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Ethiopian airliner down in Africa

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Ethiopian airliner down in Africa

Old 13th Mar 2019, 14:47
  #1041 (permalink)  
 
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Originally Posted by Ian W
From Positive Rate


Interesting that there are other trim problems than MCAS for the Max8. Neither of the ASRS reports would be due to MCAS as they occurred with autopilot engaged and MCAS is disabled when autopilot is engaged.
Yes there are quite a few trim reports including numerous when electric trim is inoperable. Off the track a wee bit here, but, I found this report by a FO clearly confused by automated trim- except it's on a 737-700 in November 2017?

At the gate, I adjusted the trim setting for a flaps one takeoff. It was a normal taxi to the runway. As FO, I was the Pilot Flying. As we climbed through 400 feet AGL, I noticed the trim switch on my control wheel was not operating. I called for Heading Select as per the departure procedure and at 1000 feet AGL called for "Set Speed" and "Climb Thrust". (Still no trim response from my control wheel trim switch.) As we climbed out the "speed trim" seemed to be picking up the slack and providing adequate trimming. As I called for flaps up I expected the speed trim to stop operating and again tried to trim through use of the control wheel trim switch; still nothing. I asked the Captain to try trimming forward on his trim switch. His was also inoperative. I requested VNAV at 3000 feet AGL.

As power and speed was increased there became a pronounced nose high flight control pressure. The trim wheel continued to intermittently rotate. My thought was that the "Speed Trim" was still somehow still active and was interfering with normal trimming. I waited to see if speed trim would catch up. It did not and excessive forward control wheel pressure continued to be required to maintain 250 knots in the climb. We were then cleared to 13,000 feet. We leveled off and began to troubleshoot the problem. I asked the Captain to take the controls while I re-adjusted my seat for better leverage on the control wheel. At that point the Captain and I agreed that he would fly the aircraft and I began working the check list, radios, and we would return to the departure airport.

Although we still had reasonable control over the aircraft, I explained the problem to Approach Control and that we would need to return to the airport. I requested a straight in ILS Approach with vectors since the weather at the departure airport reported at 10 miles and 1000 feet and slight right cross-winds. I selected the ILS Approach to the departure airport as listed in the approach section of the FMS. The Captain was busy flying (without autopilot due to the trim issue) as I was setting up the radios, minimums, requesting landing information, talking to Flight Attendants and making the PA announcement that we would be returning to the departure airport; while still trying to do that "Pilot Monitoring" thing. I thought I was still in the "Green". Apparently, I wasn't.
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Old 13th Mar 2019, 14:47
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Originally Posted by SLFinAZ
Amazing reading.

Basically what it confirms is that for competent well rested crews the potential MCAS issues are a minor speed bump.
1. Should not be MCAS, as they had AP engaged!

2. They had more altitude than the crashed crews

On a side note, the fact that the FAA kept the plane flying is (borderline?) manslaughter.
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Old 13th Mar 2019, 14:50
  #1043 (permalink)  
 
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Originally Posted by Roger_Murdock
Originally Posted by bauble
Does anyone have any information on instances of irregular MCAS activation that have been successfully handled?
We only have two confirmed instances of MCAS activation ever. JT 610 (not handled) and the flight immediately preceding it (handled).

MCAS is only supposed to operate well outside the normal flight envelope.
I think there was potentially another instance. Perhaps, this one is also related to one [maybe both??] of the two instances where "extreme trimming" while AP engaged being reported at Aviation Safety Reporting System.

However, at the time, Southwest was concerned about the source of the automatic throttle problem during autopilot that their pilots had reported. During two separate diagnostics, they decided to replace the AOA vanes even though neither seemed to have contributed to the problem. In other word, that automatic throttle problem experienced by Southwest is still unsolved even now. Those infamous vanes escaped unscathed after a close scrutiny.

