Memory Item UAS A330: Flawed
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Memory Item UAS A330 : Flawed
AF is 5°/85% yet other majors' procedure is 2°/82%.
AF's 5° will inuduce climb as opposed to 2°.
I believe that Airbus' is still 5°/85%.
Why can not one standardised procedure be valid for all carriers regarding this memory item in the wake of AF447?
This did not come up in the BEA report because crew did not apply any UAS procedure which is why it has not been addressed.
Furthemore, AF's 5°/85% is approved by DGAC and EASA so have they missed something?
BTW, If I recall, UAS memory item is a recent introduction sometime at the beginning of 2005 which never had existed before in any FCOM and FCTM.
Bottom line: 2°/82% should be the standard for all A330 carriers.
AF's 5° will inuduce climb as opposed to 2°.
I believe that Airbus' is still 5°/85%.
Why can not one standardised procedure be valid for all carriers regarding this memory item in the wake of AF447?
This did not come up in the BEA report because crew did not apply any UAS procedure which is why it has not been addressed.
Furthemore, AF's 5°/85% is approved by DGAC and EASA so have they missed something?
BTW, If I recall, UAS memory item is a recent introduction sometime at the beginning of 2005 which never had existed before in any FCOM and FCTM.
Bottom line: 2°/82% should be the standard for all A330 carriers.
Last edited by Kimon; 4th Dec 2012 at 19:10.
This is a somewhat long post but I've been reading all the various threads related to AF, pilot skills etc ad nauseum without making very many comments. Something about this subject made me feel like posting so here goes.
No disrespect is intended toward the OP, I just feel compelled to comment in this instance because I have finally come to realize that there are actually pilots out there who believe that a single correct combination of thrust and pitch attitude can be appropriate under such widely variable circumstances as are encountered in any normal leg flown in a jet. I can hardly believe that anyone could think so. Not just due this thread but rather the overall impression I get from reading the aforementioned threads related to this subject.
I am not commenting on Airbus, Boeing or any other manufacturer but rather on how the UAS scenario should be perceived by pilots. I don't know much about what's contained in an A330 AFM but I do know that each airline around the world will be responsible for what's in their own training and crew manuals. I hope none of them consider a single pitch/thrust combo to be appropriate in all UAS scenarios and that latitude is still given to apply good airmanship in lieu of an over-simplified approach to a scenario requiring a knowledgeable and considered response.
The problem with creating a single pitch/thrust combination that all pilots flying a particular type should to revert to in the event of suspected or total failure of one or more airspeed indicating systems is that no single combination of thrust and pitch attitude will be appropriate for all circumstances under which an UAS scenario may occur. Obviously the combination of pitch/thrust required to clear terrain while maintaining a safe minimum airspeed during initial departure will be different compared to the pitch/thrust combo required during high altitude cruise where both high and low speed buffet margins must be respected. Any attempt to find one pitch/thrust combo to use in either scenario would be less than ideal to meet either circumstance at best and potentially disastrous at worst.
So rather than seeking a single unified pitch/thrust combination to revert to in the UAS case, it makes far more sense to revert to a pitch/thrust combo that will achieve an airspeed and vertical profile that's appropriate to the circumstances at hand. Even if one reverted to the pitch/thrust combo that one is accustomed to watching the A/P fly in that phase of a normal flight, they'd likely achieve a better outcome more often than if they followed this canned response of seeking a single fixed pitch/thrust combo under all circumstances.
In consideration of the above I can only conclude that it makes far more sense to consider the situation before selecting an appropriate pitch attitude and thrust setting should the IAS go blank or is suspected of being unreliable. In many circumstances the current pitch/thrust combo might be entirely sufficient and only need be maintained as is!
So in short:
If near the ground fly upward at high thrust, maintaining a pitch attitude which you know from experience will result in a safe airspeed plus a reasonable margin. Inform ATC of your situation and get to a safe altitude. After achieving a safe altitude, select a pitch/thrust combo that you know will result in level flight at a safe and comfortable airspeed then utilize all available resources to isolate the problem and come up with a plan to arrive safely back on the ground.
If at or near maximum altitude considering weight and temperature, don't do anything for a moment! Take a sip of your coffee or tea while you and your fellow crew consider the best plan of action. Consider whether a slight reduction in both pitch and thrust might be in order to descend towards an altitude where the high/low speed buffet margin will be greater or whether it might be better to remain above weather below. Would a course change be appropriate?
