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Could the pilot of flight JT610 have overridden the autopilot by sheer force?
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A New York Times article from today about the crash of flight JT610 claims that in order to wrest control over the plane from the autopilot,
Captain Suneja could have braced his feet on the dashboard and yanked the yoke, or control wheel, back with all his strength.
Is that true? If so, what is the underlying mechanism? Is the system designed such that it can be overridden simply by applying an unusually strong force or would that be just a violent and "unofficial" way to control the yoke despite the best efforts of the autopilot?
A design which would allow a pilot to control the plane even in autopilot mode just by applying excessive and unusual force (as opposed to perform a complicated series of button presses and/or touch screen actions to disable the autopilot) would in my opinion make a lot of sense.
I understand that the main flight controls of this recent incarnation of the Boeing 737, the MAX 8, are still hydraulic. Does that play a role in the "override by sheer force" possibility?
boeing-737 autopilot accident-investigation hydraulic-system
asked 3 hours ago
Peter A. Schneider
1146
add a comment |
up vote
1
down vote
favorite
A New York Times article from today about the crash of flight JT610 claims that in order to wrest control over the plane from the autopilot,
Captain Suneja could have braced his feet on the dashboard and yanked the yoke, or control wheel, back with all his strength.
Is that true? If so, what is the underlying mechanism? Is the system designed such that it can be overridden simply by applying an unusually strong force or would that be just a violent and "unofficial" way to control the yoke despite the best efforts of the autopilot?
A design which would allow a pilot to control the plane even in autopilot mode just by applying excessive and unusual force (as opposed to perform a complicated series of button presses and/or touch screen actions to disable the autopilot) would in my opinion make a lot of sense.
I understand that the main flight controls of this recent incarnation of the Boeing 737, the MAX 8, are still hydraulic. Does that play a role in the "override by sheer force" possibility?
boeing-737 autopilot accident-investigation hydraulic-system
asked 3 hours ago
Peter A. Schneider
1146
add a comment |
up vote
1
down vote
favorite
up vote
1
down vote
favorite
A New York Times article from today about the crash of flight JT610 claims that in order to wrest control over the plane from the autopilot,
Captain Suneja could have braced his feet on the dashboard and yanked the yoke, or control wheel, back with all his strength.
Is that true? If so, what is the underlying mechanism? Is the system designed such that it can be overridden simply by applying an unusually strong force or would that be just a violent and "unofficial" way to control the yoke despite the best efforts of the autopilot?
A design which would allow a pilot to control the plane even in autopilot mode just by applying excessive and unusual force (as opposed to perform a complicated series of button presses and/or touch screen actions to disable the autopilot) would in my opinion make a lot of sense.
I understand that the main flight controls of this recent incarnation of the Boeing 737, the MAX 8, are still hydraulic. Does that play a role in the "override by sheer force" possibility?
boeing-737 autopilot accident-investigation hydraulic-system
asked 3 hours ago
Peter A. Schneider
1146
A New York Times article from today about the crash of flight JT610 claims that in order to wrest control over the plane from the autopilot,
Captain Suneja could have braced his feet on the dashboard and yanked the yoke, or control wheel, back with all his strength.
Is that true? If so, what is the underlying mechanism? Is the system designed such that it can be overridden simply by applying an unusually strong force or would that be just a violent and "unofficial" way to control the yoke despite the best efforts of the autopilot?
A design which would allow a pilot to control the plane even in autopilot mode just by applying excessive and unusual force (as opposed to perform a complicated series of button presses and/or touch screen actions to disable the autopilot) would in my opinion make a lot of sense.
I understand that the main flight controls of this recent incarnation of the Boeing 737, the MAX 8, are still hydraulic. Does that play a role in the "override by sheer force" possibility?
boeing-737 autopilot accident-investigation hydraulic-system
boeing-737 autopilot accident-investigation hydraulic-system
asked 3 hours ago
Peter A. Schneider
1146
asked 3 hours ago
Peter A. Schneider
1146
edited 3 hours ago
asked 3 hours ago
Peter A. Schneider
1146
asked 3 hours ago
Peter A. Schneider
1146
asked 3 hours ago
Peter A. Schneider
1146
1146
add a comment |
add a comment |
2 Answers
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Im not sure of the full story here. But if you pull the controls of a 737 while the autopilot is engaged the autopilot will trip and the pilots will have to fly the plane manually, this requires about 25 lbs of force.
