Voyager Plummets (Merged)
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As no incident reports change of procedures etc or rectification,released by EASA/AirTanker, presume crew finger trouble?
Well, given the rumours that the autopilot wouldn't disconnect, I would strongly suspect a problem in the left hand sidestick system. But surely there's redundancy built in to the sidestick design? Or is that supposed to be achieved by having 2 sidesticks?
As for blaming the crew, if anyone was stupid enough to try that they'd soon wish they hadn't.....
Is there something else we haven't been told? From the local rag: More people spotted fireball falling from sky (From Witney Gazette)
As for blaming the crew, if anyone was stupid enough to try that they'd soon wish they hadn't.....
Is there something else we haven't been told? From the local rag: More people spotted fireball falling from sky (From Witney Gazette)
Last edited by BEagle; 22nd Feb 2014 at 10:17.
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On the point of blaming flight crew, it is vital that any aviation organisation has the culture that allows people to admit mistakes however large. It very much depends on the Sqn culture and I have seen situations where a lot of technical investigation was needed because the culture prevented a crew fessing up to a mistake. I point out that as I have no knowledge of the facts in this case I am not making a judgement of this situation, just making a general point.
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Heard a rumour, beagle or starting one? I only ask because in 19 years operating fbw Airbuses I've never seen a bulletin or reported instance of an autopilot refusing to disconnect.
If true that Voyager has returned to flight and there are no safety bulletins, nor engineering action, it must be very frustrating for those who have been peddling their pet prejudices concerning Airbus, FBW and AirTanker.
Still, never let a lack of facts get in the way of a good conspiracy theory. After all this is a rumours network.
Still, never let a lack of facts get in the way of a good conspiracy theory. After all this is a rumours network.
ShotOne
Thats the initial recent "informed rumour" from crew reports, as no offical word being released by AirTanker. All being kept very close to chests.
From the above, the crew error conjecture incorrect.
From the above, the crew error conjecture incorrect.
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On 7 October 2008, an Airbus A330-300 being operated by Qantas on a scheduled passenger flight from Singapore to Perth, Western Australia was in the cruise at FL370 with the AP engaged when one of the air data inertial reference units (ADIRUs)[1] malfunctioned and two sudden uncommanded pitch downs followed. A PAN, later upgraded to a MAYDAY after the extent of occupant injuries became apparent, was declared to ATC and a diversion to Learmonth initiated with an approach and landing there about an hour later. Of the 315 occupants, 11 passengers and 1 cabin crew member were seriously injured and a further 99 passengers and 8 cabin crew received minor injuries.
Investigation
An Investigation was carried out by the ATSB. FDR, Quick access recorder (QAR) and CVR data was all successfully replayed to support the Investigation. A Preliminary Report and two Interim Factual Reports were published whilst the Investigation was in progress.
The aircraft commander had been PF when, after a previously uneventful flight, an uncommanded AP1 disconnect occurred followed by a series of caution messages on the EICAM and transient activation of obviously false stall and over speed warnings. These cautions and warnings occurred frequently and continued for the remainder of the flight. The airspeed and altitude indications on the left main PFD (only) were also fluctuating. Although numerous ECAM caution messages were annunciated, none of them required urgent action, and none of them indicated any potential problems with the aircraft’s flight control system. Two minutes after the AP1 disconnect, the aircraft abruptly pitched nose down. FDR data showed that this was due to a sudden change in the position of the aircraft elevators, and that the aircraft reached a maximum nose-down pitch angle of 8.4°. The flight crew described the pitch-down movement as very abrupt, but smooth. It was considered not to be like turbulence-related movements and was solely in the pitching plane. Side stick back pressure to counteract the pitch was applied and after about 2 seconds the aircraft responded normally and recovery to the assigned altitude was accomplished. Overall, the aircraft descended 690 ft over a period of 23 seconds before regaining FL370.
During the upset, the FDR recorded a peak vertical acceleration of -0.8g and a significant number of occupants were thrown around the cabin, resulting in both personal injuries and damage to cabin overhead fittings. The operating co pilot switched on the seat belt signs soon after the upset and made a PA announcement for passengers and cabin crew to return to their seats and fasten their seat belts immediately.
Two and a half minutes after the first pitch down event, a second less severe one occurred while the crew were responding to the ECAM messages. The aircraft reached a maximum pitch angle of about 3.5° nose down and side stick back pressure to counter this was promptly applied. As with the first case, the action initially had no effect but soon afterwards, the aircraft responded normally. The aircraft descended 400 feet over a period of 15 seconds before regaining FL370.
