Air Canada A319 hits turbulence
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thanks for the first meaningful post in a long time on this thread.
while it may be a few days before we know the sequence of events, we now know what is meant by "landing manually"
In our sim training, direct law is initiated and the box is flown that way for awhile...some pilots prefer it to regular ops.
One does wonder if the plane is flying again...or if stress during recovery exceeded any limits?
while I know the A300 is not the A320, I am reminded of an american flight with an upset...pilots didn't advance power on leveloff and stalled.
thanks for the first meaningful post in a long time on this thread.
while it may be a few days before we know the sequence of events, we now know what is meant by "landing manually"
In our sim training, direct law is initiated and the box is flown that way for awhile...some pilots prefer it to regular ops.
One does wonder if the plane is flying again...or if stress during recovery exceeded any limits?
while I know the A300 is not the A320, I am reminded of an american flight with an upset...pilots didn't advance power on leveloff and stalled.
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sweker
and
407 Driver
Encountering severe turbulence on an 319 might cause the autopilot to disengage and the aircraft to revert to the so called 'Abnormal Attitude Law' (this is by design, althought turbulence must be really extreme for this to happen).
The Abnormal Attitude Law is 'direct control' with G-load protection. When control is regained, the aircraft reverts to 'alternate law', i.e.
Maybe this was the reason, why the crew was flying manually.
So, if this happenend, than there was no computer failure - the system worked as designed. But let's just wait for the report to be published in a couple of weeks.
Regards,
DBate
P.S. It's been a while since I flew an aircraft from the A320 family, so any current pilot who cares to correct me - go ahead.
eagle21 beat me by a couple of minutes with his post
Much more familiar with the NG than A319, but is it likely that the 'severe' turbulence caused the AutoPilot to disconnect, requiring manual intervention from the PF?
407 Driver
In my humble opinion...it seems as if there is more information pointing to a massive comuter glitch over any turbulence issue?
The Abnormal Attitude Law is 'direct control' with G-load protection. When control is regained, the aircraft reverts to 'alternate law', i.e.
- Roll is 'direct'
- Yaw is 'alternate'
- Pitch is 'alternate'
Maybe this was the reason, why the crew was flying manually.
So, if this happenend, than there was no computer failure - the system worked as designed. But let's just wait for the report to be published in a couple of weeks.
Regards,
DBate
P.S. It's been a while since I flew an aircraft from the A320 family, so any current pilot who cares to correct me - go ahead.
eagle21 beat me by a couple of minutes with his post
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Hello, this link below gives a few more details. I just placed a section of the article for quick viewing. I like the "This is not CSI" comment
http://www.cbc.ca/canada/story/2008/...t-calgary.html
"This is not CSI," Transportation Safety Board spokesman John Cottreau told the Canadian Press. "It's not just bing, bang, boom. There's an awful lot that goes on.
"We deal in facts. We don't deal in speculation. Sure, we can hypothesize, but those need to be scientifically examined and either proven or discounted."
The board has confirmed what many passengers have already said — that Air Canada Flight 190 not only lost altitude but also pitched violently from right to left before dropping 900 feet.
"The aircraft rolled to the right to about 35 degrees of bank and rolled to the left about 50 degrees of bank and effectively the auto pilot was disconnected," said Nick Stoss of the Transportation Safety Board.
http://www.cbc.ca/canada/story/2008/...t-calgary.html
"This is not CSI," Transportation Safety Board spokesman John Cottreau told the Canadian Press. "It's not just bing, bang, boom. There's an awful lot that goes on.
"We deal in facts. We don't deal in speculation. Sure, we can hypothesize, but those need to be scientifically examined and either proven or discounted."
The board has confirmed what many passengers have already said — that Air Canada Flight 190 not only lost altitude but also pitched violently from right to left before dropping 900 feet.
"The aircraft rolled to the right to about 35 degrees of bank and rolled to the left about 50 degrees of bank and effectively the auto pilot was disconnected," said Nick Stoss of the Transportation Safety Board.
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I may be repeating some of the excellent descriptions given by other Airbus pilots but for non-Airbus pilots it may be helpful to have a 'Noddy's guide' to Airbus fly-by-wire control laws. There are 4 recognised states of Airbus flight control capability depending on computer and hydraulic serviceability. They are known as Normal Law, Alternate Law, Direct Law and Mechanical Back-up.
'Normal Law' is the standard flight control mode that pilots see every working day. Most pilots will go their whole professional career and never see any other mode except in the simulator. It requires that most flight control computers are operating normally and all hydraulic systems are functioning correctly. That is the mode for which the Airbus has become famous, whereby such features as limited g-loading, a maximum bank angle of 67° and the inability to stall are provided. Alternate Law is a degraded mode that still provides certain protections but will allow the aircraft to stall and to overbank, for example.