There is also a button on the yoke where you can disengage the AP. So if the AP was controlling the plane and going in to a violent descent the pilots should have been able to cancel it by pulling the yoke or pushing the button on the yoke or the AP panel.
And no, the controls being hydraulic doesn't play a role in the "override by sheer force" possibility.
Edit:
The autopilot servos are limited to 25 lb of force for single channel operation. Separate force sensors measure pilot column input and the autopilot will disconnect if the force applied by the pilot(s) exceeds 21 lbs.
answered 2 hours ago
Douglas Pettersson
1413
New contributor
Douglas Pettersson is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Why would the override be only triggered on such high stick forces? 25 lbs sounds like a decent amount of force.
– curious_cat
2 hours ago
I'm not sure why they constructed the plane this way. But my guess is that the underlying cause is margin for error without disconnecting the AP. 21-25 lbs of force is not really that much especially not in an emergency, just give the yoke a solid "pull" and it'll be enough. Keep in mind it's force and not pressure
– Douglas Pettersson
2 hours ago
@curious_cat I would assume that it's a safety requirement that disengaging the autopilot requires a conscious act by the pilots. 21 lbs of force are probably high enough to not be exerted accidentally but still low enough to be produced ad hoc. (21 lbs seem to contradict the "feet on the dashboard" bit in the article. OK, maybe one needs a bit of pushing against the dashboard because it's a horizontal force.)
– Peter A. Schneider
1 hour ago
Thank you for the answer. Can you give us the source of your quote?
– Peter A. Schneider
1 hour ago
Hi, the data i quoted can be read here: b737.org.uk/incident_ei-ebw.htm
– Douglas Pettersson
9 mins ago
add a comment |
up vote
1
down vote
With typical hydraulic controls, the mechanical control cable circuit just operates control valves on the hydraulic actuators. The control valves normally only have fairly light centering springs that take only a few pounds of force to overcome. With no other devices in the control circuit, you could move the control column with your pinky finger.
Control feedback forces come from pitch feel devices in the control circuit that use internal spring packs (bungees) and/or roller cam devices to provide a variable resistive force. But the feel units won't drive the circuit, only provide resistance. Two devices can drive the elevator circuit in theory; the autopilot servo and the stick pusher (which is like an autopilot servo that only operates one way).
Autopilot and stick pusher servos have two clutches, a meshing teeth on/off clutch, and a friction slip override clutch. If the A/P servo runs away for some reason, and you can't trigger a disconnect electrically, it is possible to overpower the slip clutch in the servo, but it is like the stick is in not-quite-solidified concrete the whole time you are trying to move it. But you can move it.
The stick pusher servo is similar, but the stick pusher is designed to drive full nose down and release almost immediately.
In any case, if you had an elevator hard over like that and the electrical disconnects (there are usually several difference switches that can perform the disconnect function), the next action would be to operate the mechanical pitch disconnect to separate the left and right elevator circuits. You end up with one free elevator, which will give some control, at least enough to neutralize the overall input.
One possibility is the shock and surprise of the event, whatever it was, overwhelmed the crew and they didn't follow through on all the memory items for that kind of emergency. At this point, who knows.
Also remember that media stories on these kinds of incidents are almost always wildly inaccurate. Anyone who has worked in any kind of technical specialty and reads media reports related to their specialty knows that they are wrong most of the time.
answered 1 hour ago
John K
10.8k1132
Thanks for the details. (Btw, I have more confidence in the NYT than in most others. They pay a lot of attention to factual correctness and do publish corrections. If you think the article is factually incorrect don't hesitate to send a correction; they surely appreciate it.)
– Peter A. Schneider
32 mins ago
add a comment |
2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
3
down vote
Im not sure of the full story here. But if you pull the controls of a 737 while the autopilot is engaged the autopilot will trip and the pilots will have to fly the plane manually, this requires about 25 lbs of force.
There is also a button on the yoke where you can disengage the AP. So if the AP was controlling the plane and going in to a violent descent the pilots should have been able to cancel it by pulling the yoke or pushing the button on the yoke or the AP panel.
And no, the controls being hydraulic doesn't play a role in the "override by sheer force" possibility.
Edit:
The autopilot servos are limited to 25 lb of force for single channel operation. Separate force sensors measure pilot column input and the autopilot will disconnect if the force applied by the pilot(s) exceeds 21 lbs.
answered 2 hours ago
Douglas Pettersson
1413
New contributor
Douglas Pettersson is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Why would the override be only triggered on such high stick forces? 25 lbs sounds like a decent amount of force.
