AF 447 Search to resume
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A enlarged image of the DFDR trace is here
The A319 is the baby brother of the A330. Much smaller but with a strong family resemblance. As such, many of the design concepts that went into the A320 family are reflected in the A330, but executed or packaged in slightly different ways. If the A319 is showing signs of control rate limiting, then it is likely that the A330 can do the same.
With this in mind, I would like to call attention to some anomalous indications in the DFDR trace.
First, look at the position of the R & L elevators. Wouldn't you expect both elevators to be moving synchronously? But just before 14:48:10, the L elevator (brown trace) follows a stick pulse, but the R elevator (blue trace) does not. Then at 14:48:12, the R elevator responds to a stick input, but the L elevator does not. This split behavior continues until 14:48:17 at which point the aircraft has apparently flown out of the turbulence and is in a recovery phase.
Now look at the blue and magenta traces in the middle of the graphic. This is rudder position(magenta) and rudder pedal position(blue). Wouldn't you expect the two to be nearly synchronized with a slight lag for the hydraulics to catch up with the pedals? But at 14:48:06, before the autopilot is switched off, we are beginning to see the rudder lagging the pedals. (I don't wish to get into a discussion about whether he should have been on the pedals in the first place, just how well the aircraft followed the pilots commands.) By 14:48:15, the rudder acts as if it has a mind of its own and is doing other than what the pedals commanded. Finally by 14:48:23, the rudder starts to follow the rudder pedals (coincident with the aileron trace quieting down).
There are other indications in the aileron traces themselves. Yes the right and left ailerons mirror each other fairly well, but they are lagging the control input by almost a second and the position traces are becoming triangular in shape.
To me, these events in the trace may be the results of hydraulic supply rate limiting, but I realize that yaw damper inputs can superimpose on the pilots rudder inputs. Others on this forum have no doubt seen such DFDR traces before and may have better insight as to the cause, but I am concerned that the hydraulic demand from continually moving ailerons and spoilers could cause a control problem in very turbulent conditions on Airbus aircraft.
And if I am definitely barking up the wrong tree, please set me straight.
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Hi,
Family associations with the help of some aviation professionals suggested to search first around LKP
I agree with that... but it's make of me a conspiracy accomplice
Like those conspirators from one of the family association :
MARNET-CORNUS Henri
MECIFI Amine
TERRACHER Jacques
ARNOUX Gérard
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Methink AF447 go in a irrecuperable stall by all means even if Svetlana Kapanina was in command.
I can buy it that this was ineptitude caused by the intense political pressure, just barely. I am suppressing comments from accident investigators about the reliability of reports. If the accident happens in a third world area, the report quality is poor because of the untrained and inexperienced investigators. If the accident is not politically charged and is in a "first world" nation the reports tend to be pretty good. If politics enters the picture the reports are what the politicians wanted them to say. That's from their experience. I suspect that is what this investigation started out to be. This latest search probably fell out of the unrelenting public oversight and demands. It would not go away. So the plane had to be found. At least that's what I get if I let my cynicism and "too many decades of real world experience" get out of hand. I still expect a political report. But I expect it's going to be as honest as the politicians permit. (And Wikileaks exists as a means of forcing honesty on politicians.)
(As a pair of side notes it has been reported here that the Russians, with (heh) more experience than others with crashes, have found that you start at or near the LKP when searching for crash locations. And I further note that mm43's current backtraces also placed the accident location fairly close to LKP but, if I recall, a bit South of where BEA hinted it actually fell.)
(As a pair of side notes it has been reported here that the Russians, with (heh) more experience than others with crashes, have found that you start at or near the LKP when searching for crash locations. And I further note that mm43's current backtraces also placed the accident location fairly close to LKP but, if I recall, a bit South of where BEA hinted it actually fell.)
