ABZ pilots are we flying tomorrow?
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Cyclic,
The implications of your post are rather worrying. It seems that you are suggesting that planning of flights should be done once airbourne. It's a bit like saying I don't know for sure what the wind is at cruising altitude, so I will go and find out so that my plan is accurate. I am sure you don't mean that.
The implications of your post are rather worrying. It seems that you are suggesting that planning of flights should be done once airbourne. It's a bit like saying I don't know for sure what the wind is at cruising altitude, so I will go and find out so that my plan is accurate. I am sure you don't mean that.
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Of course not. What I am saying is that an actual in these circumstances can be a little misleading as it very much depends exactly where the temperature is measured. Yesterday by anyone's admission was a very unusual day. No need to worry about me either, I have flown all over Northern Europe (and a few hot places) for the past 25 years and have managed to make well judged decisions so far in a variety of unusual circumstances! There again, I have never worked for the Aberdeen company who invented helicopter flying...
The responsibility for operational supervision does not rest with the regulator but with the operator.
The regulator, before issuing an AOC, makes an assessment on whether qualified staff (post-holders etc) and appropriate systems (procedures) are in place so that operational control can be maintained. In the system of continuing oversight, the regulator periodically samples the product to establish whether adequate control is being exercised within the system.
If Helicomparator's contention is correct, then all operations manuals will be generic and have identical text. Yes JARs do have an OM template for the operators to use but you should not infer from that the text of the template is that which should appear in the OM.
For example the paragraph 'Operational Control and Supervision' merely says "A description of the system for the supervision of the operation by the operator..."; it is expected that the operator's system will be described here.
When it says in a later paragraph ..."Operational control. A description of the procedures and responsibilities necessary to exercise operational control with respect to flight safety"; I would expect to see a description of the system (and the person responsible for that system) of providing a serviceable aircraft on the ramp; the system for ensuring that the aircraft are dispatched within precise criteria (and the person responsible for that system).
Later in the template where it requires "Flight Preparation Instructions. As applicable to the operations."; I would expect to see precisely the information that is being discussed in this thread.
Sox6, yes I have understood the banter and appreciate the situation in Aberdeen. Clearly, the understanding of the limitation on the DA was part of the culture of one of the companies but not of the others. It would also appear that this is not part of the written procedures in that company but one of adherence to the limitations of the RFM.
My view is that a company culture that relies upon the memory of pilots is not an adequate safety culture - these high pressure and low temperature regimes occur very infrequently in the North Sea, and that should be recognised by the operators. Why is it do you think that before every winter, most fixed wing companies issue a reminder about cold weather operations?
I also take issue with your contention that the CAA should (in your words) 'regulate current rules and requirements' (in fact I am not sure what that statement means). As part of its SMS, each company should have quality assurance procedures that ensure that its product is (re)produced as described. It is for the CAA to ensure that the product described is, in their opinion, adequate for purpose.
I have to say that I see similarities in this thread to discussions that we had following the EC225 ditching. It is not good enough to rely upon the judgement (memory) of the crew members; there have to be adequate SOPs in place to ensure that the frailty of the human is not exposed.
Jim
The regulator, before issuing an AOC, makes an assessment on whether qualified staff (post-holders etc) and appropriate systems (procedures) are in place so that operational control can be maintained. In the system of continuing oversight, the regulator periodically samples the product to establish whether adequate control is being exercised within the system.
If Helicomparator's contention is correct, then all operations manuals will be generic and have identical text. Yes JARs do have an OM template for the operators to use but you should not infer from that the text of the template is that which should appear in the OM.
For example the paragraph 'Operational Control and Supervision' merely says "A description of the system for the supervision of the operation by the operator..."; it is expected that the operator's system will be described here.
When it says in a later paragraph ..."Operational control. A description of the procedures and responsibilities necessary to exercise operational control with respect to flight safety"; I would expect to see a description of the system (and the person responsible for that system) of providing a serviceable aircraft on the ramp; the system for ensuring that the aircraft are dispatched within precise criteria (and the person responsible for that system).
Later in the template where it requires "Flight Preparation Instructions. As applicable to the operations."; I would expect to see precisely the information that is being discussed in this thread.