– curious_cat
2 hours ago
I'm not sure why they constructed the plane this way. But my guess is that the underlying cause is margin for error without disconnecting the AP. 21-25 lbs of force is not really that much especially not in an emergency, just give the yoke a solid "pull" and it'll be enough. Keep in mind it's force and not pressure
– Douglas Pettersson
2 hours ago
@curious_cat I would assume that it's a safety requirement that disengaging the autopilot requires a conscious act by the pilots. 21 lbs of force are probably high enough to not be exerted accidentally but still low enough to be produced ad hoc. (21 lbs seem to contradict the "feet on the dashboard" bit in the article. OK, maybe one needs a bit of pushing against the dashboard because it's a horizontal force.)
– Peter A. Schneider
1 hour ago
Thank you for the answer. Can you give us the source of your quote?
– Peter A. Schneider
1 hour ago
Hi, the data i quoted can be read here: b737.org.uk/incident_ei-ebw.htm
– Douglas Pettersson
9 mins ago
add a comment |
up vote
3
down vote
Im not sure of the full story here. But if you pull the controls of a 737 while the autopilot is engaged the autopilot will trip and the pilots will have to fly the plane manually, this requires about 25 lbs of force.
There is also a button on the yoke where you can disengage the AP. So if the AP was controlling the plane and going in to a violent descent the pilots should have been able to cancel it by pulling the yoke or pushing the button on the yoke or the AP panel.
And no, the controls being hydraulic doesn't play a role in the "override by sheer force" possibility.
Edit:
The autopilot servos are limited to 25 lb of force for single channel operation. Separate force sensors measure pilot column input and the autopilot will disconnect if the force applied by the pilot(s) exceeds 21 lbs.
answered 2 hours ago
Douglas Pettersson
1413
New contributor
Douglas Pettersson is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Why would the override be only triggered on such high stick forces? 25 lbs sounds like a decent amount of force.
– curious_cat
2 hours ago
I'm not sure why they constructed the plane this way. But my guess is that the underlying cause is margin for error without disconnecting the AP. 21-25 lbs of force is not really that much especially not in an emergency, just give the yoke a solid "pull" and it'll be enough. Keep in mind it's force and not pressure
– Douglas Pettersson
2 hours ago
@curious_cat I would assume that it's a safety requirement that disengaging the autopilot requires a conscious act by the pilots. 21 lbs of force are probably high enough to not be exerted accidentally but still low enough to be produced ad hoc. (21 lbs seem to contradict the "feet on the dashboard" bit in the article. OK, maybe one needs a bit of pushing against the dashboard because it's a horizontal force.)
– Peter A. Schneider
1 hour ago
Thank you for the answer. Can you give us the source of your quote?
– Peter A. Schneider
1 hour ago
Hi, the data i quoted can be read here: b737.org.uk/incident_ei-ebw.htm
– Douglas Pettersson
9 mins ago
add a comment |
up vote
3
down vote
up vote
3
down vote
Im not sure of the full story here. But if you pull the controls of a 737 while the autopilot is engaged the autopilot will trip and the pilots will have to fly the plane manually, this requires about 25 lbs of force.
There is also a button on the yoke where you can disengage the AP. So if the AP was controlling the plane and going in to a violent descent the pilots should have been able to cancel it by pulling the yoke or pushing the button on the yoke or the AP panel.
And no, the controls being hydraulic doesn't play a role in the "override by sheer force" possibility.
Edit:
The autopilot servos are limited to 25 lb of force for single channel operation. Separate force sensors measure pilot column input and the autopilot will disconnect if the force applied by the pilot(s) exceeds 21 lbs.
answered 2 hours ago
Douglas Pettersson
1413
New contributor
Douglas Pettersson is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Im not sure of the full story here. But if you pull the controls of a 737 while the autopilot is engaged the autopilot will trip and the pilots will have to fly the plane manually, this requires about 25 lbs of force.
There is also a button on the yoke where you can disengage the AP. So if the AP was controlling the plane and going in to a violent descent the pilots should have been able to cancel it by pulling the yoke or pushing the button on the yoke or the AP panel.
And no, the controls being hydraulic doesn't play a role in the "override by sheer force" possibility.
