Otherwise the new engines might need a new wing, pylons and fuselage adjustments for the CG differences. Airbus A32X and Bombardier A series planes are naturally unstable aircraft — and along with the new Embraer E2 series which had its wing moved forward to make it unstable- and the whole aircraft rely on FBW to enable them to fly.
The aircraft are naturally stable throughout the flight regime, however the normal laws provide additional augmentation to lower workload and improve the flight characteristics. A mismatch in air data indications which has been the focus here would possibly cause a degradation to alternate or direct modes, which are closer to command by wire and would allow the pilot to fly manually, even using pitch and power tables if air data is completely unusable.
I worded that badly and mixed it up. To answer the Question, Airbus would not let the aircraft go to stall even if the pilot tried normal mode. The auto throttle does not quit in normal mode what it does in alternate and none I do not know. What would be the behavior of the aircraft if stalled without the MCAS? Ted: The answer is no, it has to do with the engines and from what I am reading, almost a niggling issue that a Pilot would have no issue dealing with you would put the nose down in a stall yourself. MAX only, engine location on the two types is different enough to have added some control issues though it seems miner or irrelevant.
He said his training on moving from the old NG model cockpit to the new MAX consisted of little more than a one-hour session on an iPad. There will be documents outlining why this system is needed to keep the aircraft safe at the edges of the envelope. And those documents are probably compelling otherwise they would have never added the MCAS.
So now they will not be able to recommend it be disabled. We will have to see, its going to come out slowly as a lot of Silos are about to get their walls blown in. Pprune has a vidio of a simulator B classic stabilizer runaway which is easy to find on the web. It shows the pilot holding the yoke back, wheels running and alarms going off. It looks terrifying to me! Do the wheels visibly and audibly run like that with MCAS? Now in a scenario of conflicting signals such as in the Lion Air case, where you experience a stick shaker and stall warnings among other things, would you do what he was doing?
It all happened at ft, which is not a lot of room to recover from if you trusted the wrong warnings to heed. The revision Date is July Hold firmly 2 Autopilot if engaged. Disengage Do not re-engage the autopilot. Control aircraft pitch attitude manually with control column and main electric trim as needed. Disengage Do not re-engage the autothrottle. Grasp and hold 6 Stabilizer. Trim manually 7 Anticipate trim requirements. How dare you bring facts into the situation, Fixer? Please make us know how you can prove that EASA pilots have more information than airlines pilots?
Which is located just South of Seattle Tacoma Airport. It couldnt be more in Boeings pocket if it was just across the road from Boeing HQ at Oakesdale Ave Tukwilla Generally international agencies follow the lead of someone like FAA and rely on their approvals. There must be Failure mode effect and cause analysis done also by EASA to check off each box in their compliance sheets.
Then redo it for a combination of faults and double check with certifiation test reports. Still test pilots are used to faulty systems and shut off automation quickly as soon as it behaves unexpected, that can be different from normal airline pilots that are used that systems works pretty normal year after year unless they fly old soviet planes.
Are you sure? Just like the engine pitch up moment at high AOA is part of the MAX, the compensation of it could also be baked into the fcs logic, independent of trim. Its all very well having something buried in a QRH, but if you are totally unaware of the new systems existence, what use would those instructions be … and in the middle of a crisis. Not thats not easy peasy. That approach is what car dealers do when handing over a new car. If — as some of the comments above seem to indicate — it was done to preserve the old type certificate for the MAX it is simply greed allowed to prevail criminally over safe operations.
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What — if any — heads are going to roll at Boeing? So far no indication of such and not any expression of contrition either. Perhaps they feel they can tough it out and plow through with business as usual? Interesting to see what airlines customers are going to say and do. Was the FAA aware — or complicit in this omission? If unaware they were not doing their job.
If aware and coopted by their Boeing neighbors across the street, as suggested above, heads should roll there too. You assume a conspiracy when pole are fully capable of and continue to prove creating a complete balls up without any help from said conspirators. Chance are there will be fingerprints all over this as I would bet good money a few actual pilots in the shop advocated for transparency and were overruled — in writing!
As far as I can see, this is identical to the MAX checklist with revision date posted above by fixer, except for no mention of autothrottles and the addition of a note about RVSM restrictions. Is it then the case that what is new with the MAX is not what the recommended response to a runaway trim situation is, but that the MCAS system adds new and unfamiliar failure modes that could cause undesired and inappropriate trimming? Condition: Continuing rotation of the stabilizer trim wheel in a manner not appropriate for flight conditions. Control column. Control airplane pitch attitude manually with control column and main electric trim as required.
Contact ATC. If runaway continues: Stabilizer trim wheel. Trim manually. Anticipate trim requirements. See page 9. For some reason, the Leeham website keeps rejecting any post in which I include the direct web address to this document. I think I am a poster child for that kind of event. In a spin, the controls via the yoke in my case that are normal simply quit working. You might want to try that in a simulator, its like the Sun rose in the West, shocked is not quite it. Your whole world goes si wash for a second, or two or three. Pilots are like people, some poor, most in between and a few really good ones.
