Ethiopian plane crash
Discussion
hidetheelephants said:
It wouldn't meet FAA airworthiness requirements, that's why they fitted MCAS in the first instance; having an airliner with uncommanded pitch-up when you open the taps isn't a particularly good idea.
Pretty much every pre fly by wire jet I’ve flown pitches nose up with power increases. On many you have to apply forward control column pressure in a go around to counter it. I remember some of the 767s I flew even took power off in a go around at light weights to maintain the go around rate of climb.
Didn’t the soux city guys control the DC10 in pitch using thrust when they lost all the hydraulics?
El stovey said:
Pretty much every pre fly by wire jet I’ve flown pitches nose up with power increases.
On many you have to apply forward control column pressure in a go around to counter it. I remember some of the 767s I flew even took power off in a go around at light weights to maintain the go around rate of climb.
Didn’t the soux city guys control the DC10 in pitch using thrust when they lost all the hydraulics?
Yes they did. I believe some of the newer stuff even has the ability to fly using just the throttles for just this situation. I know after soul city NASA and Boeing developed a system where the pilot uses the control yoke to fly the plane and the computers would alter the throttle to try and mimic that movement using the auto throttle. On many you have to apply forward control column pressure in a go around to counter it. I remember some of the 767s I flew even took power off in a go around at light weights to maintain the go around rate of climb.
Didn’t the soux city guys control the DC10 in pitch using thrust when they lost all the hydraulics?
I know speaking to some of our flight engineers and pilots that at low weight go arounds do indeed require a known engine power which the engineer calculates pre landing. In the event of a go around full throttle would generate significant pitch up and requires significant nose down pressure from the skipper. To prevent this they only go to a pre calculate power setting.
Lemming Train said:
If they don't fly until some time in March as predictions are going with, that's approx 125 further frames to find parking spots for if they continue production. They've just about run out of space on their own land so it's likely they'd have to start paying for storage at places like Victorville and Marana. I expect the companies at both those locations will be rubbing their fat hands together waiting for the phone to ring so they can give Boeing some obscene prices, knowing they're up s
t Creek.
Boeing presumably considers those costs to be prohibitive vs stopping the line, especially if the FAA continue to drag their heels with the recertification.
To give you some numbers of the current situation, they have 402 undelivered frames parked up :
232 at Grant County
72 at Kelly Field
8 at Paine Field
84 at Boeing Field (some currently production flight testing)
6 in storage at the factory at Renton
On top of this there are (based on the monthly production cut since the grounding) approx 100+ fuselage barrels at Wichita and stored on train carriages in sidings because the Renton factory can't take them. By March you'd add approx another 30 to that count if production continued as per Boeing instruction - space that I doubt Spirit have available, nor does Renton which already has 100+ fuselages stacked up ready to come on the train.
Something has to give.
Fuselage barrels piled up at Spirit Aero, Wichita :t Creek.Boeing presumably considers those costs to be prohibitive vs stopping the line, especially if the FAA continue to drag their heels with the recertification.
To give you some numbers of the current situation, they have 402 undelivered frames parked up :
232 at Grant County
72 at Kelly Field
8 at Paine Field
84 at Boeing Field (some currently production flight testing)
6 in storage at the factory at Renton
On top of this there are (based on the monthly production cut since the grounding) approx 100+ fuselage barrels at Wichita and stored on train carriages in sidings because the Renton factory can't take them. By March you'd add approx another 30 to that count if production continued as per Boeing instruction - space that I doubt Spirit have available, nor does Renton which already has 100+ fuselages stacked up ready to come on the train.
Something has to give.
https://twitter.com/violetpilot1/status/1207455887...
MB140 said:
Yes they did. I believe some of the newer stuff even has the ability to fly using just the throttles for just this situation. I know after soul city NASA and Boeing developed a system where the pilot uses the control yoke to fly the plane and the computers would alter the throttle to try and mimic that movement using the auto throttle.
I know speaking to some of our flight engineers and pilots that at low weight go arounds do indeed require a known engine power which the engineer calculates pre landing. In the event of a go around full throttle would generate significant pitch up and requires significant nose down pressure from the skipper. To prevent this they only go to a pre calculate power setting.
I presume you meant "Sioux City" I know speaking to some of our flight engineers and pilots that at low weight go arounds do indeed require a known engine power which the engineer calculates pre landing. In the event of a go around full throttle would generate significant pitch up and requires significant nose down pressure from the skipper. To prevent this they only go to a pre calculate power setting.
Eric Mc said:
MB140 said:
Yes they did. I believe some of the newer stuff even has the ability to fly using just the throttles for just this situation. I know after soul city NASA and Boeing developed a system where the pilot uses the control yoke to fly the plane and the computers would alter the throttle to try and mimic that movement using the auto throttle.
I know speaking to some of our flight engineers and pilots that at low weight go arounds do indeed require a known engine power which the engineer calculates pre landing. In the event of a go around full throttle would generate significant pitch up and requires significant nose down pressure from the skipper. To prevent this they only go to a pre calculate power setting.
I presume you meant "Sioux City" I know speaking to some of our flight engineers and pilots that at low weight go arounds do indeed require a known engine power which the engineer calculates pre landing. In the event of a go around full throttle would generate significant pitch up and requires significant nose down pressure from the skipper. To prevent this they only go to a pre calculate power setting.
hidetheelephants said:
Presumably there is a magnitude of pitch-up, or a magnitude/applied force of opposing control beyond which the regulator decides it's not allowed? I will concede to the gentleman with the ATPL.