Sox6, yes I have understood the banter and appreciate the situation in Aberdeen. Clearly, the understanding of the limitation on the DA was part of the culture of one of the companies but not of the others. It would also appear that this is not part of the written procedures in that company but one of adherence to the limitations of the RFM.
My view is that a company culture that relies upon the memory of pilots is not an adequate safety culture - these high pressure and low temperature regimes occur very infrequently in the North Sea, and that should be recognised by the operators. Why is it do you think that before every winter, most fixed wing companies issue a reminder about cold weather operations?
I also take issue with your contention that the CAA should (in your words) 'regulate current rules and requirements' (in fact I am not sure what that statement means). As part of its SMS, each company should have quality assurance procedures that ensure that its product is (re)produced as described. It is for the CAA to ensure that the product described is, in their opinion, adequate for purpose.
I have to say that I see similarities in this thread to discussions that we had following the EC225 ditching. It is not good enough to rely upon the judgement (memory) of the crew members; there have to be adequate SOPs in place to ensure that the frailty of the human is not exposed.
Jim
Well, some good lessons learned. I think it is fair to say that yesterday at Aberdeen was a pretty extreme day, and with a million rules to remember, it is hardly surprising that pilots are not in the habit of calculating Density Altitude.
Thank you P3 Bellows for confirming that someone from Bristow did try to contact the other operators. I accept that there is no standard procedure for this, but given what HC says regarding the seriousness of this issue, it is good to know that pilots from all companies do look out for each other - As I would expect.
Kudos to Bristow for spotting this issue and I guess that comes from having the greatest experience on the type - I seem to remember there was a similar issue when the 225 first arrived on the North Sea - I do find it amazing however that such issues can be fixed in the latest 'Service Pack 4' or whatever its called !! Thank goodness for steam driven aircraft !
Thank you P3 Bellows for confirming that someone from Bristow did try to contact the other operators. I accept that there is no standard procedure for this, but given what HC says regarding the seriousness of this issue, it is good to know that pilots from all companies do look out for each other - As I would expect.
Kudos to Bristow for spotting this issue and I guess that comes from having the greatest experience on the type - I seem to remember there was a similar issue when the 225 first arrived on the North Sea - I do find it amazing however that such issues can be fixed in the latest 'Service Pack 4' or whatever its called !! Thank goodness for steam driven aircraft !
Jim
But how else could it be? Whether or not the relevant info is in the OM or the RFM is surely irrelevant. Pilots cannot reasonably trawl through all 200 pages of the OM part A and then the 100 pages of the OMB then the hundreds of pages of the RFM before each takeoff. And what about reading through the entire ANO and AIP sections relating to the area of operations?
Sorry but pilot knowledge and memory has to be a key factor in safety culture. That is why we have ground training.
There have on occasion been some attempts to produce flow charts (normally by line trainers for some reason!), in particular relating to weather issues, but they either become ridiculously complicated or only cater for a subset of possibilities.
Sorry Jim but I am not one to subscribe to the view that safety can be created with bits of paper. Safety has to rely on the knowledge, skill and good judgement of the pilots (and of course the other supporting staff)
HC
My view is that a company culture that relies upon the memory of pilots is not an adequate safety culture
Sorry but pilot knowledge and memory has to be a key factor in safety culture. That is why we have ground training.
There have on occasion been some attempts to produce flow charts (normally by line trainers for some reason!), in particular relating to weather issues, but they either become ridiculously complicated or only cater for a subset of possibilities.
Sorry Jim but I am not one to subscribe to the view that safety can be created with bits of paper. Safety has to rely on the knowledge, skill and good judgement of the pilots (and of course the other supporting staff)
HC
Special
A bit of a non-sequeter there and your ludditism is showing!
The issue of control instability is (as with any control system) that if the gain of the control loop is greater than unity at the frequency where there is 180deg phase shift in the feedback, divergent instability results.
Gain in this case is related to "control power" which for a helicopter varies with rotor speed and with air density - ie slow rotors = little control power, fast rotors = lots of control power, thin air = little control power etc.
So with very thick air, control power/gain can be reduced back to below unity by slowing down the rotors. This is what your SP4 will give us - the FADEC will reduce the Nr when thick air is detected. At the moment it only takes it down to 100% but with SP4 it will go down to 97.7% (I think) thus allowing ops down to -6000'DA
So I say "thank goodness for software driven aircraft" - the software can be tweaked to fix an inherent structural/control problem.
