AS332L2 Ditching off Shetland: 23rd August 2013
HC
So having read DB's post and many others what now seems to be occurring is that the autopilot is very good - which I have never disputed, but the training of how to use it is not.
Did the ETAP HP take the autopilot protection out because he didn't understand fully what it could do and then his manual flying skills didn't allow a safe approach.
It seems the Sumburgh HP may have used an inappropriate method of using the autopilot which had a trap in it which allowed the a/c to try and maintain height without enough power selected and a UP ensued which was not recognised and flown out of, either by selecting the correct autopilot function or by manual intervention.
We can't ignore the fact that 2 very capable SPs with modern autopilots ended up in the water!!
I am never in favour of the term "pilot error" there is always a chain of events which end up with an accident - The RAF had some very good Flight Safety films which emphasised that it was everybody's responsibility to try and spot links in the chain and break them - this extended from management to the coal face.
HF
Mmmh, so one SP in the sea following no use of the autopilot at all (other than basic stability of course). Another SP in the drink with what looks like a partial (or some would say inadequate) use of the autopilot, and your response is its all due to a "culture of over use of the autopilot".
Did the ETAP HP take the autopilot protection out because he didn't understand fully what it could do and then his manual flying skills didn't allow a safe approach.
It seems the Sumburgh HP may have used an inappropriate method of using the autopilot which had a trap in it which allowed the a/c to try and maintain height without enough power selected and a UP ensued which was not recognised and flown out of, either by selecting the correct autopilot function or by manual intervention.
We can't ignore the fact that 2 very capable SPs with modern autopilots ended up in the water!!
I am never in favour of the term "pilot error" there is always a chain of events which end up with an accident - The RAF had some very good Flight Safety films which emphasised that it was everybody's responsibility to try and spot links in the chain and break them - this extended from management to the coal face.
HF
Last edited by Hummingfrog; 6th Sep 2013 at 09:02.
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It seems, from the report, that the crew had not "selected" an airspeed, and were operating with just VS and Localiser coupled. In this instance the vertical mode is being controlled by cyclic, snd airspeed is being controlled manually by collective. If the collective is set in the right position airspeed is maintained but if not the airspeed will change as it is the only parameter available to the ac to maintain the chosen VS (in this case, the same happens in level flight if Alt is engaged).
If the collective is set too low, ie not producing enough 'power', then the aircraft will reduce airspeed to try and maintain the desired VS. If you are only slightly out then it will stabilise at lower speed. If you're a bit more than slightly too low the airspeed will keep reducing as the system continues to try to give you what you've asked for. However, once the speed passes Vy (which is usually around 68/70kts) the rate of speed drop can be very quick, until at an airspeed none of us can remember the autopilot gives up the ghost and the upper modes drop out.
If the collective is set too low, ie not producing enough 'power', then the aircraft will reduce airspeed to try and maintain the desired VS. If you are only slightly out then it will stabilise at lower speed. If you're a bit more than slightly too low the airspeed will keep reducing as the system continues to try to give you what you've asked for. However, once the speed passes Vy (which is usually around 68/70kts) the rate of speed drop can be very quick, until at an airspeed none of us can remember the autopilot gives up the ghost and the upper modes drop out.
On the 225, yes IAS is always on the cyclic of course, but in 3 axis, VS / ALT is on the cyclic if speed is above ~65 kts (varies slightly with dv/dt), and on the collective if below that. As it transitions from vertical mode (ie VS / ALT) on the cyclic, to the collective, as the speed drops below ~65, IAS automatically engages on the cyclic, but you can decouple it if you want, to be left with the vertical mode on the collective, right down to zero airspeed if you wish.
Last edited by HeliComparator; 6th Sep 2013 at 09:30.
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OBF on E225 you can fly 3 Axis (why though) and the V/S or ALT will be alone on the cyclic longitudinal channel, but only when the IAS is above 65 KIAS.
However if you do not have enough power such that speed decays, the DAFCS automatically engages the 4th axis (collective), and the helicopter is remains in the safe flight envelope.
The EC225 DAFCS is a complex beast to explain on paper BUT utterly instinctive to use AND in its behaviour. In essence, whatever you try to do, it will respond to safely recover the Attitude, IAS and ALT.
Passengers and non EC225 pilots. We, the lucky ones on the EC225 cannot overstate the massive leap forward in safety the EC225 and EC175 represent. The L2 is Great ship, lacking only in the protections that are built into the modern DAFCS.
DB
However if you do not have enough power such that speed decays, the DAFCS automatically engages the 4th axis (collective), and the helicopter is remains in the safe flight envelope.
