AF 447 Thread No. 8
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I was wondering whether (similar to wind speed and direction) the 'estimated sideslip' is a function of indicated airspeed and hence erroneous if airspeed is erroneous (AoA>25°). Does anybody know how it is calculated?
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estimated sideslip trace.
For the guys with the graphs:
The estimated sideslip (elaborated in FCPC) is NOT used in ALT2(& DIRECT) and replaced by Ny rear accelerometer.
The FCPCs are located below cockpitfloor and the Ny rear accelerometer in the tail compartment.
@HN39:
Don't know the equation but it is Ny acceleration corrected by Rudder deflection and roll and yaw rate. (Inertial data)
Seems to be ADR DATA is supplied also:
The estimated sideslip (elaborated in FCPC) is NOT used in ALT2(& DIRECT) and replaced by Ny rear accelerometer.
The FCPCs are located below cockpitfloor and the Ny rear accelerometer in the tail compartment.
@HN39:
Don't know the equation but it is Ny acceleration corrected by Rudder deflection and roll and yaw rate. (Inertial data)
Seems to be ADR DATA is supplied also:
Last edited by A33Zab; 28th Apr 2012 at 09:33.
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@ Dozy, Owain Glyndwr, A33Zab;
Thanks for all your inputs, but as the sun is on the backside of the planet in this part of the world, I'll have a closer a look at all your contributions in my morning.
Thanks for all your inputs, but as the sun is on the backside of the planet in this part of the world, I'll have a closer a look at all your contributions in my morning.
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A330 AF447 report leak?
The Daily Telegraph claims to have a leaked draft of AF447 (central Atlantic, all lost) final acc. reprt. Doesn't look too credible/accurate to me. Comments?
Air France Flight 447: 'Damn it, we're going to crash - Telegraph
Air France Flight 447: 'Damn it, we're going to crash - Telegraph
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There is not one thing new, which would lead to the conclusion, that it originates on the future final report.
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Maybe they changed the story, but I couldn't find any claim that they actually have a copy of the report (or its draft). Only wording like "All the indications are that the final crash report will confirm ...", which implies the opposite.
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The telegraph throws in it's tuppence:
Air France Flight 447: 'Damn it, we’re going to crash’ - Telegraph
Air France Flight 447: 'Damn it, we’re going to crash’ - Telegraph
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Appalling performance
Yes GUMS,
Performance of big jets is appalling, compared to fighters.
At optimum flight level, at cruise speed, pitch will be around 2 1/2 degrees nose up. For a climb to the next level, once you have burned off enough fuel so that optimum level will have increased by 2.000 ft, you increase thrust (wow, an extra sneeze is all you get) and you "pull up the nose" by about one degree. Of course you will not stall immediately if you pull up steeper, but you will not maintain speed if you do.
If you want to speed up at cruise level, well you will accelerate with about 1 knot per 10 seconds - a long way removed from the 1 second per 10 knots of our previous life!
The margin between high speed red line and low speed red line is not nearly as small as on the U-2, but thrust margin is not big; when you reach cruise level, 1.000 to 1.500 ft/min is all the climb capability that's left.
In the handling of the situation by the pilots of AF447, the biggest communication error, in my opinion, is the talking about "climbing" and "descending" instead of "pitch, check pitch attitude, set pitch 0 degrees".
Performance of big jets is appalling, compared to fighters.
At optimum flight level, at cruise speed, pitch will be around 2 1/2 degrees nose up. For a climb to the next level, once you have burned off enough fuel so that optimum level will have increased by 2.000 ft, you increase thrust (wow, an extra sneeze is all you get) and you "pull up the nose" by about one degree. Of course you will not stall immediately if you pull up steeper, but you will not maintain speed if you do.
If you want to speed up at cruise level, well you will accelerate with about 1 knot per 10 seconds - a long way removed from the 1 second per 10 knots of our previous life!
The margin between high speed red line and low speed red line is not nearly as small as on the U-2, but thrust margin is not big; when you reach cruise level, 1.000 to 1.500 ft/min is all the climb capability that's left.
In the handling of the situation by the pilots of AF447, the biggest communication error, in my opinion, is the talking about "climbing" and "descending" instead of "pitch, check pitch attitude, set pitch 0 degrees".
Dairy Torygraph's journalists have seemingly trawled through the AF447 threads on the PPRuNe, being quite unselective what pieces of info they used for the article - some pretty realistic insight is indiscriminately mixed with utter tosh.
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Taken from the article
Can someone explain what this particular sentence means 
Boeing has always begged to differ, persisting with conventional controls on its fly-by-wire aircraft, including the new 787 Dreamliner, introduced into service this year. Boeing’s cluttering and old-fashioned levers still have to be pushed and turned like the old mechanical ones, even though they only send electronic impulses to computers. They need to be held in place for a climb or a turn to be accomplished, which some pilots think is archaic and distracting. Some say Boeing is so conservative because most American pilots graduate from flying schools where column-steering is the norm, whereas European airlines train more crew from scratch, allowing a quicker transition to side stick control
Patchwork of different posts on the PPRuNe, stitched together in single sentence by someone whose knowledge of aviation is seemingly comparable to average Neanderthals knowledge of quantum physics.
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Hazelnuts,
AF33Zab' posting answers your question I think.
They would need dynamic pressure (Vc) and Mach to calculate the rudder deflection correction, so if either of these go NCD the estimated sideslip will also.
AF33Zab' posting answers your question I think.
They would need dynamic pressure (Vc) and Mach to calculate the rudder deflection correction, so if either of these go NCD the estimated sideslip will also.
Thank you, EMIT.
