China Airlines goes down with 132 souls on board

Larry in TN said:
https://en.wikipedia.org/wiki/Coffin_corner_(aerodynamics)

It's not a factor at FL291 in a 737-800.


There is no boom. There is a constant pressure wave moving along with the supersonic airplane formed by the transition between sub-sonic and super-sonic flow--the shockwave. As this pressure wave passes those outside the airplane, they perceive the rapid change in pressure as a sonic boom.

The high-speed or mach stall is when the shockwave disrupts airflow above the wing in a manner very similar to a low-speed stall. The result is the same. Loss of airflow causes the wing to stall.

Coffin corner is when your low-speed, and high-speed stall speeds converge. Going faster, or slower, results in a stall. The only way out of it is to descend.

The 737 is thrust-limited so it doesn't have the power to climb to an altitude where it becomes an issue. Or, at least, it would be very difficult to get to such an altitude.
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can you you/anyone explain what you mean by thrust-limited?
 
EricVKX said:
can you you/anyone explain what you mean by thrust-limited?
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When the airplane reaches an altitude, based on prevailing weight, where it does not have enough thrust to maintain a specific rate of climb (especially when banking) It is said to be at it's thrust limited altitude.
 
Sifossifoco said:
https://nypost.com/2022/03/21/the-moment-china-eastern-boeing-737-nosedives-before-fiery-crash/

"was en route to Guangzhou when it crashed at about 2:30 p.m. local time"
"Contact with the plane was lost at about 2:15 p.m."

It still looks like somebody wasn't talking on the radio for a while before the drop. Like everyone else I am just guessing and speculating, but it does look unusual to have no communication for 15 minutes. I apologize if it doesn't make sense to people with much more experience than me, and I would be very curious to hear the opinion of someone with solid knowledge of 737s.
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Dan already solved this one. I think were done here. He indicated that there is no way for that 737 to fly like that without pilot inputs. Ok now from actual 737/jet drivers is that true?
 
Flying Doc said:
Dan already solved this one. I think were done here. He indicated that there is no way for that 737 to fly like that without pilot inputs. Ok now from actual 737/jet drivers is that true?
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Having only a few hundred hours on the 737, 31,000 fpm seems pretty steep. During a rapid de pressurization I think we saw 10000fpm, with full speed brakes, autopilot on and at the barber pole in the sim. I don’t remember the descent rate being much more than that. Couldn’t tell you exactly though. Could be wrong though.
 
EricVKX said:
can you you/anyone explain what you mean by thrust-limited?
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You max altitude can be limited by the wing, if it's incapable of producing the lift it needs to go higher, or the thrust.

In the old DC8, we were limited by the wing. Our max altitude was calculated based on how much margin we had between our low-speed buffet and high-speed buffet.

In the 737 we are thrust limited. Even when max continuous thrust isn't able to keep us climbing, we still have a comfortable buffet margin.

I was in a fully loaded (pax) 737-900 today at FL340. There was more than 75 knots between our low-speed buffet and our high-speed buffet. I say "more than" because the hi-speed buffet was higher than Mmo (M0.82) so it wasn't displayed on the airspeed tape.

Flying Doc said:
Dan already solved this one. I think were done here. He indicated that there is no way for that 737 to fly like that without pilot inputs. Ok now from actual 737/jet drivers is that true?
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I have no idea what that means.

The airplane was in an upset. It was stalled, high-speed or low-speed, I don't know. It was no longer flying. What was needed was the correct control inputs to affect a recovery (Push, Roll, Thrust, Stabilize). They still would have lost many thousands of feet in the recovery but they would have recovered.

The question we have to answer is, what caused the upset?
 
Larry in TN said:
The question we have to answer is, what caused the upset?
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FYI: according to the latest they found a piece of wreckage 6 miles from the impact crater but don't know if was from prior to or after the inflight "upset." Plus they started to listen to the CVR today.
 
Larry in TN said:
...
The question we have to answer is, what caused the upset?
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According to Dan Gryder, it was the pilot or F/O, acting intentionally.
But we know maintenance and simple incompetence can cause such things, and I'll lean that way until evidence suggests otherwise.
 
We can spin whatever tale we like. We certainly aren't going to hear the truth from the Chinese. Question for the jet jocks here. If I point my spam can direct south the thing won't keep headed that way unless I push hard on the stick. The airplane has a tendency to just pull out of a dive. Don't jets do that too?
 
There was mention of part(s) from this plane found 6 or more miles away? Depending on what, could get harder to fly without critical control surfaces.

Then we can back up to the reason/cause for the ‘upset’, then inflight breakup. During ‘normal’ flight parameters, parts falling off would be most uncommon. With severe over stress, anything’s possible.
 
Yep, they do. Fast equals more lift, starts to recover. Especially nice stable ones. Little pointy maneuverable ones not as much. Also, speed can develop fast enough to get into Mach tuck which exacerbates the problem.
 
steingar said:
The airplane has a tendency to just pull out of a dive. Don't jets do that too?
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Your airplane doesn't know if it's in a dive or not. All it knows is velocity is increasing and it will try to return to it's last trimmed airspeed - it can accomplish this only if the wings are somewhere close to level.
 
martym said:
Your airplane doesn't know if it's in a dive or not. All it knows is velocity is increasing and it will try to return to it's last trimmed airspeed - it can accomplish this only if the wings are somewhere close to level.
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Brainiac, as the speed increases so does the lift off the wings. It therefore has an inherent tendency to pull out of a dive, unless I keep the stick full forward which can get difficult as airspeed increases. If I let the stick go the airplane will pull itself out of a dive. It doesn't have to "know" anything, it's pretty simple physics. I would assume jets to the same thing.
 
steingar said:
Brainiac, as the speed increases so does the lift off the wings. It therefore has an inherent tendency to pull out of a dive, unless I keep the stick full forward which can get difficult as airspeed increases. If I let the stick go the airplane will pull itself out of a dive. It doesn't have to "know" anything, it's pretty simple physics. I would assume jets to the same thing.
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That’s only true in airplanes that have positive stability. I’m not sure about airliners but my sonex has neutral stability. If I point the nose down it stays there regardless of the speed it gains. It makes it a horrible IFR platform but a blast to fly aerobatics in.
 
