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Originally Posted by tdracer
(Post 10476677)
Not too long ago I was at special event at the Museum of Flight - not only was I seated at a table with a bunch of current and retired Alaska Air pilots, during the cocktail hour....
It is all rather removed from the confines of a flightdeck with the stick shaker rattling your vision, doubling your pulse rate, and drowning out any noise from the trim wheel which is highly likely to be doing exactly what you want and need it to be doing for you... until you realise that it is no longer your friend, and it has put you in an in-recoverable corner in a matter of seconds, while you're gathering your ***** together over the stick shaker and other unbelievable symptoms which just don't add up. Pass me another bevvy, 'cos the alcohol is beginning to work its magic on me and I've got a few more views on how bad pilots are these days to get off my chest while I have an audience... now sit yourselves down, make yourselves comfortable, and recharge your glasses! |
Originally Posted by Ian W
(Post 10477063)
The implication of your post is that the 737 pilot is happy to accept a significantly out of trim aircraft.
What was being assumed is that an experienced pilot would not let the automatics whatever they were put the trim where they didn't want it.- so when the Stab Trim cutout occurred there would not be a large out of trim condition to wind back. There is also a lot of confusion between 'manual trim' with the column electric trim switch and manual trim with the non-powered trim wheel. Up until MCAS probably the most likely cause of runaway trim was a HW failure of some sort such as stuck relay which the thumb switches might/might not override so would be logical to hit cutout as soon as possible before stab ran to the limits. Only takes seconds of runaway to get to a bad state. An unanswered question is why the initial re-trim by ET pilot only removed about 1/2 of the MCAS trim, that and failure to manually trim after cutout are the final causes. |
Originally Posted by pilotmike
(Post 10477097)
And there's the rub - anyone can spout off about what they'd do from the comfort of a chair at a table during cocktail hour, loaded with a beverage or 2.
It is all rather removed from the confines of a flightdeck with the stick shaker rattling your vision, doubling your pulse rate, and drowning out any noise from the trim wheel which is highly likely to be doing exactly what you want and need it to be doing for you... until you realise that it is no longer your friend, and it has put you in an in-recoverable corner in a matter of seconds, while you're gathering your ***** together over the stick shaker and other unbelievable symptoms which just don't add up. Pass me another bevvy, 'cos the alcohol is beginning to work its magic on me and I've got a few more views on how bad pilots are these days to get off my chest while I have an audience... now sit yourselves down, make yourselves comfortable, and recharge your glasses! The "unbelievable symptoms" were discussed in great detail after the Lion Air loss, were they not? Stickshaker on one side, trim goes wonky after the flaps are retracted and the AP won't engage.... meanwhile let's leave the thrust at T/O and off we go. - GY |
Originally Posted by MurphyWasRight
(Post 10477160)
What I was trying to point out is that the "greybeards" statement was that the first thing they would instinctively do when trim acted up for whatever reason was to hit the cutout switches then use the manual wheel to trim, not first attempt to correct the trim using thumb switches.
So, after all it appears that for some experienced US pilots, the first thing to do was throw the cutout switches ASAP and then use the manual trim wheel. |
2 Attachment(s)
Originally Posted by MurphyWasRight
(Post 10477160)
What I was trying to point out is that the "greybeards" statement was that the first thing they would instinctively do when trim acted up for whatever reason was to hit the cutout switches then use the manual wheel to trim, not first attempt to correct the trim using thumb switches.
Peter Lemme (satcom.guru) has tweeted parts of 727 manuals and found the procedure was to hit cutouts "immediately" with no mention of trimming in opposition (see image attached). He also shows other bits of the manual that were specifically advising against it. Of course the greybeards also had the rollercoaster technique in their manuals and were possibly in their training too. It is possible that everything changed at the same point between classic and NG: 1. "Control airplane pitch attitude manually with control column and main electric trim as needed" added to procedure 2. trim wheel made smaller so manual trim less likely to work if mistrimmed 3. rollercoaster taken out of manuals EDIT: and quite possibly related: 4. Stab trim actuators combined - classic had AP servo and main trim motor, NG has just single motor driven by AP or main elec trim Then the MAX removed the separate autopilot-trim cutout too. |
Originally Posted by GarageYears
(Post 10477165)
I'm beginning to wonder if the pilot-less aircraft isn't really the answer then. Given that the folks up front apparently can't handle a real emergency, might as well not be there at all.
