Chinook - Still Hitting Back 3 (Merged)
Join Date: Sep 2003
Location: Perth, Western Australia
Posts: 786
Likes: 0
Received 0 Likes
on
0 Posts
Cazatou
The witnesses you refer to were either in the mist or, if high enough, in the solid orographic cloud.
Approaching the landmass in the conditions that I have laboured to describe previously. there would have been streaking mist following the slope up to the start of the orographic cloud.
One witness at the site I have spoken to, who was in a position of authority and also a local, described clear patches with bright sunlight on the lower slopes - he was familiar with the phenomenon of the layer of mist that I have described.
They would not have been in it until the last moment.
They would have been able to identify the slope - with the odd blotchy ground texture sporadically visible - from a long way off provided that they were beneath the orohraphic cloud, which at the time, as best I can derive from the various accounts, started about 8-900ft.
Their problem would have been that they could not have visually estimated their range from it to any degree of accuracy (no detail, texture, or familiar objects) and so would not have been able to question any other source of local information that they may have been referring too.
For reasons I have already given, the course change to the right was significant and deliberate.
Their power setting was such that there was obviously no intention to overfly the Mull (low and matched and which had already resulted in a slowing down of 20kts air speed) - and why would they when the Mull is after all just an isolated low hill of limited extent which was not in their way to the next waypoint and would have required only a small turn to the left to avoid.
One of the proponents for a control jam had to concede at one of the inquiries that the odds of a control jam affecting two axes that cleared itself in the last moments was billions to one - let us forget this nonsense.
And that suggested engine runaway? (for which there is no evidence) - the immediate action for such being an increase in collective which could have incresed their height (to keep the RPM down) - if such had occurred after waypoint change at their altitude, would it not have been the hand of God that could have saved them?
On their deliberate course was the previously used landing area that I have described previously; they had settings consistent with a landing or low pass at the altitude of that area.
You would not go in there without a local reference - why not discuss candidates for such a reference?
The witnesses you refer to were either in the mist or, if high enough, in the solid orographic cloud.
Approaching the landmass in the conditions that I have laboured to describe previously. there would have been streaking mist following the slope up to the start of the orographic cloud.
One witness at the site I have spoken to, who was in a position of authority and also a local, described clear patches with bright sunlight on the lower slopes - he was familiar with the phenomenon of the layer of mist that I have described.
They would not have been in it until the last moment.
They would have been able to identify the slope - with the odd blotchy ground texture sporadically visible - from a long way off provided that they were beneath the orohraphic cloud, which at the time, as best I can derive from the various accounts, started about 8-900ft.
Their problem would have been that they could not have visually estimated their range from it to any degree of accuracy (no detail, texture, or familiar objects) and so would not have been able to question any other source of local information that they may have been referring too.
For reasons I have already given, the course change to the right was significant and deliberate.
Their power setting was such that there was obviously no intention to overfly the Mull (low and matched and which had already resulted in a slowing down of 20kts air speed) - and why would they when the Mull is after all just an isolated low hill of limited extent which was not in their way to the next waypoint and would have required only a small turn to the left to avoid.
One of the proponents for a control jam had to concede at one of the inquiries that the odds of a control jam affecting two axes that cleared itself in the last moments was billions to one - let us forget this nonsense.
And that suggested engine runaway? (for which there is no evidence) - the immediate action for such being an increase in collective which could have incresed their height (to keep the RPM down) - if such had occurred after waypoint change at their altitude, would it not have been the hand of God that could have saved them?
On their deliberate course was the previously used landing area that I have described previously; they had settings consistent with a landing or low pass at the altitude of that area.
You would not go in there without a local reference - why not discuss candidates for such a reference?
Join Date: Apr 2005
Location: France 46
Age: 77
Posts: 1,743
Likes: 0
Received 0 Likes
on
0 Posts
Boslandew
I think the paper you describe is in fact the MOD response to the Select Committee in which it notes the Committee's report but does not accept its conclusion.