Quite probably, I don’t really know what magnitude is acceptable and on fly by wire it’s not really an issue, depending on the aircraft and how the control laws work. The 737 max isn’t really fly by wire (except the spoilers) I was just saying, and I’m sure you know anyway, pitching up with a power increase is quite normal on pre fly by wire jets, on modern fly by wire jets this is all controlled by computers and increasing power just accelerates you in the direction you’re pointing and you have to pullback if you want to climb after increasing power.
Without opening a can of worms, this isn’t just for jets but most aircraft with a low thrust line will pitch up with power increases due to the thrust line being below the CofG and also then exacerbated by also being below the aircraft drag line. On prop aircraft this affect can also be influenced by the position of the tailplane and airflow over it.
I’m sure you knew all this anyway, I expect you’re talking about the amount of pitch up not just the fact that it will pitch up.
Like this.
Lemming Train said:
Fuselage barrels piled up at Spirit Aero, Wichita :
https://twitter.com/violetpilot1/status/1207455887...
Hot dog! https://twitter.com/violetpilot1/status/1207455887...
El stovey said:
hidetheelephants said:
Presumably there is a magnitude of pitch-up, or a magnitude/applied force of opposing control beyond which the regulator decides it's not allowed? I will concede to the gentleman with the ATPL.
Quite probably, I don’t really know what magnitude is acceptable and on fly by wire it’s not really an issue, depending on the aircraft and how the control laws work. The 737 max isn’t really fly by wire (except the spoilers) ie. if the pilot is putting it towards a stall the aircraft actually helps them do it.
Hence the "fix" to automatically trim nose down at that point and increase the force on the controls to something more linear.
JuniorD said:
Lemming Train said:
Fuselage barrels piled up at Spirit Aero, Wichita :
https://twitter.com/violetpilot1/status/1207455887...
Hot dog! https://twitter.com/violetpilot1/status/1207455887...
Even if they fix MCAS with feeds from both sensors, the issue could return if sensor A is destroyed and Sensor B is borked already. Why not use 4 sensors dispersed and then work from opposing symmetry?
I understand it that SE bought their planes with 5 sensors - wonder if they were strongly advised to?
I understand it that SE bought their planes with 5 sensors - wonder if they were strongly advised to?
Drihump Trolomite said:
Even if they fix MCAS with feeds from both sensors, the issue could return if sensor A is destroyed and Sensor B is borked already. Why not use 4 sensors dispersed and then work from opposing symmetry?
I understand it that SE bought their planes with 5 sensors - wonder if they were strongly advised to?
You're hypothesising something very remote. All redundancy/duplicate/triplicate system decisions come down to risk vs cost.I understand it that SE bought their planes with 5 sensors - wonder if they were strongly advised to?
SE (XL Airways France) didn't operate 737's before it went bust but airlines like Southwest went for two AOA sensors. They probably didn't appreciate at the time why that would be such a good decision when MCAS behaviour wasn't understood. If an airframer makes something optional airlines will come to different decisions based on their knowledge, the published "benefit" and the cost. Boeing simply shouldn't have made it optional.
if two sensors are placed at risk locations (as the AOA sensors are on the Max) it is very reasonable to expect if one gets damaged the other could in the same strike or other damage is easy - https://airlinerwatch.com/boeing-never-tested-aoa-...
"The original software design is relying on data from a single Angle of Attack (AOA) sensor. The experts say these sensors are vulnerable to defects and can be easily damaged."
"The original software design is relying on data from a single Angle of Attack (AOA) sensor. The experts say these sensors are vulnerable to defects and can be easily damaged."
Less stable yet but still controllable with the correct training which where Boeing started with the shortcuts.
I wonder if some of the issues may be around the limited processing capability of the main flight control CPU. This was touched on earlier. The CPU is very old and has to used the same memory addresses for multiple data and sometimes get confused and overloaded. Net effect is that it needs replacing but Boeing will not do that due to costs and delay time. Where have we heard that before?
Side note. The original CPU was developed using some military technology and pushed out the civil market without this being spotted. Boeing got a real rocketing for the unauthorised export to everywhere the 737 fleet had been to. Oops!
I wonder if some of the issues may be around the limited processing capability of the main flight control CPU. This was touched on earlier. The CPU is very old and has to used the same memory addresses for multiple data and sometimes get confused and overloaded. Net effect is that it needs replacing but Boeing will not do that due to costs and delay time. Where have we heard that before?
Side note. The original CPU was developed using some military technology and pushed out the civil market without this being spotted. Boeing got a real rocketing for the unauthorised export to everywhere the 737 fleet had been to. Oops!
Speed 3 said:
MCAS was introduced to counter poor airmanship in go-arounds loss of control (at least a couple of crashes) due to the thrust line on TOGA power. The Max is even more vulnerable than the NG's & Classics in this respect. At this point of public opinion trading one reason for crashing for another isn't going to work so Boeing will be holding onto MCAS on the 737, just making it less invasive and less (falsely) trigger-happy.
https://assets.publishing.service.gov.uk/media/542... - Thomson 737-300 ended up flying at a 44 degree angle at 80kts after a fluffed go around at Bournemouth Edited by Speed 3 on Wednesday 18th December 20:00
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