The aircraft commander noted that the auto trim was no longer working and decided to fly the aircraft manually with both AP and A/T disconnected, believing the aircraft flight control system to have reverted to Direct Law[1]. In fact, although absence of auto trim is a feature of Direct Law, in this case, it had been lost as a consequence of the specific sequence of fault messages associated with the Flight Control Primary Computer (FCPC) and only reversion to Alternate Law[1] had occurred.
Soon after recovery from the second upset, the decision to make an en route diversion was made and a ‘PAN’ declared to ATC. The diversion to Learmonth was accomplished without further event other than the discovery that the extent of cabin injuries amongst unsecured passengers and crew was greater than had at first been appreciated. A descent was accomplished in the vicinity of the airfield before positioning for a visual approach and landing.
An Investigation was carried out by the ATSB. FDR, Quick access recorder (QAR) and CVR data was all successfully replayed to support the Investigation. A Preliminary Report and two Interim Factual Reports were published whilst the Investigation was in progress.
The aircraft commander had been PF when, after a previously uneventful flight, an uncommanded AP1 disconnect occurred followed by a series of caution messages on the EICAM and transient activation of obviously false stall and over speed warnings. These cautions and warnings occurred frequently and continued for the remainder of the flight. The airspeed and altitude indications on the left main PFD (only) were also fluctuating. Although numerous ECAM caution messages were annunciated, none of them required urgent action, and none of them indicated any potential problems with the aircraft’s flight control system. Two minutes after the AP1 disconnect, the aircraft abruptly pitched nose down. FDR data showed that this was due to a sudden change in the position of the aircraft elevators, and that the aircraft reached a maximum nose-down pitch angle of 8.4°. The flight crew described the pitch-down movement as very abrupt, but smooth. It was considered not to be like turbulence-related movements and was solely in the pitching plane. Side stick back pressure to counteract the pitch was applied and after about 2 seconds the aircraft responded normally and recovery to the assigned altitude was accomplished. Overall, the aircraft descended 690 ft over a period of 23 seconds before regaining FL370.
During the upset, the FDR recorded a peak vertical acceleration of -0.8g and a significant number of occupants were thrown around the cabin, resulting in both personal injuries and damage to cabin overhead fittings. The operating co pilot switched on the seat belt signs soon after the upset and made a PA announcement for passengers and cabin crew to return to their seats and fasten their seat belts immediately.
Two and a half minutes after the first pitch down event, a second less severe one occurred while the crew were responding to the ECAM messages. The aircraft reached a maximum pitch angle of about 3.5° nose down and side stick back pressure to counter this was promptly applied. As with the first case, the action initially had no effect but soon afterwards, the aircraft responded normally. The aircraft descended 400 feet over a period of 15 seconds before regaining FL370.
The aircraft commander noted that the auto trim was no longer working and decided to fly the aircraft manually with both AP and A/T disconnected, believing the aircraft flight control system to have reverted to Direct Law[1]. In fact, although absence of auto trim is a feature of Direct Law, in this case, it had been lost as a consequence of the specific sequence of fault messages associated with the Flight Control Primary Computer (FCPC) and only reversion to Alternate Law[1] had occurred.
Soon after recovery from the second upset, the decision to make an en route diversion was made and a ‘PAN’ declared to ATC. The diversion to Learmonth was accomplished without further event other than the discovery that the extent of cabin injuries amongst unsecured passengers and crew was greater than had at first been appreciated. A descent was accomplished in the vicinity of the airfield before positioning for a visual approach and landing.
lj101, that is the previously-mentioned 'QF72' incident. Caused by faulty hardware in an ADIRU and a software characteristic which (at that time)hadn't been designed to cope with the specific nature of the ADIRU fault.
Back to the Voyager plummet, what I find very perplexing is that, even though Airbus state
it seems that, in this case a spurious pitch demand was received which subjected the aircraft to both an excessive manoeuvre and exceedance of the flight envelope. Whereas in the QF72 incident, though alarming, both pitch attitude and peak vertical acceleration remained within the protected envelope.
Back to the Voyager plummet, what I find very perplexing is that, even though Airbus state
• Regardless of pilot inputs, the (EFCS) computers will prevent :
- excessive maneuvres
- exceedance of the safe flight envelope.
- excessive maneuvres
- exceedance of the safe flight envelope.
When a certain airline was in the early days of operating the A320 they suffered a spate of incidents with autopilots disconnecting and also an uncommanded roll. The engineers scratched their heads and it started occurring on different aircraft. The problem could not be replicated by the engineers but following a lot of component replacements and trouble shooting the problem was narowed down to one particular pilot.It transpired that he was crossing his legs and knocking the stick with his foot. He was completely unaware that he wss doing it, but once he was made aware the problem never reappeared.