MOD seem quite clear (the rules after all are their rules) that a helicopter flying below 140 knots airspeed requires the aircraft to remain clear of cloud, in sight of the ground or water and with a forward visibility of at least 1000 metres.
I agree that it does appear that some contributors have a different view.
I think the paper you describe is in fact the MOD response to the Select Committee in which it notes the Committee's report but does not accept its conclusion.
MOD seem quite clear (the rules after all are their rules) that a helicopter flying below 140 knots airspeed requires the aircraft to remain clear of cloud, in sight of the ground or water and with a forward visibility of at least 1000 metres.
I agree that it does appear that some contributors have a different view.
Just a numbered other
MOD seem quite clear (the rules after all are their rules) that a helicopter flying below 140 knots airspeed requires the aircraft to remain clear of cloud, in sight of the ground or water and with a forward visibility of at least 1000 metres.
The weather below cloud was not a problem, as Mr Holbrook's evidence confirms. Those on the Mull and in cloud can have no idea what the weather was like out to sea.
So at waypoint change I would suggest all was normal, or they would not have made it. What happened next to cause a turn in the wrong direction and a climb into cloud in the full knowledge that a climb to MSA was impossible due to the pathetic iceing clearance, no one will ever know.
The negligence occurred long before waypoint change. It occurred in a MOD office when someone thought it a good idea to release an aircraft into service when even Boscombe Down would not fly it.
Join Date: Oct 2006
Location: cornwall UK
Age: 80
Posts: 236
Likes: 0
Received 0 Likes
on
0 Posts
Weather Minima
Cazatou
The report is entitled "The Governments Response .." but was no doubt written by the MOD. I would still be interested to know what the cloud base limit was for SH helicopters flying at more than 140 knots over land. Given the forcast and actual winds and an average groundspeed of 158-160, the airspeed must have been about 140 knots. The actual minima which would have applied must be relevant to a full understanding of this flight.
Would the restriction limiting flight within 500 feet of persons or buildings etc have applied as this was not a designated low-flying area?
Regards
Boslandew
The report is entitled "The Governments Response .." but was no doubt written by the MOD. I would still be interested to know what the cloud base limit was for SH helicopters flying at more than 140 knots over land. Given the forcast and actual winds and an average groundspeed of 158-160, the airspeed must have been about 140 knots. The actual minima which would have applied must be relevant to a full understanding of this flight.
Would the restriction limiting flight within 500 feet of persons or buildings etc have applied as this was not a designated low-flying area?
Regards
Boslandew
Join Date: Apr 2005
Location: France 46
Age: 77
Posts: 1,743
Likes: 0
Received 0 Likes
on
0 Posts
Arkroyal
Nice to hear from you again.
The problem with the evidence of Mr Holbrook is that to the BOI he gave evidence on oath that, when some 2 NM SW of the lighthouse he had seen the Chinook fly past his yacht, the weather was as follows: "The visibility was about one mile and limited by haze."
Some 19 months later he told the Fatal Accident Inquiry on oath " I recall the conditions of visibility at sea level as being fine, perhaps as much as five miles. I think at that point I could even see the Antrim coast so it might have been as much as six or seven miles."
The only way I can think of explaining the disparity between those 2 statements is that he forgot to inform the BOI that he was using Swedish miles (10km = 1 Swedish Mile) for his distance assessment and he used English miles for the FAI. He also did not mention to the BOI his cabin boy or the fishing vessels that he was manoeuvring around at that time (according to his evidence to the FAI).
We have no way of knowing which of his evidence, if any, is correct.
Best wishes
Nice to hear from you again.
The problem with the evidence of Mr Holbrook is that to the BOI he gave evidence on oath that, when some 2 NM SW of the lighthouse he had seen the Chinook fly past his yacht, the weather was as follows: "The visibility was about one mile and limited by haze."
Some 19 months later he told the Fatal Accident Inquiry on oath " I recall the conditions of visibility at sea level as being fine, perhaps as much as five miles. I think at that point I could even see the Antrim coast so it might have been as much as six or seven miles."