Sifossifoco said:
The theory that one of the pilots was in the bathroom and the other went mad is a tempting explanation
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f you drive a Jet: Please go to the bathroom before the flight, for the safety of the passengers. This way I can watch my movie and eat stale biscuits without worry.
 
Flying Doc said:
f you drive a Jet: Please go to the bathroom before the flight, for the safety of the passengers. This way I can watch my movie and eat stale biscuits without worry.
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They served you biscuits? All I got was 4oz of sprite and a crushed bag of pretzels!
 
The third pilot was probably a newby getting some sort of IOE. Riding the jump seat as an observer is not uncommon for new pilots. We often used it for part of the IOE requirement.
It's a really good experience for new hires, or even transitioning to a new plane. I often took the opportunity on new airplanes to observe the real world, wither required or not. Looks like one of the pilots had lots of experience. Was he a check airman? Was he giving IOE? Lots of questions, and lots of speculation. The forensic experts are really good at putting things together if given the chance. Give them the chance.
 
Seen on another forum where someone said debris is being found buried as far down as 60' in the dirt.
 
steingar said:
Brainiac, as the speed increases so does the lift off the wings.
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and if the resultant lift vector is pointing in an undesirable direction it may exacerbate, not resolve the situation.
 
martym said:
and if the resultant lift vector is pointing in an undesirable direction it may exacerbate, not resolve the situation.
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Lift vector is usually roughly perpendicular to the wings. All things being equal that in and of itself should pick up the nose.
 
steingar said:
Lift vector is usually roughly perpendicular to the wings. All things being equal that in and of itself should pick up the nose.
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unless it's inverted in which case "up" has a new meaning.
 
Flying Doc said:
f you drive a Jet: Please go to the bathroom before the flight, for the safety of the passengers. This way I can watch my movie and eat stale biscuits without worry.
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Hey, some of us have to pee as soon as the wheels leave the runway, regardless of our last trip.
 
Kenny Phillips said:
Sixty feet is an almost impossible number, unless the ground is swampy.
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Didn't say that I agreed with what was said mostly because it sounds so incredible, I don't know what they may have known or, as you noted, how soft the terrain might have been. Needless to say there was a large smoking crater where it plowed into mother Earth. 8~(
 
Larry in TN said:
Chinese airlines fly with three pilots in the cockpit.
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You sure about that? Is that a fact or urban legend? I'm see Chinese crews all the time, and although I haven't been keeping an eye on it, I think I'm sure I've seen 2-pilot crews. I'll have to keep a look out next week.
 
I have flown on several Chinese domestic airline flights including a couple on China Eastern. I never noticed a tendency to have a three man crew though I guess it is possible. I am fairly observant and am the type that likes to watch as much of the operation as possible so I would hope I’d have noticed. Then again, the cabin crew tend to be distracting.

What I have noticed are professional, proficient and efficient operations and smooth flights. And yes, I know my small sample size is statistically insignificant and will not impact anyone’s opinion on the subject of their pilots and operations.
 
Well let's hope that history does not have a morbid way of repeating itself because prior to the TWO 737-MAX crashes there were TWO identical crashes of 737-200's - United flight 585 in Colorado (1991) and USAir flight 427 in Pennsylvania (1994) caused by faulty rudder PCU's. FWIW they both had lawn-dart trajectories to the crash site.
 
Silvaire said:
Well let's hope that history does not have a morbid way of repeating itself because prior to the TWO 737-MAX crashes there were TWO identical crashes of 737-200's - United flight 585 in Colorado (1991) and USAir flight 427 in Pennsylvania (1994) caused by faulty rudder PCU's. FWIW they both had lawn-dart trajectories to the crash site.
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USAir Flight 427 was a Boeing 737-300, with CFM56 turbofan engines.
 
steingar said:
Lift vector is usually roughly perpendicular to the wings. All things being equal that in and of itself should pick up the nose.
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By definition, the lift vector is perpendicular to the relative wind.

What was that Chinese plane crash in California a few years back, where it hit a berm on takeoff or landing? I don't recall all the details, but IIRC one of the pilots was relatively inexperienced and there was a check pilot or something like that in the cockpit and there was some talk of an Asian reluctance of a junior to contradict a senior pilot even when that senior pilot was wrong?

That was down low where there's not much time to react, though, here there should have been time to fix things unless it was mechanical failure or deliberate action.
 
Dana said:
What was that Chinese plane crash in California a few years back, where it hit a berm on takeoff or landing? I don't recall all the details, but IIRC one of the pilots was relatively inexperienced and there was a check pilot or something like that in the cockpit and there was some talk of an Asian reluctance of a junior to contradict a senior pilot even when that senior pilot was wrong?

That was down low where there's not much time to react, though, here there should have been time to fix things unless it was mechanical failure or deliberate action.
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That sounds like Asiana 214 into SFO. Asiana is a *Korean* carrier.

Nauga,
continentally drifted
 
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