Go Back  PPRuNe Forums > Flight Deck Forums > Rumours & News
Reload this Page >

Ethiopian airliner down in Africa

Rumours & News Reporting Points that may affect our jobs or lives as professional pilots. Also, items that may be of interest to professional pilots.

Ethiopian airliner down in Africa

Old 15th Mar 2019, 21:03
  #1541 (permalink)  
 
Join Date: Jan 2008
Location: Reading, UK
Posts: 9,920
Originally Posted by Livesinafield View Post
southwest nearly 3 years, with no such issues
Those ASRS reports that have been widely circulated are anonymous. How do you know none of them were from SWA pilots?

DaveReidUK is offline  
Old 15th Mar 2019, 21:18
  #1542 (permalink)  
 
Join Date: Nov 2006
Location: Dallas
Posts: 421
Originally Posted by Livesinafield View Post
Guys, think people need to ease of the aircraft a little as if its got some huge design defect especially until we have some more facts, bear in mind many operators have been using this type for a fair while southwest nearly 3 years, with no such issues, also bear in mind that both operators here that have managed to "fly it into the ground" have very questionalble safety records as an operator.
For the record, Southwestís first MAX revenue flight was October 1, 2017. Closer to 1.5 years than 3 years. Yes, Southwest has flown it a lot, and has a lot of data, but itís not three years of data.

Hoke

ILUVHOKE is offline  
Old 15th Mar 2019, 21:29
  #1543 (permalink)  
 
Join Date: Dec 2013
Location: US
Age: 61
Posts: 360
Originally Posted by joig View Post
How many turns does it take to go from max down to say a neutral position? Given they they were never that high from the ground , How long would it take them to trim from max down to something that would save the flight? What am trying to say is OK we have a trim problem disable trim motor via cut out switches.. Turn the manual trim wheel . Would they have the time to do this if the are only approximately 1000ft above ground?
Depending on speed they aircraft can be controlled with full nose down trim. Itís highly unlikely MCAS trimmed the aircraft full nose down since it only moves in increments of 2.5 degrees and if the pilot countered it with the electric trim the aircraft would remain close to a trimmed state. Any pilot with a basic level of competence would counter the trim to attempt to remain in trim. The MCAS if getting bad inputs would again after a period of time input 2.5 units of trim again. Itís not instantaneous and the pilot would be alerted by feel, sight and noise. At the point you would expect the pilot to disconnect the trim and continue the flight using manual trim. Pretty much a non event for a competent crew.
Sailvi767 is offline  
Old 15th Mar 2019, 21:33
  #1544 (permalink)  
 
Join Date: Dec 2006
Location: Florida and wherever my laptop is
Posts: 1,255
Originally Posted by Just This Once... View Post


I keep reading such explanations but to be clear, MCAS is always powered on. When and where it functions is defined by software alone. As such this is safety critical software and should meet the highest assurance levels. The designer did not wish for the aircraft to crash and may have set all the protection methods they could think of as a credible design goals. We have yet to learn if MCAS, as implemented, did respect the AP selection, flap configuration or anything else the designer had in mind.

MCAS being 'live' when it should not have been remains a plausible explanation. It ticks all the boxes for a latent failure - no direct indication to the crew, no failure modes displayed, no routine interaction with other systems, no BITE or similar and does not drive the stab at any point during a normal sortie. As long as it thinks the AoA is ok it does nothing.

Time will tell if functions like trim cutout, AP cutout, configuration cutout etc actually work. Given that the system seems to be blissfully unaware of the actual flight dynamics beyond simple unmonitored raw sensor data and will willingly fly the aircraft into the ground, I remain reluctant to accept the claimed operating envelope as gospel.

I guess I have spent too many years flight testing aircraft and my level of 'trust' has been swamped by 'verify'. As an aside, flight testing has become inconvenient in the last 15 years or so. We get more facetime and interaction these days post-crash - everyone is 'all ears' at that point. We need to get flight testing and training verified before an aircraft is released to the line. Kicking over aluminium at an accident site is just too late.
I understand your lack of trust in testing. I have similar experience in software acceptance testing. However, in this case not only would MCAS be incorrectly active with the autopilot engaged without AOA disagree and without being at extreme AOA and cease to be active when autopilot is disconnected when that is in the opposite sense for activating MCAS. The numbers of improbabilities would seem to be too high to be likely, Occam would have us check that there was nothing mis-set in the autopilot first.
Ian W is offline  
Old 15th Mar 2019, 21:37
  #1545 (permalink)  
 