Now I've never had an actual total failure of an air data system in flight but a couple of instances of partial failure definitely inspired me to give the matter some thought long before the AF 447 affair. Even if nothing else good ever comes of that occurrence, at least the matters of basic attitude instrument flying skills and various system failure scenarios have come to the fore in various discussion forums and even the training organizations have been forced to look inward. Hopefully the pilot community will take the opportunity to re-assess their own capabilities and re-learn the most important truth of all: That regardless of the state of airlines, training and regulatory policies worldwide, it's your rear end up there and you are the last line of defense against another "unfortunate occurrence". Equip yourselves with all the knowledge and skill you can acquire and don't allow the grind of routine uneventful flights and ever more pervasive cockpit bureaucracy to dull your senses into a state of robotic complacency. Until the day when they actually fire you in favor of "autonomous aerial systems" BE A PILOT!
That is all...
westhawk
No disrespect is intended toward the OP, I just feel compelled to comment in this instance because I have finally come to realize that there are actually pilots out there who believe that a single correct combination of thrust and pitch attitude can be appropriate under such widely variable circumstances as are encountered in any normal leg flown in a jet. I can hardly believe that anyone could think so. Not just due this thread but rather the overall impression I get from reading the aforementioned threads related to this subject.
I am not commenting on Airbus, Boeing or any other manufacturer but rather on how the UAS scenario should be perceived by pilots. I don't know much about what's contained in an A330 AFM but I do know that each airline around the world will be responsible for what's in their own training and crew manuals. I hope none of them consider a single pitch/thrust combo to be appropriate in all UAS scenarios and that latitude is still given to apply good airmanship in lieu of an over-simplified approach to a scenario requiring a knowledgeable and considered response.
The problem with creating a single pitch/thrust combination that all pilots flying a particular type should to revert to in the event of suspected or total failure of one or more airspeed indicating systems is that no single combination of thrust and pitch attitude will be appropriate for all circumstances under which an UAS scenario may occur. Obviously the combination of pitch/thrust required to clear terrain while maintaining a safe minimum airspeed during initial departure will be different compared to the pitch/thrust combo required during high altitude cruise where both high and low speed buffet margins must be respected. Any attempt to find one pitch/thrust combo to use in either scenario would be less than ideal to meet either circumstance at best and potentially disastrous at worst.
So rather than seeking a single unified pitch/thrust combination to revert to in the UAS case, it makes far more sense to revert to a pitch/thrust combo that will achieve an airspeed and vertical profile that's appropriate to the circumstances at hand. Even if one reverted to the pitch/thrust combo that one is accustomed to watching the A/P fly in that phase of a normal flight, they'd likely achieve a better outcome more often than if they followed this canned response of seeking a single fixed pitch/thrust combo under all circumstances.
In consideration of the above I can only conclude that it makes far more sense to consider the situation before selecting an appropriate pitch attitude and thrust setting should the IAS go blank or is suspected of being unreliable. In many circumstances the current pitch/thrust combo might be entirely sufficient and only need be maintained as is!
So in short:
If near the ground fly upward at high thrust, maintaining a pitch attitude which you know from experience will result in a safe airspeed plus a reasonable margin. Inform ATC of your situation and get to a safe altitude. After achieving a safe altitude, select a pitch/thrust combo that you know will result in level flight at a safe and comfortable airspeed then utilize all available resources to isolate the problem and come up with a plan to arrive safely back on the ground.
If at or near maximum altitude considering weight and temperature, don't do anything for a moment! Take a sip of your coffee or tea while you and your fellow crew consider the best plan of action. Consider whether a slight reduction in both pitch and thrust might be in order to descend towards an altitude where the high/low speed buffet margin will be greater or whether it might be better to remain above weather below. Would a course change be appropriate?
Now I've never had an actual total failure of an air data system in flight but a couple of instances of partial failure definitely inspired me to give the matter some thought long before the AF 447 affair. Even if nothing else good ever comes of that occurrence, at least the matters of basic attitude instrument flying skills and various system failure scenarios have come to the fore in various discussion forums and even the training organizations have been forced to look inward. Hopefully the pilot community will take the opportunity to re-assess their own capabilities and re-learn the most important truth of all: That regardless of the state of airlines, training and regulatory policies worldwide, it's your rear end up there and you are the last line of defense against another "unfortunate occurrence". Equip yourselves with all the knowledge and skill you can acquire and don't allow the grind of routine uneventful flights and ever more pervasive cockpit bureaucracy to dull your senses into a state of robotic complacency. Until the day when they actually fire you in favor of "autonomous aerial systems" BE A PILOT!