The EC225 DAFCS is a complex beast to explain on paper BUT utterly instinctive to use AND in its behaviour. In essence, whatever you try to do, it will respond to safely recover the Attitude, IAS and ALT.
Passengers and non EC225 pilots. We, the lucky ones on the EC225 cannot overstate the massive leap forward in safety the EC225 and EC175 represent. The L2 is Great ship, lacking only in the protections that are built into the modern DAFCS.
DB
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If the METAR was telling them that the cloudbase was at 200ft then presumably CHC SOP's would instruct them to make an approach which would involve cloudbreak occurring in the final phase of the approach while on automatic and pointing down the middle of the Sumburgh centreline?
I'm sure it doesn't say:
"In the event that the cloud base is 200', carry out an approach to achieve cloudbreak in the final phase of the approach while on automatic and pointing down the middle of the runway centreline"
Which is what your post implied, to me anyway, it should say.
So having read DB's post and many others what now seems to be occurring is that the autopilot is very good - which I have never disputed, but the training of how to use it is not.
Did the ETAP HP take the autopilot protection out because he didn't understand fully what it could do and then his manual flying skills didn't allow a safe approach.
HF
Did the ETAP HP take the autopilot protection out because he didn't understand fully what it could do and then his manual flying skills didn't allow a safe approach.
HF
As to ETAP HP, maybe "old school" would be a good descriptor.
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OFW a clarification then: Irrespective of the cloudbase when flying an IFR approach into an ILS equipped airport in IMC are there not set procedures which, to put it bluntly, keep the airframe well away from terrain until over the runway?
<Confusion Alert> There is no ILS at this airport on this runway!
I must re-check the Bristow Ops Man, but I'm pretty sure it doesn't say "Pilots shall not cause their aircraft to crash into the ground / sea whilst flying an instrument approach".
So THAT is the problem! If only the Ops Mans contained such a statement, there would be no more crashery!
I must re-check the Bristow Ops Man, but I'm pretty sure it doesn't say "Pilots shall not cause their aircraft to crash into the ground / sea whilst flying an instrument approach".
So THAT is the problem! If only the Ops Mans contained such a statement, there would be no more crashery!
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GF
The crew would have been expected to fly in accordance with the published procedure -- look at the plate I linked to a couple of pages back -- and in accordance with their SOPs.
Two further points; it was a localiser approach not an ILS, and their SOPs were unlikely to have had direction about how a mixed mode approach should be flown. Myself, I think I would probably have coupled to airspeed rather than V/S, but I can see why they would have coupled V/S -- to get a constant descent type approach.
Two further points; it was a localiser approach not an ILS, and their SOPs were unlikely to have had direction about how a mixed mode approach should be flown. Myself, I think I would probably have coupled to airspeed rather than V/S, but I can see why they would have coupled V/S -- to get a constant descent type approach.
It seems from a FW perspective that you have a powerful tool in your automatics but the training and philosophy of operation isn't there. The hand flying/automation debate rages this side of the fence too, but from what I read it seems the SOPs (and the technical standards for alerting) are slightly more advanced in the FW world.
I work for a company where hand flying is encouraged in appropriate conditions, and most captains are fairly keen when asked. However, in an approach to minima, the SOPs mandate maximum use of the automation.
In the Boeing I fly, the top of the PFD is the FMA (Flight Mode Annunciator) which displays the A/T, Roll and Pitch modes. Active modes are displayed in green, armed in white, and any change in mode generates a green box around it for 10s. An autopilot disconnect gives you flashing red lights and an audible tone that has to be silenced.
There are still plenty of traps - you can stall the aircraft in V/S even with the autothrottle engaged as it will pitch to maintain the selected V/S in the Climb. It should revert to a safer mode, pitching for selected speed before it does though.
The monitoring task on final is made easier by knowing the expected pitch, IAS and power settings to maintain the path, and by standard callouts. There are also stable approach "gates" which require the aircraft to be fully configured and within speed/profile limits at 1000' in IMC. Are there similar stable approach gates in the rotary world?
I work for a company where hand flying is encouraged in appropriate conditions, and most captains are fairly keen when asked. However, in an approach to minima, the SOPs mandate maximum use of the automation.
In the Boeing I fly, the top of the PFD is the FMA (Flight Mode Annunciator) which displays the A/T, Roll and Pitch modes. Active modes are displayed in green, armed in white, and any change in mode generates a green box around it for 10s. An autopilot disconnect gives you flashing red lights and an audible tone that has to be silenced.