There is a further sub-mode somehwere between Normal Law and Alternate Law known as 'Abnormal Attitude Law' which caters for a scenario where the aircraft is thrown into a flight regime way outside the situations normally catered for in Normal Law. I have no idea if that is what happened in this case, but to give you a feel for what the pilots may have experienced, these are the paramaters that would have to occur for Abnormal Attitude Law to be invoked:
Pitch attitude > 50° nose up or 30° nose down
Bank angle > 125°
Angle of attack > 30° or < - 10° (- 15° for A319 and A321)
Speed > 440 knots or < 60 knots
Mach > 0.91 or < 0.1
The system applies an abnormal-attitude law in pitch and roll if the aircraft exceeds any of these limits in flight. The law in pitch is the alternate law with no protection except load-factor protection and without auto trim. In roll it is a full-authority direct law with a yaw mechanical.When the aircraft has recovered from its abnormal attitude, the flight control laws in effect are :
in pitch : alternate law without protection with autotrim.
in roll : full authority direct law with yaw alternate law.
There is no reversion to direct law when the pilot extends the landing gear.
I hope that may be helpful to non-Airbus pilots, but in no way suggests that is what occured in this case. It nonetheless gives you a feel for the severity of the situation required to enter this scenario.
'Normal Law' is the standard flight control mode that pilots see every working day. Most pilots will go their whole professional career and never see any other mode except in the simulator. It requires that most flight control computers are operating normally and all hydraulic systems are functioning correctly. That is the mode for which the Airbus has become famous, whereby such features as limited g-loading, a maximum bank angle of 67° and the inability to stall are provided. Alternate Law is a degraded mode that still provides certain protections but will allow the aircraft to stall and to overbank, for example.
There is a further sub-mode somehwere between Normal Law and Alternate Law known as 'Abnormal Attitude Law' which caters for a scenario where the aircraft is thrown into a flight regime way outside the situations normally catered for in Normal Law. I have no idea if that is what happened in this case, but to give you a feel for what the pilots may have experienced, these are the paramaters that would have to occur for Abnormal Attitude Law to be invoked:
Pitch attitude > 50° nose up or 30° nose down
Bank angle > 125°
Angle of attack > 30° or < - 10° (- 15° for A319 and A321)
Speed > 440 knots or < 60 knots
Mach > 0.91 or < 0.1
The system applies an abnormal-attitude law in pitch and roll if the aircraft exceeds any of these limits in flight. The law in pitch is the alternate law with no protection except load-factor protection and without auto trim. In roll it is a full-authority direct law with a yaw mechanical.When the aircraft has recovered from its abnormal attitude, the flight control laws in effect are :
in pitch : alternate law without protection with autotrim.
in roll : full authority direct law with yaw alternate law.
There is no reversion to direct law when the pilot extends the landing gear.
I hope that may be helpful to non-Airbus pilots, but in no way suggests that is what occured in this case. It nonetheless gives you a feel for the severity of the situation required to enter this scenario.
Last edited by Norman Stanley Fletcher; 12th Jan 2008 at 17:33. Reason: edited for typo!
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@ India Four Two
METAR for Lethbridge:
http://english.wunderground.com/hist...tename=Alberta
METAR for Cranbrook:
http://english.wunderground.com/hist...q_statename=NA
Unfortunately no winds aloft history found.
Regards
METAR for Lethbridge:
http://english.wunderground.com/hist...tename=Alberta
METAR for Cranbrook:
http://english.wunderground.com/hist...q_statename=NA
Unfortunately no winds aloft history found.
Regards
If I may intrude, for a moment...
What a clear piece of writing; many thanks. Illuminating.
But isn't >125 degrees bank rather more than a "severe" situation, as in "more than halfway to inverted"? I would have guessed that a severely abnormal situation might start at 60 degrees bank or even less, in a commercial jet.
Or am I muddling my degrees?
What a clear piece of writing; many thanks. Illuminating.
But isn't >125 degrees bank rather more than a "severe" situation, as in "more than halfway to inverted"? I would have guessed that a severely abnormal situation might start at 60 degrees bank or even less, in a commercial jet.
Or am I muddling my degrees?
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Please do not jump up and shout at me. I AM NOT SAYING THIS COULD HAVE HAPPENED IN THIS CASE.
When my company first got their A320's we had similar incident. The cause was put down to the F/O sitting cross legged and his Knee pressing on to the side stick. If I remember correctly they thought either the pressure gradually increased untill the autopilot let go or that he moved and knocked the side stick hard over. Neither pilot could remember this happening but the FDR showed the side stick movement.