Your odds are you are flying with an in between pilot. Like Boeing auto throttle in the FLCH that turns off as part of another mode change, you can created a trap — the idea behind automation is to make it easier, not have to known bad design that then has to be over come with knowing the drill while you have a lot of other stuff to understand.
Anyway, the FAA should be getting the same or more scrutiny than Boeing since they certified the whole thing. Boeing clearly should have, FAA manual review may not have caught that the tech group approved it and an update was needed. All depends on the credibility of the cross check process. Keep in mind its the same FAA that agreed a good test of an Li Ion battery was to drive a nail in it! Some alarms go off but the pilots realize the AOA is fine by visual reference?
More like a light burned out though that was the core cause of the L crash into the Florida Everglades, trying to trouble shoot a stupid light problem. I did not know that, plus the subject is all new to me.
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But it not only has to fail, it has to fail with bad data saying its stalled to invoked the MCAS and flaps up and flying by hand if I have that right. It sounds like a borderline situation that is not that critical, more a technicality of FAA deciding it needed a fix and Boeing doing so, but will stay tuned. While the fact, that an apparently critical new system was not included in the documentation is highly worrying, I find the Boeing statement from a few days ago extremely troubling. At least morally this is a real shame.
Instead of admitting that there was information withheld, Boeing tried to create the impression it is a proven system and by apparently not following existing known procedures read simple pilot error the crash happened. Its not one item, its when they compound that the issues begin and Bjorn feels that it was compounded by another issue in air speed system, computer or?????? Horribly implemented in all regards with single point of failure, no documentation and no training to alert of that change vs what you know and that the first thing you do regardless is disable it, so you can deal with the other compounding issue.
Boeing has been trying to parse their words carefully. Critical stuff. You understand companies like BA have dedicated staff to prepare for such events. Companies like that have a duty to their shareholders not to admit guilt. No matter what. Their are manuals pun intended on how to do such circus mangement. Personally I would not admit guilt until I knew what really happened. Reminds me of the Catholic Church when they started siting Church Law.
Design shortcuts meant to make a new plane seem like an old, familiar one are to blame
Hmm, really, you think your internal operation MO trumps the Law of the Land? While I think this is a balls up and I doubt it was deliberate in a conspiracy way, someone made some very specific decisions not to comply with the regulations. Arrogance and or ego and who knows. Legally the Boeing Corporation put a product into service that does not begin to meet a miner change that does not affect ops.
It will only cost them money. Oddly, as far as I know unless the Supreme rule otherwise Corporations still are not allow to kill people. Technically this is somewhere between person slaughter and 2nd degree probably with a bias to person slaughter. This damaged the engines, until eventually, they failed completely. While the ATR system was described, if you read the manufacturers documents carefully, SAS never included them in the manuals for its pilots. The seems to have been somewhat rejuvenated 3 times at least in the past.
Instinctively this seems more unstable. But as said many times no aircraft is anymore inherently stable for performance reasons. I can only relate having built million lines level software systems all my life. These are also inherently patched over read: rejuvenated as it is too costly to rebuilt from the ground up. They last decades for sure. And we tell our customers they will work. Convinced as we are engineers that we get it right. We write self correcting code to correct runtime faults etc.
And many many code simulator runs convince us we have seen everything. We learn as we go. See the car reference in a comment above. Some behavior may be criminal but most organizations realty try to do the right thing. The question is how many oversight layer systems have been added on top of the existing ones to handle a perhaps larger inherent in stability flight envelop in the MAX? Should BA or anyone inform folks on all of them? Tricky plquestion. Yet sure they may have been way too optimistic. While that is good sense, also keep in mind that pilots are trained to expect things to work the way they should.
When something is NOT working the way it should, then there is confusions. Throw in another issue and the fog of confusion sets in. How are they related. Why is it doing X and Y. Whats the link when in fact x and y may be two different failures. Something like that stall system should never be a result of a single bad input, computer or even a bad logic path. Code in aircraft is supposed to be sorted, not like sloppy programs you get from Microsoft. More like the old CPM programs that were paired down to the bare basics as you did not have processor to run excess code and unknown results.
I have run into cases in my world where they had a problem and rather than solve it they threw more code at it. Is that right? How much time did they have to sort this out before they lost control? Thanks Bilbo. Ofcouse a big mound of cheese slices had already been munched through by the failure to get on top of the technical problems and possibly a failure to appreciate a previous near miss, that might only have been saved by luck or above average piloting. I think that as they were apparently flying in manual mode, they were probably thinking that they had turned it all off. As a pilot and a technician, the first thing that flashes through your mind when its not working the way you understood and were trained for?