I wonder if the left AOA vane removed from Lion Air's PK-LQP in DPS, two flights prior to the fateful one, which was thought to be the source of erroneous indications would come clean as well. That will be interesting because the problem would then be in a much deeper area in the flight control sytem.


Here's the little summary of that news...

Southwest Replaced Flight-Control Sensors of the Kind Implicated in Lion Air Crash

...The accidents in the South-West caused no emergencies and no one was hurt. They pushed what appear to be routine reports from mechanics who experience sensor problems. One was written on October 9 in Baltimore and the other on October 21 in Houston, the documents show, and indicate that both sensors have been repaired...Boeing and FAA did not have immediate comments on the Southwest maintenance records. The Southwest spokeswoman said the carrier replaced the two sensors in October on the same aircraft and determined that they were not the source of the automatic throttle problem. Two other Southwest 737 MAX 8s have replaced an attack angle sensor as part of routine maintenance due to external damage, such as a bird's shot in flight...
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Old 13th Mar 2019, 14:55
  #1044 (permalink)  
 
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Originally Posted by DaveReidUK
The NTSB, as a party to the investigation, had (not unreasonably) been pressing for the recorders to go to the USA, but despite their fierce independence from the FAA, it would seem that the latter's decision to allow continued operation of the Max in the USA (not to mention Trump's comments) may have had a bearing on the decision.
It is not unreasonable to believe that given a choice, the Ethiopian authorities would rather an outcome that showed a fault with a foreign made aircraft than a problem with their own carrierís training or maintenance.

Given that MAXs are being grounded like dominoes around the world, and the FAA is rightly or wrongly, being perceived as putting US commercial interests before safety, no one should be surprised at the decision to send the boxes to BEA or the NTSB.
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Old 13th Mar 2019, 14:58
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Originally Posted by Whispering T-Jet
Whilst that crew proved they could actually fly, they then made an appalling "airmanship" decision to fly hundreds of miles over high terrain to Jakarta with an effectively jammed stab and no autopilot instead of returning to the 10,000' RWY in Bali 20-30 nm away. Furthermore the incident was not fully written up in the tech log. Commercial pressure maybe....

At this point MCAS has NOT been implicated although something - voice reports from other aircraft indicate unreliable airspeed - happened. It seems probable they didn't even make flap retraction height (thereby discounting MCAS unless they retracted flaps below flap ret. ht.).

While we are waiting for some actual CVR/DFDR facts maybe you would like to read about Ethiopian's last 737 prang here: https://www.bea.aero/docspa/2010/et-...b100125.en.pdf which in one sentence can be summarised as: pilots can't fly.

I'll get on a Max tomorrow if flown by say, Southwest.
They did not have a jammed stab. The manual trim system works just fine and is easy to use. Itís a non event.
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Old 13th Mar 2019, 14:58
  #1046 (permalink)  
 
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Originally Posted by SLFinAZ
Amazing reading.

Basically what it confirms is that for competent well rested crews the potential MCAS issues are a minor speed bump. Doesn't mean that it isn't a very real issue but the bottom line specific to Lion Air is simple and compelling....crew error. As for the current tragedy we really don't know enough but it doesn't have any of the trim related oscillation seen in Flight 610...

At some point the various regulatory agencies will need to figure it out.
Since risk assessment for safety purposes in any environment needs to allow for circumstances and variables - ie there is no such thing as 'safe or 'unsafe' - it's not an absolute - if you are saying that flight crew can only deal with the MCAS system if a certain (highest) level of competence, alertness, awareness and training, then that is very worrying. It's akin to saying that Top Gun fighter pilots are capable of handling the MCAS scenario we've been discussing, so only Top Gun fighter pilots should be allowed to fly the Max 8. I know I'm stretching the point, but surely flight crew within the bell curve must be able to respond effectively on a model of aircraft with thousands of orders? If not, I have to ask whether the MCAS system itself and the circumstances in which it is deployed has been correctly risk assessed.
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Old 13th Mar 2019, 15:03
  #1047 (permalink)  
 
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Originally Posted by DaveReidUK
Nothing so complicated.

