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Ethiopian airliner down in Africa

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Ethiopian airliner down in Africa

Old 2nd Apr 2019, 11:10
  #2901 (permalink)  
 
Join Date: Jun 2009
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Originally Posted by bsieker View Post

I have a feeling Boeing's idea that the pilot has to save the day will fall short of regulators' approval. They can no longer maintain after two accidents (where in the second one the crew almost certainly knew about the first) that any pilot "without exceptional skill" (which is the regulatory requirement, and, if you think about it, is a lot less than "average") will be able to handle it.


Bernd
I absolutely agree. The aviation authorities have the hardest of evidence possible that “average” pilots are unlikely to cope. Boeing’s dilemma is this then means the MCAS system (at least) has to be considered as a “catastrophic” safety critical system. The MCAS software then has to be “Level A” according to DO-178C.

IMO no amount of software patching can turn a Level C software package into a Level A.

The Level A process is a full life-cycle development process, starting with the top level system requirements down through the coding process and then through the validation and verification processes; a lot of the reviewing and compliance checking has to be carried out “independently”, i.e. not by the supplier. In addition any “safety critical” item of data, such as AoA, has to be at the appropriate level. Typically this means triplex sensors, BUT without Common Mode Failure characteristics. So, another (same technology) vane on the nose would not be suitable.


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Old 2nd Apr 2019, 11:11
  #2902 (permalink)  
 
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Spot on Icarus. You know I am starting to think Boeing and FAA are off the hook with this one. That is assuming something new doesn't turn up. If the thing malfunctions at approach to stall speeds control loads are light and any runaway is a non-event. If it malfunctions at higher speed, accelerating after flaps up for instance, it is a straight forward runaway. In either case, follow the memory items in the QRH. So how did it get away from them? Yes. Well. Pre-employment history. The country regulator. Training and checking systems. After that we may be heading into the murky waters of leadership, culture, etc..

It is going to take a while.

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Old 2nd Apr 2019, 11:23
  #2903 (permalink)  
 
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Originally Posted by 73qanda View Post

I know it sounds unlikely but I have seen one pilot so taken aback by the aircraft misbehaving that he was angrily pushing the A/P button hoping it would engage even though the flight path was not where he wanted it to be. ( why not? he’s virtually never flown an aircraft anyway, why start now when things are turning to custard?)
I’m not suggesting that’s what happened here at all, but I am aware that the difference in pilot standards around the world is significant. I’m of the belief that we need to double up on mandated sim time and make the extra all manual flying. Tickets would have to go up about a buck per passenger. So be it.
I know it will never happen but I think it anyway
I am actually not surprised by that story. In fact, I know of at least one accident where the same thing happened:

At time 00:39:40 the captain was heard saying in Amharic “OK, engage autopilot”. However, the DFDR data does not show any engagement of any auto-pilot throughout the flight. At the time of the call the DFDR shows the control wheel was Aft from the neutral position and the aircraft roll angle reaching 64° left bank

That is an excerpt from the final report of Ethiopian flight 409 in 2010 in which the Captain attempted to engage the autopilot when it was at a 64° left bank.

I agree with you that there should be a much greater emphasis on manual flying. At my company manual raw data flying is allowed at any time and I believe on a clear day, with little traffic, at a familiar airport, it adds greatly to a pilot's confidence and skill set to regularly fly manually (this subject has been discussed endlessly at PPRuNe already though). Practicing in the simulator will work as well of course.

Overall you may be right, that among other reasons the actions of the Lion Air crew could be explained by a lack of manual flying skills, which has to be countered by more training in this regard.
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Old 2nd Apr 2019, 12:25
  #2904 (permalink)  
 
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Originally Posted by VicMel View Post
I absolutely agree. The aviation authorities have the hardest of evidence possible that “average” pilots are unlikely to cope. Boeing’s dilemma is this then means the MCAS system (at least) has to be considered as a “catastrophic” safety critical system. The MCAS software then has to be “Level A” according to DO-178C.

