corethatthermal wrote: ↑Sun Oct 20, 2019 9:46 pm
Obviously, Being Ethiopian and calling on "god" He was most likely calling on allah ! There have been other accidents where this scenario played out and they have often given up on the fight and prayed to their god (Satan) but with no effect !
Actually, the majority in Ethiopia practice a form of Christianity, the largest group being Ethiopian Orthodox, who outnumber the Muslim population without adding in the Protestants and Catholics.
The Indian-born captain was said to be silent at the end before the plane hit the water, while the Indonesian first officer said “Allahu Akbar”, or “God is greatest”, a common Arabic phrase in the majority-Muslim country that can be used to express shock or distress.
BTW Allahu Akbar does NOT mean God is greatest. It means Allah is greatest OR greater than your God! The MSM and other politically correct bought out tools like to tell you that we have the same god and Islam is a religion of peace Blah blah blah blah blah !
I am going to suggest that there be a thread called "Pissing Contests." Whenever two posters use a thread to become combatants and drift the thread away from the topic at hand, their posts get moved to the "Pissing Contest" thread.
That's the thing: the higher the airspeed, the less out of trim you will be. Nose down trim means you are trimmed for a high airspeed. The more your airspeed increases, the smaller the difference between your actual speed and the speed you are trimmed for.
Even with full trim down, the airplane would have descended and stabilized at an altitude where the IAS was reached for which the plane was trimmed, if there was sufficient altitude available, and if the plane wouldn't have fallen apart due to the extreme speed.
Seriously - Do you fly anything bigger than a Cessna?
With full nose down trim you would be going so fast you run into other aerodynamic problems. Full nose down is way more than you would ever need...it's there so you have a necessary range at low speed. At higher speed - the aircraft is actually trimmed nose up to counter Mach tuck.
Mach trim is automatically applied above M0.615 to the elevators. This provides speed stability against Mach Tuck; i.e. as Mach increases, the centre of pressure moves aft and the nose of the aircraft tends to drop.
corethatthermal wrote: ↑Mon Oct 21, 2019 10:54 am
From the lion air flight 610:
The Indian-born captain was said to be silent at the end before the plane hit the water, while the Indonesian first officer said “Allahu Akbar”, or “God is greatest”, a common Arabic phrase in the majority-Muslim country that can be used to express shock or distress.
BTW Allahu Akbar does NOT mean God is greatest. It means Allah is greatest OR greater than your God! The MSM and other politically correct bought out tools like to tell you that we have the same god and Islam is a religion of peace Blah blah blah blah blah !
You seem pretty bent out of shape about which God is which. Don’t you know all Gods are made up anyway.
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That's the thing: the higher the airspeed, the less out of trim you will be. Nose down trim means you are trimmed for a high airspeed. The more your airspeed increases, the smaller the difference between your actual speed and the speed you are trimmed for.
Even with full trim down, the airplane would have descended and stabilized at an altitude where the IAS was reached for which the plane was trimmed, if there was sufficient altitude available, and if the plane wouldn't have fallen apart due to the extreme speed.
Seriously - Do you fly anything bigger than a Cessna?
With full nose down trim you would be going so fast you run into other aerodynamic problems. Full nose down is way more than you would ever need...it's there so you have a necessary range at low speed. At higher speed - the aircraft is actually trimmed nose up to counter Mach tuck.
Mach trim is automatically applied above M0.615 to the elevators. This provides speed stability against Mach Tuck; i.e. as Mach increases, the centre of pressure moves aft and the nose of the aircraft tends to drop.
I'm not sure mach tuck had any effect on the accidents. Their speeds at low altitude were fairly low.
You keep bringing up new subjects and keep deflecting my original question: why would it have helped to reduce the throttles? Reducing the throttles while maintaining altitude would have increased control forces, not reduce them.
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As an AvCanada discussion grows longer:
-the probability of 'entitlement' being mentioned, approaches 1
-one will be accused of using bad airmanship
The Ethiopian FDR shows column input and has a maximum range. The graphs show control column position, not “force”. When the aircraft accelerates to VMO it is very clear that the control column position is fully aft, ie the only thing that saved them was increasing the airspeed as the elevator was fully aft at the time. According to the radar altimeter they were 1000 feet AGL at this time. If the aircraft would have been going slower, it would have crashed. The aircraft was flying at maximum lift, due to the commanded nose down trim of MCAS. This event happens 100 seconds into the flight, full aft elevator deflection due to nose down trim, the only recourse to keep the plane flying is full power.
After the aircraft accelerated to VMO, you’re right it took about 1/2 column input to keep the aircraft flying, thankfully they were going that fast! And thank you for proving my point.
Now it could have been possible to reduce the thrust before this event, but why? Do you always reduce thrust on takeoff? Pull the throttles back when you get a stall indication? Reduce thrust on takeoff because there’s a problem? Now if Boeing had done a proper job of trading pilots on MCAS, perhaps there would have been a training drill to reduce thrust and airspeed with the anticipation of nose down trim.
