AS332L2 Ditching off Shetland: 23rd August 2013
My posting a couple of pages back got trampled in a handbagging incident between Pitts and HC (Ladies, please!). Any thuoght on this as a theory?
http://flightsafety.org/hs/hs_may_june97.pdf
http://flightsafety.org/hs/hs_may_june97.pdf
Technology does move on, and if that exact same scenario was re-enacted on a 225, the outcome would have been completely different with a safe landing made. That of course is no consolation to those who perished (and their relatives) but it does show the benefits of developments in HMI. Its one thing to make a reasonably functional autopilot, another thing to make it pilot-proof, but the recent offerings from EC are pretty much pilot proof!
Tragic though this accident is, it is in fact a boost for the beleaguered EC225 for those that actually understand the detail.
Last edited by HeliComparator; 5th Sep 2013 at 14:18.
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So at three miles they are at a 1000' with the speed 'decreasing steadily'. A mile on they are at 470' and 68kts. That is getting very close to levelling off just above minima of 300'. I wonder what mode selection was happening in those final moments. Coupling to Alt would presumably increase the nose up pitch as the autopilot attempted to level the aircraft. Or would the autopilot have any effect at all by then?
Plate here if it hasn't been linked to before:
https://flydev.rocketroute.com/plate...2275&icao=EGPB
Plate here if it hasn't been linked to before:
https://flydev.rocketroute.com/plate...2275&icao=EGPB
RJC the AAIB report doesn't mention ALT.A therefore (if it wasn't armed) the aircraft would not automatically level at MDA. The engaged modes are recorded on the FDR and I think the AAIB would have mentioned it if VS changed to ALT. But it would be ALT on the cyclic with manual intervention required to raised the collective to avoid even more rapid loss of IAS, so no practical difference in this case.
I shall take a bit of a Contrarian view on this Special AAIB Report.
My view is this report should not have been released.
The AAIB should have waited until they had digested the CVR data and decided what it meant....then released a Special Report that would go much further in describing the sequence of events and the time line of the CVR.
The Report as it reads now...tells very little and only generates more conjecture than it would otherwise had they waited to put out the CVR information.
Far too little information to justify a Report at this time.
My view is this report should not have been released.
The AAIB should have waited until they had digested the CVR data and decided what it meant....then released a Special Report that would go much further in describing the sequence of events and the time line of the CVR.
The Report as it reads now...tells very little and only generates more conjecture than it would otherwise had they waited to put out the CVR information.
Far too little information to justify a Report at this time.
Because the L2 doesn't have the same power limiting functionality, its not normal to fly the L2 in 4-axis in the cruise or climb, but no reason not to for an approach. However much of the time the L2 will be being flown in 3 axis and perhaps that makes the fleet culture a bit different.
We are presuming of course that the collective axis was functional at the time, but that the crew chose not to use it.
As I mentioned earlier, I suspect that after this, there will be a tightening up of SOPs for use of automation, something which has mostly been at pilot's discretion up to now.
Last edited by HeliComparator; 5th Sep 2013 at 14:30.
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HC
I guess what I was getting at with the level off was did they exacerbate things by selecting ALT manually and not using sufficient collective or was it already past recovering by that stage. As you say, given the lack of mode selection information in the report, then probably the latter.
HC,
in the L2 I assume there is a minimum IAS at which coupled modes are 'dropped out' if in 3-axis (again, another improvement in the 225/155 which automatically revert to 4 axis). If this assumption is correct, what cautions and indications would be presented? In teh S-92 the EICAS generates an FD DEGRADE caption accompanied by the master caution illuminating - which is a significant distraction and could delay reaction/response.
in the L2 I assume there is a minimum IAS at which coupled modes are 'dropped out' if in 3-axis (again, another improvement in the 225/155 which automatically revert to 4 axis). If this assumption is correct, what cautions and indications would be presented? In teh S-92 the EICAS generates an FD DEGRADE caption accompanied by the master caution illuminating - which is a significant distraction and could delay reaction/response.
Last edited by 212man; 5th Sep 2013 at 14:33.
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Because the L2 doesn't have the same power limiting functionality, its not normal to fly the L2 in 4-axis in the cruise or climb, but no reason not to for an approach. However much of the time the L2 will be being flown in 3 axis and perhaps that makes the fleet culture a bit different.
212 sorry, can't remember the detail of min speeds for modes - I last flew an L2 in 2006! However, I think there is no substantial indication of a mode dropping out other than the engaged mode disappearing with perhaps a bit of amber flashery. Nothing to attract the attention if you are not looking at it.
I've always thought this was a weakness (in the 225) since with the amount of dependency on, and the reliability of the autoflight system, it would be good if the pilots were made clearly aware when a mode had dropped out for some reason. We (as in a group comprising CHC, Bond and BHL) did suggest to EC that there should be an aural warning anytime autopilot functionality was lost to the point the pilot had to take manual control, but so far that hasn't been implemented.
I've always thought this was a weakness (in the 225) since with the amount of dependency on, and the reliability of the autoflight system, it would be good if the pilots were made clearly aware when a mode had dropped out for some reason. We (as in a group comprising CHC, Bond and BHL) did suggest to EC that there should be an aural warning anytime autopilot functionality was lost to the point the pilot had to take manual control, but so far that hasn't been implemented.
We (as in a group comprising CHC, Bond and BHL) did suggest to EC that there should be an aural warning anytime autopilot functionality was lost to the point the pilot had to take manual control, but so far that hasn't been implemented.