IMO no amount of software patching can turn a Level C software package into a Level A.

The Level A process is a full life-cycle development process, starting with the top level system requirements down through the coding process and then through the validation and verification processes; a lot of the reviewing and compliance checking has to be carried out “independently”, i.e. not by the supplier. In addition any “safety critical” item of data, such as AoA, has to be at the appropriate level. Typically this means triplex sensors, BUT without Common Mode Failure characteristics. So, another (same technology) vane on the nose would not be suitable.
You may be right. However, all automation systems currently have a predicate that in the 'otherwise case' or if things get difficult, the automation can drop out and give the aircraft to the pilot.

As soon as pilots start to say 'we cannot cope in manual flight; we cannot switch off systems that are in error - even though the switches have been there for decades as have the NNC for the failure and we were specifically told of the issues..... THEN money will be spent on automation that does not hand back to a pilot but manages itself even in cases of unknown error. There will then be no pilot shortage as the automation will have taken over entirely and automation doesn't need a pension or a union and doesn't care about hours worked.
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Old 2nd Apr 2019, 12:37
  #2905 (permalink)  
 
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Icarus2001, #2923; ( jafa, #2926)

From your ‘immortal’ view, have you considered the difficulty in identifying a trim malfunction, particularly with a mindset of unreliable airspeed since takeoff. Add to which an immensely annoying - distracting stick shake. See many other posts, and reports from some who have evaluated this in the simulator.

Also, with the strength of wax wings, what magnitude of force can be pulled, both hands, both pilots; and for how long. MCAS training should have involved some visits to the gym.
I don’t have the stick force gradients immediately to ‘hand’, but with trim offset they can be large, and further increase with airspeed increase due to the marginally - uncontrollable nose down trim situation.
Who is going to release the stick - allowing more nose down input, to inhibit the trim, which might not be at the forefront of thought.
A third person on the flight deck; another mod option for Boeing.
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Old 2nd Apr 2019, 12:55
  #2906 (permalink)  
 
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Originally Posted by Icarus2001 View Post

Us mere mortals turn off the stab trim.
...while pulling 60 pounds with the left hand only on the control column and then manually turn the aerodynamically loaded (from high speed) STAB TRIM wheel with the right hand at least a hundred revolutions, within seconds?
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Old 2nd Apr 2019, 12:57
  #2907 (permalink)  
 
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Originally Posted by 737mgm View Post
I am actually not surprised by that story. In fact, I know of at least one accident where the same thing happened:

At time 00:39:40 the captain was heard saying in Amharic “OK, engage autopilot”. However, the DFDR data does not show any engagement of any auto-pilot throughout the flight. At the time of the call the DFDR shows the control wheel was Aft from the neutral position and the aircraft roll angle reaching 64° left bank

That is an excerpt from the final report of Ethiopian flight 409 in 2010 in which the Captain attempted to engage the autopilot when it was at a 64° left bank.

I agree with you that there should be a much greater emphasis on manual flying. At my company manual raw data flying is allowed at any time and I believe on a clear day, with little traffic, at a familiar airport, it adds greatly to a pilot's confidence and skill set to regularly fly manually (this subject has been discussed endlessly at PPRuNe already though). Practicing in the simulator will work as well of course.