I agree with that... but it's make of me a conspiracy accomplice
Like those conspirators from one of the family association :
MARNET-CORNUS Henri
MECIFI Amine
TERRACHER Jacques
ARNOUX Gérard
Liste des membres du Conseil d
Methink AF447 go in a irrecuperable stall by all means even if Svetlana Kapanina was in command.
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Originally posted by 777fly ...
The photographs of the left wing section show that a large section of the outboard upper wing surface is missing and broken wing spars can be clearly seen. This kind of damage is often seen when a wing is overstressed in a high speed dive recovery. Of course, such damage might have occured at impact, but it would be interesting to know if those missing outboard wing sections are found with the main wreckage, elsewhere, or not at all.
The photographs of the left wing section show that a large section of the outboard upper wing surface is missing and broken wing spars can be clearly seen. This kind of damage is often seen when a wing is overstressed in a high speed dive recovery. Of course, such damage might have occured at impact, but it would be interesting to know if those missing outboard wing sections are found with the main wreckage, elsewhere, or not at all.
If any hydraulic control system had suffered damage, that would have certainly generated an ECAM and subsequent ACARS message. With the information we have, none of that happened. That doesn't preclude the Outer Spoiler mentioned above from having left in the air, but the visual evidence of its found condition has all the hallmarks of a upward punch by the sea surface, and I suspect the lack of symmetry would have created another warning - before the Cabin Vertical Speed advisory.
Machinbird;
There is an alternate explanation which might help. It comes from the way flight data recording works.
Remember how popular strobe lights were? Let's put two such strobes in a dark room where a lot of people are dancing to disco music...(yes, I remember). Let's point one strobe one way and the other in the opposite direction, (left and right); let's pretend they're shielded so they dont' light up the whole room but just where they're pointed.
Let's then fire one strobe a bit later than the other and film the position of the dancers lit as the first strobe fires, and compare their positions with the dancers lit by the second, later-firing strobe and ask, Are the dancers lit by the second strobe in the same position they were in when the first strobe was fired?
We know by now that they're not. Dancers are always moving!
Are the second group of dancers "lagging" behind the first? Again, no, we just see them slightly later because of the "snapshot" way the data was taken and recorded.
The same happens with digital flight data recorders. The process is sequential, not all at once.
So we know each parameter has it's place and time of recording and it is different than all the others.
All aircraft parameters are also generated and recorded at different rates per second.
Fuel quantity is recorded every four seconds because a faster rate isn't needed to notice change. Heading is recorded once per second, roll is recorded at twice a second, pitch at 4x/sec, while vertical 'g', which changes rapidly, is recorded up to 16x per second and sometimes higher.
These "frame rates" are a matter of design and software programming. QARs, (Quick Access Recorders used in FOQA/FDA programs) often record
many more parameters and at far faster frames per second than DFDRs or SSFDRs.
The key point is, parameters can't be recorded all at once. If there are 1800 parameters (in binary form) coming into the system, the system must have a way of "listening, parsing and recording". The data frame software is how that process is handled.
As the second begins at '0' and proceeds to '1', the data frame runs through all parameters, sometimes "flashing the strobe" 16x a second, sometimes less, sometimes not, and then places the binary data received in the data frame cells (much like a spreadsheet...simple data frames are 4 columns, 64 rows, filled each second), at the programmed recording rate.
Without getting more complicated, (because it has to if we go any further and everyone will be asleep), the nature of recording can give the appearance of a 'lag', when there "may, or may not" have been one.
I say "may or may not", because there is one more thing to know.
As with the strobe light, when the lights are "off", no one knows what position the dancers are in, until the next strobe fires. This is equivalent to the position of the aileron or sidestick, etc, not being recorded, even when these devices will always have a certain position.
Further, one can make absolutely no assumptions whatsoever, about the positions of the dancers, while the lights are off. Similarly, in the time between the snapshots of the left aileron position and the right, one can make no assumptions about what these controls were doing while not being recorded, even as they logically had a position at all times.