Keep in mind, this is your car going out of control, you are turning into the skid and the skid gets tighter not stops. So what happens if you get into your vehicle and it suddenly has counter steer? I think that the solution will require more than just increased training.
Boeing will have to change the system to make it more failsafe to bad sensor information. A clear example is a Halon System yes I know we have no new halon system but a lot of legacy and it applies to the replacement. I had one in a bank vault that was feet through passage to get out of. When the tech set the system up, it was cross linked to two sensors. I also trained the vault personal on what to do and how to inhibit it until all were out of the vault. Both AOA should say the same before action other than a input disagreement, still chewing on adding more into it. The following post by Fixer is a curve ball for all the statements so far.
See the date of the QRH update. July So can the claims that Boeing hid the system details completely from Pilots, true? Yes or No? I am not a B Pilot. So just curious. If the MCAS on the MAX does not cause the trim wheels to rotate when it kicks in, I think that this be a much bigger curveball for pilots used to having autoflight systems move the airplane controls along with autoflight control inputs, than anything else that has been mentioned in this thread. Again, this is not the only issue the pilots faced, they also had another one going or maybe more.
In this case, there will be instant confusion as the system is also calling out stall and it is taking action that is not what you expect, let alone why you would be stalled when you know you are not. So the first instinct is to pull back on the yoke to stop it which it should. Then it does it again which is against all previous system knowledge.
What else did the pilot have to look at that was compounding this as not the only emergency going on? You also have a co pilot who may or may not be in sync with you as things are happening so fast that even communicating is not possible — he may be seeing different information than you are and confused by the stall warnings. And when things are going totally wonky, how much faith do you have left in even turning the whole automation system off?
Its easy to be sitting at a key board saying how they should, its a lot different being on the sharp point of the spear. Some might recognize part of it right way and turn off the MCAS trim — but which do you do first and whats the most aware thing? Trust me, its not a well you want to visit once, let alone more than once. You could manually reset the trim.
The procedure is there in our manual, and we practice this over and over again. The first time I see an adverse event, I want to see it in a simulator, not with people behind me. I am always looking for things to go awry, and I am always prepared to take control if that happens. I wait for something to go wrong because then I can use all those years of training that I have.
As a pilot you are trained to go through the drill. But you are also taught that the aircraft is not actively trying to kill you. As I noted, I was there once, I did get it sorted out before I died fortunately only me but it was a really close thing. Half a second more and …….. Given enough time, maybe they would have got there. Sometimes you run out of time and altitude. Runaway trim would normally be obvious, sudden the plane pitches up or down, the wheel is spinning, OFF.
But it does not start off with a stall screaming at you with all the associated stick shaker doing the same. The QRH consists of all checklists, both emergency and non-emergency, for a particular aircraft. It includes only, or almost only, the checklists, additional training or explanatory material such as system diagrams or design philosophy, that may be found in the full aircraft manuals are stripped out.
It is typically kept in a special compartment within arms reach of the pilots. Memory items are a small subset of the contents of the QRH. Only those emergency checklists items that it is judged must be completed immediately before there is time to flip to the appropriate page of the QRH, or its electronic equivalent, are memory items. Recurrent training will typically include all memory items, but not every checklist in the QRH will be practiced in every training session.
A QRH for an airliner is hundreds of pages long, memorizing the whole thing would be beyond the memorization capabilities of most people. Recall items are critical steps that must be done from memory and are placed within a box. Each crew member is required to know all recall items. Bullets, notes and bracketed items within the recall box support action steps and are not considered recall items.
Reference items are actions to be done while reading the checklist. In the Table of Contents for each non-normal checklist section, the titles of checklists containing memory items are printed in bold type. This checklist contained no memory items. See page CI. See below for a video of some student pilots practicing a runaway stabilizer emergency in a classic simulator.
Most importantly, the classic, NG, and MAX procedures all call for turning the stabilizer trim motor off if disengaging the autopilot does not stop the runaway. The runaway stabilizer simulator training session video that I posted a link to above, was posted to YouTube on According to the excerpts below from the Seattle Times article at the link after the excerpts, I am apparently not the only person in the world who thinks that based on long established emergency procedures, pilots should know to turn trim motors off if trim is running away or behaving erratically. Reading this article makes me inclined to fly United instead of Southwest or American when I have a choice.
An airline whose Chief Pilot says his pilots are confident flying their aircraft manually with auto everything off, is an airline that I will prefer to fly on. But Insler at United, the only U. He said people should wait for the investigation to come up with a definitive account of what caused the crash. On this aircraft the stab cutout switch names are different. Which ever motor moves the stab, the cockpit wheel has to move as it is back driven by cable.
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You seem to have a pretty detailed knowledge of the inner workings of the MAX. Systems, controls, and associated monitoring and warning means must be designed to minimize crew errors which could create additional hazards.