Overall you may be right, that among other reasons the actions of the Lion Air crew could be explained by a lack of manual flying skills, which has to be countered by more training in this regard.
For Lion Air, from pp. 4-5 of Preliminary Accident Investigation of PK-LQP Flight JT-610:

1.5.1 Pilot in Command
Age:31 years
Nationality:India
Date of joining company:25 April 2011
License:ATPL
Date of issue:28 July 2016
Aircraft type rating:Boeing 737
Instrument rating validity:31 May 2019

Medical certificate:First Class
Last of medical:5 October 2018
Validity:5 April 2019
Medical limitation:Pilot shall wear corrective lenses
Last line check:19 January 2018
Last proficiency check:7 October 2018

Flying experience
Total hours: 6,028 hours 45 minutes
Total on type: 5,176 hours
Last 90 days: 148 hours 15 minutes
Last 30 days: 81 hours 55 minutes
Last 7 days: 15 hours 45 minutes

This flight:about 11 minutes



1.5.2 Second in Command
Age:41 years
Nationality:Indonesia
Date of joining company:31 October 2011
License:CPL
Date of issue:15 May 1997
Aircraft type rating:Boeing 737
Instrument rating validity:31 August 2019

Medical certificate:First Class
Last of medical:28 September 2019
Validity:28 March 2019
Medical limitation:Pilot shall possess glasses that correct for near vision
Last line check:4 July 2017
Last proficiency check:25 August 2018

Flying experience
Total hours: 5,174 hours 30 minutes
Total on type: 4,286 hours
Last 90 days: 187 hours 50 minutes
Last 30 days: 32 hours 55 minutes
Last 7 days: 20 hours 20 minutes

This flight:About 11 minutes
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Old 2nd Apr 2019, 13:37
  #2908 (permalink)  
 
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Boeing, FAA say more time needed for fix of troubled 737 Max
Boeing and U.S. aviation regulators say the company needs more time to finish changes in a flight-control system suspected of playing a role in two deadly crashes.

The Federal Aviation Administration said Monday it anticipates Boeing’s final software improvements for 737 Max airliners “in the coming weeks.”

Boeing was expected to complete the work last week, but FAA spokesman Greg Martin said the company needs more time to make sure it has identified and addressed all issues.

Chicago-based Boeing offered the same timetable as it works to convince regulators that it can fix software on the planes.

“Safety is our first priority, and we will take a thorough and methodical approach to the development and testing of the update to ensure we take the time to get it right,” said Boeing spokesman Charles Bickers.

Boeing needs approval not just from FAA, but elsewhere, including Europe and China, where safety officials have indicated they will conduct their own reviews.

The planes have been grounded around the world since mid-March...



- https://www.bostonherald.com/2019/04...-coming-weeks/
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Old 2nd Apr 2019, 14:19
  #2909 (permalink)  
 
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Originally Posted by Icarus2001 View Post

Us mere mortals turn off the stab trim.

Icarus, did you miss the lesson on Safety Management or were you too busy polishing your Ray-Bans?

I'll try and keep this simple. $120m aircraft has a single point of failure (AOA vane) that will subsequently cause HAL to become suicidal. The ONLY layer of safety in place now is Biggles and Biggles Minor who are expected to treat that failure with the flick of a switch. At this point any sensible person in our industry will already be sucking their teeth at the risks and lack of inherent safety protections. But this one gets better because Biggles didn't even know about the existence of this failure mode or how to resolve it (flick the switch). Nothing in his QRH/AFM, no training, nyada. For sure, there's something called a trim runaway but he's not sure this is a runaway because it's stopping.......... thump.

Perhaps Biggles could have done better. I'm pretty sure Boeing could have done far better.

Last edited by Cows getting bigger; 2nd Apr 2019 at 14:30.
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Old 2nd Apr 2019, 14:22
  #2910 (permalink)  
 
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There was also the Kenya airways flight 507
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Old 2nd Apr 2019, 14:37
  #2911 (permalink)  
 
Join Date: Feb 2015
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Question

Has anyone knowledge of stab motor overheat scenarios or motor specs on the Max?

If the stab trim is trimmed continuously - down, then up, then down - etc. for minutes on end, is it possible that the motors can eventually overheat and quit?

If so, and the trim is at AND limit that could change a cockpit scenario from manageable to marginal.