If the sidestick (recorded on the A319/A320/A321 at 8x second in most frames) is moved so rapidly that the frame rate can't catch every important position, then what we see in the data may be misleading. A rapid sidestick movement full forward then full aft in about a second will not look like a smooth fore and aft movement and, depending when in the entire recording sequence such motion was made, the data may not show full aft or full forward because "the strobe was off at full deflection"...
So it is with all aircraft parameters.
To introduce what will be a reasonable complexity, there may actually exist some lead or lag in the flight controls. But there is no way to tell as slower frame rates and ground testing is the only process that can answer the question.
I haven't studied the Air Canada traces so can't comment in detail but this kind of explanation is the way recording works.
This isn't to say that the recordings aren't still extremely useful, obviously. But it takes experience and training, and in cases as fine-tuned as these it would be up to the maintenance people and the aeronautical engineers to say whether the positions of the flight controls, as they relate to the side-stick and rudder pedals even with the lag, affected control of the aircraft in a certain way vice another way.
This is why I think, even when the recorders are found and read, (which I am confident they will be), that the real discussion will just be starting.
I would like to call attention to some anomalous indications in the DFDR trace.
. . . .
First, look at the position of the R & L elevators. Wouldn't you expect both elevators to be moving synchronously? But just before 14:48:10, the L elevator (brown trace) follows a stick pulse, but the R elevator (blue trace) does not. Then at 14:48:12, the R elevator responds to a stick input, but the L elevator does not. This split behavior continues until 14:48:17 at which point the aircraft has apparently flown out of the turbulence and is in a recovery phase.
. . . .
First, look at the position of the R & L elevators. Wouldn't you expect both elevators to be moving synchronously? But just before 14:48:10, the L elevator (brown trace) follows a stick pulse, but the R elevator (blue trace) does not. Then at 14:48:12, the R elevator responds to a stick input, but the L elevator does not. This split behavior continues until 14:48:17 at which point the aircraft has apparently flown out of the turbulence and is in a recovery phase.
Remember how popular strobe lights were? Let's put two such strobes in a dark room where a lot of people are dancing to disco music...(yes, I remember). Let's point one strobe one way and the other in the opposite direction, (left and right); let's pretend they're shielded so they dont' light up the whole room but just where they're pointed.
Let's then fire one strobe a bit later than the other and film the position of the dancers lit as the first strobe fires, and compare their positions with the dancers lit by the second, later-firing strobe and ask, Are the dancers lit by the second strobe in the same position they were in when the first strobe was fired?
We know by now that they're not. Dancers are always moving!
Are the second group of dancers "lagging" behind the first? Again, no, we just see them slightly later because of the "snapshot" way the data was taken and recorded.
The same happens with digital flight data recorders. The process is sequential, not all at once.
So we know each parameter has it's place and time of recording and it is different than all the others.
All aircraft parameters are also generated and recorded at different rates per second.
Fuel quantity is recorded every four seconds because a faster rate isn't needed to notice change. Heading is recorded once per second, roll is recorded at twice a second, pitch at 4x/sec, while vertical 'g', which changes rapidly, is recorded up to 16x per second and sometimes higher.
These "frame rates" are a matter of design and software programming. QARs, (Quick Access Recorders used in FOQA/FDA programs) often record
many more parameters and at far faster frames per second than DFDRs or SSFDRs.
The key point is, parameters can't be recorded all at once. If there are 1800 parameters (in binary form) coming into the system, the system must have a way of "listening, parsing and recording". The data frame software is how that process is handled.
As the second begins at '0' and proceeds to '1', the data frame runs through all parameters, sometimes "flashing the strobe" 16x a second, sometimes less, sometimes not, and then places the binary data received in the data frame cells (much like a spreadsheet...simple data frames are 4 columns, 64 rows, filled each second), at the programmed recording rate.