I had an hour and re-read the last interim report and mainly the annotated CVR with system conditions and sensor readouts and.....
I still cry. If was already a ghost ( not there quite there yet), and whispering in those guys' ears, I think I could have helped a lot.
A surprising thing I saw and not focused upon was the bank angles. They re-inforced my initial feeling that the jet was in a really good stall and close to a spin or other completed loss of control. I had previously believed it was more stable in the roll and yaw axis.
And BTW, I flew about 500 hours in the T-33 and we had a climb rate at 35,000 ft of about 1,000 fpm. BFD.
I come back to the basic control laws and the blatant disregard for AoA when airspeed data is deemed unreliable by Hal. So I took my primitive FBW system laws and divided by eight.
- max AoA about 4 degrees
- max gee about 1 or 2 gees
That seemed close enough to fit the 'bus, IMHO.
Our system used the gee input until it hit the AoA limit, then AoA ruled! Our body rates were also in the loop and would come to play if the speed, gee and AoA stuff went FUBAR.
So I look at the traces and annotation and can't understand why the AoA inputs couldn't "limit" or "protect" compared to what I had experienced. So my feeling is that the crew was still locked into the belief that the jet could not be pulled hard enough to stall. And some of the comments seem to indicate this - "we have been trying to climb", and similar.
I then cut the crew some slack and blame the system for the disregard of AoA if weight is off the gear, regardless of the airspeed inputs' validity. AoA rules!! It's something we were taught as clueless yutes when 15 or 16 years old and learning to fly in Cessnas and Luscombes and Aeronicas and....
Further, the warning/advisory systems didn't seem to help.
The "connected" side sticks" argument still has life, but pitch and power still rules, as does some good comm between the folks in the multi-pilot planes. I don't buy all of the side stick complaints, but they do have merit.
As with another contributor here, the final report and recommendations shall be a landmark.
I had an hour and re-read the last interim report and mainly the annotated CVR with system conditions and sensor readouts and.....
I still cry. If was already a ghost ( not there quite there yet), and whispering in those guys' ears, I think I could have helped a lot.
A surprising thing I saw and not focused upon was the bank angles. They re-inforced my initial feeling that the jet was in a really good stall and close to a spin or other completed loss of control. I had previously believed it was more stable in the roll and yaw axis.
And BTW, I flew about 500 hours in the T-33 and we had a climb rate at 35,000 ft of about 1,000 fpm. BFD.
I come back to the basic control laws and the blatant disregard for AoA when airspeed data is deemed unreliable by Hal. So I took my primitive FBW system laws and divided by eight.
- max AoA about 4 degrees
- max gee about 1 or 2 gees
That seemed close enough to fit the 'bus, IMHO.
Our system used the gee input until it hit the AoA limit, then AoA ruled! Our body rates were also in the loop and would come to play if the speed, gee and AoA stuff went FUBAR.
So I look at the traces and annotation and can't understand why the AoA inputs couldn't "limit" or "protect" compared to what I had experienced. So my feeling is that the crew was still locked into the belief that the jet could not be pulled hard enough to stall. And some of the comments seem to indicate this - "we have been trying to climb", and similar.
I then cut the crew some slack and blame the system for the disregard of AoA if weight is off the gear, regardless of the airspeed inputs' validity. AoA rules!! It's something we were taught as clueless yutes when 15 or 16 years old and learning to fly in Cessnas and Luscombes and Aeronicas and....
Further, the warning/advisory systems didn't seem to help.
The "connected" side sticks" argument still has life, but pitch and power still rules, as does some good comm between the folks in the multi-pilot planes. I don't buy all of the side stick complaints, but they do have merit.
As with another contributor here, the final report and recommendations shall be a landmark.
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A33Zab,
Thanks, that answers my question.
Maybe that is so, but I don't see it in the trace. Doesn't A33Zab say that in Alt2 it is replaced by Ny without correction?
Thanks, that answers my question.
Originally Posted by Owain Glyndwr
They would need dynamic pressure (Vc) and Mach to calculate the rudder deflection correction, so if either of these go NCD the estimated sideslip will also.
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#HN39:
Doesn't A33Zab say that in Alt2 it is replaced by Ny without correction?
The rudder deflection in ALT2 (ALTERNATE YAW) is only a function of pedal and/or Yaw damper input. (based upon the yaw rate).
In ALT2 Yaw damper has a limited authority of +/- 4 degrees in CONFIG 0 (=CLEAN)
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Written in layman speak but generally nails the issue. And I say that as an Airbus pilot. Non repeating side sticks and frozen thrust levers have always been a problem along with general lack of physical feedback - a fault first revealed in the Air- Inter A320 prang.
I say to Airbus: spend the $ and buy a few servo motors to make things repeat and move!
I say to Airbus: spend the $ and buy a few servo motors to make things repeat and move!
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Inaccurate and Ill Researched
"and the jet was state-of-the-art, a type that had never before been involved in a fatal accident."
1994 at Toulouse 7 people died in a take off accident, not commercial flight however still unfortunately a fatal accident. The title of my post says the rest.
1994 at Toulouse 7 people died in a take off accident, not commercial flight however still unfortunately a fatal accident. The title of my post says the rest.
D.Laminate wrote:
And Boeing pilots of course *always* notice Autothrust disconnects, and the levers moving back to Idle.....
Written in layman speak but generally nails the issue. And I say that as an Airbus pilot. Non repeating side sticks and frozen thrust levers have always been a problem along with general lack of physical feedback - a fault first revealed in the Air- Inter A320 prang.
I say to Airbus: spend the $ and buy a few servo motors to make things repeat and move!
I say to Airbus: spend the $ and buy a few servo motors to make things repeat and move!