This could and did happen for instance on the MD-80

Last edited by bill fly; 2nd Apr 2019 at 14:49. Reason: Additional Info
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Old 2nd Apr 2019, 14:51
  #2912 (permalink)  
 
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Originally Posted by Ian W View Post
all automation systems currently have a predicate that in the 'otherwise case' or if things get difficult, the automation can drop out and give the aircraft to the pilot.

As soon as pilots start to say 'we cannot cope in manual flight; we cannot switch off systems that are in error - even though the switches have been there for decades as have the NNC for the failure and we were specifically told of the issues..... THEN money will be spent on automation that does not hand back to a pilot but manages itself even in cases of unknown error.
I’m not sure if you are misinterpreting my point. I am concerned about any automation system that might not do what it is supposed to, for example, it might refuse to drop out and hand over when it should! Or, as an extreme example, a system that has gone berserk because it is “stuck in a loop” and continually drives a flight surface to its extreme position, or (as happened on one of the “faster, cheaper, better” Mars missions) turns the engine off because it decided the lander leg had touched the surface when in fact it was still way up high – I bet that was Level C software!

I think pilots will always be needed, real AI is still many decades away. And pilots should have the option to turn a system off, BUT the aircraft safety case (with Human Factor considerations) must show in detail how they will then cope. Perhaps, extra, specific to emergency, information needs to appear to assist them, also what warnings/alarms will be muted – who needs an 11 minute stick shaker!!
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Old 2nd Apr 2019, 15:02
  #2913 (permalink)  
 
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A little excerpt from NY Times:
..
Between Two Boeing Crashes, Days of Silence and Mistrust
..

April 2 2019
When a new Boeing 737 Max 8 plunged into the waters off Indonesia last October, a terrifying mystery confronted the aviation industry: What could have caused Lion Air Flight 610, flown by experienced pilots in good weather, to fall out of the sky just 12 minutes after takeoff?

But it took the second, equally terrifying crash of an identical aircraft under similar conditions five months later, in Ethiopia, to reveal the climate of mistrust that has plagued inquiries into what caused the first disaster....

...In November, Haryo Satmiko, the deputy chief of Indonesia's National Transportation Safety Committee, known as KNKT, recounted confusing conversations he was having with Boeing employees who had arrived in Jakarta. Mr. Haryo said he brought up whether inaccurate data readings could have prompted Flight 610's sudden descent.

What Mr. Haryo was describing, though he did not know it at the time, was a malfunction of MCAS, which automatically forces the plane's nose down if data indicates that the jet is angled too sharply upward and might stall.

Nurcahyo Utomo, the head of the safety group's air-accident subcommittee, said he first learned of the term MCAS from news reports....

...Days after Flight 610 crashed, Polana Pramesti, the head of Indonesia's civil aviation authority, waited for visiting Boeing and F.A.A. officials to talk to her. As head of Indonesia's version of the F.A.A., she wanted advice on whether to ground Max 8 jets in Indonesia. But the Americans, who did spend time with transportation safety committee officials, never came to her, she said.

The official in her office in charge of airworthiness and aircraft operation, Avirianto, who like many Indonesians goes by one name, fired off messages to the F.A.A. asking for an explanation of MCAS, which at the time was only vaguely understood, even by aviation experts, because Boeing had failed to put information about it in the plane's manual.

Although he conducted four teleconferences with F.A.A. officials, Mr. Avirianto said he was never given a clear explanation of how MCAS worked or whether it was safe. "They kept saying they were still analyzing, evaluating," he said. "We never received any guidance because there were never any clear answers for us.",,,

...Ms. Polana also sent a letter to Boeing in November, asking for guarantees about the Max. But Boeing was not forthcoming, either, she said. "Of course, we were worried," Ms. Polana said. "We wanted reassurance that the Boeing 737 Max 8s in Indonesia are airworthy."

Boeing and the F.A.A. have come under scrutiny since the Lion Air crash. The United States Department of Transportation is examining the F.A.A.'s certification of the Max model, amid revelations that Boeing employees may have facilitated that process.