HC
I do find it amazing however that such issues can be fixed in the latest 'Service Pack 4' or whatever its called !! Thank goodness for steam driven aircraft !
The issue of control instability is (as with any control system) that if the gain of the control loop is greater than unity at the frequency where there is 180deg phase shift in the feedback, divergent instability results.
Gain in this case is related to "control power" which for a helicopter varies with rotor speed and with air density - ie slow rotors = little control power, fast rotors = lots of control power, thin air = little control power etc.
So with very thick air, control power/gain can be reduced back to below unity by slowing down the rotors. This is what your SP4 will give us - the FADEC will reduce the Nr when thick air is detected. At the moment it only takes it down to 100% but with SP4 it will go down to 97.7% (I think) thus allowing ops down to -6000'DA
So I say "thank goodness for software driven aircraft" - the software can be tweaked to fix an inherent structural/control problem.
HC
HC,
I'm not sure I am asking for (more) bits of paper; it would be nice to have a system with flags so that when envelope limits are approaching (or for any other occasion), an alert is signalled.
Really no different to that you are describing for software improvements for the control problems - i.e. it could be part of your computerised planning/dispatch system.
It doesn't really matter how its done provided it's not left to an individual pilot's memory - i.e. a systematic approach. After all, it sounds important enough to have some control in place.
Jim
I'm not sure I am asking for (more) bits of paper; it would be nice to have a system with flags so that when envelope limits are approaching (or for any other occasion), an alert is signalled.
Really no different to that you are describing for software improvements for the control problems - i.e. it could be part of your computerised planning/dispatch system.
It doesn't really matter how its done provided it's not left to an individual pilot's memory - i.e. a systematic approach. After all, it sounds important enough to have some control in place.
Jim
Jim
Yes I suppose there could be something on our base Flight Planning system, however that would only cater for takeoffs from Base. Takeoffs from offshore back to base, or to an alternate could not be covered since surface temperature and pressure are not forecast in TAFs etc. (I am discounting density altitude offshore since it never gets that cold)
I suggest that (just like EGPWS obstacle data) its better to have no electronic system than one that only covers half our flight sectors. That way the pilot is in no doubt that he is responsible for compliance with flight envelope limits. Not all operators have electronic flight despatch systems anyway.
One of our complaints about this limit (which you may remember was introduced a couple of years after we started operating the aircraft) is that its not really possible for the pilot to predict the density altitude at his destination at the end of a long flight. Experience and good judgement are the only weapons available. If you don't like the sound of that you are not alone, but what is the alternative?
HC
Yes I suppose there could be something on our base Flight Planning system, however that would only cater for takeoffs from Base. Takeoffs from offshore back to base, or to an alternate could not be covered since surface temperature and pressure are not forecast in TAFs etc. (I am discounting density altitude offshore since it never gets that cold)
I suggest that (just like EGPWS obstacle data) its better to have no electronic system than one that only covers half our flight sectors. That way the pilot is in no doubt that he is responsible for compliance with flight envelope limits. Not all operators have electronic flight despatch systems anyway.
One of our complaints about this limit (which you may remember was introduced a couple of years after we started operating the aircraft) is that its not really possible for the pilot to predict the density altitude at his destination at the end of a long flight. Experience and good judgement are the only weapons available. If you don't like the sound of that you are not alone, but what is the alternative?
HC
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Did the guy with the Lama helicopter in his altitude record get this? Did he know about it?
The Indian and Pakistani rescues in the Himalayayas never mention 'divergent oscillation in the cyclic control'.
Appreciate we don't all fly the 225, but what on earth causes 'divergent oscillation in the cyclic control' ?
Sounds horrible.
The Indian and Pakistani rescues in the Himalayayas never mention 'divergent oscillation in the cyclic control'.
Appreciate we don't all fly the 225, but what on earth causes 'divergent oscillation in the cyclic control' ?
Sounds horrible.
Last edited by MrR; 10th Jan 2010 at 10:03.
MrR
I think you need to read my previous expanation again - the problem is not with high density altitude (ie the Lama pilot) its quite the opposite, low density altitude below -3500'. (note that low density altitude = high air density! confusing!)
