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To be blunt, hitting the ground at 300kts is what caused 346 deaths. There hasn't even been a preliminary report on the Ethiopian crash so we can't say with any

To be blunt, hitting the ground at 300kts is what caused 346 deaths. There hasn't even been a preliminary report on the Ethiopian crash so we can't say with any certainty that the failure was the same. It is quite likely that the pilots were overwhelmed with warnings (e.g. stick shaker activation) and conflicting data. It's not clear that presenting yet more conflicting data would have averted the disasters. Limiting the authority of the MCAS system is likely to be the real fix.

Someone1234 8y ago
> There hasn't even been a preliminary report on the Ethiopian crash so we can't say with any certainty that the failure was the same. But there has been on Lion Air, compelling ADS-B data for Ethiopian, and every regulatory agency in the world agrees they're similar enough to warrant grounding the entire fleet. > Limiting the authority of the MCAS system is likely to be the real fix. They're already changing it to take data from both sensors, and there's been talk of requiring a third for voting logic. So the "real fix" is treating a safety critical sensor as a safety critical sensor.
- VBprogrammer 8y ago
  > They're already changing it to take data from both sensors, and there's been talk of requiring a third for voting logic. So the "real fix" is treating a safety critical sensor as a safety critical sensor. Not according to the press release. https://boeing.mediaroom.com/news-releases-statements?item=130402 https://boeing.mediaroom.com/news-releases-statements?item=1... Interconnects like that are quite unusual. For example the autopilot is typically driven from either the same data source as pilot or the co-pilots system. There are some exceptions, for example in full auto-land mode both systems are engaged. But that really is an exception, only a fraction of the worlds runways have CATIII certification and they require special ground operations to support them. There are procedures designed to ensure the systems agree on certain critical data, for example the 'pilot not flying' will usually call out 80 knots and cross check that the speed agrees between both sides.
  - Someone1234 8y ago
    > Not according to the press release. Questionable conclusion, the press release doesn't go into details either way. To quote this NYT article: > Boeing is updating the software to require data from both sensors for the system to kick in, according to pilots at several major airlines and two lawmakers briefed on the matter. https://www.nytimes.com/2019/03/15/business/boeing-ethiopian-crash.html https://www.nytimes.com/2019/03/15/business/boeing-ethiopian... > Interconnects like that are quite unusual. Not in aviation, for example the Airbus A330 has triple redundant Pitot tubes, the B737CL (Boeing 737 "classic") has four, the B737NG has three (737 Next Gen), etc. So this "quite unusual" system appears on the very airplane we're discussing for the Pitot-Static System, a safety critical sensor.
    - VBprogrammer 8y ago
      On the 737NG 3 pitot tubes are pilot, co-pilot and the elevator control feel input. They aren't averaged, voted upon or compared in any way. I don't know much about the Airbus pitot system, except one ended up at the bottom of the Atlantic due, in part, to a frozen pitot tube.
      - Someone1234 8y ago
        > On the 737NG 3 pitot tubes are pilot, co-pilot and the elevator control feel input. They aren't averaged, voted upon or compared in any way. You're mistaken. To quote Boeing themselves: > The most modern systems today use an air data inertial reference unit (ADIRU), which incorporates the best information from three pitot and static sources and provides a single set of data to both pilots. An ADIRU receives information from air data modules, which are located close to the pressure sources. This is used on, at least the Boeing 757, 737 and Airbus A319, A320, A321, A330, & A340.
        VBprogrammer 8y ago
        I believe your source is unreliable. For example read this report: https://assets.publishing.service.gov.uk/media/578df0f5e5274a0da3000176/Boeing_737-86N_EI-FHG_08-16.pdf https://assets.publishing.service.gov.uk/media/578df0f5e5274...
mannykannot 8y ago
Knowing that it was impact that killed people is not a very useful conclusion. You might as well say that AF 447 ended up at the bottom of the Atlantic because it flew into the water.
- VBprogrammer 8y ago
  Yes, sorry, I was reacting to the appeal to 'think of the children'.
crististm 8y ago
Does this suggest there are two different defects on a new plane model?

Someone1234 8y ago

> There hasn't even been a preliminary report on the Ethiopian crash so we can't say with any certainty that the failure was the same. But there has been on Lion Air, compelling ADS-B data for Ethiopian, and every regulatory agency in the world agrees they're similar enough to warrant grounding the entire fleet. > Limiting the authority of the MCAS system is likely to be the real fix. They're already changing it to take data from both sensors, and there's been talk of requiring a third for voting logic. So the "real fix" is treating a safety critical sensor as a safety critical sensor.

VBprogrammer 8y ago
> They're already changing it to take data from both sensors, and there's been talk of requiring a third for voting logic. So the "real fix" is treating a safety critical sensor as a safety critical sensor. Not according to the press release. https://boeing.mediaroom.com/news-releases-statements?item=130402 https://boeing.mediaroom.com/news-releases-statements?item=1... Interconnects like that are quite unusual. For example the autopilot is typically driven from either the same data source as pilot or the co-pilots system. There are some exceptions, for example in full auto-land mode both systems are engaged. But that really is an exception, only a fraction of the worlds runways have CATIII certification and they require special ground operations to support them. There are procedures designed to ensure the systems agree on certain critical data, for example the 'pilot not flying' will usually call out 80 knots and cross check that the speed agrees between both sides.
- Someone1234 8y ago
  > Not according to the press release. Questionable conclusion, the press release doesn't go into details either way. To quote this NYT article: > Boeing is updating the software to require data from both sensors for the system to kick in, according to pilots at several major airlines and two lawmakers briefed on the matter. https://www.nytimes.com/2019/03/15/business/boeing-ethiopian-crash.html https://www.nytimes.com/2019/03/15/business/boeing-ethiopian... > Interconnects like that are quite unusual. Not in aviation, for example the Airbus A330 has triple redundant Pitot tubes, the B737CL (Boeing 737 "classic") has four, the B737NG has three (737 Next Gen), etc. So this "quite unusual" system appears on the very airplane we're discussing for the Pitot-Static System, a safety critical sensor.
  - VBprogrammer 8y ago
    On the 737NG 3 pitot tubes are pilot, co-pilot and the elevator control feel input. They aren't averaged, voted upon or compared in any way. I don't know much about the Airbus pitot system, except one ended up at the bottom of the Atlantic due, in part, to a frozen pitot tube.
    - Someone1234 8y ago
      > On the 737NG 3 pitot tubes are pilot, co-pilot and the elevator control feel input. They aren't averaged, voted upon or compared in any way. You're mistaken. To quote Boeing themselves: > The most modern systems today use an air data inertial reference unit (ADIRU), which incorporates the best information from three pitot and static sources and provides a single set of data to both pilots. An ADIRU receives information from air data modules, which are located close to the pressure sources. This is used on, at least the Boeing 757, 737 and Airbus A319, A320, A321, A330, & A340.
      - VBprogrammer 8y ago
        I believe your source is unreliable. For example read this report: https://assets.publishing.service.gov.uk/media/578df0f5e5274a0da3000176/Boeing_737-86N_EI-FHG_08-16.pdf https://assets.publishing.service.gov.uk/media/578df0f5e5274...

mannykannot 8y ago

Knowing that it was impact that killed people is not a very useful conclusion. You might as well say that AF 447 ended up at the bottom of the Atlantic because it flew into the water.

VBprogrammer 8y ago
Yes, sorry, I was reacting to the appeal to 'think of the children'.

crististm 8y ago

Does this suggest there are two different defects on a new plane model?