The analysis must consider—. For electrical generation, distribution, and utilization equipment required by or used in complying with this chapter, except equipment covered by Technical Standard Orders containing environmental test procedures, the ability to provide continuous, safe service under foreseeable environmental conditions may be shown by environmental tests, design analysis, or reference to previous comparable service experience on other aircraft.
Keep in mind, Bjorn feels there was another significant issue. Both would have to be dealt with without understanding why the stall alarm ans supposed was going on. Its the one independent from the main pitot static system system backup but it is not where I would want it. Assuming there is a Pitot system aspect to the situation, once quick cross check is what I call the AI attitude indicator.
Nose up, nose down, ok, we are level, cross check to the independent system, VSI steady or in reason also on the horizon or in reason not turn, airspeed good. Interesting it has its own battery power so its stand alone from the rest that way as well. Just what you want other than awkward cross check location. The backup instruments also has air speed as well as altimeter and VSI assumed from a complete separate stand alone pitot static system two static and one Pitot.
Wrong again. The reason is that the static margin increases. The CofL has moved forward by an amount significantly greater than the forward movement of the CofG, causing a significant reduction in the safe AofA before stall. So yes the engine cowling is producing lift but at all AofA. That is very, very bad for it increases the likelihood of flow separation at high AofA and also reduces static margin.
A reduced static margin increases sensitivity to pitching moment. You should apologise to dead people. Trashing me is one thing, trashing two dead pilots is another! How is that trashing two dead pilots? My one column on this listed a dozen areas of investigation, including pilot error, as routine areas of investigation. We have nothing to apologize for. I saw comments that Sullenberg could have made it back to Newark as well. We are not trained to make it back, but to do the best you can ahead. Turn backs are so low a success rate as to be only if you are at feet directly over an airport.
The fact that the aircraft is screaming at you its stalled when everything else says its not, and taking action on its own is going to cause a major confusion. The absence of the Cockpit Voice Recorder is a critical missing piece. Were so many audible alarms going off as to be distracting? Most importantly, were there a cascading set of issues that simply overwhelmed the pilots, which caused them to run out of time and altitude before they could figure out how to fly a plane with flight control issues?
Think of United Sioux City, Three pilots were faced with control issues that were beginning to overwhelm them. A fourth pilot joined from the cabin and as a coordinated four-man crew, they performed a miracle and made it to the airport. This event started at cruising altitude. Had it stated at 5, ft, they would have crashed. Think of Qantas Fortunately, they never faced a control issue. This flight incident began on the extended climb out to cruise altitude after takeoff. Two pilots would likely have been overwhelmed.
We also need the whole FDR and the breakdown of what was going on at what point including all the other data inputs. If so, the PFD sitting in front of the pilot could be lying on both speed and altitude situation both what it is and the VSI. QR32 I still believe is still in the myth stage. They kept trying to sort through alarms when all they told you was something was totally FUBAR on the left wing and you better get it on the ground. Sullenberg did two things, actually three he kept his head not easy he picked the Hudson right move but a lot of dead pilots have not and he started the APU that was not on the checklist full control — that kept the aircraft flying normally though engines kaput.
And if its not doing what is normal despite the emergency the laws of physics should not have the sun rising in the West what that does to your thought process. And that is where the human bell curve comes in. Is this emergency where you are strong or weak? While my instructor never got me messed up on the unusual attitude instrument recovery, he also could not induce false information into the panel.
He simply took away instruments with a cover. Only a couple of seconds. In a spin or a dive a couple of seconds is two or three turns or more and …….. Philip thanks for this insight. I concur with fog of the problem, conflicting and confusing warning signals, trim wheels winding, normal pilot inputs doing nothing and not much time to figure it all out. I believe that the fundamental problem may lie in statistics. How many transport category jets on revenue flights with flaps up have stalled in flight with no recovery? Perhaps 4 or 5 in say a billion cycles? Why are we addressing this now?
Apparently normal flight training handled this event quite well. This unfortunately covert fix introduced some electronic and software complexities that did fail. From what we know of this air frame from the inbound log, the aoa had failed along with other significant input to the ADC introducing a rather exciting flight in the vertical mode for all aboard flightracker24 trace. I believe I read, perhaps from Reuters, that there were even additional aoa an pitch problems experienced by this same air frame that had been logged before the inbound leg.
Here, the prevention statistically is much more lethal than the event it was designed to prevent! I suspect that nearly every pilot who flies something with an aoa aboard has seen them fail. The fix was usually immediate and effective, ignore it. In this case, the MCAS stall prevention system becomes a greater concern by a very large factor than the stall it is designed to prevent! Unfortunately, in this case it could not be ignored. Whatever happened to reducing power on these lethal forward and closer to the wing mounted engines?