The aircraft simply transmits either a Ground Position ADS-B message, which for obvious reasons doesn't need to contain an altitude, or an Airborne Position, which does.
So how does a 737-MAX 8 or a 738NG or any other late model aircraft know when to transmit via ADS-B that it has become airborne? And if it does, and gets it wrong at 93kts groundspeed, against what are all its subsequent pressure altitude reports calibrated?
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Old 13th Mar 2019, 15:18
  #1048 (permalink)  
 
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Originally Posted by CONSO
post 1041 ...




Hmmm . . . . SUPPOSED to be disabled... but if not ?????
Well we know that MCAS is enabled when flaps up in manual flight - and the pilots flew flaps up in manual flight to 'avoid the problem'.
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Old 13th Mar 2019, 15:20
  #1049 (permalink)  
 
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Originally Posted by davionics
Witness accounts need to be impeccably interpreted. Surprised to see witness accounts publicity released so fast.

I believe they are worthless. A colleague who works on eye witness interpretation comments:
  • These witnesses appear to have discussed with each other, so contaminated each-other’s recall, so they are not independent witnesses, rather one compound account
  • The account will have passed through a non-specialist translator with their own pre-conceptions and interpretation.
  • With all due respect to these farmers, they likely have no experience of any technology other than perhaps a mobile phone and a bus
  • Even the best witnesses mix-up the sequence of events in fast and traumatic events, tales of fire/smoke in plane crashes are literally text book examples
Also, in case anyone is unaware, there are dozens of fake videos circulating in Kenya and presumably elsewhere. I was shown one yesterday purporting to be from inside ET302 as it went down, I was shown this by an intelligent person who truly believed that it had been sent to a friend by her son on the flight. Sick, but all this nonsense adds to the cloud of confusion and hysteria.
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Old 13th Mar 2019, 15:23
  #1050 (permalink)  
 
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Originally Posted by RTM Boy
Since risk assessment for safety purposes in any environment needs to allow for circumstances and variables - ie there is no such thing as 'safe or 'unsafe' - it's not an absolute - if you are saying that flight crew can only deal with the MCAS system if a certain (highest) level of competence, alertness, awareness and training, then that is very worrying. It's akin to saying that Top Gun fighter pilots are capable of handling the MCAS scenario we've been discussing, so only Top Gun fighter pilots should be allowed to fly the Max 8. I know I'm stretching the point, but surely flight crew within the bell curve must be able to respond effectively on a model of aircraft with thousands of orders? If not, I have to ask whether the MCAS system itself and the circumstances in which it is deployed has been correctly risk assessed.

Agree in total

However, one question is the training of the pilots to a standard of knowledge applicable to the product they are flying. The pilots may be experienced and of sufficient skills to fly, but have they been given an adequate knowledge for this aircraft ?

These questions are for us to ask and answer, without relying on politicians or bureaucrats
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Old 13th Mar 2019, 15:25
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FWIW- as a SLF who has been in the industry- Boeing for decades a few items tweak me

1) To allow a SINGLE sensor with NO comparison/matching/voting to take control on a ' intermittent ' or ' sometimes ' basis is just plain wrong wrong wrong
2) Without splittinh hairs regarding just when most pilots engage autopilot, or put flaps up, both seem to commonly happen at ** relatively ** low altitudes. And most birds/fowl also fly at relatively low altitudes. Yes some have been found at 15,000 to 20,000 feet- but I'm focusing on majority issues. Birds strike aircraft often in the 'nose' area, which means a slightly higher probability of damage to AOA sensor - AT LOW ALTITUDE which when coupled with a single path control again IMHO is a bad idea.
3) Inertial systems can now define an approximate flight path, ground speed, altitude and work as a simple ' crude' backup or possibly a non external sensor compare ( believe 777/787 does incorporate similar INS compare/standby function ??? )
4) Both the Boeing/FAA games re certification/analysis and change in the DER process need be scrubbed as it seems to have alllowed/overlooked the basic ' redundancy'/"safety' issue for 'critical " sensors/controls. ( and 787batteries ! )