Again if I remember rightly the a/c went 60 deg one way then 60 the other as the other pilot grabbed his side stick to correct. Then a bit of dual stick input (it sums the inputs) untill things settled down. Luckily no one was hurt.
Anyway as a matter of interest. & be careful crossing your legs, especially with one ankle on the oposite knee in an Airbus.
When my company first got their A320's we had similar incident. The cause was put down to the F/O sitting cross legged and his Knee pressing on to the side stick. If I remember correctly they thought either the pressure gradually increased untill the autopilot let go or that he moved and knocked the side stick hard over. Neither pilot could remember this happening but the FDR showed the side stick movement.
Again if I remember rightly the a/c went 60 deg one way then 60 the other as the other pilot grabbed his side stick to correct. Then a bit of dual stick input (it sums the inputs) untill things settled down. Luckily no one was hurt.
Anyway as a matter of interest. & be careful crossing your legs, especially with one ankle on the oposite knee in an Airbus.
Lufthansa requires passengers to wear seatbelts AT ALL TIMES when they're seated.
Cockpit also notifies SLF of any KNOWN expected turbulence, but it certainly makes sense to me.
Is there any reason NOT to comply with Jimmy Saville's "Clunk Click Every Trip" exhortation?
Cockpit also notifies SLF of any KNOWN expected turbulence, but it certainly makes sense to me.
Is there any reason NOT to comply with Jimmy Saville's "Clunk Click Every Trip" exhortation?
Lufthansa requires passengers to wear seatbelts AT ALL TIMES when they're seated
However, the emphasis is "when seated". Not everyone might be seated at a given moment for a variety of valid reasons. This may have been the case here. We don't know, we weren't there.
I keep my seat belt fasten at all times when seated. I often reflect how that's not going to save me if we happen to hit unexpected turbulence as I make my way to the lavatory. Sod's Law!
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Been a while since I flew any "bus", but isn't pitch alternate and roll direct the same regime as is blended in when the aircraft enters "FLARE" mode? In this regime, it's pretty much just a regular, old-fashioned airplane.
I remember one morning climbing out of YYZ over west Pennsylvania out of 380 on the way to 390 in an A330...literally smooth as glass from surface to about 383...not a cloud in the sky...and then all $%^& broke loose. CAT was so severe that we couldn't even read the FCU/Instruments. A/P kicked off and A/T was disengaged in record speed with consensus rapidly achieved that a rather more expeditious return than normal to 350 would be a sound course of action.
Moral of the story: keep your seatbelts fastened!
I remember one morning climbing out of YYZ over west Pennsylvania out of 380 on the way to 390 in an A330...literally smooth as glass from surface to about 383...not a cloud in the sky...and then all $%^& broke loose. CAT was so severe that we couldn't even read the FCU/Instruments. A/P kicked off and A/T was disengaged in record speed with consensus rapidly achieved that a rather more expeditious return than normal to 350 would be a sound course of action.
Moral of the story: keep your seatbelts fastened!
Sun worshipper
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When there is confusion...
From Norman Stanley Fletcher and some others :
..."to give you a feel for what the pilots may have experienced, these are the paramaters that would have to occur for Abnormal Attitude Law to be invoked:
Pitch attitude > 50° nose up or 30° nose down
Bank angle > 125°
Angle of attack > 30° or < - 10° (- 15° for A319 and A321)
Speed > 440 knots or < 60 knots
Mach > 0.91 or < 0.1..."
All the above is correct as are all the posts dealing with flight control reversions.
They, IMHO, are hardly applicable in this case as :
Please note that in this case, they could have re-connected the A/P when calm conditions were resumed. The reason why they - apparently - did not could be explained by caution and - maybe - confusion as to the causes of the upset.
..."to give you a feel for what the pilots may have experienced, these are the paramaters that would have to occur for Abnormal Attitude Law to be invoked:
Pitch attitude > 50° nose up or 30° nose down
Bank angle > 125°
Angle of attack > 30° or < - 10° (- 15° for A319 and A321)
Speed > 440 knots or < 60 knots
Mach > 0.91 or < 0.1..."
All the above is correct as are all the posts dealing with flight control reversions.
They, IMHO, are hardly applicable in this case as :
- They were on autopilot
- A passenger was quoted as reporting that the captain came on the PA and said that " the A/P had been knocked-out and they were flying manually".
- This points to an A/P disconnect.
The conditions are a lot smaller than those for a reversion :
-High speed protection is active (Vmo bust)
-Alpha protection is active (AoA greater than Alpha prot +1° )
-Pitch attitude over 25° nose up or 13° nose down
-Bank angle in excess of 45°
Please note that in this case, they could have re-connected the A/P when calm conditions were resumed. The reason why they - apparently - did not could be explained by caution and - maybe - confusion as to the causes of the upset.