No software to mess up, no avionic sensor that decides to bail out and put your nose straight down. I think that in this case hindsight is a bit cruel. Leave a perceived problem alone if its is statistically irrelevant for your fix may become a very relevant and statistically significant problem. To have left the MCAS in a box and never have placed it on or near any airplane I believe would have prevented this horrific accident. My suggestion is not simply come up with an emergency AD but to figure out how to get these things out of every machine that has the misfortune to be so fitted before they create another tragedy.
I made your very words clear through a series of e-mails initiated by Scott. The FCC deprived the pilots of hearing, sight and touch by displaying wrong flight data, issuing wrong audio data and producing wrong physical movements at the controls. Only leaves smell and taste left. The pilots had no chance. It did not occur to me that it had significantly reduced the safe AofA before stall, until now.
This is an interesting point. There have been previous occasions Bs have rocketed into the sky followed by spearing into the ground. Its a big problem to analyse though,because these events are statistically tiny, the plane statistically ultra safe and the pilots have been found to be at fault and theoretically should have been able to overcome any fierce handling properties. To turn it round. I had an acquaintance who said never argue with an idiot, they will beat you to death with their experience. TransWorld: Watch it. Yes, but I parsed it like a Republican, I simply commented on poor knowledge level followed by a philosophical statement attached to no name.
Philip,I meant the NG has an amazing safety record. The MAX currently has a statistically poor safety record. Thanks TransWorld, but not worried about by knowledge of the laws of physics. I spent 50 years studying the laws of physics. Thanks Grubbie. The issue of static margin is beginning to be more clear. That adds to the debate on MCAS. My view was the safe AofA before stall when flying through still air. Add a fierce response to pitch then we begin to know why MCAS was written.
Philip, Talking about fierce, I find you posts very interesting but we are all speculating about the cause of the crash. Only test pilots can talk with any real authority at the moment, and possibly dead pilots. To say the least, the FAA was not very happy with Boeing. Boeing have kept every quiet ever since. The FA have the data recorder. It tells all about the flight except what the pilots said to each other. They know where the blame lies. It is not the pilots. With regard to MCAS.
There can only be one reason for it, safe AofA before stall. Safe AofA before stall is determined by longitudinal stability. Botttom line. The stall margin is lousy so they developed MCAS to keep the pilot under control when flying manually. Imagine the confusion that would cause. For the record, when you flick the switch in an Airbus to fly manually that is what you get. I remember the example of a pilot flying an A into a bunch of trees. The pilot forgot that it takes 6 seconds for the engines to go from idle to full power. Anybody else remember. I think the pilots would have got home even in all visual data and all audio data was wrong.
So in a sense tge two pilots were elevated to the position of test pilots. But test pilots have reference data created through theoretical and emperical simulation, starting with computational fluid dynamics and wind tunnel tests leading into full blown simulation of flying characteristics. All of this reference data became invalid. Instead it responded to something neither pilot knew existed, MCAS.
MCAS was doing its own thing using unpublished reference data and unpublished control algorithms. If the airplane add responded to the pilots touching the controls they would have got it home. It was a clear day with a clear horizon. When you have stall screaming at you and the stick shaking, that puts you into stall recovery mode, not runaway trim mode. Think of traction control on a car. On my car there is a symbol on the dashboard showing traction control is on or off. When engaged the symbol flashes. Not hard. As I said it was a clear day with a clear horizon. In other words the pilots could have used the horizon as their reference point.
In simple terms point the nose at the horizon and then have a think about what to do next. Instead MCAS insisted on nose down whilst shaking the stick to indicate stall. In other words, the nose is below the horizon but the stick is shaking. As I said the pilots were elevated to test pilots. But they were flying the airplane without reference data. There one hope. The horizon. The first law of flight control laws. If the pilots want to fly the airplane let them fly the airplane. I do know on you can cause one to go full up and full down I asked a flight instructor on that as the Egyptian crash made no sense as that was the result of the pilot pulling back and the co pilot pushing down committing suicide.
Keeping in mind the stabilizer affect is huge vs the elevators, its going to cause an out of proportion force. Transworld: Where did you get this? Quote I think there is one trim motor for each stabilizer. Ergo, two circuits. I do know on you can cause one to go full up and full down Unquote. There is only one Stab actuator Screwjack , and both stab move together.
The screw jack can be driven by any of the two elect actuators in different functional modes.
Yet to see anyone design something otherwise. Ergo the elevators can split on a FBW. Getting into the stabilize operation that used for trim but more affect due to size. Hmm, two motors and two separate jack screws? One jack screw, connected to a single electric motor and both trim wheels. If the trim motor fails, either trim wheel can be manually turned to move the stabilizer through mechanical advantage.
From Slide Elevator Control Column Override Mechanism In the event of a control column jam, an override mechanism allows the control columns to be physically separated. Whichever column moves freely after the breakout can provide adequate elevator control. Although total available elevator travel is significantly reduced, there is sufficient elevator travel available for landing flare.
