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Old 11th March 2019, 13:58   #16
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Default Re: Lion Air Boeing 737 MAX crashes in Jakarta

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Originally Posted by V.Narayan View Post
Warning:Long Post
...
Because the cockpit voice recorder has not yet been recovered from the sea bed we do not know more of what was transpiring in the cockpit.
...
I thought the CVR was recovered 2 months ago, and they were working on removing background noise and analyzing it.
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Old 11th March 2019, 14:10   #17
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Default Re: Lion Air Boeing 737 MAX crashes in Jakarta

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Originally Posted by vharihar View Post
I thought the CVR was recovered 2 months ago, and they were working on removing background noise and analyzing it.
My mistake. You are right.
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Old 11th March 2019, 14:26   #18
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Default Re: Lion Air Boeing 737 MAX crashes in Jakarta

While comparisons to the Lion Air crash of last year is being made, here is the Altitude and Airspeed chart of both crashes, courtesy of FlightRadar24. The Ethiopian flight appears to be smoother in both altitude and airspeed where data is available. Would it be too early to assume both are victims of MCAS malfunction?
Attached Thumbnails
Boeing 737 Max crashes and grounding-compare_lion_vs_eth.jpg  

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Old 11th March 2019, 14:51   #19
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Default Re: Lion Air Boeing 737 MAX crashes in Jakarta

Jet Airways and SpiceJet are the two Indian carriers currently using this aircraft. Indigo is not affected by this. If Jet Airways has already grounded them, SpiceJet is the only Indian company flying them as of now. Hope DGCA asks them to ground this plane till the truth comes out. There is too much at stake to take a risk as things stand now

Last edited by ajmat : 12th March 2019 at 10:31. Reason: typo
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Old 11th March 2019, 15:43   #20
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Default Re: Lion Air Boeing 737 MAX crashes in Jakarta

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Originally Posted by longhorn View Post
Jet Airways and SpiceJet are the two Indian carriers currently using this aircraft. Indigo is not affected by this. If Jet Airways has already grounded them, SpiceJet is the only Indian company flying them as of now. Hope DGCA asks them to ground this plae till the truth comes out. There is too much at stake to take a risk as things stand now
As we speak, only SpiceJet B737 MAXs are in air, 6 of them to be precise. SpiceJet flies B737 MAX 8s.
Boeing 737 Max crashes and grounding-screenshot_20190311153904.jpg

As far as Indigo is concerned, we have engine issues with the 320neos.
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Old 11th March 2019, 15:50   #21
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Default Re: Lion Air Boeing 737 MAX crashes in Jakarta

Facts of individual accidents aside, the part that stands out was Boeing's apparent insistence that the MAX variant was similar enough to the earlier 737 to not necessitate crew retraining. They released the following Operational Manual Bulletin (OMB) on Nov 6 after the Lion Air crash, causing outrage as to why it wasn't included in standard training documentation:

Quote:

This bulletin directs flight crews to existing procedures to address this condition. In the event of erroneous AOA data, the pitch trim system can trim the stabilizer nose down in increments lasting up to 10 seconds. The nose down stabilizer trim movement can be stopped and reversed with the use of the electric stabilizer trim switches but may restart 5 seconds after the electric stabilizer trim switches are released. Repetitive cycles of uncommanded nose down stabilizer continue to occur unless the stabilizer trim system is deactivated through use of both STAB TRIM CUTOUT switches in accordance with the existing procedures in the Runaway Stabilizer NNC. It is possible for the stabilizer to reach the nose down limit unless the system inputs are counteracted completely by pilot trim inputs and both STAB TRIM CUTOUT switches are moved to CUTOUT.

Additionally, pilots are reminded that an erroneous AOA can cause some or all of the following indications and effects:

- 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.
- Inability to engage autopilot.
- Automatic disengagement of autopilot.
- IAS DISAGREE alert.
- ALT DISAGREE alert.
- AOA DISAGREE alert (if the AOA indicator option is installed)
- FEEL DIFF PRESS light.

In the event an uncommanded nose down stabilizer trim is experienced on the 737 - 8 / - 9, in conjunction with one or more of the above indications or effects, do the Runaway Stabilizer NNC ensuring that the STAB TRIM CUTOUT switches are set to CUTOUT and stay in the CUTOUT position for the remainder of the flight.
Source

The full bulletin can be seen here.

US Federal Aviation Administration released an Emergency Airworthiness Directive on Nov 7.

Another excerpt from this article (emphasis mine):

Quote:
In the brutally competitive jetliner business, the announcement in late 2010 that Airbus would introduce a more fuel-efficient version of its best-selling A320 amounted to a frontal assault on its archrival Boeing’s workhorse 737.

Boeing scrambled to counterpunch. Within months, it came up with a plan for an upgrade of its own, the 737 Max, featuring engines that would yield similar fuel savings. And in the years that followed, Boeing pushed not just to design and build the new plane, but to persuade its airline customers and, crucially, the Federal Aviation Administration, that the new model would fly safely and handle enough like the existing model that 737 pilots would not have to undergo costly retraining.