Edit:
The autopilot servos are limited to 25 lb of force for single channel operation. Separate force sensors measure pilot column input and the autopilot will disconnect if the force applied by the pilot(s) exceeds 21 lbs.
answered 2 hours ago
Douglas Pettersson
1413
New contributor
Douglas Pettersson is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
answered 2 hours ago
Douglas Pettersson
1413
New contributor
Douglas Pettersson is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
answered 2 hours ago
Douglas Pettersson
1413
answered 2 hours ago
Douglas Pettersson
1413
1413
New contributor
Douglas Pettersson is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
Douglas Pettersson is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Douglas Pettersson is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Why would the override be only triggered on such high stick forces? 25 lbs sounds like a decent amount of force.
– curious_cat
2 hours ago
I'm not sure why they constructed the plane this way. But my guess is that the underlying cause is margin for error without disconnecting the AP. 21-25 lbs of force is not really that much especially not in an emergency, just give the yoke a solid "pull" and it'll be enough. Keep in mind it's force and not pressure
– Douglas Pettersson
2 hours ago
@curious_cat I would assume that it's a safety requirement that disengaging the autopilot requires a conscious act by the pilots. 21 lbs of force are probably high enough to not be exerted accidentally but still low enough to be produced ad hoc. (21 lbs seem to contradict the "feet on the dashboard" bit in the article. OK, maybe one needs a bit of pushing against the dashboard because it's a horizontal force.)
– Peter A. Schneider
1 hour ago
Thank you for the answer. Can you give us the source of your quote?
– Peter A. Schneider
1 hour ago
Hi, the data i quoted can be read here: b737.org.uk/incident_ei-ebw.htm
– Douglas Pettersson
9 mins ago
add a comment |
Why would the override be only triggered on such high stick forces? 25 lbs sounds like a decent amount of force.
– curious_cat
2 hours ago
I'm not sure why they constructed the plane this way. But my guess is that the underlying cause is margin for error without disconnecting the AP. 21-25 lbs of force is not really that much especially not in an emergency, just give the yoke a solid "pull" and it'll be enough. Keep in mind it's force and not pressure
– Douglas Pettersson
2 hours ago
@curious_cat I would assume that it's a safety requirement that disengaging the autopilot requires a conscious act by the pilots. 21 lbs of force are probably high enough to not be exerted accidentally but still low enough to be produced ad hoc. (21 lbs seem to contradict the "feet on the dashboard" bit in the article. OK, maybe one needs a bit of pushing against the dashboard because it's a horizontal force.)
– Peter A. Schneider
1 hour ago
Thank you for the answer. Can you give us the source of your quote?
– Peter A. Schneider
1 hour ago
Hi, the data i quoted can be read here: b737.org.uk/incident_ei-ebw.htm
– Douglas Pettersson
9 mins ago
Why would the override be only triggered on such high stick forces? 25 lbs sounds like a decent amount of force.
– curious_cat
2 hours ago
Why would the override be only triggered on such high stick forces? 25 lbs sounds like a decent amount of force.
– curious_cat
2 hours ago
I'm not sure why they constructed the plane this way. But my guess is that the underlying cause is margin for error without disconnecting the AP. 21-25 lbs of force is not really that much especially not in an emergency, just give the yoke a solid "pull" and it'll be enough. Keep in mind it's force and not pressure
– Douglas Pettersson
2 hours ago
I'm not sure why they constructed the plane this way. But my guess is that the underlying cause is margin for error without disconnecting the AP. 21-25 lbs of force is not really that much especially not in an emergency, just give the yoke a solid "pull" and it'll be enough. Keep in mind it's force and not pressure
– Douglas Pettersson
2 hours ago
@curious_cat I would assume that it's a safety requirement that disengaging the autopilot requires a conscious act by the pilots. 21 lbs of force are probably high enough to not be exerted accidentally but still low enough to be produced ad hoc. (21 lbs seem to contradict the "feet on the dashboard" bit in the article. OK, maybe one needs a bit of pushing against the dashboard because it's a horizontal force.)
– Peter A. Schneider
1 hour ago
@curious_cat I would assume that it's a safety requirement that disengaging the autopilot requires a conscious act by the pilots. 21 lbs of force are probably high enough to not be exerted accidentally but still low enough to be produced ad hoc. (21 lbs seem to contradict the "feet on the dashboard" bit in the article. OK, maybe one needs a bit of pushing against the dashboard because it's a horizontal force.)
– Peter A. Schneider
1 hour ago
Thank you for the answer. Can you give us the source of your quote?
– Peter A. Schneider
1 hour ago
Thank you for the answer. Can you give us the source of your quote?