That is all...
westhawk
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Hi,
This is why AF had two different procedures in force for UAS before the AF447 event
They can be seen in the BEA final report (Eng) page 106
. Obviously the combination of pitch/thrust required to clear terrain while maintaining a safe minimum airspeed during initial departure will be different compared to the pitch/thrust combo required during high altitude cruise where both high and low speed buffet margins must be respected. Any attempt to find one pitch/thrust combo to use in either scenario would be less than ideal to meet either circumstance at best and potentially disastrous at worst.
They can be seen in the BEA final report (Eng) page 106
Last edited by jcjeant; 2nd Dec 2012 at 11:33.
This is why AF had two different procedures in force for UAS before the AF447 event
westhawk
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Actual Airbus Procedure
Now, it's easy to generalize a procedure that is to be applied to all situations of unreliable airspeed that can happen at any time, for any reason (radome, pitots, etc). The 5° remark is only one small bit of the immediate memory items and only applicable IF the safe conduct of the flight is impacted.
Despite 5° not being the perfect pitch for cruise flight at M.82, if the pilots of AF447 had gone to 5° pitch (instead of 15+,or maintained their current pitch attitude), they would have climbed a bit initially, but it would have been an easy recovery back to level flight. Then only a minor pitch correction would be required if/when the stall warning sounded. It probably would not have degraded to the deep stall that it did.
The ACTUAL procedure says (emphasis mine, sorry if the dot leaders don't line up):
If the safe conduct of the flight is impacted:
MEMORY ITEMS:
AP/FD.......................................................... ................... OFF
A/THR......................................................... .................... OFF
PITCH/THRUST:
Below THRUST RED ALT...............................................15° / TOGA
Above THRUST RED ALT and Below FL 100......................................................... ....10° / CLB
Above THRUST RED ALT and Above FL 100......................................................... ......5° / CLB
FLAPS (if CONF 0(1)(2)(3))...................... MAINTAIN CURRENT CONF
FLAPS (if CONF FULL)....................... SELECT CONF 3 AND MAINTAIN
SPEEDBRAKES................................................. ..CHECK RETRACTED
L/G........................................................... ........... UP
When at, or above MSA or Circuit Altitude: Level off for troubleshooting.
** end of memory items **
GPS ALTITUDE.................................................... ......splay on MCDU
To level off for troubleshooting:
AP/FD.......................................................... .......OFF
A/THR......................................................... ........OFF
THEN.... the FCOM provides a chart of pitch and power settings to level off for troubleshooting, and then troubleshooting steps including identifying a bad ADR, and procedures, including pitch and power settings for a landing with unreliable airspeed.
I think what most pilots are surprised to learn is how the stall angle of attack is influenced by Mach number. For the A330, the stall warning coming on at only 4° aoa at M.82 and about 10° aoa at M0.3.
A recovery also has to consider that as speed (Mach) is recovered the stall margin narrows again, and gentle control inputs are required to prevent secondary stall.
So in this case, as they slowed due to the rapid climb, the stall angle of attack was actually increasing along with their actual angle of attack, until about the time that they got to FL380 and they ran out of energy. Then the actual AOA went rapidly through 10° up to 40+, and thing really became incomprehensible to them.
Despite 5° not being the perfect pitch for cruise flight at M.82, if the pilots of AF447 had gone to 5° pitch (instead of 15+,or maintained their current pitch attitude), they would have climbed a bit initially, but it would have been an easy recovery back to level flight. Then only a minor pitch correction would be required if/when the stall warning sounded. It probably would not have degraded to the deep stall that it did.
The ACTUAL procedure says (emphasis mine, sorry if the dot leaders don't line up):
If the safe conduct of the flight is impacted:
MEMORY ITEMS:
AP/FD.......................................................... ................... OFF
A/THR......................................................... .................... OFF
PITCH/THRUST:
Below THRUST RED ALT...............................................15° / TOGA
Above THRUST RED ALT and Below FL 100......................................................... ....10° / CLB
Above THRUST RED ALT and Above FL 100......................................................... ......5° / CLB
FLAPS (if CONF 0(1)(2)(3))...................... MAINTAIN CURRENT CONF
FLAPS (if CONF FULL)....................... SELECT CONF 3 AND MAINTAIN
SPEEDBRAKES................................................. ..CHECK RETRACTED
L/G........................................................... ........... UP
When at, or above MSA or Circuit Altitude: Level off for troubleshooting.