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Column forces are higher and exceed those experienced during manual reversion. If the jam exists during the landing phase, higher forces are required to generate sufficient elevator control to flare for landing. Stabilizer trim is available to counteract the sustained control column force. Slide Stabilizer The horizontal stabilizer is positioned by a single electric trim motor controlled through either the stab trim switches on the control wheel or autopilot trim. The stabilizer may also be positioned by manually rotating the stabilizer trim wheel. Trim motor used by both Autopilot and Trim switches.
Gear box Cable Drum turned by moving trim wheels and back drives trim wheels when trim moves electrically Screw jack turned by the motor or trim wheels. Slide Manual stabilizer control is accomplished through cables which allow the pilot to position the stabilizer by rotating the stabilizer trim wheels. The stabilizer is held in position by two independent brake systems. Manual rotation of the trim wheels can be used to override autopilot or main electric trim.
The effort required to manually rotate the stabilizer trim wheels may be higher under certain flight conditions. Grasping the stabilizer trim wheel will stop stabilizer motion. The tail compartment tour video at the link below includes footage clearly showing the stabilizer jackscrew, the electric stabilizer trim motor, and the drum through which the cockpit trim wheels drive or are backdriven by the jackscrew. All Boeing aircrfat from B thro have two trim motors. Only on NG there is only one motor.
Later aircraft on wards the motor is Hydraulic. All have only one screw jack. How can people moan about air travel? Look at that thing, basically a car jack operated by cables, designed 50 years ago. But for a small amount of money you can travel at speeds unimaginable years ago at a height where you should die of lack of oxygen and cold. And 3 hours away from an airfield and above the sea is absolutely normal. When mooring some boats the throttle control can sometimes reverse itself by trying to engage reverse from forwards too quickly,so this only happens when you are already under a lot of pressure.
The reality is that no one can and everybody piles on the revs and hits the wall. Just a few seconds more and you would probably manage to get it into neutral. The United chief pilot is making a reckless statement and tempting fate when he says that he makes the plane do what he wants. My understanding is FedEx is a leader in the area as they recognized earlier that it was an issue and began to train to challenge the pilots in unusual not the rote.
I think Ak Airlines teach unload, unload unload. I wonder if they got that from Boeing. Right thing to do in some situations, not in this case. Like Sullengerg, the nit pickers said he could have turned back and they did it in simulations. But that is not what you are or should be trained to do, its a crap shoot and a bit of wrong and you kill your whole plane and those on the ground.
I think the DC engine loss was the same. But you had to train for it and be ready. Fly another 5, hours and how ready would you be for something that should never occur? That too was a massive error as the slats should stay locked down not held down by hydraulic pressure ie check valve. NTSB agrees. Boeing sadly resists. One glaring issue is that the is a LCC workhorse with many low hours first officers. A far greater workload for the PIC than a more established airline. Whenever there is an accident the press often comment on the pilots lack of hours.
I propose that qualified but inexperienced pilots might actually be safer. If you think about it, they have the same training as more experienced pilots, but much less experience of the plane doing exactly what they expect to happen. Experience is only useful if you survive it. Are you a mechanic, an engineer, …….
Yes I am an engineer. Started on B through and , and all the Airbuses till A The only missing piece was B in my portfolio. Now retired after 40yrs and enjoying Collecting from friends in the industry and reading tech books about all aircraft. Also contributing my two pence worth in these columns. Any info on the trim motors and how that system works to be gleaned from those who know on the ? I see two of them in the circuit and clearly the two shutoff and or CB switch for them up front. Typically there are two geartrains, each with its own motor. They are both driving the a gear on the common jackscrew, in an active-standby logic, i.
The cutouts have the effect of i applying brakes on both motors and ii cutting-off electrical power to the motors, in this order. Pretty much all stab unarrested runaway failure conditions may result in a CAT event. Not sure how it actually works on the MAX, but from leafing thru the posts it seams to be similar. Hope this clarifies things a bit. According to the videos and NG ground school slides I posted links to above, there is only one stabilizer trim motor on the NG. The trim motor can be activated either by switches on each control wheel, the autopilot, the speed trim system see slide 55 , or the stall warning system see slide I stand corrected about Stab trim motors.
There is only one electric Trim motor on NG. Either control wheel trim switches or the auto pilot trim channel can move the stab through this motor. I was writing from memory from earlier Boeing aircraft. In fact all Boeing From Boeing aircraft have two trim motors for stab, and even on later aircraft From B through have Hyd motors. MAX ,I am not sure. With the autopilot engaged, stabilizer trim is accomplished through the autopilot stabilizer trim circuit.
The main electric and autopilot stabilizer trim have two speed modes: high speed with flaps extended and low speed with flaps retracted. If the autopilot is engaged, actuating either pair of stabilizer trim switches automatically disengages the autopilot. The trim wheels follow automatically when electric stabilizer trim is actuated and the stabilizer trim indicator shows the trim unit setting.
