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Because if you did that, you'd have to alert the pilots when the AoA sensors disagree and MCAS has been disabled. And you can't do that without training them o
by mhandley 8y ago
Because if you did that, you'd have to alert the pilots when the AoA sensors disagree and MCAS has been disabled. And you can't do that without training them on what that means, notably how the plane will now fly differently with what you might call "relaxed stability" at high angles of attack. And Boeing really really wanted to avoid retraining of pilots because apparently they had a contract with SouthWest that would cost then $1M per plane if retraining was required.
- isolli 8y agoRelated question: how does regulatory approval of planes work, worldwide? I read a few times that the FAA had approved the new plane too quickly, but don't other regulators have their word?
- Svip 8y agoFAA have (or had) such a good record, that other regulators, like EASA, simply trusted a FAA certification. In the same way, FAA trusts an EASA certification for an Airbus plane.
- peeters 8y agoBilateral certification agreements. Canada and U.S. have one as well (it goes both ways): https://www.tc.gc.ca/eng/civilaviation/standards/int-baa-usa-2000-3676.htm https://www.tc.gc.ca/eng/civilaviation/standards/int-baa-usa.... It's good in theory (cutting down on a giant amount of repeat work), as long as both certifying bodies maintain their standards and don't get politicized.
- SilasX 8y agoWell, they're working hard to change that, I guess...
- ricardobeat 8y agoNot only that, but apparently they also delegated most of the certification duties to Boeing itself.
- theelous3 8y agoBuy toilet duck.
- VBprogrammer 8y agoIt's worth noting that there are other more engineering reasons it could be tricky to use both. An aircraft in a side slip will show different reading on the left and right sensors. Also, there are failures which are likely to impact both at much the same time, icing being a big one.
- mhandley 8y agoAgreed. Boeing's revised MCAS will disable itself if the AoA sensors disagree by more than 5.5 degrees when MCAS activates, or a sustained difference of more than 10 degrees otherwise. This is to take into account the fact that the sensors disagree to some degree in normal circumstances. These are fairly relaxed limits, but does demonstrate that a reasonable solution is possible.
- yg6ht5 8y ago$1M sounds like pocket change after all that has happened.
- 2sk21 8y agoReally! This looks like a case of local optimization.
- bredren 8y agoMarket cap loss since crash of flight 303 is $27 billion. https://ycharts.com/companies/BA/market_cap https://ycharts.com/companies/BA/market_cap
- acqq 8y agoWhich is still nothing compared to the increase in Boeing’s market cap since some three years ago.
- deleted 8y ago[deleted]
- dingaling 8y agoNone of which matters to Boeing as an entity. Market cap is not liquidity. Outstanding Max order backlog is $600 billion at list price. That is what matters.
- ddalex 8y ago> None of which matters to Boeing as an entity. Market cap is not liquidity. > Outstanding Max order backlog is $600 billion at list price. That is what matters. So at 600 billion in orders they got greedy and didn't want to spend 1M extra per plane to make it safe.
- marijnz 8y agoExactly, -after-.
- saiya-jin 8y ago
- snarf21 8y agoRight, they wanted to keep the type rating but it clear flies differently and now we have two crashes and hundreds dead.
- gok 8y agoBut don't Southwest planes already have the AoA disagree light, which they bought as an option?
- mhandley 8y agoYes. But the AoA disagree indicator did not disable MCAS. In similar circumstances, SouthWest pilots would not have taken off, because AoA disagree would have indicated as soon as they'd begun their takeoff roll. But if an AoA sensor had failed in flight, it would still have been up to the pilots to manually disable stabilizer trim.