- GY Maybe the flights might have ended sooner, so the people on board would have had less time to get bounced around before the crash ? The "unbelievable symptoms" were discussed in great detail after the Lion Air loss, were they not? Stickshaker on one side, trim goes wonky after the flaps are retracted and the AP won't engage.... meanwhile let's leave the thrust at T/O and off we go. Not sure of what procedure you are referring to with "Stickshaker on one side". What would it look like ? "In case stickshaker activation, first reach over to the other yoke to make sure only one shaker motor is running. If so, then stickshaker alarm is spurious, ignore it and consider MCAS . If not, then do stickshaker memory items" Are you sure you would be able to diagnose the number of shaker motors running before running memory items ? Really ? |
Originally Posted by GarageYears
(Post 10477165)
I'm beginning to wonder if the pilot-less aircraft isn't really the answer then. Given that the folks up front apparently can't handle a real emergency, might as well not be there at all.
The "unbelievable symptoms" were discussed in great detail after the Lion Air loss, were they not? Stickshaker on one side, trim goes wonky after the flaps are retracted and the AP won't engage.... meanwhile let's leave the thrust at T/O and off we go. - GY Was it the aircraft? Was it automation? Was it MCAS? Was it a computer? Wrong, wrong, wrong and WRONG again! The automation was going beserk and was trying to kill them all. The correct answer is, it was.... ... ... a pilot! Yes, a pilot saved everyone from the unthinking actions of an ill-conceived and very badly implemented computerised system. Pilots 1, automated system gone wrong NIL on that occasion. Unfortunately, MCAS equalised very soon after. And then MCAS went on to score the decider some months later, against Ethiopian. Finally, the ref has called FOUL, and has had the good sense to stop the match. But your solution is to remove the pilot? Incredible, given all the evidence! |
Originally Posted by pilotmike
(Post 10477411)
The automation was going beserk and was trying to kill them all.
... Yes, a pilot saved everyone from the unthinking actions of an ill-conceived and very badly implemented computerised system. |
Originally Posted by fizz57
(Post 10477428)
Rather poor choice of example seeing that MCAS is not active during automatic flight.
With a faulty AOA sensor ? Really ? My bet is, as soon as the AOA vane/synchro/whatever would have failed, the autopilot would have called it a day, and another mode of auto flight would have taken place : free fall... |
Pilot Mike and Fly Aiprt, you're rather missing the point. MCAS (and countless other systems) are less than 100% robust because it's assumed that if they do something stupid, the carbon based life forms sitting in row zero will take over and fly the aircraft. However, it's been repeatedly demonstrated that at least some of those carbon based life forms - otherwise known as pilots - are not completely up to the task (forget MCAS, think AF 447). If the designers have to design all the systems on the aircraft assuming the pilots won't take over and do the right thing when something fails, then why have pilots?
Of course this would take a complete re-think of how aircraft and automatics/avionics are designed, with many levels of redundancy and backups. The 'we must have pilots' side keeps pointing to cases where the pilots stepped in and saved the day when the automatics went south - but that's how the system is designed, assuming that when things go wrong the pilots will step in and save the day. The designers would not design the automatics that way if they couldn't count on the pilots to step in. Now, I'm not suggesting we're to the point where we can design the aircraft so we don't need pilots - that's still decades away. But when pilots become completely overwhelmed and demonstrate the inability to even remember to pull the throttles back so they don't overspeed when something goes wrong, it moves us one more step in that direction. |
My experience in designing aircraft systems (not for Boeing ;-) is, the key is research for graceful failure.
If when your system fails, average crews get overwhelmed, then something is wrong with the system, not the crew... That is, provided you actually test your system in real life in real airplanes, which we are not sure Boeing actually did. And there is no need to this day, to resort to full autonomous commercial flight the technology is not mature to envisage yet. As a designer, just do your homework, do study ergonomics and human factors, and you'll be the guy up to the task. As to considering the crews being overwhelmed as not being "up to the task", well the people I know of, that have actually encountered life threatening situations with complex multiple alarms/failures, are far more tolerant than you are. Because they know that they also have been overwhelmed, like anyone of us would have been, whatever our abilities, real or supposed. |
Originally Posted by Fly Aiprt
(Post 10477552)
My experience in designing aircraft systems (not for Boeing ;-) is, the key is research for graceful failure.
If when your system fails, average crews get overwhelmed, then something is wrong with the system, not the crew... That is, provided you actually test your system in real life in real airplanes, which we are not sure Boeing actually did. And there is no need to this day, to resort to full autonomous commercial flight the technology is not mature to envisage yet. As a designer, just do your homework, do study ergonomics and human factors, and you'll be the guy up to the task. As to considering the crews being overwhelmed as not being "up to the task", well the people I know of, that have actually encountered life threatening situations with complex multiple alarms/failures, are far more tolerant than you are. Because they know that they also have been overwhelmed, like anyone of us would have been, whatever our abilities, real or supposed. Computers, automating & system design have a long long way to go before we can even begin to think eliminating carbon based pilots. |
Originally Posted by tdracer
(Post 10477514)
But when pilots become completely overwhelmed and demonstrate the inability to even remember to pull the throttles back so they don't overspeed when something goes wrong, it moves us one more step in that direction.