Join Date: Feb 2009
Location: Seattle
Posts: 379
Originally Posted by iamhives View Post
Which to me seems a huge issue. Before this second incident (assuming they're related) Boeing was downplaying the issue, basically trying to put lipstick on the pig. The second instance of this problem, in short order, shows that more is required than what was likely the lowest cost, most expedient fix Boeing could come up with. The assumption that Boeing made previously that pilots should be able to safely deal with another instance of this problem (hence justifying that grounding the fleet wasn't necessary, even after the second crash) proved to be sadly wrong and hence I conclude that the fix that Boeing had conceived before the second instance must also be flawed since it was based on their same myoptic attitude. To implement the 'fix' conceived of before this second incident within the next 10 days seems untenable. Unfortunately Boeing is motivated by $ to get any fix out there asap whether its a real fix or not. Today when news was leaked that the fix would be ready in 10 days (by Boeing?), the Boeing stock bumped 1.5%. If they had announced the fix would take another 5 months then likely the opposite would have happened or much worse. Hopefully, common sense will prevail and the required fix/action will be fully re-evaluated. I'm considering shorting Boeing stock but that would assume common sense will prevail.
In order for the pending Boeing MCAS update to be ready for release "in April" it must have been fully defined and most of the way through the required implementation, lab, and flight testing required before the ET accident. If Boeing and FAA are now saying they can get it out to the fleet any sooner that must be a matter of moving the last steps toward certification of that FCC software update to the left on the schedule. There is no way that the proposed change could be modified in reaction to the ET accident and remain on track for anything close to the forecast schedule.
FCeng84 is offline  
Old 15th Mar 2019, 21:52
  #1546 (permalink)  
 
Join Date: Oct 2018
Location: New york
Posts: 3
Total Bewilderment

I recognize that there are serious issues with the MCAS system but.... I am not a 737 Max driver but based on the Lion Air crash and the airworthiness directive my hand would be at the ready to flick a switch to deactivate the MCAS system if there are any flight control issues. That is less than a 1 second procedure. The thought that 157 souls died because the pilot did not flip a switch..which he knew was there ... total bewilderment. Iím sure the Boeing team is thinking the same thing. Maybe the stabilizer trim cutoff switches were indeed flipped but not likely. Time will tell.
AVAT is offline  
Old 15th Mar 2019, 21:56
  #1547 (permalink)  
 
Join Date: Apr 2009
Location: Hotel Gypsy
Posts: 2,832
Originally Posted by Sailvi767 View Post


Depending on speed they aircraft can be controlled with full nose down trim. It’s highly unlikely MCAS trimmed the aircraft full nose down since it only moves in increments of 2.5 degrees and if the pilot countered it with the electric trim the aircraft would remain close to a trimmed state. Any pilot with a basic level of competence would counter the trim to attempt to remain in trim. The MCAS if getting bad inputs would again after a period of time input 2.5 units of trim again. It’s not instantaneous and the pilot would be alerted by feel, sight and noise. At the point you would expect the pilot to disconnect the trim and continue the flight using manual trim. Pretty much a non event for a competent crew.
So, aircraft are thumping into ground with full nose down trim, maybe twice. There’s record of at least one US Max pilot (presumably with the mandated 1500hrs+) saying he was line flying and didnt really know how to operate the aircraft. Boeing appear to have designed and implemented a system with a single point of failure and then neglected to tell anyone about it’s existence, never mind foibles. Our industry is failing the public, whether that is with cost-cutting finance-driven design, inadequate training & flight manuals, or so-called third world operators who are being gleefully sold the ‘latest’ technology. Meanwhile, in corporate HQs ‘risk assessments’ are done, complete with acceptable loss rates. The only winners appear to be lawyers who will now make careers and private yatchs from obfuscating and finger pointing.

If your taxi driver pitched-up in a vehicle that first hit the roads on 9 April 1967, 9 days after my birthday, would you get in or would you wait for the next ride? The broomhandle and the broom have been replaced/modified numerous times over but were still waxing-lyrical about how it’s the same broom we bought 50 years back. Yes, I’m being a bit simplistic but it’s still time to wake up.