Boeing’s strategy set off a cascading series of engineering, business and regulatory decisions that years later would leave the company facing difficult questions about the crash in October of a Lion Air 737 Max off Indonesia.

Last edited by Chetan_Rao : 11th March 2019 at 16:11. Reason: Additional Sources
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Old 11th March 2019, 16:10   #22
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Default Re: Lion Air Boeing 737 MAX crashes in Jakarta

SpiceJet still flying their Max8s as per current FR24 stats (filtered).

Any grounding is really going to impact them badly!
Attached Thumbnails
Boeing 737 Max crashes and grounding-screenshot_20190311160820.jpg  

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Old 11th March 2019, 16:20   #23
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Default Re: Lion Air Boeing 737 MAX crashes in Jakarta

News is coming in that the black boxes of the doomed Ethiopian jet have been recovered from the crash site.
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Old 11th March 2019, 16:37   #24
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Default Re: Lion Air Boeing 737 MAX crashes in Jakarta

Quote:
Originally Posted by AirbusCapt View Post
In the Airbus the fly by wire system only kicks in when the angle of attack goes over a preset limit called alpha protection angle, this is dependant on the configuration, cg etc. Even then the pilot can perform a full backstick manuver and the aircraft only adds toga power to keep speed 1.23 times above stall speed. "
Your name suggest you are familiar with Airbus, but I am not so sure on what you are claiming here.

When an aircraft is stalling you do not want to pull back on the stick/yoke. You need to push it out and add power. Using the term TOGA in relation to a stall is a bit unusual. I believe TOGA is a Boeing term (not sure what Airbus uses, do they have a different term?) In a Boeing TOGA is a switch that allows the pilot to command calculated Take off thrust during Take off or a Go Around Maneuvre. It is only available when the aircraft is in an specific configuration (take off, landing config). Also, it is not necessarily the same as full thrust. Shoving the throttles into the firewall will get you real full or max thrust, at least on a Boeing these are different things

If you hit TOGA (which is the usual mode of operation) during the take off, the flight management system will command the level of thrust calculated for that particular runway, wind, (de-rate) etc. So it is generally less than full thrust.

It might be different on an Airbus?

Quote:
Originally Posted by AirbusCapt View Post
If you release your side stick the nose will pitch down until speed is just outside alpha protection and the toga power will help increase speed."
Eh, no! A Boeing does not have a side stick but a yoke. On a Boeing if you release the stick the plane will generally level, unless badly trimmed. On an airbus you have a side stick. I am not familiar with airbus flight controls, but I always thought it would keep the plane in whatever orientation you put it. Releasing the side stick, keeps the plane going wherever you point it. You need positive input to make it change its trajectory. (I might be wrong on this, but at least from what I understood that is a fundamental difference between Boeing and Airbus FBW principles.

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Originally Posted by sun_king View Post
While comparisons to the Lion Air crash of last year is being made, here is the Altitude and Airspeed chart of both crashes, courtesy of FlightRadar24. The Ethiopian flight appears to be smoother in both altitude and airspeed where data is available. Would it be too early to assume both are victims of MCAS malfunction?
Purely going by the altitude and Airspeed they are very different. The Ethiopian flight crashed very early on after take off. The problem with the MCAS / AoA sensor can only happen with flaps fully up. This early on in the take off, they are likely to have the flaps out still.

Time will tell.

Lots of people seem to be very upset about Boeing not having provided sufficient information to the pilots. And are referring to the various FAA and Boeing bulletin. Please read those carefully as they are all referring to existing procedures. Not new ones. Remember the first Lion crew that encountered this problem, executed the relevant Boeing check list and disabled the MCAS system with no problem.

Jeroen

Last edited by Jeroen : 11th March 2019 at 16:39.
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Old 11th March 2019, 16:44   #25
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Default Re: Lion Air Boeing 737 MAX crashes in Jakarta

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Originally Posted by itwasntme View Post
SpiceJet still flying their Max8s as per current FR24 stats (filtered).

Any grounding is really going to impact them badly!
I believe when planes are grounded due to manufacturing defect, manufacturer is liable to pay compensation to the operating airlines.

Examples:

IndiGo gets compensation from Pratt & Whitney for faulty engines

Air India to be compensated by Boeing for Dreamliner battery trouble
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Old 11th March 2019, 16:47   #26
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Default Re: Lion Air Boeing 737 MAX crashes in Jakarta

@jeroen..sir kindly read up on Airbus manuals before commenting. Let's take this offline, neither the forum nor the requirement of holding a detailed discussion. I am not commenting on you/r posts any further. Peace
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Old 11th March 2019, 17:21   #27
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Default Re: Lion Air Boeing 737 MAX crashes in Jakarta

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Originally Posted by Jeroen View Post
.....referring to the various FAA and Boeing bulletin. Please read those carefully as they are all referring to existing procedures. Not new ones....
Question: Are you indicating to existing stall correction procedures for 737 aircraft, or instructions specific to the MCAS on the 737 MAX (quoted text below), because there are multiple claims by pilots they hadn't received any formal training or documentation on that system until the Nov 6 bulletin.