Read my post again.....I said ET302 shows column position and Lion air shows column force. A disclaimer the they are not quite the same as I was comparing the 2 flights in which Lion air was able to control the aircraft just fine without going Mach 2 with their hair on fire.
As for ET302 position - they only reached full back yoke At roughly 05:43:35 during the final dive...about 8 secs before they hit the ground. Pior to that they were at approx. half yoke deflection the whole time they were at VMO. So no - your theory is full of holes. Read again - the more out of trim you are with higher airspeed - the more nose down force you get, and hence - the more back pressure you need to maintain level flight.
the only recourse to keep the plane flying is full power.
No it's not....the simple thing is to push that little switch on the Column under your right thumb called a trim switch. Works like a charm - and the FDR data proves that!
No they reached full aft column 100s in. At that time the MCAS had trimmed fully nose down. They did trim the nose up, enough to get the aircraft flyable and climbing away from the ground, when the GPWS warning stopped, they hit the trim cutout switches.
They did trim the aircraft, then actioned the drill like they were supposed to.
There are no holes, keep dreaming with your emotional bias. The aircraft is not flyable with full nose down trim without excessive airspeed.
You seem pretty bent out of shape about which God is which. Don’t you know all Gods are made up anyway.
I would think that an atheist has these opinions. The majority of homosapiens living on this 3rd rock from the son believe in some sort of god or gods, and who am I to get bent out of shape for that simple reality, The problem is when certain "religions" believe in a "god" that tells them they are superior and everyone else is inferior and also commands them to hate the inferior ones and subdue them and conquer them and kill them! That's when I have a little problem with religion ! IF YOU were living in certain countries that the majority had the above ideology and YOU were the infidel, then I would imagine that you would a little concern about what this "god" is and why are they persecuting you and what can be done to stop the pain and suffering !
No they reached full aft column 100s in. At that time the MCAS had trimmed fully nose down. They did trim the nose up, enough to get the aircraft flyable and climbing away from the ground, when the GPWS warning stopped, they hit the trim cutout switches.
They did trim the aircraft, then actioned the drill like they were supposed to.
There are no holes, keep dreaming with your emotional bias. The aircraft is not flyable with full nose down trim without excessive airspeed.
It was not quite fully back at that point - and that was only in response to the nose down trim - it last only a second or so. As the stab moved nose up - the column was relaxed. So - your statement about only flying faster to stay aloft is not true.
Now if they held that trim another 10 secs - they would have trimmed the airplane for normal flight and landed just fine. So no - they did not action the drill as they were supposed to. The only reason the stab got so far out of trim was because they let it.
I'm not sure mach tuck had any effect on the accidents. Their speeds at low altitude were fairly low.
You keep bringing up new subjects and keep deflecting my original question: why would it have helped to reduce the throttles? Reducing the throttles while maintaining altitude would have increased control forces, not reduce them.
I'm not sayin it did. Mach trim kicks in at Mach 0.6 which is roughly 400 kts. They were doing 350 kts so they weren't that fast - but they weren't that slow either. My point was - you were saying the only way they could stay up was to go faster, faster, faster...thinking the nose would come up due to increased lift - I'm simply saying that that is not the case - you get to a point where the nose will drop whether you like it or not due to aerodynamic forces (Mach tuck)
I'm not deflecting anything. Your claim of reducing the throttles would have increased forces is not true. Again - with a grossly mis-trimmed airplane the forces will increase with a higher speed. The increased lift provided by higher speed is negligible compared to the forces acting on a stab that is - for all intents and purposes - hanging down in the breeze.(aerodynamically). In any case - there are many different dangers of exceeding the VMO of an aircraft.
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Last edited by boeingboy on Mon Oct 21, 2019 4:37 pm, edited 1 time in total.
I'm not deflecting anything. Your claim of reducing the throttles would have increased forces is not true. Again - with a grossly mis-trimmed airplane the forces will increase with a higher speed. The increased lift provided by higher speed is negligible compared to the forces acting on a stab that is - for all intents and purposes - hanging down in the breeze.(aerodynamically)
Why is this not true? If the stab was hanging in the breeze (stalled/ineffective/useless) the plane would have crashed right away. It didn't, it was doing its job, albeit at an undesired angle.
Look at this FAA AD triggered by an unrelated accident in 737-8. It talks about the most basic trim/column forces, and then all the added augmentation. https://www.satcom.guru/2018/11/stabilizer-trim.html. The actual AD doesn't matter for our discussion, but it has a graph that shows that what I'm saying is true for transport category jets as well.
Figure 4 is what I am referring to:
Why would this relationship not be valid in the MCAS runaway case?
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As an AvCanada discussion grows longer:
-the probability of 'entitlement' being mentioned, approaches 1
-one will be accused of using bad airmanship
When I said it was hanging in the breeze - I meant aerodynamically - not literally. A very simple demonstration can be done in your car....drive at 40 MPH with you hand at a given angle, now - without changing the angle of your hand, increase to 70 MPH and keep your hand at the same elevation. The force acting on your hand increases as a result of higher speed and you apply a higher force to compensate.