We're talking of flying real airplanes, experiencing real spinning, gees, etc. not calibrated sim exercices with a warned crew. And my trainees ranged from low time students to multi kilo-hour F117 pilots or airline captains. So... Besides, confronted with a stickshaker alarm and severe AND trim at low altitude, retarding the throttles seems a rather odd idea... But I may be wrong. |
Originally Posted by Fly Aiprt
(Post 10477552)
My experience in designing aircraft systems (not for Boeing ;-) is, the key is research for graceful failure.
If when your system fails, average crews get overwhelmed, then something is wrong with the system, not the crew... https://cimg2.ibsrv.net/gimg/pprune....5a6649a7ec.png Standard deviation Lots of posters here assume they themselves are, and everybody else should also be nothing but a "top gun" (the blue graph above). Does that reflect reality? I'll let yourself answer that. But of course the reality is even more complex. Top guns have bad days. Could be a headache, could be a divorce. That stuff will kick you out of your best, within the magenta graph. In essence, even a top gan is only top gun on their best days. Then of course we'd need to measure different parameters. Somebody might be an ace pilot, but will miss a detail, like say trim spinning in the wrong direction (while somebody else might suck at hand flying but would thought, "hmm, this is weird"). So what can you do? Two things: - stringent certification requirements which measure not only the knowledge and skill, but also "soft skills*" like "ability to keep calm while overspeeding 1000 feet AGL with severe trim down"; in essence making sure nobody by say level 90 on the magenta graph passes (which would run the industry crazy due to "shortage**" of pilots) - design the systems so that not an average crew can handle it, but any certified crew can handle it. There is a big difference between the two, but I'm sure everyone can agree a certified crew should be able to handle a plane, or there is a problem. *not really skills as those can't be learned. **perhaps a big part of a problem - HR market requirements allow subpar pilots to be certified? |
Originally Posted by fizz57
(Post 10477428)
Rather poor choice of example... In fact the sole reason for MCAS is to provide pilot-friendly handling characteristics,
The fact is, MCAS was an ill-considered and very badly bodged attempt to fix another much more serious problem, purely for financial reasons, and the un-intended consequences had horrific results. If it was anything other than a totally unsafe and unsatisfactory system, why would the aircraft be banned by every administration, with no satisfactory fix or end to the desperately sorry saga in sight? It was nothing whatsoever about being "pilot-friendly" - rather it was a cynical, cheapskate fix for a bigger problem, which was pushed through the regulatory system inappropriately, many would say, and it has killed far too many people. |
Originally Posted by pilotmike
(Post 10477660)
It was nothing whatsoever about being "pilot-friendly" - rather it was a cynical, cheapskate fix for a bigger problem, which was pushed through the regulatory system inappropriately, many would say, and it has killed far too many people.
Regards Alchad |
Right person for the job
Hi Jodel, I think we should distinguish between average folk and average professional pilots in this argument. Pilots only get (and stay) where they are after stringent selection, training and repeated checking. They are a small part of the community. That doesn’t mean they have to be especially clever or elite - but just ideal people for their job. Other people are ideally suited to other professions, at which many pilots may fail. A professional pilot should be well up on your scale - if that scale applies to flying skills/aptitude as applied to the general community. The bad ones get found out with very few exceptions. A doctor or an architect doesn’t go through this process - has to prove him(her)self to stay in business in other ways... So an aircraft designer has the right to expect a certain level of skill. I seem to remember in my manual, that Boeing were pretty clear on the skill tests their pilots were expected to pass. That needs to be borne in mind when using terms like “average”. On the other hand, a professional pilot has the right to expect a level of skill from the manufacturer. This includes honest self criticism such as is required of a professional pilot. B |
Originally Posted by bill fly
(Post 10477789)
Hi Jodel, I think we should distinguish between average folk and average professional pilots in this argument. Pilots only get (and stay) where they are after stringent selection, training and repeated checking. They are a small part of the community. That doesn’t mean they have to be especially clever or elite - but just ideal people for their job. Other people are ideally suited to other professions, at which many pilots may fail. A professional pilot should be well up on your scale - if that scale applies to flying skills/aptitude as applied to the general community. The bad ones get found out with very few exceptions. A doctor or an architect doesn’t go through this process - has to prove him(her)self to stay in business in other ways... So an aircraft designer has the right to expect a certain level of skill. I seem to remember in my manual, that Boeing were pretty clear on the skill tests their pilots were expected to pass. That needs to be borne in mind when using terms like “average”. On the other hand, a professional pilot has the right to expect a level of skill from the manufacturer. This includes honest self criticism such as is required of a professional pilot. B He is already distinguishing between average folk (me) and average professional pilots. There will be always an average, no matter how high you set the bar, some will be above the average and other below the average. In fact, in my opinion, he has a very good point. Aircraft certification requires that the design is made for average certified professional pilot, which implies that a number (no matter how stringent is the certification process) of professional pilots will not fall in that category, therefore he is suggesting to have system designed (for aircraft certification purpose) for every certified professional pilot (not the average). |
Originally Posted by bill fly
(Post 10477789)
Hi Jodel, I think we should distinguish between average folk and average professional pilots in this argument. We are.