The only way I can think of explaining the disparity between those 2 statements is that he forgot to inform the BOI that he was using Swedish miles (10km = 1 Swedish Mile) for his distance assessment and he used English miles for the FAI. He also did not mention to the BOI his cabin boy or the fishing vessels that he was manoeuvring around at that time (according to his evidence to the FAI).
We have no way of knowing which of his evidence, if any, is correct.
Best wishes
Join Date: Feb 2003
Location: canada
Posts: 20
Likes: 0
Received 0 Likes
on
0 Posts
Cazatou
You suggest an inconsistency on the point of Mark Holbrook's evidence, in sharp contrast to ear witnesses upon the Mull.
The Lords found the following:
---
(Sir William Wratten) ... Mr Holbrook, in particular, changed profoundly what he said to the FAI from what he said to the Board of Inquiry.
Chairman: I think, in fairness to Mr Holbrook, it should be said that before the Board, I think, he was asked two or three questions, and that was about it; before the Sheriff, he was subject to cross-examination by counsel for the Ministry of Defence and others, so his evidence was tested far more. And, just in case it is thought that he had an interest in this matter, he came here because we asked him to, and he did not ask to appear, or anything, we asked him out of the blue.
----
Your failure to present this context is grossly unfair.
---
You also declare that "Data extracted from the SuperTANS showed that Waypoint Change to Corran was selected 0.81 NM from the first waypoint (0.95 NM from impact)."
To the Lords we go again:
152. We have approached the foregoing question upon the basis that the way point change was made when the aircraft was some 600 metres from the cliff. This assumes that the position divulged by the TANS was precisely accurate - an assumption which may not be justified. It will be remembered that the TANS recorded the height above sea level of the point of impact as 665 ft (± 50), whereas in fact it was 810 ft (see above, para 53). If the aircraft had been on the programmed track it would probably have been 1 kilometre from land ahead at the way point change and there is no suggestion that an alteration of course at that point would have resulted in a crash.
---
Much doubt and debate. AP3207 remains unsatisfied.
You suggest an inconsistency on the point of Mark Holbrook's evidence, in sharp contrast to ear witnesses upon the Mull.
The Lords found the following:
---
(Sir William Wratten) ... Mr Holbrook, in particular, changed profoundly what he said to the FAI from what he said to the Board of Inquiry.
Chairman: I think, in fairness to Mr Holbrook, it should be said that before the Board, I think, he was asked two or three questions, and that was about it; before the Sheriff, he was subject to cross-examination by counsel for the Ministry of Defence and others, so his evidence was tested far more. And, just in case it is thought that he had an interest in this matter, he came here because we asked him to, and he did not ask to appear, or anything, we asked him out of the blue.
----
Your failure to present this context is grossly unfair.
---
You also declare that "Data extracted from the SuperTANS showed that Waypoint Change to Corran was selected 0.81 NM from the first waypoint (0.95 NM from impact)."
To the Lords we go again:
152. We have approached the foregoing question upon the basis that the way point change was made when the aircraft was some 600 metres from the cliff. This assumes that the position divulged by the TANS was precisely accurate - an assumption which may not be justified. It will be remembered that the TANS recorded the height above sea level of the point of impact as 665 ft (± 50), whereas in fact it was 810 ft (see above, para 53). If the aircraft had been on the programmed track it would probably have been 1 kilometre from land ahead at the way point change and there is no suggestion that an alteration of course at that point would have resulted in a crash.
---
Much doubt and debate. AP3207 remains unsatisfied.
Join Date: Apr 2005
Location: France 46
Age: 77
Posts: 1,743
Likes: 0
Received 0 Likes
on
0 Posts
antenna
From the minutes of the HOL Commitee:
CHAIRMAN "It should be said that before the Board, I think, he was asked two or three questions and that was about it."
Hardly a definitive statement.
The fact remains that to the BOI his written statement on oath, signed by him, states that the visibility was "1 mile limited by haze". In addition he did not mention his "cabin boy" being called up on deck to look at the helicopter -nor the fishing vessels that he told the FAI he was manouvering around.