Only after the Ethiopian Airlines crash, Ms. Polana said, did the F.A.A. and Boeing become more responsive. On March 22, she had her inaugural teleconference with F.A.A. officials -- the first time Indonesian officials received a precise explanation of how MCAS worked and how Boeing was planning to fix it, they said...

...After the crash, the replaced angle of attack sensor was shipped to Minnesota, home of Rosemount Aerospace, the Boeing subcontractor that made it, Mr. Nurcahyo said. He and other Indonesian investigators went to Minneapolis in December. The sensor, he said, was deemed defective...

...For Lion Air Flight 610, even after the vane was changed, the Max 8 continued to malfunction, producing an array of errant data. Some aviation experts believe the variety of airspeed problems points not to a defective sensor but a more fundamental problem with the processor that collects the data displayed in the cockpit.

"I don't think it's a vane failure. It makes no sense," said Bjorn Fehrm, an aeronautical engineer. "It's more like a computer failure or a component failure, a system failure."

The air data inertial reference unit is the processor that helps collect data from the probes and vanes on the plane. A malfunction in that system could be consistent with data inaccuracies that triggered MCAS, aviation experts said.

Mr. Nurcahyo acknowledged that Indonesian investigators were looking into the possibility of an issue with the air data inertial reference unit...


Source:
- https://www.nytimes.com/2019/04/02/w...-lion-air.html
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Old 2nd Apr 2019, 15:05
  #2914 (permalink)  
 
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Originally Posted by Cows getting bigger View Post
Icarus, did you miss the lesson on Safety Management or were you too busy polishing your Ray-Bans?

I'll try and keep this simple. $120m aircraft has a single point of failure (AOA vane) that will subsequently cause HAL to become suicidal. The ONLY layer of safety in place now is Biggles and Biggles Minor who are expected to treat that failure with the flick of a switch. At this point any sensible person in our industry will already be sucking their teeth at the risks and lack of inherent safety protections. But this one gets better because Biggles didn't even know about the existence of this failure mode or how to resolve it (flick the switch). Nothing in his QRH/AFM, no training, nyada. For sure, there's something called a trim runaway but he's not sure this is a runaway because it's stopping.......... thump.

Perhaps Biggles could have done better. I'm pretty sure Boeing could have done far better.
Well Biggles may not understand what to do - but Ginger has read about the problems and learned that a UAS with all the bells and whistles in the cockpit on takeoff was one of the first indications of a problem that could lead to a crash and that either not fully raising flap or switching off the Stab Trim would prevent the issue. So he turned down Biggles' offer of the weight training courses and went instead for switching off Stab Trim as first action on a UAS or if it was immediately on take off just leave some flap down as this was what was in the ACs/ADs that Biggles was using as a coffee mat.
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Old 2nd Apr 2019, 15:08
  #2915 (permalink)  
 
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Once is airplane error; twice is pilot error.
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Old 2nd Apr 2019, 15:35
  #2916 (permalink)  
 
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Originally Posted by Cows getting bigger View Post
I'll try and keep this simple. $120m aircraft has a single point of failure (AOA vane) that will subsequently cause HAL to become suicidal.
#1 radio altimeter failure can have the same effect.

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Old 2nd Apr 2019, 15:42
  #2917 (permalink)  
 
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Originally Posted by Ian W View Post
Well Biggles may not understand what to do - but Ginger has read about the problems and learned that a UAS with all the bells and whistles in the cockpit on takeoff was one of the first indications of a problem that could lead to a crash and that either not fully raising flap or switching off the Stab Trim would prevent the issue. So he turned down Biggles' offer of the weight training courses and went instead for switching off Stab Trim as first action on a UAS or if it was immediately on take off just leave some flap down as this was what was in the ACs/ADs that Biggles was using as a coffee mat.
When Ginger read (if she did) the updated manual she would have seen, from the emergency AD.
g) Revision of Airplane Flight Manual (AFM): Certificate Limitations Within 3 days after receipt of this AD, revise the Certificate Limitations chapter of the applicable AFM to include the information in figure 1 to paragraph (g) of this AD. Figure 1 to paragraph (g) of this AD – Certificate Limitations Required by AD 2018-23-51