Shame on our industry.
Cows getting bigger is offline  
Old 15th Mar 2019, 22:17
  #1548 (permalink)  
 
Join Date: Feb 2009
Location: Seattle
Posts: 379
Originally Posted by Just This Once... View Post


I keep reading such explanations but to be clear, MCAS is always powered on. When and where it functions is defined by software alone. As such this is safety critical software and should meet the highest assurance levels. The designer did not wish for the aircraft to crash and may have set all the protection methods they could think of as a credible design goals. We have yet to learn if MCAS, as implemented, did respect the AP selection, flap configuration or anything else the designer had in mind.

MCAS being 'live' when it should not have been remains a plausible explanation. It ticks all the boxes for a latent failure - no direct indication to the crew, no failure modes displayed, no routine interaction with other systems, no BITE or similar and does not drive the stab at any point during a normal sortie. As long as it thinks the AoA is ok it does nothing.

Time will tell if functions like trim cutout, AP cutout, configuration cutout etc actually work. Given that the system seems to be blissfully unaware of the actual flight dynamics beyond simple unmonitored raw sensor data and will willingly fly the aircraft into the ground, I remain reluctant to accept the claimed operating envelope as gospel.

I guess I have spent too many years flight testing aircraft and my level of 'trust' has been swamped by 'verify'. As an aside, flight testing has become inconvenient in the last 15 years or so. We get more facetime and interaction these days post-crash - everyone is 'all ears' at that point. We need to get flight testing and training verified before an aircraft is released to the line. Kicking over aluminium at an accident site is just too late.
Just This Once - I am glad to hear your reluctance to take software designers' word for proper function and robustness to failure without rigorous validation and verification testing. That attitude drives the diligence that has brought the safety of our industry to such a high level. Let's not lose that as we move forward. With regard to MCAS and the Lion Air event, the response of the control system and the airplane as revealed via the flight data recorder was entirely consistent with intended MCAS functionality given the errant AOA signal it was following and the flight crew inputs. In addition, Boeing assures us that all of the interlocks and protections in the MCAS engagement logic that you reference were rigorously tested.

As I have stated before, I think a key element in evaluating the safety of any system (aviation related or otherwise) that involves operator interface is clearly stating what the assumptions are with regard to how the operator will respond to the various scenarios to that he or she will encounter. Those assumptions then need to be evaluated and challenged before they can be relied upon as part of the foundation of a safe system. From all that has been written about the motivation for MCAS and the way it operates I believe that the baseline MCAS design assumed the following:
(1) If the flight crew uses their pilot commanded electric trim (thumb switches) they will not stop trimming for more that 5 seconds until the column force has been trimmed to (or close to) zero.
(2) Repeated events of the automatic stabilizer control running the stabilizer away from trim when starting from an otherwise trimmed, relatively steady flight condition will be recognized by the flight crew as errant behavior of the automatic stabilizer control system and that the flight crew response will be to activate the stabilizer cutout switches to disable further automatic stabilizer control commands.
(3) The impact of an errant AOA signal feeding into MCAS would be acceptable at the expected failure rate based on assumptions (1) and (2) above.

Much of what we have discussed for a couple of hundred PPRuNe pages across several threads over the past four plus month has been essentially the merits of these three assumptions. I suggest that a good way to evaluate the MCAS updates that Boeing is about to introduce will be to ask what pilot responses they assume. Furthermore I recommend that we check the revised design specifically against these three assumptions to see which of them are no longer needed to declare MCAS safe. If the new design includes provisions that eliminate dependence on all three of these assumptions I will have much greater peace of mind the next time that anyone (particularly anyone I care deeply for) files into the back of a 737MAX.
FCeng84 is offline  
Old 15th Mar 2019, 22:33
  #1549 (permalink)  
 
Join Date: Jun 2010
Location: Nanaimo, B.C.
Age: 61
Posts: 21
This will IMHO turn out to be a failure of FMECA - https://en.wikipedia.org/wiki/Failur...ality_analysis. The programmers failed to test the case where the AOA sensors disagreed and then project forward to the effect on the aircraft if the pilot either didn't know about or was slow to disable the autotrim. Code should have been written to either limit the horizontal stabilizer travel or to find another way to confirm that the angle of attack was really nearing the stall angle.

OTOH, if it is really necessary to drive the trim to full nose down to prevent stalls then arguably there is a fundamental design flaw in the aircraft. Maybe it just needs bigger elevators period.
dash34 is offline  
Old 15th Mar 2019, 22:40
  #1550 (permalink)  
 
Join Date: Jun 2009
Location: florida
Age: 76
Posts: 1,020
Salute Cows and FC eng !

