example, flaps come up exactly and only this precise amount at this precise altitude or speed and such, on every single take-off. I do respect physical impossibilities, however.

"Pilots do the darndest things..." - apologies to Art Linkletter. But don't take that as automatically meaning "pilot error."
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