Without getting more complicated, (because it has to if we go any further and everyone will be asleep), the nature of recording can give the appearance of a 'lag', when there "may, or may not" have been one.
I say "may or may not", because there is one more thing to know.
As with the strobe light, when the lights are "off", no one knows what position the dancers are in, until the next strobe fires. This is equivalent to the position of the aileron or sidestick, etc, not being recorded, even when these devices will always have a certain position.
Further, one can make absolutely no assumptions whatsoever, about the positions of the dancers, while the lights are off. Similarly, in the time between the snapshots of the left aileron position and the right, one can make no assumptions about what these controls were doing while not being recorded, even as they logically had a position at all times.
If the sidestick (recorded on the A319/A320/A321 at 8x second in most frames) is moved so rapidly that the frame rate can't catch every important position, then what we see in the data may be misleading. A rapid sidestick movement full forward then full aft in about a second will not look like a smooth fore and aft movement and, depending when in the entire recording sequence such motion was made, the data may not show full aft or full forward because "the strobe was off at full deflection"...
So it is with all aircraft parameters.
To introduce what will be a reasonable complexity, there may actually exist some lead or lag in the flight controls. But there is no way to tell as slower frame rates and ground testing is the only process that can answer the question.
I haven't studied the Air Canada traces so can't comment in detail but this kind of explanation is the way recording works.
This isn't to say that the recordings aren't still extremely useful, obviously. But it takes experience and training, and in cases as fine-tuned as these it would be up to the maintenance people and the aeronautical engineers to say whether the positions of the flight controls, as they relate to the side-stick and rudder pedals even with the lag, affected control of the aircraft in a certain way vice another way.
This is why I think, even when the recorders are found and read, (which I am confident they will be), that the real discussion will just be starting.
Parallel data recording, et al
Salute!
PJ has some great points about digital recording on a serial bus.
Working with flight test recorders in my previous life, we had several "channels" of data streams, all synched with time stamps. Even the analog data. The biggest difference between test profile recording and day-to-day maintenance and such recording for the big jets is the update rate. If we sample at 100hz or faster, we can build very accurate relationships between all the inputs. But then we need a huge storage capacity.
Looks to me that the stuff we see from the "maintenance" recorders and transmissions from the AF jet was only "blips" of all the data that still resides in the flight data recorders.
There are several independent "channels" on the flight recorders, and just look at some of the traces for various accidents/mishaps. We can see all kindsa things that happened at the same time.
and now back to the experts and regular program.
PJ has some great points about digital recording on a serial bus.
Working with flight test recorders in my previous life, we had several "channels" of data streams, all synched with time stamps. Even the analog data. The biggest difference between test profile recording and day-to-day maintenance and such recording for the big jets is the update rate. If we sample at 100hz or faster, we can build very accurate relationships between all the inputs. But then we need a huge storage capacity.
Looks to me that the stuff we see from the "maintenance" recorders and transmissions from the AF jet was only "blips" of all the data that still resides in the flight data recorders.
There are several independent "channels" on the flight recorders, and just look at some of the traces for various accidents/mishaps. We can see all kindsa things that happened at the same time.
and now back to the experts and regular program.
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Thank you PJ2 for the excellent reminder about the vagaries of data collection and an interesting presentation of the concept.
Just because a point is plotted on a DFDR chart does not mean it is not an interpolated or smoothed point seems to be a key element of your message.
There is one more factor to be considered in analyzing flight control data. The maximum uncertainty of position for those items that are moving (such as control surfaces and actual controls). Real objects move at characteristic rates. A control stick will not move from full left to full right in a millisecond. Even if it could, and then immediately returned to its original position, could a hydraulically driven control surface follow such a short signal?
Suppose a rudder surface takes a full second to go from neutral to full right at maximum control input. If sampled 4 times a second, you may not know exactly when it reaches maximum deflection or exactly when it reversed its direction of motion, but you can still know it moved at close to its maximum rate and achieved approximately full travel. Estimates can be made for the uncertainty and approximate behavior determined.