Most of us here are not of the "Chuck Yeager" variety and "any competent crew" stock that could quickly save the day when a new feature of the airplane appears at the worst possible time.

Sad day for the flying public.

Gums....


gums is offline  
Old 15th Mar 2019, 22:50
  #1551 (permalink)  
fdr
 
Join Date: Jun 2001
Posts: 508
Originally Posted by deltafox44 View Post
Altitude data are not 100% reliable either. It is between 7200 and 7250 ft during takeoff roll then descend to 7075 ft after rotation (is there a hole in the runway ?)

Vertical speed is coherent with altitude variation. In 60 seconds between 05:38:39 and 05:39:39 altitude varies from 7200 to 8000 ft (800 ft/mn) and I computed the mean value of VS which is 822 ft/mn.

Of course, VS is very unstable and we don't know which part is due to the instrument errors and which (if any) to piloting or troubles with the controls...
On almost all air data systems and on all direct reading static systems, there is a difference in the static measurement with attitude, so the aircraft at approximately zero pitch attitude has a different sensed altitude to being at liftoff attitude. On Boeing and Airbus data analysis, you will usually note a slight dip in recorded altitude as the aircraft obtains liftoff attitude. The radar altitude also has a fixed offset that is based on approximately the attitude on an approach, so it will tend to under read on the first part of a takeoff, and over read at the liftoff attitude. Both systems could be corrected to give accurate readings at all times, for the reference point on the static and wheel height for radar altitude, but that has not been done on Boeings from the 737-777 (haven't looked at 78 datasets) and the A320-330-340 (don't know about the 350,380)

It is also possible the runways are not level, like NFFN RWY02.
fdr is offline  
Old 15th Mar 2019, 23:06
  #1552 (permalink)  
 
Join Date: Feb 2009
Location: Seattle
Posts: 379
Originally Posted by deltafox44 View Post
It needs a new aircraft. Or reduce weight and balance limits of the 737 to have enough control authority at any point of the flight enveloppe
MCAS is able to do its job with 2.5 degrees of stabilizer up to Mach 0.4 and less than 1/3rd of that at cruise. That MCAS can insert more stabilizer motion that this design limit is beyond its design requirements. There is not a control power deficiency as there is plenty of elevator to counter the design levels of stabilizer that MCAS needs.
FCeng84 is offline  
Old 15th Mar 2019, 23:13
  #1553 (permalink)  
 
Join Date: Aug 2006
Location: Looking for the signals square at LHR
Posts: 164
Originally Posted by dash34 View Post
OTOH, if it is really necessary to drive the trim to full nose down to prevent stalls then arguably there is a fundamental design flaw in the aircraft. Maybe it just needs bigger elevators period.
Maybe it just needs the CG moved to a position of improved intrinsic balance and reduced polar moments of inertia?
Gipsy Queen is offline  
Old 15th Mar 2019, 23:25
  #1554 (permalink)  
601
 
Join Date: Mar 1999
Location: Brisbane, Qld, Australia
Age: 73
Posts: 977
MCAS appears to be doing its job.
Adding a system like the MCAS to an aircraft it no different than adding a stick pusher to an aircraft has has suspect stall recovery?
I think everyone is missing the elephant in the room.
The MCAS is getting all the attention in the media and on this forum when it appears that the input to the MCAS is the suspect.
The MCAS is acting on what information it is fed. Why are we not looking at the source of that information?
601 is offline  
Old 15th Mar 2019, 23:27
  #1555 (permalink)  
fdr
 
Join Date: Jun 2001
Posts: 508
Originally Posted by FCeng84 View Post
(1) If the flight crew uses their pilot commanded electric trim (thumb switches) they will not stop trimming for more that 5 seconds until the column force has been trimmed to (or close to) zero.
(2) Repeated events of the automatic stabilizer control running the stabilizer away from trim when starting from an otherwise trimmed, relatively steady flight condition will be recognized by the flight crew as errant behavior of the automatic stabilizer control system and that the flight crew response will be to activate the stabilizer cutout switches to disable further automatic stabilizer control commands.
(3) The impact of an errant AOA signal feeding into MCAS would be acceptable at the expected failure rate based on assumptions (1) and (2) above
FC; those seem to be reasonable compliance requirements for the PSCP for a 25.672 system, the FAA SEA TAD will likely be looking at some criteria along those lines. Note that JT610's data provided in the preliminary report by Indonesia's NTSC shows that the prior flight (DPS-JKT) had an apparent DC offset of the L and R AOA from the get go, as did the accident flight. Prior to the earlier flight from DPS, maintenance reportedly replaced the AOA sensor, and that along with the offset looks like the probe was incorrectly installed/calibrated before departure DPS. That would result in an additional area of reinforcement needed for that particular MEDA issue.