The problem is an old one that surfaced on the AS332L back in 1982. I think the primary cause is that the flight controls are "anchored" at one end (the pilot's end) by the AP Hydraulics etc, at the other end they are attached to the servos that are mounted on the main transmission. The main transmission is mounted on the fuselage by a slightly flexible mounting system. The problem is that forces generated by changing the disc attitude (ie cyclic input) cause the transmission to move slightly, which changes the distance from the servo to the AP hydraulics thus effectively makes a slight cyclic control input, which in turn modifies the disc attitude, which in turn causes the transmission to move slightly etc etc. If this "control loop" has a gain of more than unity, it rapidly diverges (ie the forces and movements mentioned above rapidly increase in magnitude). The natural frequency of this (ie the frequency where the phase shift is 180 degrees) was about 12 Hz for the 332L and 14 Hz for the 225.
It was fixed on the 332L by adding a bellcrank and rod to the forward servo control run. The other end of the rod was attached to the MGB and had the effect of nulling out the effect of transmission movement on the forward servo position.
On the 225 this reappeared due to the more powerful rotor system. Initial attempts to add more bellcranks on the other servos etc didn't seem to work, but reducing the Nr did work and that is the line EC have taken, for the time being at least.
So with current FADEC version the Nr is reduced according to the measured density altitude. Only problem is that its not easy to accurately measure the density altitude at low speed IGE - exhaust gas recirculation can artificially raise the temperature around the probes and then the system could calculate that the density altitude is higher than it is, increase the Nr and go into the oscillation. So a large margin has to be built in that causes the Nr to be lower than optimal - so there is less thrust in the hover etc.
The new FADEC version will have additional temperature sensors in the tail - the system will use the lower of the sensors to calculate the DA and having the more appropriate Nr allows them to have a minimum Nr lower than 100%, hence moving the limit from -3500' to -6000'.
HC
I think you need to read my previous expanation again - the problem is not with high density altitude (ie the Lama pilot) its quite the opposite, low density altitude below -3500'. (note that low density altitude = high air density! confusing!)
The problem is an old one that surfaced on the AS332L back in 1982. I think the primary cause is that the flight controls are "anchored" at one end (the pilot's end) by the AP Hydraulics etc, at the other end they are attached to the servos that are mounted on the main transmission. The main transmission is mounted on the fuselage by a slightly flexible mounting system. The problem is that forces generated by changing the disc attitude (ie cyclic input) cause the transmission to move slightly, which changes the distance from the servo to the AP hydraulics thus effectively makes a slight cyclic control input, which in turn modifies the disc attitude, which in turn causes the transmission to move slightly etc etc. If this "control loop" has a gain of more than unity, it rapidly diverges (ie the forces and movements mentioned above rapidly increase in magnitude). The natural frequency of this (ie the frequency where the phase shift is 180 degrees) was about 12 Hz for the 332L and 14 Hz for the 225.
It was fixed on the 332L by adding a bellcrank and rod to the forward servo control run. The other end of the rod was attached to the MGB and had the effect of nulling out the effect of transmission movement on the forward servo position.
On the 225 this reappeared due to the more powerful rotor system. Initial attempts to add more bellcranks on the other servos etc didn't seem to work, but reducing the Nr did work and that is the line EC have taken, for the time being at least.
So with current FADEC version the Nr is reduced according to the measured density altitude. Only problem is that its not easy to accurately measure the density altitude at low speed IGE - exhaust gas recirculation can artificially raise the temperature around the probes and then the system could calculate that the density altitude is higher than it is, increase the Nr and go into the oscillation. So a large margin has to be built in that causes the Nr to be lower than optimal - so there is less thrust in the hover etc.
The new FADEC version will have additional temperature sensors in the tail - the system will use the lower of the sensors to calculate the DA and having the more appropriate Nr allows them to have a minimum Nr lower than 100%, hence moving the limit from -3500' to -6000'.
HC
albatross
After Q1 2010 we should be able to go down to -6000' DA, however I agree that the aircraft will still have a problem in places like Canada in winter. EC realise this as well and its their stated intention to address the issue in a more fundamental way (ie modifying the control run geometry etc). But this is not going to happen quickly so I think you are right, there will not be many EC225s in N Canada, Siberia etc for some time!
HC
After Q1 2010 we should be able to go down to -6000' DA, however I agree that the aircraft will still have a problem in places like Canada in winter. EC realise this as well and its their stated intention to address the issue in a more fundamental way (ie modifying the control run geometry etc). But this is not going to happen quickly so I think you are right, there will not be many EC225s in N Canada, Siberia etc for some time!