There are still plenty of traps - you can stall the aircraft in V/S even with the autothrottle engaged as it will pitch to maintain the selected V/S in the Climb. It should revert to a safer mode, pitching for selected speed before it does though.
The monitoring task on final is made easier by knowing the expected pitch, IAS and power settings to maintain the path, and by standard callouts. There are also stable approach "gates" which require the aircraft to be fully configured and within speed/profile limits at 1000' in IMC. Are there similar stable approach gates in the rotary world?
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Thank you for the clarifications re: localiser/ILS approach.
A little facetious HC. Simply asking whether there are any SOP's which encourage compliance with certain minimas (I suppose those published in the plates?) in order to understand what a normal approach might look like in those circumstances into that airport.
I must re-check the Bristow Ops Man, but I'm pretty sure it doesn't say "Pilots shall not cause their aircraft to crash into the ground / sea whilst flying an instrument approach".
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Originally Posted by Jwscud
I work for a company where hand flying is encouraged in appropriate conditions, and most captains are fairly keen when asked. However, in an approach to minima, the SOPs mandate maximum use of the automation.
Originally Posted by HeliComparator
So THAT is the problem! If only the Ops Mans contained such a statement, there would be no more crashery!
Si
Last edited by bigglesbutler; 6th Sep 2013 at 10:20.
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IMO, Mixed Mode (in any of its variouis forms) is the Devil's work!
Would you consider it "normal" to have one pilot flying one control and the other pilot flying another control during an approach?
If your answer is "No!", then I suggest that the same opinion should carry over to Mixed Mode when using automation. Having more than one pilot in charge of manipulating the controls baffles me, and that includes "George" as one of those two manipulators.
Granted, in 3-axis only aircraft, you have no choice, but to purposely do that in a fully-functional 4-axis AFCS?
Not for me, thank you.
Add to this, the actual or potential mixing of the longitudinal axis (cyclic) for both airspeed and altitude control is the Devil's finest work.
P.S. Generically, I do like the terms "3-axis" and "4-axis" since they fairly accurately describe the fundamental functions/capabilities of the AFCS. "Mixed Mode"? Not a big fan. Too indistinct, especially since there are several different brews you could be mixing.
Would you consider it "normal" to have one pilot flying one control and the other pilot flying another control during an approach?
If your answer is "No!", then I suggest that the same opinion should carry over to Mixed Mode when using automation. Having more than one pilot in charge of manipulating the controls baffles me, and that includes "George" as one of those two manipulators.
Granted, in 3-axis only aircraft, you have no choice, but to purposely do that in a fully-functional 4-axis AFCS?
Not for me, thank you.
Add to this, the actual or potential mixing of the longitudinal axis (cyclic) for both airspeed and altitude control is the Devil's finest work.
P.S. Generically, I do like the terms "3-axis" and "4-axis" since they fairly accurately describe the fundamental functions/capabilities of the AFCS. "Mixed Mode"? Not a big fan. Too indistinct, especially since there are several different brews you could be mixing.
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GF
A little facetious HC. Simply asking whether there are any SOP's which encourage compliance with certain minimas (I suppose those published in the plates?) in order to understand what a normal approach might look like in those circumstances into that airport.
Jwscud I think you are absolutely right. One difference between us and you is that you (as I understand it) have a well defined final approach speed (dependent on mass, density altitude etc), and things ain't going to work out if you deviate from that by much, especially near the threshold.
For us, a very wide range of final approach speeds will result in a satisfactory landing, and as a consequence the Ops Mans are much less prescriptive about what the final approach speed will be, containing such concepts as its OK to slow down as low as Vy (80kts) in poor weather, or do 165 in nice weather if you like. There is nothing wrong with this in principle as long as all the crew are on the same page. With appropriate briefing (and not just parroting some SOB) this can be done, but I fear we can be lax in this area. So a combination of a wide range of possibilities, and repetitive and uninforming briefs, means that PM (PNF) may not be that clear what the intended speed actually is, or at what point he should prompt, or at what point he should take control.
Good briefings, covering all the variables and not the SOB, empower even a copilot of limited experience to take action when things are clearly not going as advertised.
From this, I think we all see a need for a company by company and fleet by fleet review of SOPs on briefing, monitoring and use of automation in poor conditions so that we are all on the same page, and the best page at that.
For us, a very wide range of final approach speeds will result in a satisfactory landing, and as a consequence the Ops Mans are much less prescriptive about what the final approach speed will be, containing such concepts as its OK to slow down as low as Vy (80kts) in poor weather, or do 165 in nice weather if you like. There is nothing wrong with this in principle as long as all the crew are on the same page. With appropriate briefing (and not just parroting some SOB) this can be done, but I fear we can be lax in this area. So a combination of a wide range of possibilities, and repetitive and uninforming briefs, means that PM (PNF) may not be that clear what the intended speed actually is, or at what point he should prompt, or at what point he should take control.