From the minutes of the HOL Commitee:
CHAIRMAN "It should be said that before the Board, I think, he was asked two or three questions and that was about it."
Hardly a definitive statement.
The fact remains that to the BOI his written statement on oath, signed by him, states that the visibility was "1 mile limited by haze". In addition he did not mention his "cabin boy" being called up on deck to look at the helicopter -nor the fishing vessels that he told the FAI he was manouvering around.
Join Date: Jul 2000
Location: Nova
Posts: 1,242
Likes: 0
Received 0 Likes
on
0 Posts
On the second day of the Fatal Accident Inquiry (9th January 1996) under cross examination, Mr Holbrook, under oath, made the following statement:
As the ONLY eye witness to SEE the helicopter AND the Mull, would that qualify as being definitive?
"If you are seeking to establish do I believe the pilot could see the location of the Mull lighthouse, yes, I believe he could
Join Date: Sep 2003
Location: Perth, Western Australia
Posts: 786
Likes: 0
Received 0 Likes
on
0 Posts
Arkroyal
<<What happened next to cause a turn in the wrong direction and a climb into cloud ...>>
Well, it must have been right for something because the handling pilot's HSI had a course of 035 (M) selected which was the exact direction from waypoint change to impact.
Is it not reasonable to assume that if a handling pilot had his course selector on his HSI set to the track he was actually on then that track was intended?
<<What happened next to cause a turn in the wrong direction and a climb into cloud ...>>
Well, it must have been right for something because the handling pilot's HSI had a course of 035 (M) selected which was the exact direction from waypoint change to impact.
Is it not reasonable to assume that if a handling pilot had his course selector on his HSI set to the track he was actually on then that track was intended?
Just a numbered other
WK
I think not. Not sure of the super tans display in a Chinook, but I doubt if the HSI bar was used for VFR navigation. In the Sea King the 'Charlie bar' was used, and only as a cross check.
In this case I would imagine that the coast was the intended navigation aid.
Hi, Caz. Nice to be back from a year of oersonal turmoil
I think not. Not sure of the super tans display in a Chinook, but I doubt if the HSI bar was used for VFR navigation. In the Sea King the 'Charlie bar' was used, and only as a cross check.
In this case I would imagine that the coast was the intended navigation aid.
Hi, Caz. Nice to be back from a year of oersonal turmoil
Join Date: Nov 2005
Location: Norfolk England
Posts: 247
Likes: 0
Received 0 Likes
on
0 Posts
Waypoint Changes
WK,
As an engineer I have tried to avoid dipping into the operating issues, but surely if you look at the BOI track analysis 035(M) had been the course all the way from Northern Ireland, so it is not surprising that it was set on the HSI.
Please read again the section from the BOI on "Navigation
Navigation Techniques.
At the time of impact, the SuperTANS was selected to ‘Tac Steer’ to WP B, Corran, on the western end of the Great Glen. This WP had been selected at a point on track, 1.75 km before the impact point. Although the Board were unable to establish the SuperTANS selection prior to this WP change, it is considered most likely that a ‘Tac Steer’ to WP A was selected, as this was the first WP programmed into the SuperTANS route and the first turning point on the crew's plan. This selection would have provided the crew with accurate distance to run and bearing information to the Mull of Kintyre lighthouse, up to the point of WP change.
Regardless of the WP selected prior to the WP change, once the change had been made, the crew were dependent upon comparing SuperTANS range and bearing information to Corran, approximately 87 miles to the north, with range and bearing information from their maps, to determine their current position. More importantly, this would also have deprived them of immediately apparent range and bearing information from the landmass of the Mull of Kintyre. The Board determined that the WP change would have produced a required heading change in the order of 14 degrees to port. The decision to change the WP selection to WP B would have been inappropriate if the crew had intended to continue to route to WP A or to a landfall on the Mull of Kintyre, without first having established visual contact with the WP or land.
However, if this plan had changed, and the new intention was to route initially direct to Corran, the selection of WP B would have been appropriate, providing that they had taken action to avoid confliction with the Mull of Kintyre. The Board therefore concluded that navigation technique was not a factor in the accident.