There have also been problems with crews placing teas etc on the pedestal next to the stick, and the contents being dislodged into the mechanism underneath it.
Side Stick Controller Photo by Jetdoc1 | Photobucket
There have also been problems with crews placing teas etc on the pedestal next to the stick, and the contents being dislodged into the mechanism underneath it.
Side Stick Controller Photo by Jetdoc1 | Photobucket
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Beags, heard of this?
In the past Airbus has insisted its use of Kapton is safe, because it coats it in a thin layer of ‘FEP’ – fluorinated ethylene propylene – making it less likely to crack. But other experts disagree, and in 2008 the Federal Aviation Administration, America’s rule-making body, stated that even when coated with FEP, ‘Kapton wire insulation materials should not be used in airborne applications.’ But didn’t ban its use, aware perhaps that to do so would call into question the safety of any aircraft using Kapton – as many as 14,000 planes.
The introduction of fly-by-wire aircraft has furthered the frequency of these situations,’ he says. ‘But as with QF72, the anomalies often can’t be reproduced on the ground by maintenance personnel, because there the vibrations and humidity experienced in flight are no longer an issue.’
For four years from 1999, a special investigation group set up by the FAA stripped down six ageing passenger aircraft, including a Kapton-wired Airbus A300, the predecessor of the A330. It found widespread evidence of wire bundles that had become charred, cracked, brittle and prone to arcing, as well as contaminated by dust, lint and fluid from leaking toilets. Yet when its report was produced, the Bush White House took no action.
Arcing may not only cause fires or systems to fail: it can also lead to ‘uncommanded inputs’, such as the sudden plunges experienced by QF72.
There’s still no effective way to test wires’ integrity while they remain in use. Nasa would not have to be retiring the Space Shuttle fleet if there were a simple test. On the other hand, if there were a test, and it showed the Kapton in individual planes is dangerous, thousands of planes might have to be retired.’
The introduction of fly-by-wire aircraft has furthered the frequency of these situations,’ he says. ‘But as with QF72, the anomalies often can’t be reproduced on the ground by maintenance personnel, because there the vibrations and humidity experienced in flight are no longer an issue.’
For four years from 1999, a special investigation group set up by the FAA stripped down six ageing passenger aircraft, including a Kapton-wired Airbus A300, the predecessor of the A330. It found widespread evidence of wire bundles that had become charred, cracked, brittle and prone to arcing, as well as contaminated by dust, lint and fluid from leaking toilets. Yet when its report was produced, the Bush White House took no action.
Arcing may not only cause fires or systems to fail: it can also lead to ‘uncommanded inputs’, such as the sudden plunges experienced by QF72.
There’s still no effective way to test wires’ integrity while they remain in use. Nasa would not have to be retiring the Space Shuttle fleet if there were a simple test. On the other hand, if there were a test, and it showed the Kapton in individual planes is dangerous, thousands of planes might have to be retired.’
That's interesting, lj101. But I don't know whether Kapton wiring is used extensively in the A330?
I assume that the fleet grounding has only been lifted if the cause of this event has been conclusively identified beyond all reasonable doubt. And if it was indeed a faulty side-stick system, I would assume that all other Voyagers have been checked...and rectified.
Are commercial pressures influencing the return to flight status? Surely not.
Both MoD and ATr have used mealy-mouthed terms such as a 'pause' in operations and an 'unscheduled change in flight level'. They both seem terrified of using the term 'grounded' - why?
tucumseh, it would be interesting to hear your opinion....
mr snow, see post #59....
I assume that the fleet grounding has only been lifted if the cause of this event has been conclusively identified beyond all reasonable doubt. And if it was indeed a faulty side-stick system, I would assume that all other Voyagers have been checked...and rectified.
Are commercial pressures influencing the return to flight status? Surely not.
Both MoD and ATr have used mealy-mouthed terms such as a 'pause' in operations and an 'unscheduled change in flight level'. They both seem terrified of using the term 'grounded' - why?
tucumseh, it would be interesting to hear your opinion....
mr snow, see post #59....
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Post #59 that you refer to, beagle, contains a report from a passenger in the rear cabin (interestingly making his first ever pprune post five days after the incident). He gave the descent angle as "20 to 40 degrees, or maybe 60".With respect, how could he possibly have known whether the envelope was exceeded?
ShotOne, the post actually read
As someone with
doubtless you'll be able to tell us the pitch attitude and g protection limits in Normal Law?
Or was the excursion sufficiently extreme to have caused the aircraft to degrade to Abnormal Attitude Law?