Good briefings, covering all the variables and not the SOB, empower even a copilot of limited experience to take action when things are clearly not going as advertised.
From this, I think we all see a need for a company by company and fleet by fleet review of SOPs on briefing, monitoring and use of automation in poor conditions so that we are all on the same page, and the best page at that.
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For someone with a little more patience than others, could you clarify whether an IFR equipped L2 is capable of making a fully automated approach into an airport fitted with a localiser or is this "mixed mode" semi-automated approach arrangement the only option?
RJC - Thank you for being a gentleman.
RJC - Thank you for being a gentleman.
Given that an autopilot is only as good as the information it is receiving, how much training and simulator time does one get to practice identifying the effects of abnormal transducer outputs, and the procedures to follow if these are detected?
How much commonality is there between the transducers used by the autopilot and those for the multifunction displays?
If you were flying in manual mode, or a mixed mode which did not require a particular transducer, would you have any way of knowing its readings were erroneous before switching to a flight mode which was dependent upon it?
How much commonality is there between the transducers used by the autopilot and those for the multifunction displays?
If you were flying in manual mode, or a mixed mode which did not require a particular transducer, would you have any way of knowing its readings were erroneous before switching to a flight mode which was dependent upon it?
GF, the L2 can make a non-precision approach by coupling cyclic to airspeed at the nominated approach speed, coupling lateral guidance from the localiser signal to the yaw/roll channels, and coupling vertical speed and a level-off altitude to the collective. So fully coupled in 4 axes, but the pilot has to manage the vertical profile by means of adjusting the vertical speed datum (beeped on the collective in this circumstance) to match up with the descent profile on the plate. I would say that this if fully automated.
There remains the possibility to couple vertical guidance from an overlay approach in the FMS so that the FMS controls the vertical profile, but the L2 doesn't have this facility and neither does the 225.
HC - not a gentleman.
There remains the possibility to couple vertical guidance from an overlay approach in the FMS so that the FMS controls the vertical profile, but the L2 doesn't have this facility and neither does the 225.
HC - not a gentleman.
Last edited by HeliComparator; 6th Sep 2013 at 11:11.
Having instructed on 332L/L1s for years, with fully functioning 4-axis autopilots, I was amazed at how many guys who were quite uncomfortable engaging that fourth axis.
Granted the old steam driven AP on the older 332s left a lot to be desired, and in cruise the collective pulsed too much to provide a smooth ride for the pax, but guys with considerable experience very rarely engaged that fourth axis at all, and it worked swimmingly with descent/approaches, climb outs etc.. The system was not smart, and would easily overtorque the bird or drop below Vy and fall out of the sky, if mismanaged, and had no alt acquire type modes, simply VS or ALT or GS, so most found it increased their workload rather than reduced it, for lack of understanding and practice in my opinion. The full system was always demonstrated and expected to be utilized in sim sessions (with OEI overshoots, etc) and on the line, with training regarding it's obvious shortcomings and things to watch for. Myself and a few guys used the 4-axis all the time, except in cruise, but most just avoided it like the plague. That's almost a decade off Canada's East coast where we had IMC to mins (Approved Lower than Standard - 100 feet DH, etc) a few times a week, and countless rig approaches at night 200 miles offshore.
I was surprised and disappointed at the lack of utilization of the full system.
Granted the old steam driven AP on the older 332s left a lot to be desired, and in cruise the collective pulsed too much to provide a smooth ride for the pax, but guys with considerable experience very rarely engaged that fourth axis at all, and it worked swimmingly with descent/approaches, climb outs etc.. The system was not smart, and would easily overtorque the bird or drop below Vy and fall out of the sky, if mismanaged, and had no alt acquire type modes, simply VS or ALT or GS, so most found it increased their workload rather than reduced it, for lack of understanding and practice in my opinion. The full system was always demonstrated and expected to be utilized in sim sessions (with OEI overshoots, etc) and on the line, with training regarding it's obvious shortcomings and things to watch for. Myself and a few guys used the 4-axis all the time, except in cruise, but most just avoided it like the plague. That's almost a decade off Canada's East coast where we had IMC to mins (Approved Lower than Standard - 100 feet DH, etc) a few times a week, and countless rig approaches at night 200 miles offshore.
I was surprised and disappointed at the lack of utilization of the full system.
Last edited by Bladestrike; 6th Sep 2013 at 11:16.