HC
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HELICOMPARITOR
I applaud your massive brain. Although I have very little understanding of the concepts you have described here on this thread your descriptions have re-inforced my belief that as pilots, beyond a certain necessary basic undertsanding, we probably know very little about the machines we operate. A bit like the Iceberg, we know the bit at the top!!!
I with you on the memory thing though. I think ground training should produce an awareness of issues such that when the right memory hooks are triggered we know which book, and with prcatice, which part of the book to look in for the guidance and answers.
I also think Jim has a valid point as well. When it comes to more obscure issues, or just generally operating outside our comfort zones such as the WX this last fornight has afforded, the Operator's management should kick in and do a bit of research and re-inforcement training.
Remember the old days when we had a "Winter Flying" FSI or some such!!
DB
I applaud your massive brain. Although I have very little understanding of the concepts you have described here on this thread your descriptions have re-inforced my belief that as pilots, beyond a certain necessary basic undertsanding, we probably know very little about the machines we operate. A bit like the Iceberg, we know the bit at the top!!!
I with you on the memory thing though. I think ground training should produce an awareness of issues such that when the right memory hooks are triggered we know which book, and with prcatice, which part of the book to look in for the guidance and answers.
I also think Jim has a valid point as well. When it comes to more obscure issues, or just generally operating outside our comfort zones such as the WX this last fornight has afforded, the Operator's management should kick in and do a bit of research and re-inforcement training.
Remember the old days when we had a "Winter Flying" FSI or some such!!
DB
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Double Bogey,
"Remember the old days when we had a "Winter Flying" FSI or some such!!"
Our company, specifically the Line Training department, continues to provide lectures and/or produces a comprehensive precis of the relevant limitations, etc., regarding operations in winter conditions every year, and has done for many years.
LV
"Remember the old days when we had a "Winter Flying" FSI or some such!!"
Our company, specifically the Line Training department, continues to provide lectures and/or produces a comprehensive precis of the relevant limitations, etc., regarding operations in winter conditions every year, and has done for many years.
LV
Last edited by Leaky Valve; 10th Jan 2010 at 11:32. Reason: To give credit, where credit is due i.e. line trainers
It suggests that performance planning should be done more systematically, regardless of the day-to-day outcome always being "MCTOM" - because one day the answer might be "outside the flight envelope!" It also suggests that, if electronic performance planning is being done, that the software needs changing to flag up the breach of envelope.
HC, is there no onboard indication on the PFD to highlight this - particularly given the consequences you describe? The IAS tape goes red above Vne, you could imagine that the ALT tape could also go red when below (or above) the RFM envelope.
HC, is there no onboard indication on the PFD to highlight this - particularly given the consequences you describe? The IAS tape goes red above Vne, you could imagine that the ALT tape could also go red when below (or above) the RFM envelope.
212 - No, there is no onboard indication, I think for 2 reasons:
1) This limit was not known about when the aircraft was first designed/certified/sold and
2) As was alluded to earlier in this thread, any helicopter struggles to accurately measure OAT until its in OGE forward flight.
All helicopters have ultimate OAT limits but as far as I am aware they don't have any cockpit warning when you are outside those limits.
By comparison IAS is easy to measure especially when you are going fast!
HC
1) This limit was not known about when the aircraft was first designed/certified/sold and
2) As was alluded to earlier in this thread, any helicopter struggles to accurately measure OAT until its in OGE forward flight.
All helicopters have ultimate OAT limits but as far as I am aware they don't have any cockpit warning when you are outside those limits.
By comparison IAS is easy to measure especially when you are going fast!
HC
I have been following this with interest. IIRC the 330 gearbox mounting is the same as the early 332 before the strut. In 1978 we used to, and I believe they still do, wrack our Pumas around Northern Norway in the middle of solid high pressure systems at minus 26 degrees. We lost a Puma at Bodo in an in-flight break up with three fatalities. The reason was put down to a main door detaching and colliding with the tail rotor plus all that entails. The door concerned was suspect before the accident but one wonders whether a divergent ocsillation was ever set up which may have caused the door to detach.
Last edited by Fareastdriver; 11th Jan 2010 at 15:04.