Quote:
....do the Runaway Stabilizer NNC ensuring that the STAB TRIM CUTOUT switches are set to CUTOUT and stay in the CUTOUT position for the remainder of the flight.
Quote:
Allied Pilots Association spokesperson and 737 captain Dennis Tajer told Reuters that his union members were only informed of a new anti-stall system that had been installed by Boeing on 737 MAX aircraft after the Lion Air crash. “It is information that we were not privy to in training or in any other manuals or materials,” Tajer told Reuters.

Jon Weaks, president of the Southwest Airlines Pilots Association, told Bloomberg, “We don’t like that we weren’t notified.”
Now I'm no pilot, but from the bulletin text, I get the impression the MCAS system keeps making corrections and overriding pilot maneuvers unless turned off completely, which is something best documented and not left to pilot discretion to figure out in an actual emergency (which seems to have happened in the case you referred to in your post).

Obviously looking forward to more clarity from the relevant authorities.

Quote:
The Operational Manual Bulletin sent out by Boeing on November 6 provides procedures for dealing with that sort of situation, but no prior training provided by Boeing ever mentioned the automated system.
False claim?

Last edited by Chetan_Rao : 11th March 2019 at 17:33.
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Old 11th March 2019, 17:37   #28
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Default Re: Lion Air Boeing 737 MAX crashes in Jakarta

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Originally Posted by Jeroen View Post
Purely going by the altitude and Airspeed they are very different. The Ethiopian flight crashed very early on after take off. The problem with the MCAS / AoA sensor can only happen with flaps fully up. This early on in the take off, they are likely to have the flaps out still.

Time will tell.
Jeroen
Have to disagree here, the graph shows an almost linear acceleration up to about 400 knots, while I am not familiar with the B737 MAX' flight controls, I can boldly say that no aircraft is going to climb past 300 knots with flaps extended. I work for a company that makes FMS and on the platforms I work on, the FMS commanded speeds are way lower (in the range of V2+ 15 to 25) when flaps are deployed. The data suggests a clean up well before 250 knots.

MCAS can kick in during a turn too, but the available data shows an almost straight line after takeoff.
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Old 11th March 2019, 17:53   #29
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Default Re: Lion Air Boeing 737 MAX crashes in Jakarta

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Originally Posted by AirbusCapt View Post
@jeroen..sir kindly read up on Airbus manuals before commenting. Let's take this offline, neither the forum nor the requirement of holding a detailed discussion. I am not commenting on you/r posts any further. Peace
Your choice, As I said before I do not have much information or insights into Airbus, but I have some insights into Boeing systems.

But I am going for a couple of hours Airbus Simulator with an Airbus captain mate of mine later this year. Looking forward to that.

Quote:
Originally Posted by Chetan_Rao View Post
Question: Are you indicating to existing stall correction procedures for 737 aircraft, or instructions specific to the MCAS on the 737 MAX (quoted text below), because there are multiple claims by pilots they hadn't received any formal training or documentation on that system until the Nov 6 bulletin.
We need to distinguish between how systems operate and what pilots need to know. From everything I have seen/read it appears as pilots were not aware of the MCAS on the 737 MAX.

However, there were procedures that would ensure pilots could disable the system. MCAS is as far as I can tell part of the auto-trim system. You switch off the auto-trim, that also disables the MCAS. A pilot would never know, but that is how it is.

The various protocols/procedures (symptoms if you like) indicate to pilots under which circumstances they should (consider) disable the auto-trim system. And how to disable it. (It was not as straight forward as just throwing a switch). There are also numerous claims floating around pilot forums, that no matter what, based on what they were experiencing and the procedures they had, they should have disabled the auto-trim under these circumstances and that would have been the end of it.

This is what the first Lion crew, apparently, did. For some reason the second Lion crew did not manage to reach the same conclusion. They were dealing with a multitude of issues/alarms etc. I really can not comment as to whether they should have. We really need to hear/read what was happening in the cockpit. Fair to say, it was extremely stressful with a lot of ambiguous information popping up.

Pilots never know all the systems on an aircraft. It is neither feasible nor required. Part of an aircraft design is to think through what pilots need to know. It tends to focus around a lot of functional knowledge, rather then deep insights into how all the individual systems and components work.

So the question that does remain, if pilots should have known about this system, and if so, to what extend? Where are the current procedures/checklist falling short?

As part of the design process there is a very elaborate risk assessment done on all system and components as to what needs to be included into the operational guide lines, training, certification, training of pilots. Part of what Boeing, is most likely, already doing is to check whether this process was not followed correctly, or if MCAS should have been mentioned in a more explicit and or elaborate way.

This is just me glancing over a huge wealth of information on the Internet and how I perceive it / cobble my own understanding together. It could well be different of course.

Jeroen
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Old 11th March 2019, 19:05   #30
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Default Re: Lion Air Boeing 737 MAX crashes in Jakarta

Ethiopian Airlines: Flight recorders recovered from crash site.

Quote:
Investigators have found the flight data recorders from an Ethiopian Airlines plane that crashed on Sunday.

The devices recovered at the crash site were the Boeing 737 Max 8's cockpit voice recorder and digital flight data recorder.
Source

Cheers
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