DPS-JKT: AOA error prior to takeoff, constant difference between AOA's. Crew recognise a problem exists to pitch force, Capt sees trim being applied automatically against FO's elevator input, and Capt selects cutout on Stab. Capt then reverses cutout, problem re-occurs, and cutout reselected, nose down trim stops. Crew use trim wheel for rest of flight, and operate non RVSM, manual flight. Stall warning is on from nose wheel lift off until landing in JKT. partial writeup in logbook, not whole story.

JKT accident flight: wash-rinse-repeat, except the stab is not selected to cutout. crew fight the trim with pickle switches nose up, and outside of 5 sec window, auto trim giving nose down. Crew lose plot by the looks of it, and stab trim finally runs away in the end. (if the pickle switch [split ARM-CMD series switching] being used was intermittent at the end, then a runaway of the trim would result, until such time as the cutout switches were employed, or the other pickle switches were used). Throughout this situation, the stall warning system, and multiple EICAS messages are adding to competing cognitive tasks.

Sensor validation by voting with the other AOA output and inhibiting function with a detected difference, or comparison of AOA to pitot/static-attitude-inertial/GPS data to determine validity would be needed to avoid reliance on crew detection and correct response. In the end, a failure of the system will still be a possibility, however remote, and crew timely intervention to isolate the system is needed to be reinforced. There is an inherent reticence to alter system states on the aircraft ( a good thing in normal RPT ops) but the training matrix is filled with warm fuzzy time expenditure on LOFT etc vs dealing with vignettes of HQ problems, time critical detection and response events. We continuously squander training resources to appease training programs that fail to meaningfully train. HF stuff can be done in a classroom or in front of a cardboard bomber, HQ stuff needs to be done in a sim, procedural stuff needs at least PTTs to be undertaken effectively. The travelling public are being sold lemons by the nonsensical Part 61/JAR/EU FCL requirements.

On the missing information to the crew, the same problem in a Cessna, Learjet, Citation, or B747 would exhibit in the same manner, that there is an undesirable state, which is readily apparent to the crew, and which needs to be responded to promptly, and to which mechanism to provide intervention exists, being a off switch, cutout, or CB depending on the flavor of the ride. The crew detected the fault in the DPS-JKT leg, and actioned correctly. The actual reason why is not needed at that time, only the detection of an undesirable state, and the intervention necessary to achieve a satisfactory outcome. In both accident flights, it appears that the crew did not achieve a state of affairs where they had detected the condition and from that, from training or knowledge, continued to effective intervention.
fdr is offline  
Old 15th Mar 2019, 23:35
  #1556 (permalink)  
fdr
 
Join Date: Jun 2001
Posts: 508
Originally Posted by svhar View Post
Or fail passive?
ß 25.672 Stability augmentation and automatic and power-operated systems

If the functioning of stability augmentation or other automatic or power-operated systems is necessary to show compliance with the flight characteristics requirements of this part, such systems must comply with ß 25.671 and the following:

(a) A warning which is clearly distinguishable to the pilot under expected flight conditions without requiring his attention must be provided for any failure in the stability augmentation system or in any other automatic or power-operated system which could result in an unsafe condition if the pilot were not aware of the failure. Warning systems must not activate the control systems.

(b) The design of the stability augmentation system or of any other automatic or power-operated system must permit initial counteraction of failures of the type specified in ß 25.671(c) without requiring exceptional pilot skill or strength, by either the deactivation of the system, or a failed portion thereof, or by overriding the failure by movement of the flight controls in the normal sense.

(c) It must be shown that after any single failure of the stability augmentation system or any other automatic or power-operated system -

(1) The airplane is safely controllable when the failure or malfunction occurs at any speed or altitude within the approved operating limitations that is critical for the type of failure being considered;

(2) The controllability and maneuverability requirements of this part are met within a practical operational flight envelope (for example, speed, altitude, normal acceleration, and airplaneconfigurations) which is described in the Airplane Flight Manual; and

(3) The trim, stability, and stall characteristics are not impaired below a level needed to permit continued safe flight and landing.