Apparently most comments are from pilots the following link will interest you. Well made video by a pilot about MAX. Does the MAX have the most reduced stability? The engines seem to have a large area and be forward of the wing, same with the Aneo. How do these compare to the MAX? What does the pitch up force or rate compare on these aircraft? As this is the first anyone public was ware of the pitch up issue on the MAX, we have to wait the details. Its not the pitch up I suspect, its the pitch up into past stall. So coming up on stall or into it it pitches up.
I flew small aircraft, they did not do that. Location and mounting of the engine as well as the shape all play a role. MAX is pushing it into that area due to the needs to get as large as they can on an old tube engine frame. But runaway trim does not start with a stall, stick shaker and the squawking.
Out of context even if the remedy is the same your cross checks are different because you have to take a stall warning as top priority until you confirm otherwise. Then it becomes a split decision as to fly the airplane and ignore it or figure out why in the world its telling you its stalled when i never did that in any similar training. I teach fire response in buildings. The first thing you assume is it is a fire. To respond by turning pumps off is not allowed.
This truly gets into a issue as if the initial response is to turn it off and its right, then follow up actions are wrong. What was the profile of the final dive? I think it misses to a degree the issue if you are not aware of a system on an aircraft, then its behaviors when gone wrong makes no sense. Any alert that what it can do and its symptom triggers the required, turn it off — not because its a runaway trim but its a Runaway MCAS as your main AH and backup still tell you what degree of vertical the aircraft is in.
Issues with the static pitot speeds adds a huge aspect and the need to shift to the backup combo display in the center. This is also interesting. One of the item is that the AOA on that flight and the previous one disagreed by 20 degrees on the ground. It appears the previous flight resolved their immediate issue with by turning off the trim systems after 12 evoluations so they too were confounded — not as long unfortunately as the next6 crew. The comments by an ex-Boeing flight control engineer in the excerpt below from the Seattle Times article probably the same one TransWorld referenced above at the link after the excerpt, pretty much agree with what I have been thinking based on what has been reported so far about the Lion Air accident.
I can understand how given only tens of seconds to react the pilots might not have thought of checking the pitch trim when unusual control forces were encountered, but it is baffling to me that given minutes to react, airline pilots would not closely examine the control trim that changes control forces and neutral position and turn off the pitch trim motor off if the trim wheel was spinning in the direction that would apply the control forces they were fighting. Flicking two cutoff switches stops the movement completely. The NTSC preliminary report confirms that, shortly after takeoff, the pilots experienced issues with altitude and airspeed data.
There are human factors involved. He said MCAS is designed to kick in only in extreme circumstances that an airliner should basically never face: something like a high-bank, high-stress turn, experiencing many times the ordinary force of gravity and approaching stall. Some logic could also be inserted to consider the reliability of the AOA readings when the plane is still on the ground.
When I was taking flying lessons many years ago I quit before I got my license , I was certainly nowhere close to airline pilot caliber, to put it very kindly, but once when I was surprised by how hard I had to pull the yoke back to take off in a lowly hp Cessna , it only took me a few seconds to think of checking the elevator trim wheel, at which time that I discovered that I had not set the elevator trim wheel to the takeoff mark. For those who are not pilots or ex wannabe pilots, when hand flying an aircraft most pilots are constantly making trim adjustments to set the control neutral point to the current aircraft configuration, rather than having to spend most of the flight pushing or pulling on the control wheel to maintain the desired speed, level flight, climb, or descent.
Since the Cessna trainers I flew had no autopilots, hand flying was the only option, there were no auto land, or auto climb, or auto anything buttons to use instead. Here is a trim cheat sheet for the lowly 50 to mph Cessna with requires much less trimming than a to mph airliner. Thus, the full flap short approach requires no change in trim unless power is off. This setting is constant for nearly every loading. The instructor will help the student determine this initial setting.
If the C has been landed with full flaps it will be near the correct setting for level cruise but not for takeoff climb. From this starting point of the trim wheel the following apply:.
To level off from this climb it must be moved up one full finger tip turn. Three full down finger tip turns from level will give descent at 60 kts at RPM. Trim down four finger tip turns for a no flap glide at 60 kts with power off. Trim full down four finger tip turns for minimum controllable without flaps.
About RPM no flaps. For full flap slow flight or minimum controllable trim up one finger tip turn. Full power. Most Cessnas have one full finger tip turn of the trim between level and climb settings. In each case fine trim movement may be required. Removal of the flaps during the go-around finds you trimmed for level cruise. One full finger tip trim down will give Vy climb at 65 knots.
This same procedure can illustrate why, when making a short approach, reduction of power to and application of full flaps at the white arc will give you a hands-off approach speed of 60 knots. And what is the source for the assertion that the source of this instability is increased lift generated by larger engine nacelles only at high angles of attack? When thrust is increased such as during stall recovery , underwing-mounted engines create a well-understood nose-up pitching moment. The amount of this thrust-induced moment will obviously change based upon the position of the engines relative to the aircraft center of gravity.