** end of memory items **
GPS ALTITUDE.................................................... ......splay on MCDU
To level off for troubleshooting:
AP/FD.......................................................... .......OFF
A/THR......................................................... ........OFF
THEN.... the FCOM provides a chart of pitch and power settings to level off for troubleshooting, and then troubleshooting steps including identifying a bad ADR, and procedures, including pitch and power settings for a landing with unreliable airspeed.
I think what most pilots are surprised to learn is how the stall angle of attack is influenced by Mach number. For the A330, the stall warning coming on at only 4° aoa at M.82 and about 10° aoa at M0.3.
A recovery also has to consider that as speed (Mach) is recovered the stall margin narrows again, and gentle control inputs are required to prevent secondary stall.
So in this case, as they slowed due to the rapid climb, the stall angle of attack was actually increasing along with their actual angle of attack, until about the time that they got to FL380 and they ran out of energy. Then the actual AOA went rapidly through 10° up to 40+, and thing really became incomprehensible to them.
Moderator
In a previous life in sim playtime I presented (to the extent practical) a total anciliary information loss to students as a routine exposure to the problem ie they ended up with nothing much left during the takeoff other than ball and thrust indications (and heading .. unless they opted for the "self-flagellation/glutton for punishment" scenario ..), and ILS for recovery in serious IMC. I might add that this generally was ramped up to a single pilot exercise to maximise the confidence value to the student. It rarely took more than a couple of runs to achieve the joint aim.
I suggest it doesn't matter what the precise pitch/thrust setting memorised is for any given Type/configuration/performance requirement provided that the particular combination is reasonably close to the precise figures for the situation. That way, the aircraft can be stabilised to a reasonable degree and the pilot can tweak things according to whatever other information may be available.
The exercise in our case was to effect a safe recovery to landing for confidence building. Finesse is a secondary consideration in the extreme of minimal information remaining available.
Clearly, one can't run the exercise by reference to the QRH .. the routine figures have to be memorised.
A general sideline benefit is that routine I/F polish is enhanced because the pilot knows where the ball and thrust ought to be during routine flight ..
I suggest it doesn't matter what the precise pitch/thrust setting memorised is for any given Type/configuration/performance requirement provided that the particular combination is reasonably close to the precise figures for the situation. That way, the aircraft can be stabilised to a reasonable degree and the pilot can tweak things according to whatever other information may be available.
The exercise in our case was to effect a safe recovery to landing for confidence building. Finesse is a secondary consideration in the extreme of minimal information remaining available.
Clearly, one can't run the exercise by reference to the QRH .. the routine figures have to be memorised.
A general sideline benefit is that routine I/F polish is enhanced because the pilot knows where the ball and thrust ought to be during routine flight ..
Exactly, most of my fellow A330 Pilots know that in cruise at around the mid thirties at typical weights we need 2.5 deg pitch and 78 to 80% N1 for S+L flight.
Those recall attitudes are only initial targets until you "level off above MSA for troubleshooting" .......
Those recall attitudes are only initial targets until you "level off above MSA for troubleshooting" .......
Last edited by nitpicker330; 2nd Dec 2012 at 23:26.
westhawk;
Well said.
The notion of "doing nothing"...(meaning, be a pilot and fly the airplane, meaning keep it stable while sorting out the problem), was broached shortly after the AF447 accident on the second thread. Subsequently, a fairly long discussion on the interpretation of the UAS drill and checklist took place throughout the AF447 threads.
mm43 very kindly constructed a search facility specifically for the AF447 threads and can be found here. I believe the link to the second thread, (begun June 04, 2009 after the first thread was shut down) may be broken however...just in case, the second thread can be found here.
Kind regards,
PJ2
Well said.
The notion of "doing nothing"...(meaning, be a pilot and fly the airplane, meaning keep it stable while sorting out the problem), was broached shortly after the AF447 accident on the second thread. Subsequently, a fairly long discussion on the interpretation of the UAS drill and checklist took place throughout the AF447 threads.
mm43 very kindly constructed a search facility specifically for the AF447 threads and can be found here. I believe the link to the second thread, (begun June 04, 2009 after the first thread was shut down) may be broken however...just in case, the second thread can be found here.
Kind regards,
PJ2