[Amdt. 25-23, 35 FR 5675 Apr. 8, 1970]
fdr is offline  
Old 15th Mar 2019, 23:38
  #1557 (permalink)  
 
Join Date: Sep 2016
Location: USA
Posts: 417
Originally Posted by 601 View Post
MCAS appears to be doing its job.
Adding a system like the MCAS to an aircraft it no different than adding a stick pusher to an aircraft has has suspect stall recovery?
I think everyone is missing the elephant in the room.
The MCAS is getting all the attention in the media and on this forum when it appears that the input to the MCAS is the suspect.
The MCAS is acting on what information it is fed. Why are we not looking at the source of that information?
I don't think anyone missed the faulty AOA information in the Lion Air crash. That's very straightforward. Trying to eliminate the possibility of a AOA sensor (or any other sensor or single piece of gear in aerospace) going bad would be a fool's errand. (I guess, other than the middle part of a helicopter's rotor hub!)

Therefore, it is very appropriate to put attention on the manner in which that information is used by the system using it, and designing that system to be tolerant to a fault like the one experienced. I.e., redundancy. Such as the 2/3 voting that's been put forth multiple times in these threads, or a 1 vs. 1 disagree inhibiting the system and posting a caution to the crew, etc.

Put another way, MCAS handling this bad information in a graceful way should be considered to be part of "its job."

On my airplane that is 100% hydraulic dependent, I'm glad that there are 6 hydraulic pumps instead of 1 hydraulic pump that's supposed to be really really really reliable.
Vessbot is offline  
Old 15th Mar 2019, 23:49
  #1558 (permalink)  
 
Join Date: Feb 2007
Location: Glasgow
Age: 54
Posts: 24
Originally Posted by 601 View Post
MCAS appears to be doing its job.
Adding a system like the MCAS to an aircraft it no different than adding a stick pusher to an aircraft has has suspect stall recovery?
I'd respectfully disagree. A stick pusher is an emergency recovery system that basically assumes the pilot is effectively "dead" (or at least their brain is). Not dissimilar to a dead man's handle on a train in some limited respects. It's on all/most airliners regardless of their design and is independent of the manoeuvring characteristics of the particular type.

MCAS on the other hand is a substitute for adequate aerodynamic behaviour of the airframe. (It's even in the title - Manoeuvring Characteristics "Augmentation"....). It's something that only needs to be there if the aerodynamic design is sub-optimal. (Which is never has been on the 737 until the "Max" - as far as I'm aware).
indigopete is offline  
Old 16th Mar 2019, 00:07
  #1559 (permalink)  
 
Join Date: Nov 2018
Location: Vancouver
Posts: 49
Originally Posted by Livesinafield View Post
Guys, think people need to ease of the aircraft a little as if its got some huge design defect especially until we have some more facts, bear in mind many operators have been using this type for a fair while southwest nearly 3 years, with no such issues, also bear in mind that both operators here that have managed to "fly it into the ground" have very questionalble safety records as an operator.
It needs a "little" correction. The first delivery of Boeing 737 MAX 8 [B38M] was on May 6, 2017 to Malindo Air [9M-LRC]- a Lion Air subsidiary. They placed the aircraft into commercial service on May 22, 2017. Coincidently, that plane is now being operated in Indonesia by Lion Air, now coded as PK-LQK. Originally, SWA was intended to be the launch customer for B38M.

In other words, Boeing 737 Max 8 has only been flown commercially since May 6, 2017, less than 20 Months ago to be exact.
patplan is offline  
Old 16th Mar 2019, 00:19
  #1560 (permalink)  
 
Join Date: Jan 2008
Location: Herts, UK
Posts: 721
Originally Posted by 601 View Post
MCAS appears to be doing its job.
Adding a system like the MCAS to an aircraft it no different than adding a stick pusher to an aircraft has has suspect stall recovery?
I think everyone is missing the elephant in the room.
The MCAS is getting all the attention in the media and on this forum when it appears that the input to the MCAS is the suspect.
The MCAS is acting on what information it is fed. Why are we not looking at the source of that information?
i disagree... its a horrible workaround. Where do you stop with this sort of "bodge' ?

Whilst fighter aircraft with inherent instability and full FBW may be acceptable, indeed the norm...
a civil airliner without full FBW requiring a crude interruptiive add-on to a pre-existing flight control system is, to experienced aeronautical engineers, just plain asking for trouble via interpretation, secondary feedback errors or unstable malfunction (as likely in this case)..

'Add Lightness and Simplify' as an underlying philosophy has been binned it seems.
HarryMann is offline  

Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.