I was just exploring the possibility of there being a significant distraction (Master Caution) at an inopportune moment, but possibly not.
The 92 has the same problem
As a plank driver, all these discussions of automation modes, and various axes are giving me a bit of a headache.
Can somebody give me a link to an idiot's guide to Helicopter Autoflight?
V/S mode on fixed wing can be a killer as again it will maintain selected vertical speed and ignore IAS up to the point of stalling an aircraft in the climb (for example).
"Semi-automated" is a big no-no on the older Boeings - and indeed probably caused the Asiana crash. They firmly recommend either full manual flight or full automation, rather than a halfway house to avoid precisely this sort of problem.
Can somebody give me a link to an idiot's guide to Helicopter Autoflight?
V/S mode on fixed wing can be a killer as again it will maintain selected vertical speed and ignore IAS up to the point of stalling an aircraft in the climb (for example).
"Semi-automated" is a big no-no on the older Boeings - and indeed probably caused the Asiana crash. They firmly recommend either full manual flight or full automation, rather than a halfway house to avoid precisely this sort of problem.
Can somebody give me a link to an idiot's guide to Helicopter Autoflight?
By problem, I meant the autopilot causing an overtorque. Has that been sorted?
Last edited by 212man; 5th Sep 2013 at 14:59.
How distracting can a Master Caution Light and a segment light be?
One pilot is supposed to be flying the machine....always.
On an Approach such as the one in question....one Pilot is supposed to "driving" while the other monitors the other Pilot and taking care of "stuff" that arises.
Even though the Autopilot is "flying" the machine....the Handling Pilot is looking for correct function and performance.
There is far more to this crash than meets the eye here.
What it is shall be explained probably by what the CVR has to say.
Why were Target Air Speeds, ROD's, and MDA's not monitored. Any deviation from the Target or selected speeds/rates/altitudes should have been detected and corrected.
Why the deviation is less important than why the deviation was not detected and corrected. That will be the key to this puzzle.
One pilot is supposed to be flying the machine....always.
On an Approach such as the one in question....one Pilot is supposed to "driving" while the other monitors the other Pilot and taking care of "stuff" that arises.
Even though the Autopilot is "flying" the machine....the Handling Pilot is looking for correct function and performance.
There is far more to this crash than meets the eye here.
What it is shall be explained probably by what the CVR has to say.
Why were Target Air Speeds, ROD's, and MDA's not monitored. Any deviation from the Target or selected speeds/rates/altitudes should have been detected and corrected.
Why the deviation is less important than why the deviation was not detected and corrected. That will be the key to this puzzle.
Jwscud, out of interest do some modern fixed wing have flight envelope protection whereby autothrottle is automatically engaged if airspeed is reducing too much, for example due to too high a pitch attitude or vertical speed demand for the power set?
Last edited by HeliComparator; 5th Sep 2013 at 15:24.
In order that I understand the report and the approach plate:
The MDA for that approach is 300 feet.
Weather reported in the was 200 feet scattered 300 feet broken. (IFR)
If I have misread the report, please advise.
Not sure which airspeed they had selected, and which RoD they were using to get to the MAP/ decision point at 0.5 DME/SUB. (The choices on the appr plate provide ample lattitude based on aircraft, flight, conditions, etc)
Without a CVR derived insight of what one pilot said to the other, if either noted "field in sight," or if there was any other indication of going from "in the goo" to "not in the goo," it's hard for me to understand the decel from 68 knots to whatever it was that put them behind the power curve.
Appreciate the folks who have tried to explain how the automated modes interact. I have a suspicion that SASless has put his finger on most of it.
Thanks also to that Flight Safety paper from a few years back. Good stuff.
The MDA for that approach is 300 feet.
Weather reported in the was 200 feet scattered 300 feet broken. (IFR)
If I have misread the report, please advise.
Not sure which airspeed they had selected, and which RoD they were using to get to the MAP/ decision point at 0.5 DME/SUB. (The choices on the appr plate provide ample lattitude based on aircraft, flight, conditions, etc)
Without a CVR derived insight of what one pilot said to the other, if either noted "field in sight," or if there was any other indication of going from "in the goo" to "not in the goo," it's hard for me to understand the decel from 68 knots to whatever it was that put them behind the power curve.
Appreciate the folks who have tried to explain how the automated modes interact. I have a suspicion that SASless has put his finger on most of it.
Thanks also to that Flight Safety paper from a few years back. Good stuff.
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Generally speaking I don't like reports being issued before all the facts are established but in this case they'd taken all the helicopters out of service in case it was a repeat of the previous problem.
this led to major disruption of the industry and the lives of people offshore & their families
They were able to establish that it was unlikely to be a mechanical problem - and no-one would believe any statement by the manufacturers, the service companies, the field operators, the unions or even the police - the AIB are the only ones who people trust so a very limited statement seems to be a reasonable thing to do in these circumstances
this led to major disruption of the industry and the lives of people offshore & their families
They were able to establish that it was unlikely to be a mechanical problem - and no-one would believe any statement by the manufacturers, the service companies, the field operators, the unions or even the police - the AIB are the only ones who people trust so a very limited statement seems to be a reasonable thing to do in these circumstances
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GJM
You can 'fly through' easily but the autopilot may be trying to do the opposite of what you are trying to do so you need to keep on top of it.
At some point you need to disengage the upper modes or reset the datums to align them with what you require.
At some point you need to disengage the upper modes or reset the datums to align them with what you require.