Originally Posted by bill fly
(Post 10477789)
Pilots only get (and stay) where they are after stringent selection, training and repeated checking. They are a small part of the community.
Originally Posted by bill fly
(Post 10477789)
That doesn’t mean they have to be especially clever or elite - but just ideal people for their job. Other people are ideally suited to other professions, at which many pilots may fail.
Originally Posted by bill fly
(Post 10477789)
A professional pilot should be well up on your scale - if that scale applies to flying skills/aptitude as applied to the general community. The bad ones get found out with very few exceptions.
a) lack of understanding of basic statistics / probability First of all, the picture above is not a scale, it's a distribution where 100 represents the average pilot. There will always, always be pilots who are below average and pilots who are above average. The question is, how below average is the worse commercial pilot currently flying (and how good is the best one on the opposite side). The only thing that could be up to debate is weather the standard deviation is small (blue graph) and all pilots are almost equally good in skills, or is it (in the extreme) like orange graph and some pilots are way worse than the average pilot. I don't have the data to support either of the cases. I hope we are closer to the blue graph, but... are we? Interestingly, Boeing - by blaming the pilots for recent crashes - is saying that there is a wide gap between average and sub-average pilots AND that their airplanes are only meant for average skilled pilots, which in essence means, Boeing is saying the current certification is to permissive (you can't accept the current pilot certification as acceptable AND blame the pilots, it's a contradiction). b) all pilots are exactly equal You need to believe that all pilots are exactly the same if you are saying there is no distribution. Oh, I hear you, you are thinking "but that's not what I said, what I said is that the bad ones are filtered out". Then we are back to a). Because, if you have pilots who have skills 89,93,100,101,110, the average is 98.6. You filter out the bad ones and end up with 93,100,101,110. Now your average is 101, but that is not above average, that's just the new average. Now the pilot with skill of 100 is below average. By pruning the bad ones you are improving the average, but the distribution is still there There is another phenomena, if the airplane manufacturers are truly targeting "average" pilot, and that average goes up, the number of pilots who can handle the plane properly will decrease, simply because there are just so many pilots who are at or above average, which is a problem. According to wiki quoted above, Boeing expects 790,000 new pilots in 20 years from 2018. What will their skills be compared to the current population, where we still have pilots who are not "children of magenta"? Where will the average move in the next 20 years with so many fresh pilots AND old pilots retireing? My bet is, it's going to go down cosiderably, while the airplane manufacturers are building planes for just the best of them. If that is the case, perhaps MCAS (hidden system which below average but certified pilots could not handle) is just showing us the future where we are going.
Originally Posted by bill fly
(Post 10477789)
A doctor or an architect doesn’t go through this process - has to prove him(her)self to stay in business in other ways...
Originally Posted by bill fly
(Post 10477789)
So an aircraft designer has the right to expect a certain level of skill.
Originally Posted by bill fly
(Post 10477789)
I seem to remember in my manual, that Boeing were pretty clear on the skill tests their pilots were expected to pass. That needs to be borne in mind when using terms like “average”.
Originally Posted by bill fly
(Post 10477789)
On the other hand, a professional pilot has the right to expect a level of skill from the manufacturer. This includes honest self criticism such as is required of a professional pilot. B
Originally Posted by bill fly
(Post 10477789)
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Originally Posted by derjodel
(Post 10477829)
First of all, the picture above is not a scale, it's a distribution where 100 represents the average pilot. There will always, always be pilots who are below average and pilots who are above average. The question is, how below average is the worse commercial pilot currently flying (and how good is the best one on the opposite side).
It's perfectly possible that the ability distribution is actually skewed, in other words the peak isn't halfway between the two extremes, so that for example there could be a concentration of pilots towards the upper end of the ability scale. Or, perish the thought, the lower end. :O |
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