– Peter A. Schneider
1 hour ago
Hi, the data i quoted can be read here: b737.org.uk/incident_ei-ebw.htm
– Douglas Pettersson
9 mins ago
Hi, the data i quoted can be read here: b737.org.uk/incident_ei-ebw.htm
– Douglas Pettersson
9 mins ago
add a comment |
up vote
1
down vote
With typical hydraulic controls, the mechanical control cable circuit just operates control valves on the hydraulic actuators. The control valves normally only have fairly light centering springs that take only a few pounds of force to overcome. With no other devices in the control circuit, you could move the control column with your pinky finger.
Control feedback forces come from pitch feel devices in the control circuit that use internal spring packs (bungees) and/or roller cam devices to provide a variable resistive force. But the feel units won't drive the circuit, only provide resistance. Two devices can drive the elevator circuit in theory; the autopilot servo and the stick pusher (which is like an autopilot servo that only operates one way).
Autopilot and stick pusher servos have two clutches, a meshing teeth on/off clutch, and a friction slip override clutch. If the A/P servo runs away for some reason, and you can't trigger a disconnect electrically, it is possible to overpower the slip clutch in the servo, but it is like the stick is in not-quite-solidified concrete the whole time you are trying to move it. But you can move it.
The stick pusher servo is similar, but the stick pusher is designed to drive full nose down and release almost immediately.
In any case, if you had an elevator hard over like that and the electrical disconnects (there are usually several difference switches that can perform the disconnect function), the next action would be to operate the mechanical pitch disconnect to separate the left and right elevator circuits. You end up with one free elevator, which will give some control, at least enough to neutralize the overall input.
One possibility is the shock and surprise of the event, whatever it was, overwhelmed the crew and they didn't follow through on all the memory items for that kind of emergency. At this point, who knows.
Also remember that media stories on these kinds of incidents are almost always wildly inaccurate. Anyone who has worked in any kind of technical specialty and reads media reports related to their specialty knows that they are wrong most of the time.
answered 1 hour ago
John K
10.8k1132
Thanks for the details. (Btw, I have more confidence in the NYT than in most others. They pay a lot of attention to factual correctness and do publish corrections. If you think the article is factually incorrect don't hesitate to send a correction; they surely appreciate it.)
– Peter A. Schneider
32 mins ago
add a comment |
up vote
1
down vote
With typical hydraulic controls, the mechanical control cable circuit just operates control valves on the hydraulic actuators. The control valves normally only have fairly light centering springs that take only a few pounds of force to overcome. With no other devices in the control circuit, you could move the control column with your pinky finger.
Control feedback forces come from pitch feel devices in the control circuit that use internal spring packs (bungees) and/or roller cam devices to provide a variable resistive force. But the feel units won't drive the circuit, only provide resistance. Two devices can drive the elevator circuit in theory; the autopilot servo and the stick pusher (which is like an autopilot servo that only operates one way).
Autopilot and stick pusher servos have two clutches, a meshing teeth on/off clutch, and a friction slip override clutch. If the A/P servo runs away for some reason, and you can't trigger a disconnect electrically, it is possible to overpower the slip clutch in the servo, but it is like the stick is in not-quite-solidified concrete the whole time you are trying to move it. But you can move it.
The stick pusher servo is similar, but the stick pusher is designed to drive full nose down and release almost immediately.
In any case, if you had an elevator hard over like that and the electrical disconnects (there are usually several difference switches that can perform the disconnect function), the next action would be to operate the mechanical pitch disconnect to separate the left and right elevator circuits. You end up with one free elevator, which will give some control, at least enough to neutralize the overall input.
One possibility is the shock and surprise of the event, whatever it was, overwhelmed the crew and they didn't follow through on all the memory items for that kind of emergency. At this point, who knows.
Also remember that media stories on these kinds of incidents are almost always wildly inaccurate. Anyone who has worked in any kind of technical specialty and reads media reports related to their specialty knows that they are wrong most of the time.
answered 1 hour ago
John K
10.8k1132
Thanks for the details. (Btw, I have more confidence in the NYT than in most others. They pay a lot of attention to factual correctness and do publish corrections. If you think the article is factually incorrect don't hesitate to send a correction; they surely appreciate it.)
– Peter A. Schneider
32 mins ago
add a comment |
up vote
1
down vote
up vote
1
down vote
With typical hydraulic controls, the mechanical control cable circuit just operates control valves on the hydraulic actuators. The control valves normally only have fairly light centering springs that take only a few pounds of force to overcome. With no other devices in the control circuit, you could move the control column with your pinky finger.