Now if, as you contend, the crew planned to land on the field by the lighthouse, why did they change waypoints. They had a VFR flight plan and were VMC when they changed waypoints - at that point as current MOD operators have pointed out they would have expected an immediate course change, indeed geography would have dictated this as well - after the WP change the HSI would, I assume, have been showing the demanded course to WP B, but, of course, they continued on essentially the same course. Why would they take such an inconsistent set of actions?
In a previous post you said that a witness at one of the Inquiries had said that the odds of a control jam in two channels were "billions to one" - please tell me who said this as I would like to see the basis for his calculations, especially given the AAIB comments on this area. They certainly do not dismiss a major control jam as "nonsense" - indeed they accept that it could not be ruled out - what do you base your judgement on?
Like you I do not know what happened, but I do not believe that after the WP change the crew had any intention to overfly the Mull, and this has, for me, always been a major non sequitur in the BOI's finding that they had set an inappropriate ROC to clear the Mull. Were they distracted, did they suffer a major control restriction and make a last moment and obviously unsuccesssful attempt to climb over the Mull because they had no choice? I do not know, you do not know - the Reviewing Officers do not know, and even John Purdey does not know, and you cannot find someone guilty of Gross Negligence (effectively manslaughter in this case) on the basis of any of the evidence to the BOI or even the BOI's findings. For example, the join where the Air Marshalls decided to change the direction of the Stn Cdrs review of the BOI is obvious for all to see.
The "advantage" of having the cause of this accident as down to the pilots becomes more obvious with every bit of FOI material that we see, and if the AMs had left the cause of the accident as even a balance of probablities of pilot error they would probably have got away with their unjust verdict. As it is the actions of the AMs and MOD have ensured that Pandora's box is well and truly opened, and it questions the whole issue of the RAF's introduction to service of the Chinook Mk2 as well as what happened to ZD 576. The lack of a just and even supportable verdict is what all of this is about, and it always has been, for "we will never know".
JB
As an engineer I have tried to avoid dipping into the operating issues, but surely if you look at the BOI track analysis 035(M) had been the course all the way from Northern Ireland, so it is not surprising that it was set on the HSI.
Please read again the section from the BOI on "Navigation
Navigation Techniques.
At the time of impact, the SuperTANS was selected to ‘Tac Steer’ to WP B, Corran, on the western end of the Great Glen. This WP had been selected at a point on track, 1.75 km before the impact point. Although the Board were unable to establish the SuperTANS selection prior to this WP change, it is considered most likely that a ‘Tac Steer’ to WP A was selected, as this was the first WP programmed into the SuperTANS route and the first turning point on the crew's plan. This selection would have provided the crew with accurate distance to run and bearing information to the Mull of Kintyre lighthouse, up to the point of WP change.
Regardless of the WP selected prior to the WP change, once the change had been made, the crew were dependent upon comparing SuperTANS range and bearing information to Corran, approximately 87 miles to the north, with range and bearing information from their maps, to determine their current position. More importantly, this would also have deprived them of immediately apparent range and bearing information from the landmass of the Mull of Kintyre. The Board determined that the WP change would have produced a required heading change in the order of 14 degrees to port. The decision to change the WP selection to WP B would have been inappropriate if the crew had intended to continue to route to WP A or to a landfall on the Mull of Kintyre, without first having established visual contact with the WP or land.
However, if this plan had changed, and the new intention was to route initially direct to Corran, the selection of WP B would have been appropriate, providing that they had taken action to avoid confliction with the Mull of Kintyre. The Board therefore concluded that navigation technique was not a factor in the accident.
Now if, as you contend, the crew planned to land on the field by the lighthouse, why did they change waypoints. They had a VFR flight plan and were VMC when they changed waypoints - at that point as current MOD operators have pointed out they would have expected an immediate course change, indeed geography would have dictated this as well - after the WP change the HSI would, I assume, have been showing the demanded course to WP B, but, of course, they continued on essentially the same course. Why would they take such an inconsistent set of actions?