The AA587 investigation had real problems with the DFDR data because the low sampling rates masked the dynamic nature of the oscillations. Lets hope that more rapid sampling rate recorders were mandated as a consequence.
If data is recovered from AF447's recorders, will the sampling rates be high enough to definitively show dynamic behavior of the aircraft and its controls? Let us hope so.
Meanwhile, does anyone have knowledge of the sampling rates on the Air Canada A319 aircraft we were just discussing?
Just because a point is plotted on a DFDR chart does not mean it is not an interpolated or smoothed point seems to be a key element of your message.There is one more factor to be considered in analyzing flight control data. The maximum uncertainty of position for those items that are moving (such as control surfaces and actual controls). Real objects move at characteristic rates. A control stick will not move from full left to full right in a millisecond. Even if it could, and then immediately returned to its original position, could a hydraulically driven control surface follow such a short signal?
Suppose a rudder surface takes a full second to go from neutral to full right at maximum control input. If sampled 4 times a second, you may not know exactly when it reaches maximum deflection or exactly when it reversed its direction of motion, but you can still know it moved at close to its maximum rate and achieved approximately full travel. Estimates can be made for the uncertainty and approximate behavior determined.
The AA587 investigation had real problems with the DFDR data because the low sampling rates masked the dynamic nature of the oscillations. Lets hope that more rapid sampling rate recorders were mandated as a consequence.
If data is recovered from AF447's recorders, will the sampling rates be high enough to definitively show dynamic behavior of the aircraft and its controls? Let us hope so.
Meanwhile, does anyone have knowledge of the sampling rates on the Air Canada A319 aircraft we were just discussing?
grizz;
That's why it's called a PFM box... you never know for sure.
gums;
The mistake some made in the early discussion was treating the 24 ACARS messages as the same kind of information as flight data recorder information - most on the thread now know that inferences from the messages is a mug's game.
There are data recording solutions which come close to resolving the timing issues, but "granularity" becomes an issue if important parameters, (especially in older equipment) are not recorded at sufficient rates-per-second, (and can't be precisely coordinated with others which aren't recorded at the same rate. If the sidestick is recorded at 16x/sec and the elevator rate, for example, is recorded at 4x/sec, how does one match each side-stick data point with the 4 existing elevator points? And this is quite different than the problem of "filtering", which the FAA has addressed, (and towards which I do not wish to divert the thread).
Not sure what you mean by "sampling at 100hz" or how such a parallel system would work, but there is a lot of variations on a theme.
That's why it's called a PFM box... you never know for sure.
gums;
Looks to me that the stuff we see from the "maintenance" recorders and transmissions from the AF jet was only "blips" of all the data that still resides in the flight data recorders.
There are data recording solutions which come close to resolving the timing issues, but "granularity" becomes an issue if important parameters, (especially in older equipment) are not recorded at sufficient rates-per-second, (and can't be precisely coordinated with others which aren't recorded at the same rate. If the sidestick is recorded at 16x/sec and the elevator rate, for example, is recorded at 4x/sec, how does one match each side-stick data point with the 4 existing elevator points? And this is quite different than the problem of "filtering", which the FAA has addressed, (and towards which I do not wish to divert the thread).
Not sure what you mean by "sampling at 100hz" or how such a parallel system would work, but there is a lot of variations on a theme.
Machinbird;
No, I would specifically wish to avoid this interpretation of my note. "Filtering" can be used to smooth data as we know, but I don't see how it can be so smoothed when "the strobe is off", so to speak. Notwithstanding your very reasonable statement regarding logical assumptions (which I do not necessarily disagree with), the issue is decideability...by what means and by what justifications in data work is smoothing decided and for what parameters, some, all, none? I have seen both the raw, (very lumpy) data and smoothed data and both work for various purposes, but the only way to resolve the issues raised by AA587 are, as the FAA has indicated, finer granularity, (higher sample rates, larger storage capacity). A variation on the issue trivially arises when using lossy JPG formats in digital photography, which is why so many who know what they're doing prefer a form of RAW; - the information in the spaces in between is real, not derived.