Last edited by Lemurian; 15th Jan 2008 at 22:32. Reason: bullets
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it seems that the crew changed altitudes looking for smoother air prior to the "upset". if that is the case, why was anyone standing? including the fa's? I would have told the fa's to delay service if turbulence was possible.
and if the crew did look for smoother air, it should have been obvious that this was a turbulence induced event. now, has the plane been put back into service or was it overstressed?
and if the crew did look for smoother air, it should have been obvious that this was a turbulence induced event. now, has the plane been put back into service or was it overstressed?
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Here is the Anglo version:
http://www.cbc.ca/canada/calgary/sto...ght-cause.html
An Air Canada Airbus on its way from Victoria to Toronto dropped suddenly in midair likely because of the wake from a passing plane, according to a Calgary newspaper report.
The Calgary Sun quotes Real Levasseur, the chief investigator of the Transportation Safety Board, as saying there was a "high probability that an external force may have caused the incident."
Flight AC190 was diverted to Calgary on its way from Victoria to Toronto.
(CBC) The Airbus A319 had been flying for about 30 minutes on Jan. 10 when it suddenly rolled and dropped about 300 metres. Passengers said the pilots reported a computer failure onboard at the time.
Flight AC190 was diverted to Calgary, where 10 passengers and crew members were taken to hospital with mainly soft-tissue injuries. All were discharged several hours later.
The aircraft's roll of 46 degrees was described by an Air Canada pilot as an unusual occurrence. "The pitch caused by a regular turn generally ranges around 30 degrees," Serge Beaulieu, spokesman for the Air Canada Pilots Association, told the Sun. He also confirmed wake turbulence was a possible cause.
The incident happened at the edge of U.S. airspace near the B.C. Kootenay Mountains. The TSB has asked its U.S. counterpart to provide navigational recordings from the area.
Levasseur refused to speculate on the mystery aircraft, or to discuss the possibility it could have been a B-2 stealth bomber, according to the Sun report.
U.S. Air Force officials told the newspaper Tuesday that stealth bombers always leave a radar signature when they are not flying over a war zone.
This reminds me of a story a from friend of mine who was AC cabin crew. Disclaimer: (1) I am SLF; and (2) She told me this over 10 years ago, so I don't remember all the details.
She was flying out of Vancouver on a B767 and was in the cockpit when the two pilots suddenly looked concerned. Turns out, a US stealth jet was flying below them. I know she told me how many feet separated them, but I can't remember now. However, it was close enough that the two pilots were not impressed.
slinks back to steerage
http://www.cbc.ca/canada/calgary/sto...ght-cause.html
An Air Canada Airbus on its way from Victoria to Toronto dropped suddenly in midair likely because of the wake from a passing plane, according to a Calgary newspaper report.
The Calgary Sun quotes Real Levasseur, the chief investigator of the Transportation Safety Board, as saying there was a "high probability that an external force may have caused the incident."
Flight AC190 was diverted to Calgary on its way from Victoria to Toronto.
(CBC) The Airbus A319 had been flying for about 30 minutes on Jan. 10 when it suddenly rolled and dropped about 300 metres. Passengers said the pilots reported a computer failure onboard at the time.
Flight AC190 was diverted to Calgary, where 10 passengers and crew members were taken to hospital with mainly soft-tissue injuries. All were discharged several hours later.
The aircraft's roll of 46 degrees was described by an Air Canada pilot as an unusual occurrence. "The pitch caused by a regular turn generally ranges around 30 degrees," Serge Beaulieu, spokesman for the Air Canada Pilots Association, told the Sun. He also confirmed wake turbulence was a possible cause.
The incident happened at the edge of U.S. airspace near the B.C. Kootenay Mountains. The TSB has asked its U.S. counterpart to provide navigational recordings from the area.
Levasseur refused to speculate on the mystery aircraft, or to discuss the possibility it could have been a B-2 stealth bomber, according to the Sun report.
U.S. Air Force officials told the newspaper Tuesday that stealth bombers always leave a radar signature when they are not flying over a war zone.
This reminds me of a story a from friend of mine who was AC cabin crew. Disclaimer: (1) I am SLF; and (2) She told me this over 10 years ago, so I don't remember all the details.
She was flying out of Vancouver on a B767 and was in the cockpit when the two pilots suddenly looked concerned. Turns out, a US stealth jet was flying below them. I know she told me how many feet separated them, but I can't remember now. However, it was close enough that the two pilots were not impressed.
slinks back to steerage
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Second jet may have caused plane plunge???