In a previous post you said that a witness at one of the Inquiries had said that the odds of a control jam in two channels were "billions to one" - please tell me who said this as I would like to see the basis for his calculations, especially given the AAIB comments on this area. They certainly do not dismiss a major control jam as "nonsense" - indeed they accept that it could not be ruled out - what do you base your judgement on?
Like you I do not know what happened, but I do not believe that after the WP change the crew had any intention to overfly the Mull, and this has, for me, always been a major non sequitur in the BOI's finding that they had set an inappropriate ROC to clear the Mull. Were they distracted, did they suffer a major control restriction and make a last moment and obviously unsuccesssful attempt to climb over the Mull because they had no choice? I do not know, you do not know - the Reviewing Officers do not know, and even John Purdey does not know, and you cannot find someone guilty of Gross Negligence (effectively manslaughter in this case) on the basis of any of the evidence to the BOI or even the BOI's findings. For example, the join where the Air Marshalls decided to change the direction of the Stn Cdrs review of the BOI is obvious for all to see.
The "advantage" of having the cause of this accident as down to the pilots becomes more obvious with every bit of FOI material that we see, and if the AMs had left the cause of the accident as even a balance of probablities of pilot error they would probably have got away with their unjust verdict. As it is the actions of the AMs and MOD have ensured that Pandora's box is well and truly opened, and it questions the whole issue of the RAF's introduction to service of the Chinook Mk2 as well as what happened to ZD 576. The lack of a just and even supportable verdict is what all of this is about, and it always has been, for "we will never know".
JB
Bravo JB, how refreshing to read a post that so succinctly sums up the point of this long long thread. The politeness and patience extended to the armchair experts who seek to explain their pet theories of what happened on that tragic day, from rubber stamping the AMs' infamous verdict because, well, they're AMs old boy, to the bizarre conspiracy theories of intended clandestine landings (please don't bother if I've got that wrong Walt, it really is utterly irrelevant), is a credit to those simply wanting to right this wrong. The pilots have not been proven to be responsible for this crash, let alone negligent, let alone grossly negligent. That verdict has been condemned by some of the most prestigious legal institutions in the land. The ex Secretary of State has joined them in their view. Other than the handful of apologists on this thread, the only people who seem unmoved are the AMs themselves, and their monstrous machine the MOD. If you want to delve into conspiracy theories Walt, I should look there. No lack of tautological inexactitudes there to get your teeth into. As JB says the proverbial is about to hit the fan, for once the FOI stable door was opened a veritable stampede of revelations was released. The truth will out.
Let Right Be Done
Chug
Let Right Be Done
Chug
Join Date: Oct 2001
Location: Berkshire
Posts: 51
Likes: 0
Received 0 Likes
on
0 Posts
Boslandew
Just a small comment on the above.
The average groundspeed quoted is only an estimate based on an initial radio fix. That, together with the fact that the actual winds encountered are not known, do not allow us to calculate an exact IAS for the cruise. However, for what it is worth, using the estimated data available it is just as possible to show that cruise IAS might have been in the order of 135 knots.
Regards
TheAerosCo
Given the forcast and actual winds and an average groundspeed of 158-160, the airspeed must have been about 140 knots. The actual minima which would have applied must be relevant to a full understanding of this flight.
The average groundspeed quoted is only an estimate based on an initial radio fix. That, together with the fact that the actual winds encountered are not known, do not allow us to calculate an exact IAS for the cruise. However, for what it is worth, using the estimated data available it is just as possible to show that cruise IAS might have been in the order of 135 knots.
Regards
TheAerosCo
Join Date: Feb 2007
Location: Exiled in England
Age: 48
Posts: 1,015
Likes: 0
Received 0 Likes
on
0 Posts
Gent's, I am generally regarded as pretty thick (in both mind and body). Can I have reasons for how the cause (and blame) can be placed upon two pilots as "Gross Negligence"......?
If not then I submit that the BOI is wrong and someone needs to explain why. To tar two professional aviators with this when they are not even in this world to defend themselves is very wrong. ( Am I right in thinking one is innocent until proven guilty?? or is a case of the MOD "Wheeling in the guilty b4st4rds and their lying mates") and one has to prove ones innocence.