Just my .000001

Last edited by CONSO; 13th Mar 2019 at 15:40. Reason: added 787 batteries ..
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Old 13th Mar 2019, 15:31
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Originally Posted by slip and turn
So how does a 737-MAX 8 or a 738NG or any other late model aircraft know when to transmit via ADS-B that it has become airborne?
The same way as a ton of other stuff on an aircraft (ACARS, for example) knows - weight on/off wheels.

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Old 13th Mar 2019, 15:36
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Originally Posted by slip and turn
So how does a 737-MAX 8 or a 738NG or any other late model aircraft know when to transmit via ADS-B that it has become airborne? And if it does, and gets it wrong at 93kts groundspeed, against what are all its subsequent pressure altitude reports calibrated?
To meet the requirements of DO-260B 2.2.3.2.1.2 c 1 the aircraft will use the normal indication for the OFF message; weight off wheels, squat switch, rad-alt and set the airborne indicator in the ADS-B Extended Squitter message.
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Old 13th Mar 2019, 15:37
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Originally Posted by slip and turn
So how does a 737-MAX 8 or a 738NG or any other late model aircraft know when to transmit via ADS-B that it has become airborne? And if it does, and gets it wrong at 93kts groundspeed, against what are all its subsequent pressure altitude reports calibrated?
Usually a WOW (weight-on-wheels) switch, but since I fly a type made by another manufacturer, I'll defer to pilots of the type to confirm.

A WOW switch is usually just a microswitch in the MLG which indicates whether an aircraft is airborne according to the amount of oleo extension.,
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Old 13th Mar 2019, 15:41
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Canadian Transport Minister holding live press conference to address 737 MAX - Marc Garneau @ 15:30Z
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Old 13th Mar 2019, 15:49
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As an IT ex-developer we always understood that we needed a business or industry expert to look at/understand and accept our design, even if not understanding every line of geeky code.

Would any pilot anywhere accept a design that might, even in normal , not failure-mode, trim Down for 10 seconds?

How was this software ever approved?

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Old 13th Mar 2019, 15:52
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just joined the EU and others - no passenger flights over canada for max - quoted satellite data and probable similarfity to lion air

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Old 13th Mar 2019, 15:53
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BREAKING:
Canada's press conference is happening now. New information has come from validated tracking data, shows similarities to the Lion Air crash. While it's too early to make any conclusions, based on this data, they are issuing a safety notice and banning the planes from its airspace.

Source: Just dialed into the media press conference
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Old 13th Mar 2019, 15:54
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Originally Posted by CONSO
just joined the EU and others - no passenger flights over canada for max - quoted satellite data and probable similarfity to lion air
Any idea what this quoted "new unconfirmed satellite tracking data" they received as of this morning is?
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Old 13th Mar 2019, 16:01
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Originally Posted by positiverate20
Report quote:
Aircraft pitched to 260 KTS with trim inputs, then re-pitched to 240 KTS. The trim system would activate for 1-2 seconds and then immediately reverse itself, trimming in opposite direction. I directed FO to ask for intermediate stop on climb, where we then stopped at FL230. Advised ATC we were experiencing a trim system problem.
That is normal for a 737. I have lost count of the number of times that has happend, both on Classics and NGs. The sudden pitch down on engaging the autopilot is pretty standard too - it is nornally caused by a baro-error in the autopilot computer.

The really disappointing thing, is it looks like the Max is equipped with the same old autopilot that was fitted to the Classic, with all its limitations and foibles. So I presume the Max still cannot do Cat IIIb landings. What I always wonder, is where Boeing gets these old 1980s microprocessors from, to run these autopilot computers. Do they have a source in China that still makes the 286 processor?

Silver
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