Placing engines not nacelles further forward increases the nose-up moment when thrust is increased. If the author has a source for the contention that the CFM Leap 1B engine nacelles on the MAX contribute more if any lift at any angle of attack as compared with the underwing engine thrust moment, then he should publish it. If not, he should retract his erroneous analysis and conclusions. I believe the fore or aft position of the engines does not affect pitch up. The radial position of any force line engine, elevator normal to the center of gravity creates rotational moment, force times this distance.
More or less the vertical distance from centerline of thrust of the engines to the cg. Is this more, less, or the same as the NG? Pingback: When you expect Max 8 pilots to be counter-intuitive during an emergency … — Ishok Yushoku. This is an excellent article describing the issue, I learned a lot.
Anyone else here in March ? Pulling up the yoke does not pull up the plane. This is like telling drivers that stepping on the brake will accelerate the car. That is plainly inviting trouble. People are not expected to be counter-intuitive during emergencies. This is criminal on the part of Boeing and FAA. Those who took the decision to not inform pilots and operators of these changes should be brought to book for the manslaughter of over people. I shudder to think of what will happen when our streets are full of self-driving cars.
The legal precedent must be set now holding such decision makers, and the people who advise them, to account. I am pilot retired. I flew Airbus. The event both planes have experienced is so dramatic and fast, that there is no time to read any QRH procedure. How may lives woul be saved!!! As I know up today, they never asked, and nobody tell them nothing, about those switches. I too am a retired pilot. I flew all versions of the except the max.
All had a procedure for runaway stabilizer. Flight envelope is one of a number of related terms that are all used in a similar fashion. It is perhaps the most common term because it is the oldest, first being used in the early days of test flying. It is closely related to more modern terms known as extra power and a doghouse plot which are different ways of describing a flight envelope.
In addition, the term has been widened in scope outside the field of engineering, to refer to the strict limits in which an event will take place or more generally to the predictable behaviour of a given phenomenon or situation, and hence, its "flight envelope". Extra power, or specific excess power ,  is a very basic method of determining an aircraft's flight envelope.
It is easily calculated, but as a downside does not tell very much about the actual performance of the aircraft at different altitudes. Choosing any particular set of parameters will generate the needed power for a particular aircraft for those conditions. For the same conditions a fighter aircraft might require considerably more power due to their wings being designed for high speed, high agility, or both.
With this amount of extra power the aircraft can achieve very high maximum rate of climb , even climb straight up, make powerful continual manoeuvres, or fly at very high speeds. A doghouse plot generally shows the relation between speed at level flight and altitude, although other variables are also possible.
It takes more effort to make than an extra power calculation, but in turn provides much more information such as ideal flight altitude. The plot typically looks something like an upside-down U and is commonly referred to as a doghouse plot due to its resemblance to a kennel sometimes known as a 'doghouse' in American English.
The diagram on the right shows a very simplified plot which shall be used to explain the general shape of the plot. The outer edges of the diagram, the envelope, show the possible conditions that the aircraft can reach in straight and level flight. For instance, the aircraft described by the black altitude envelope on the right can fly at altitudes up to about 52, feet, at which point the thinner air means it can no longer climb. The aircraft can also fly at up to Mach 1. This outer surface of the curve represents the zero-extra-power condition. All of the area under the curve represents conditions that the plane can fly at with power to spare, for instance, this aircraft can fly at Mach 0.
In the case of high-performance aircraft, including fighters, this "1-g" line showing straight-and-level flight is augmented with additional lines showing the maximum performance at various g loadings. In the diagram at right, the green line represents, 2-g, the blue line 3-g, and so on. The F Fighting Falcon has a very small area just below Mach 1 and close to sea level where it can maintain a 9-g turn. Flying outside the envelope is possible, since it represents the straight-and-level condition only. For instance diving the aircraft allows higher speeds, using gravity as a source of additional power.
Likewise higher altitude can be reached by first speeding up and then going ballistic, a manoeuvre known as a zoom climb. All fixed-wing aircraft have a minimum speed at which they can maintain level flight, the stall speed left limit line in the diagram. As the aircraft gains altitude the stall speed increases; since the wing is not growing any larger the only way to support the aircraft's weight with less air is to increase speed.
While the exact numbers will vary widely from aircraft to aircraft, the nature of this relationship is typically the same; plotted on a graph of speed x-axis vs. Inefficiencies in the wings also make this line "tilt over" with increased altitude, until it becomes horizontal and no additional speed will result in increased altitude. This maximum altitude is known as the service ceiling top limit line in the diagram , and is often quoted for aircraft performance.
The area where the altitude for a given speed can no longer be increased at level flight is known as zero rate of climb and is caused by the lift of the aircraft getting smaller at higher altitudes, until it no longer exceeds gravity.