Runaway Stabilizer
In the event of an uncommanded horizontal stabilizer trim movement, combined with any of the following potential effects or indications resulting from an erroneous Angle of Attack (AOA) input, the flight crew must comply with the Runaway Stabilizer procedure in the Operating Procedures chapter of this manual:

• Continuous or intermittent stick shaker on the affected side only.
• Minimum speed bar (red and black) on the affected side only.
• Increasing nose down control forces.
• IAS DISAGREE alert. • ALT DISAGREE alert.
• AOA DISAGREE alert (if the option is installed).
• FEEL DIFF PRESS light.
• Autopilot may disengage. • Inability to engage autopilot
"a UAS with all the bells and whistles in the cockpit on takeoff was one of the first indications of.." does not jump out at the reader.
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Old 2nd Apr 2019, 15:50
  #2918 (permalink)  
 
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Originally Posted by bill fly View Post
Has anyone knowledge of stab motor overheat scenarios or motor specs on the Max?
If the stab trim is trimmed continuously - down, then up, then down - etc. for minutes on end, is it possible that the motors can eventually overheat and quit?
...
To test the control cable and chain adjustment you have among others "Operate the stabilizer system through 5 full cycles."
So I do not see an overheat problem...
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Old 2nd Apr 2019, 15:51
  #2919 (permalink)  
 
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Someone must have seen this coming. A massive increase in the demand for airplanes, a critical shortage of experienced pilots and technology available to completely automate every aspect of flying an airliner. These two accidents are a perfect example of a problem that is only going to get worse. You can’t make better pilots by putting them in airplanes that fly themselves until the day they don’t, then expecting them to fly it out of the fire. The days of good hands and feet flying are never coming back, and this is not news to those who make the software. The sooner we give up and turn it all over to them the better. You can rest assured they are ready for it, even if the public and the pilots are not. That said, if it was me getting kicked out of the loop they would have to pry my cold dead hands off the controls.

Last edited by ferry pilot; 2nd Apr 2019 at 16:58.
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Old 2nd Apr 2019, 19:58
  #2920 (permalink)  
 
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Salute Ferry !!
I love it.

Although I flew very sophisticated aerospace vehicles, I am not quite ready to let HAL run everything at this time. And you are correct about not providing the human crewmembers with realistic training and practice for that one day they may have to actually perform their 'Chuck Yeager" routine. The "children of the magenta line" still live, and there's more of them every year.
CASE IN POINT:
The Lion 610 and previous flight's MCAS problem would not have been handled successfully by HAL, especially if the same sfwe shop did the design and code. At the time of Lion 610, the problem facing the plane was not the basic "runaway trim" that most of us think about. Then there;s the stall warning! HAL would likely have commanded some nose down, huh? Did HAL know altitude above the terrain or note the rising terrain ahead? Did the sfwe folks think that MCAS would activate at takeoff speed, and a few hundred feet and not at the other end of the envelope doing a banked turn at 20,000 feet? Would HAL have reduced power at 700 feet with stall warning shaking and been aware that getting too fast would reduce elevator effectiveness due to "blow up" with AND trim being commanded?

The single point of failure, the AoA doofer, that everyone points out was only the first event in the sequence that eventually resulted in loss of control. Just like almost all crashes. Few are the result of one thing going tango uniform. And that is where HAL has trouble, but the carbon-based lifeforrms can connect things that HAL's father had not thot of, and then do something not "programmed". You know, turn off both electric stab switches before treating the stall warning and not experiencing continuous trim in one direction.

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