I believe the places where the symbols are placed on each parameter's line represents each sample point for that parameter.
I don't think there is anything in the A319 event that relates to the AF447 event. The AC event was wake turbulence...quite different than TCu's.
Just because a point is plotted on a DFDR chart does not mean it is not an interpolated or smoothed point seems to be a key element of your message.
Meanwhile, does anyone have knowledge of the sampling rates on the Air Canada A319 aircraft we were just discussing?
I don't think there is anything in the A319 event that relates to the AF447 event. The AC event was wake turbulence...quite different than TCu's.
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Looks like a blind one...
In order to estimate the impact location (in case when the recorders are destroyed) one can consider an INS equipped bathyscaphe starting from the position of the plane's remains and compensating on-line ocean currents when climbing up.
Such a procedure is - to some extent - a reverse of the Monte Carlo approach described by lomapaseo in http://www.pprune.org/tech-log/39510...ml#post6393355.
For the sake of precision: the information in color RAW files is real but not complete anyway due to the presence of the Bayer color filter preceding a sensor.
All images - when retrieved from a RAW data - need to be transformed by a so called demosaicing procedure (which is a kind of interpolation algorithm).
In order to estimate the impact location (in case when the recorders are destroyed) one can consider an INS equipped bathyscaphe starting from the position of the plane's remains and compensating on-line ocean currents when climbing up.
Such a procedure is - to some extent - a reverse of the Monte Carlo approach described by lomapaseo in http://www.pprune.org/tech-log/39510...ml#post6393355.
All images - when retrieved from a RAW data - need to be transformed by a so called demosaicing procedure (which is a kind of interpolation algorithm).
Sorry to disagree, but the recorders would not affect the time relationship between messages. A much more likely scenario would be for each message to be timestamped as it arrives at the recorder, then queued for writing. The queue would be of a length to ensure that no messages are lost.
Although messages may not be written in real time, or perhaps even in strict sequence of arrival is irrelevant, since each message will have it's own timestamp...
Although messages may not be written in real time, or perhaps even in strict sequence of arrival is irrelevant, since each message will have it's own timestamp...
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Way back in post #3262, Lonewolf wrote "caveat, it may be a load of rubbish if the gyros in the A330 are not prone to tumbling ..."
This has been rumbling around since day 1 and I'm not sure I've noticed an answer. I was under the impression that the notified failures were all ADC related?
Do we have any indication that the IRS attitude was faulty?
Apart from the Standby AI (which I am guessing is gyro driven?) what other 'gyros' could 'tumble' to promote this thought?
This has been rumbling around since day 1 and I'm not sure I've noticed an answer. I was under the impression that the notified failures were all ADC related?
Do we have any indication that the IRS attitude was faulty?
Apart from the Standby AI (which I am guessing is gyro driven?) what other 'gyros' could 'tumble' to promote this thought?
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Irrespective of data interpolation points versus timing interval, be it at 8Hz, 16Hz, 32Hz or as PJ2 queried 100Hz, a smoothing curve can ultimately be provided to cover the slower data rates. As PJ2 has pointed out, the side stick may be moved at a very high rate and not be recorded, however the reaction time of the hydraulics will normally reveal something that has been missed and show it as a potential overshoot/undershoot.
The feedback loop in the hydraulics system will have a gain that makes it track the inputs fairly accurately, but inevitably it will have some lag, as anticipation is not built into it by design. Rather, in the case of the rudder, a damping action to avoid excessive yaw is provided, and it is evident when looking at the TSB of Canada's A319 trace. The lateral 'g' records provide a guide as to how that correction is being applied.