Control feedback forces come from pitch feel devices in the control circuit that use internal spring packs (bungees) and/or roller cam devices to provide a variable resistive force. But the feel units won't drive the circuit, only provide resistance. Two devices can drive the elevator circuit in theory; the autopilot servo and the stick pusher (which is like an autopilot servo that only operates one way).
Autopilot and stick pusher servos have two clutches, a meshing teeth on/off clutch, and a friction slip override clutch. If the A/P servo runs away for some reason, and you can't trigger a disconnect electrically, it is possible to overpower the slip clutch in the servo, but it is like the stick is in not-quite-solidified concrete the whole time you are trying to move it. But you can move it.
The stick pusher servo is similar, but the stick pusher is designed to drive full nose down and release almost immediately.
In any case, if you had an elevator hard over like that and the electrical disconnects (there are usually several difference switches that can perform the disconnect function), the next action would be to operate the mechanical pitch disconnect to separate the left and right elevator circuits. You end up with one free elevator, which will give some control, at least enough to neutralize the overall input.
One possibility is the shock and surprise of the event, whatever it was, overwhelmed the crew and they didn't follow through on all the memory items for that kind of emergency. At this point, who knows.
Also remember that media stories on these kinds of incidents are almost always wildly inaccurate. Anyone who has worked in any kind of technical specialty and reads media reports related to their specialty knows that they are wrong most of the time.
answered 1 hour ago
John K
10.8k1132
With typical hydraulic controls, the mechanical control cable circuit just operates control valves on the hydraulic actuators. The control valves normally only have fairly light centering springs that take only a few pounds of force to overcome. With no other devices in the control circuit, you could move the control column with your pinky finger.
Control feedback forces come from pitch feel devices in the control circuit that use internal spring packs (bungees) and/or roller cam devices to provide a variable resistive force. But the feel units won't drive the circuit, only provide resistance. Two devices can drive the elevator circuit in theory; the autopilot servo and the stick pusher (which is like an autopilot servo that only operates one way).
Autopilot and stick pusher servos have two clutches, a meshing teeth on/off clutch, and a friction slip override clutch. If the A/P servo runs away for some reason, and you can't trigger a disconnect electrically, it is possible to overpower the slip clutch in the servo, but it is like the stick is in not-quite-solidified concrete the whole time you are trying to move it. But you can move it.
The stick pusher servo is similar, but the stick pusher is designed to drive full nose down and release almost immediately.
In any case, if you had an elevator hard over like that and the electrical disconnects (there are usually several difference switches that can perform the disconnect function), the next action would be to operate the mechanical pitch disconnect to separate the left and right elevator circuits. You end up with one free elevator, which will give some control, at least enough to neutralize the overall input.
One possibility is the shock and surprise of the event, whatever it was, overwhelmed the crew and they didn't follow through on all the memory items for that kind of emergency. At this point, who knows.
Also remember that media stories on these kinds of incidents are almost always wildly inaccurate. Anyone who has worked in any kind of technical specialty and reads media reports related to their specialty knows that they are wrong most of the time.
answered 1 hour ago
John K
10.8k1132
answered 1 hour ago
John K
10.8k1132
answered 1 hour ago
John K
10.8k1132
answered 1 hour ago
John K
10.8k1132
10.8k1132
Thanks for the details. (Btw, I have more confidence in the NYT than in most others. They pay a lot of attention to factual correctness and do publish corrections. If you think the article is factually incorrect don't hesitate to send a correction; they surely appreciate it.)
– Peter A. Schneider
32 mins ago
add a comment |
Thanks for the details. (Btw, I have more confidence in the NYT than in most others. They pay a lot of attention to factual correctness and do publish corrections. If you think the article is factually incorrect don't hesitate to send a correction; they surely appreciate it.)
– Peter A. Schneider
32 mins ago
Thanks for the details. (Btw, I have more confidence in the NYT than in most others. They pay a lot of attention to factual correctness and do publish corrections. If you think the article is factually incorrect don't hesitate to send a correction; they surely appreciate it.)
– Peter A. Schneider
32 mins ago
Thanks for the details. (Btw, I have more confidence in the NYT than in most others. They pay a lot of attention to factual correctness and do publish corrections. If you think the article is factually incorrect don't hesitate to send a correction; they surely appreciate it.)
– Peter A. Schneider
32 mins ago
add a comment |
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