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Ethiopian airliner down in Africa

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Ethiopian airliner down in Africa

Old 13th Mar 2019, 15:23
  #1061 (permalink)  
 
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Originally Posted by RTM Boy View Post
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
  #1062 (permalink)  
 
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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
  #1063 (permalink)  
 
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Originally Posted by slip and turn View Post
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
  #1064 (permalink)  
 
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Originally Posted by slip and turn View Post
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
  #1065 (permalink)  
 
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Originally Posted by slip and turn View Post
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
  #1066 (permalink)  
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Old 13th Mar 2019, 15:49
  #1067 (permalink)  
 
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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
  #1068 (permalink)  
 
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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
  #1069 (permalink)  
 
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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
  #1070 (permalink)  
 
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Originally Posted by CONSO View Post
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
  #1071 (permalink)  
 
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Originally Posted by positiverate20 View Post
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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Old 13th Mar 2019, 16:04
  #1072 (permalink)  
 
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Originally Posted by CONSO View Post
just joined the EU and others - no passenger flights over canada for max - quoted satellite data and probable similarfity to lion air
what satellite data?
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Old 13th Mar 2019, 16:08
  #1073 (permalink)  
 
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The up-link home? sends `service telemetry and maybe in flight sales slips?
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Old 13th Mar 2019, 16:10
  #1074 (permalink)  
 
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Originally Posted by silverstrata View Post


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
Do you have an agenda against Boeing?
I have flown the NG since it was new, and I have NEVER had any trim issues like this. Or trim issues at all.
I have a thing or two to say about the STS system, but it does what it is supposed to do.
I just donít agree with what it is doing.
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Old 13th Mar 2019, 16:16
  #1075 (permalink)  
 
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Originally Posted by lomapaseo View Post
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
According to an interview with the CEO, the pilots had read the Boeing directive and had received extra training after the Lion Air crash and subsequent directive.
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Old 13th Mar 2019, 16:18
  #1076 (permalink)  
 
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Originally Posted by Ian W View Post
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.
Well in this case the combination of those appears to have set the airborne indicator in just 20% of the paved runway available at a groundspeed of 93kts - plus maybe 10 kts wind. Not a factor in the safety of the aircraft, but it appears to have resulted in us being able to analyse reported altitude at several data points during the remaining take off roll, and whilst they are all located slap bang along the centreline and the speeds look reasonable, one or two of the altitudes look a bit odd and make me wonder like Tucoma Sailor about where rotation was first attempted.

Last edited by slip and turn; 13th Mar 2019 at 16:57. Reason: take off not tale off!
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Old 13th Mar 2019, 16:19
  #1077 (permalink)  
 
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Originally Posted by slip and turn View Post
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?
I have had some dealings with transponders, and the rule of thumb is that.

Mode-C gives 1013 baro altitude.
Mode-S gives 1013 baro altitude.
ADS-B also gives 1013 baro altitude, to be compatible with the above.
Flarm and PAW give GPS altitude.

As far as I know, FR24 is simply picking up ADS-B 1013 pressure altitudes, so you will need to know the QNH of the day, and the altitude of the airport, to calculate the true height of the aircraft. Transponders were designed for seperation on airways, not for separation with terrain, so the older units all used 1013 baro, and ADS-B follows suit.

(If ADS-B used GPS Alt, then ATC would not be comparing like with like. However, newer systems like Flarm and PAW can happily use GPS Alt, because they all use GPS, so they are comparing like with like.)

Silver
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Old 13th Mar 2019, 16:21
  #1078 (permalink)  
 
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According to this Reddit comment https://www.reddit.com/r/flying/comm...hread/eidycdx/ due to a programming error the MCAS can be triggered by transient bursts of high AoA e.g. during climb. I have no way of knowing if this is true or not, but if it is, and if Boeing knew about this as early as August 2018, it's pretty damning.
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Old 13th Mar 2019, 16:22
  #1079 (permalink)  
 
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Originally Posted by ManaAdaSystem View Post
I have flown the NG since it was new, and I have NEVER had any trim issues like this. Or trim issues at all.
You obviously do not fly for bottom-rung airlines, with airframes destined for the desert in a couple of years. Count yourself lucky.

My bitch with Boeing is that even the Classic was a revision too far. Can you imagine using 1950s B-707 systems in the 21st century..? And then the NG was a double stretch too far. But then the Max? So these 1950s B-707 systems will still be running a century after they were designed? They are having a laugh, surely.

Silver

Last edited by silverstrata; 13th Mar 2019 at 16:44.
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Old 13th Mar 2019, 16:28
  #1080 (permalink)  
 
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Originally Posted by silverstrata View Post

As far as I know, FR24 is simply picking up ADS-B 1013 pressure altitudes, so you will need to know the QNH of the day, and the altitude of the airport, to calculate the true height of the aircraft. Transponders were designed for seperation on airways, not for separation with terrain, so the older units all used 1013 baro, and ADS-B follows suit.
No, as stated up-thread ADS-B emits BOTH barometric and GNSS ellipsoid altitude when both have onboard sources. Which for the 737-8 is true.

FR24 don't export one or the other in their downloadable CSV data, I haven't determined which, but both are visible in the web UI during interactive usage.
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