Ethiopian airliner down in Africa
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What an ignorant comment. From a systems perspective, if aircraft design results in a situation that is 100% reliant on crew to flick the stab trim switches off, in a time critical, startling, highly dynamic scenario, the fault is almost entirely with the design of the aircraft. I thought we'd moved on a bit from the 'blame the human at the end of the error chain' mentality, but clearly some among us still have some way to go.
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Question from an SLF: Is it normal that you can trim an aircraft so far that you could not counteract the trim with the yoke, or is it a special feature of the 737?
What's the point of having a trim range exceeding the elevator authority? Are there any situations where this is needed?
What's the point of having a trim range exceeding the elevator authority? Are there any situations where this is needed?
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The ELT (Emergency Location Transmitter) is completely independent emergency equipment system. Nothing to do with the two main electrical system batteries that have ended up in a stainless steel fire proof box. The initial fix there was to remove the ELT or the battery.
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stainless steel fire proof box
Last edited by A. Muse; 16th Mar 2019 at 20:36. Reason: quote in wrong place
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Thought Experiment
Your lined up on the runway. All normal. Advance power. Liftoff. Now your initial climbing out. “STALL STALL” HORN STICK SHAKER
Firewall the throttles
Pitch to respect stick shaker
Look around. What’s going on?
So my question is what do you do?
???
Firewall the throttles
Pitch to respect stick shaker
Look around. What’s going on?
So my question is what do you do?
???
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I had wondered about a pitot issue given the IAS problems reported, and wondered at the chances of additional hardware failure w AoA vane tripping MCAS....
...but does this show that IAS Disagree can in fact be caused by the AoA failure?
https://hackaday.com/2019/03/14/mcas...-consequences/
So instead of pitot issue AND AoA issue we are back to all being caused by a bad alpha vane?
...but does this show that IAS Disagree can in fact be caused by the AoA failure?
https://hackaday.com/2019/03/14/mcas...-consequences/
So instead of pitot issue AND AoA issue we are back to all being caused by a bad alpha vane?
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Question from an SLF: Is it normal that you can trim an aircraft so far that you could not counteract the trim with the yoke, or is it a special feature of the 737?
What's the point of having a trim range exceeding the elevator authority? Are there any situations where this is needed?
What's the point of having a trim range exceeding the elevator authority? Are there any situations where this is needed?
As you've alluded to, the above is not an ideal situation, and one of the many reasons why it's not a good idea to hang on to common type certification by the skin of your teeth as you redesign an aircraft to within an inch of what's 'acceptable'. Now we'll likely see 'what's acceptable' being pulled back into line, leaving the 737 MAX sitting out there on it's own, essentially uncertifiable in it's current state. No doubt a quick fix will be rustled up, but it obviously won't fix the underlying issues.
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What an ignorant comment. From a systems perspective, if aircraft design results in a situation that is 100% reliant on crew to flick the stab trim switches off, in a time critical, startling, highly dynamic scenario, the fault is almost entirely with the design of the aircraft. I thought we'd moved on a bit from the 'blame the human at the end of the error chain' mentality, but clearly some among us still have some way to go.
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May I take a weekend moment to thank many contributors here for NOT disparaging those of us who are not 10+k hour Captains for their sympathetic and informative responses to some of our slightly obtuse or ill-informed questions? You are taking the subject forward, instead of just stifling discussion. Thank you to the Moderators as well ... a thankless task, as I know from ‘another place’.
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That is simply not true. Although the heat of a fire in theory has no limit (one can keep adding fuel) the combustion temperature is strictly limited by the chemical potential of the reactants. Any material that is physically and chemically stable above this temperature can contain the fire. Ceramics and refractory metals (amongst others) have no problems doing so.
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Question: When MCAS is active, does the trim wheel on the flight deck turn? Or is the MCAS trim applied without the knowledge of the pilots, similar to Yaw damper operation without rudder pedal movement?
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What an ignorant comment. From a systems perspective, if aircraft design results in a situation that is 100% reliant on crew to flick the stab trim switches off, in a time critical, startling, highly dynamic scenario, the fault is almost entirely with the design of the aircraft. I thought we'd moved on a bit from the 'blame the human at the end of the error chain' mentality, but clearly some among us still have some way to go.
and it happens again , and you have been told what to do if it does, and
you fail to do it, then who do you think is at fault? If you answer anything but the pilot, then I hope to never be your passenger.
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Ignorant seems a little rough. Ultimately, the human has to be the one capture the errors, either by system design or induced. There are some inherently dangerous designs that require a crew to be the last defense. But I cant imagine a single MAX crew in the world that doesn't brief before takeoff...Hey, when the flaps come up and if that trim wheel starts a goin"...then shut those STAB switches OFF! And I wouldn't say MCAS is a design failure...works great, until it doesn't...kind of like my brother-in-law.
Well from a pilot perspective, If you know that a 737 was lost 6 months ago due to this faulty system,
and it happens again , and you have been told what to do if it does, and
you fail to do it, then who do you think is at fault? If you answer anything but the pilot, then I hope to never be your passenger.
and it happens again , and you have been told what to do if it does, and
you fail to do it, then who do you think is at fault? If you answer anything but the pilot, then I hope to never be your passenger.
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Tosh. The manufacturer has produced a sub-standard product, pushing enhanced responsibility on aircrews. There are many layers of responsibility here, the first being Boeing’s insistence on polishing-off a 50+ year-old aircraft by adding bigger engines bringing questionable stability and mitigating it all with a poorly thought-through ‘safety system’ (MCAS).
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Yes, it was a little rough - apologies to reamer. You get my point though - reamer was just saying what a heck of a lot of 737 pilots are also saying and thinking, and it was that mindset that I was commenting on, for which 'ignorant' seems a perfect word (meant objectively, without malice).
With all due respect, you miss my point. If an aircraft designer relies on flight crew to carryout an action that ends up being essentially impossible (or very, very difficult at certain phases of flight, given certain scenarios), that is a design flaw - no sense blaming flight crew for that! The fact that all Max pilots were clearly primed for this situation after Lion only emphasises my point - don't you think the crew would have be extremely well versed with what they were expected to do in that scenario? A little causal analysis goes a long way, rather than jumping to conclusions.
With all due respect, you miss my point. If an aircraft designer relies on flight crew to carryout an action that ends up being essentially impossible (or very, very difficult at certain phases of flight, given certain scenarios), that is a design flaw - no sense blaming flight crew for that! The fact that all Max pilots were clearly primed for this situation after Lion only emphasises my point - don't you think the crew would have be extremely well versed with what they were expected to do in that scenario? A little causal analysis goes a long way, rather than jumping to conclusions.
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Thought Experiment
The aircraft has been increasing in airspeed
Now what?
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Pull up or turn.
This isn't difficult, if the trim wheel moves when it shouldn't, switch it off.
If the airspeed is unreliable, pitch up to 4 degrees and put the power around 75%.
This isn't difficult, if the trim wheel moves when it shouldn't, switch it off.
If the airspeed is unreliable, pitch up to 4 degrees and put the power around 75%.
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No, the mindset of jumping to a conclusion that disparages a deceased flight crew who aren't here to defend themselves, without seeking to understand the full picture. We clearly disagree, your points noted with thanks, back to topic!