The graph you posted has to do with desired stick forces. Your now getting into the Speed trim system which is a stability augmentation system. If you actually read through that section it explains it well - it also states you have a well trimmed airplane. A higher than normal trim setting (+ or -) and an out of control airspeed is not a well trimmed airplane.
"Stability augmentation for both phugoid and stick force gradient can be achieved simply by providing a small stabilizer offset. The offset is scaled such that the stabilizer trims nose down as the airplane slows down, and conversely stabilizer trims nose up as the airplane speeds up."
Speed trim is really much more complicated than what is going on with a seriously out of trim stab.
Nice try with the name calling, doesn't work with me ! Facts are facts !
Yes... facts are facts! You tried to claim that because the pilot was Ethiopian, he was likely Muslim; I countered with the FACT that Ethiopia has a Christian majority, so your assumption was mathematically incorrect.
I then described you as a bigot, because you seem to associate the pilots’ religion with their performance. Having flown with people from all around the world, of many different faiths, I cannot support this correlation. Using the OED definition, “a person who is intolerant toward those holding different opinions.”, I thought this was an appropriate description.
I would think that an atheist has these opinions. The majority of homosapiens living on this 3rd rock from the son believe in some sort of god or gods,
I was an atheist until I started flying outside of Canada for a living and then I found my God, Benjamin Franklin who never ever let me down.
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Last edited by C.W.E. on Mon Oct 21, 2019 5:38 pm, edited 1 time in total.
boeingboy wrote: ↑Mon Oct 21, 2019 5:00 pm
When I said it was hanging in the breeze - I meant aerodynamically - not literally. A very simple demonstration can be done in your car....drive at 40 MPH with you hand at a given angle, now - without changing the angle of your hand, increase to 70 MPH and keep your hand at the same elevation. The force acting on your hand increases as a result of higher speed and you apply a higher force to compensate.
Yes, that is Lift and Drag. It does seem logical that a stabilizer at high angles of attach generates more drag.
Let me ask you this: why would a 737 with a stabilizer trim behave aerodynamically differently than a 172 with a trim tab or a metro with a stabilizer trim (just picking random differently sized airplanes, feel free to replace it with types of similar size)?
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As an AvCanada discussion grows longer:
-the probability of 'entitlement' being mentioned, approaches 1
-one will be accused of using bad airmanship
No they reached full aft column 100s in. At that time the MCAS had trimmed fully nose down. They did trim the nose up, enough to get the aircraft flyable and climbing away from the ground, when the GPWS warning stopped, they hit the trim cutout switches.
They did trim the aircraft, then actioned the drill like they were supposed to.
There are no holes, keep dreaming with your emotional bias. The aircraft is not flyable with full nose down trim without excessive airspeed.
It was not quite fully back at that point - and that was only in response to the nose down trim - it last only a second or so. As the stab moved nose up - the column was relaxed. So - your statement about only flying faster to stay aloft is not true.
Now if they held that trim another 10 secs - they would have trimmed the airplane for normal flight and landed just fine. So no - they did not action the drill as they were supposed to. The only reason the stab got so far out of trim was because they let it.
You’re reading the graph with an intentional bias. At full power with the aircraft nose down, losing altitude, it lost over 1000 feet agl, it doesn’t take long to get to VMO. The control column was only relaxed after they electrically trimmed the aircraft. And were once again climbing. Then they hit the cutout switches.
They did do the drill perfectly correct, the drill does not call for “trim the aircraft electrically to perfect balance before hitting the cutout switches. It says cutout switches, then trim manually, which they did. Unfortunately they weren’t able to successfully trim the aircraft with the cutout switches off.
You can argue your point all you want but at the end of the day you are wrong, and your beloved Boeing machine is grounded - and for good reason.
I don't think the crews reluctance to reduce thrust was so much related to trim speed as it was due to the pitching moments. In most twin engined jets with large underslung engines, there is a marked pitch up moment with thrust increase and an equally large nose down pitch moment with a thrust decrease. And relative to the size of the aircraft and its elevators, the Max has very large engines that are very underslung. That is in fact the whole genesis of the original problem!
This effect is very noticeable on the B777 and also the A320/A330. In fact in many jet transport AOM's recommend forward elevator input to keep weight on the nosewheel during thew early stages of the take off roll for exactly the reason. Maybe somebody with Max operating experience can comment.
With this in mind, I can certainly see that if it is taking 110% effort just to keep the airplane level, at low altitude pulling the power back and removing the nose up pitching moment would probably be a guaranteed way to meet your God .... whatever flavor that may be. (See, I am following the previous posts!). Coupled with the inability to retrim the airplane manually, it was probably doomed from the outset. I am going to be near a Max sim in the next week, if I can get in to it I will give it a go and report back.
The sim will mimic the pitch force/thrust relationship. If I can I will also manually mis-trim it and see how ugly it is. I know check pilots have had their eyes opened playing with it.