We were told by the pilot that the co pilot had got up to get a drink when the aircraft dropped at an angle of between 20 and 40 degrees, some one said 60 degrees.
19 years operating fbw Airbuses
Or was the excursion sufficiently extreme to have caused the aircraft to degrade to Abnormal Attitude Law?
Both MoD and ATr have used mealy-mouthed terms such as a 'pause' in operations and an 'unscheduled change in flight level'. They both seem terrified of using the term 'grounded' - why?
tucumseh, it would be interesting to hear your opinion...
tucumseh, it would be interesting to hear your opinion...
The reluctance to say "grounded" MAY have something to do with the cost and hassle associated with re-certifying a civilian registered aircraft. But I concede I don't know much, if anything, about the Voyager programme. Nobody in his right mind volunteered for a PFI job because it would entail making a false declaration that the proposed expenditure passed requirement scrutiny rules!
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The reluctance to say "grounded" MAY have something to do with the cost and hassle associated with re-certifying a civilian registered aircraft
Because the incident happened on a mil registed aircraft during operations, all the information is being dealt with by the MAA and RAF. This is why there is a lack of information coming from airtanker as they bound by the military system. Although the MAA and RAF will have consulted with other parties, CAA/EASA etc as this is best practice.
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"The pilot told me this", "someone else said that" relating to wildly diverging figures is hardly a solid basis for your claim, beagle. Not that it stopped you making a tabloid-worthy response about being "lucky to survive!"
"Abnormal attitude law?" What on earth are you talking about?
"Abnormal attitude law?" What on earth are you talking about?
Shot One, I'm puzzled as to your unreasonably hostile netiquette. Not for the first time either...
Are you really telling me that you have never been taught about Abnormal Attitude Law?
I find that surprising. But then again, a ba training captain with whom I was talking recently simply wouldn't believe that an A320 can be stalled if it is not in Normal Law.
Anyway:
The abnormal attitude law is a subset of alternate law on the aircraft. It is triggered when the angle of attack exceeds 30° or when certain other inertial parameters - pitch and roll - become greater than threshold levels.
• Pitch (50 ̊ up, 30 ̊ down)
• Bank (125 ̊)
• AOA (30 ̊, -10 ̊)
• Speed (440 kt, 60 kt)
• Mach (0.96, 0.1).
In pitch it is alternate law without protection (except load factor protection) or auto trim. There is no upgrade to the control law once it has been triggered.
In the AF447 accident, after stalling, the angle of attack remained above 35°. But while this exceeded the threshold for the abnormal attitude law, the flight control computers had already rejected all three air data reference units and all air data parameters owing to discrepancy in the airspeed measurements.
Are you really telling me that you have never been taught about Abnormal Attitude Law?
I find that surprising. But then again, a ba training captain with whom I was talking recently simply wouldn't believe that an A320 can be stalled if it is not in Normal Law.
Anyway:
The abnormal attitude law is a subset of alternate law on the aircraft. It is triggered when the angle of attack exceeds 30° or when certain other inertial parameters - pitch and roll - become greater than threshold levels.
• Pitch (50 ̊ up, 30 ̊ down)
• Bank (125 ̊)
• AOA (30 ̊, -10 ̊)
• Speed (440 kt, 60 kt)
• Mach (0.96, 0.1).
In pitch it is alternate law without protection (except load factor protection) or auto trim. There is no upgrade to the control law once it has been triggered.
In the AF447 accident, after stalling, the angle of attack remained above 35°. But while this exceeded the threshold for the abnormal attitude law, the flight control computers had already rejected all three air data reference units and all air data parameters owing to discrepancy in the airspeed measurements.
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"Abnormal attitude law?" What on earth are you talking about?
A completely different law emerges automatically when the aircraft is in an extreme upset as follows:
* pitch attitude > 50 deg nose up or > 30 deg nose down
* bank angle > 125 deg
* AOA > 30 deg or >-10 deg
* speed > 440 kts or < 60 kts
* mach > M0.96 or < M0.1
The abnormal attitude law is:
- PITCH ALTERNATE with no protection except LOAD FACTOR protection. No automatic pitch trim.
- ROLL DIRECT with full authority
- YAW ALTERNATE
After recovery the flight law reverts to:
- PITCH ALTERNATE law
- ROLL DIRECT law
- YAW ALTERNATE
The aircraft returns to a degraded mode (not normal law as usual) because there is a certain level of suspicion about its ability to control the aircraft (that is how could it have got to the extreme flight state in the first
place? The protections should have intervened well before the pitch, bank, AOA, speed and mach limits above).