The disparity on the left/right elevator positioning is rather disconcerting, but I am sure there is a valid reason for it - part of which could be PJ2's reasoning.
Back to reality.... Does the A319 have a PTLU (Pedal Travel Limiter Unit) in the system, and is there an acceptable rate of change built in that further limits the commands to the rudder? From what I have seen in these traces, I suspect not.
As has already been suggested, the A319 example will not be valid with what is recorded by AF447 - it certainly wasn't wake turbulence that brought it down.
The feedback loop in the hydraulics system will have a gain that makes it track the inputs fairly accurately, but inevitably it will have some lag, as anticipation is not built into it by design. Rather, in the case of the rudder, a damping action to avoid excessive yaw is provided, and it is evident when looking at the TSB of Canada's A319 trace. The lateral 'g' records provide a guide as to how that correction is being applied.
The disparity on the left/right elevator positioning is rather disconcerting, but I am sure there is a valid reason for it - part of which could be PJ2's reasoning.
Back to reality.... Does the A319 have a PTLU (Pedal Travel Limiter Unit) in the system, and is there an acceptable rate of change built in that further limits the commands to the rudder? From what I have seen in these traces, I suspect not.
As has already been suggested, the A319 example will not be valid with what is recorded by AF447 - it certainly wasn't wake turbulence that brought it down.
Way back in post #3262, Lonewolf wrote "caveat, it may be a load of rubbish if the gyros in the A330 are not prone to tumbling ..."
This has been rumbling around since day 1 and I'm not sure I've noticed an answer. I was under the impression that the notified failures were all ADC related?
Do we have any indication that the IRS attitude was faulty?
This has been rumbling around since day 1 and I'm not sure I've noticed an answer. I was under the impression that the notified failures were all ADC related?
Do we have any indication that the IRS attitude was faulty?
I think the tumbling referred to tumbling due to excessive maneuvering of the aircraft.
However, I have serious doubts that the IR part of the ADIRUS are prone to tumbling like a classic gyro although I don't know for sure.
And the standby AI in this case was a Laser Ring Gyro if I remember correctly which should also not be prone to tumbling.
That said, I could well imagine that recovering a tumbling airliner in turbulence and complete darkness only by the instruments after having been taken by surprise and with a plethora of ECAM message popping up might not be quite as easy as in an aerobatic aircraft in good visibility during a planned and well trained maneuver....
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trim-tank .... CG
#3531 Fuel Distribution ......some fuel is normally transferred to the tailplane trim-tank, unless it's already full, pushing the CG aft by a suitable amount.....
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if one reduce the speed in view of turbulences, is it feasible (or generally used) to transferre the CG again to the front somewhat, or did one trust into the steering system, and deside the risk of stall vs reduce of energy, even in this case, in the same way as in normal cruise flight and let the CG aft as before ?
grity,
I see what you mean, but am afraid I can't answer that one. Never flew the 330/340. Perhaps PJ2 will when he gets up (GMT -7), or CONF_iture (if he's not flying).
I see what you mean, but am afraid I can't answer that one. Never flew the 330/340. Perhaps PJ2 will when he gets up (GMT -7), or CONF_iture (if he's not flying).
Thank you, to henra and BOAC in re attitude reference systems. Not familiar enough with what is used in big metal to have any intuitive feel for how they respond during upset. Your point on "no system fault" transmitted may have been the answer to my question in the first place.
Also a big thank you to PJ2 for the analogy in re data sampling, although I did cringe at the memory of strobe lights and the disco era. (At least you didn't meantion leisure suits and polyester shirts!
)
For syseng68:
Good point.
Also a big thank you to PJ2 for the analogy in re data sampling, although I did cringe at the memory of strobe lights and the disco era. (At least you didn't meantion leisure suits and polyester shirts!
)For syseng68:
Although messages may not be written in real time, or perhaps even in strict sequence of arrival is irrelevant, since each message will have it's own timestamp.