I would try and read this whole thread but I am not the sharpest mind in the world and I would fail to understand everything in complicated words.
If not then I submit that the BOI is wrong and someone needs to explain why. To tar two professional aviators with this when they are not even in this world to defend themselves is very wrong. ( Am I right in thinking one is innocent until proven guilty?? or is a case of the MOD "Wheeling in the guilty b4st4rds and their lying mates") and one has to prove ones innocence.
I would try and read this whole thread but I am not the sharpest mind in the world and I would fail to understand everything in complicated words.
Join Date: Oct 2006
Location: cornwall UK
Age: 80
Posts: 236
Likes: 0
Received 0 Likes
on
0 Posts
Weather Minima
The AerosCo
Point taken, I should phrased my estimate perhaps as a speed range sooner than as a specific figure.
I am not attempting to prove or disprove anything but trying to understand the flight better. If the airspeed was below 140 knots the weather minima would either be, according to recent posts, clear of ground, in sight of ground with a forward visibility of 1000 metres or a 100' cloudbase and 1000 metres vis. If the airspeed was over 140 knots it would have been 5.5kms vis and an increased cloudbase (recent post). I'm trying to discover what that increased cloudbase figure would have been.
It has been pointed out recently that civilian/military weather minima camparisons are not relevant and I accept that. However, when coasting in during North Sea operations, which I did many times in a Chinook, as well as weather minima we were required to observe the Rule about not flying within 500 feet of anything thus requiring us to fly at 500'. It would appear that this did not apply in the case in question. I wonder if someone could clarify this point and if it did not apply, on what grounds?
Point taken, I should phrased my estimate perhaps as a speed range sooner than as a specific figure.
I am not attempting to prove or disprove anything but trying to understand the flight better. If the airspeed was below 140 knots the weather minima would either be, according to recent posts, clear of ground, in sight of ground with a forward visibility of 1000 metres or a 100' cloudbase and 1000 metres vis. If the airspeed was over 140 knots it would have been 5.5kms vis and an increased cloudbase (recent post). I'm trying to discover what that increased cloudbase figure would have been.
It has been pointed out recently that civilian/military weather minima camparisons are not relevant and I accept that. However, when coasting in during North Sea operations, which I did many times in a Chinook, as well as weather minima we were required to observe the Rule about not flying within 500 feet of anything thus requiring us to fly at 500'. It would appear that this did not apply in the case in question. I wonder if someone could clarify this point and if it did not apply, on what grounds?
Avoid imitations
Join Date: Nov 2000
Location: Wandering the FIR and cyberspace often at highly unsociable times
Posts: 14,573
Received 419 Likes
on
221 Posts
I believe you refer to the so-called "500 foot rule", which is a civilian rule and it doesn't apply to military flights.
Join Date: Sep 2003
Location: Perth, Western Australia
Posts: 786
Likes: 0
Received 0 Likes
on
0 Posts
JB
Hi, I will dig out the detail but quickly now I would like to correct you on one point - you wrote:
<< ... track analysis 035(M) had been the course all the way from Northern Ireland, so it is not surprising that it was set on the HSI.>>
Actually the track from Aldergrove to the position of waypoint change was 027M.
The turn to the right has been refered to often (eg Boeing/Mitchel analysis) - it was not a continuation.
If anyone interested does the detailed chartwork, they would find that the line from the position of waypoint change to the position of initial impact was near as damn it 035M which just happened to be the course set on the handling pilot's HSI - and 8deg change is not insignificant.
Hi, I will dig out the detail but quickly now I would like to correct you on one point - you wrote:
<< ... track analysis 035(M) had been the course all the way from Northern Ireland, so it is not surprising that it was set on the HSI.>>
Actually the track from Aldergrove to the position of waypoint change was 027M.
The turn to the right has been refered to often (eg Boeing/Mitchel analysis) - it was not a continuation.
If anyone interested does the detailed chartwork, they would find that the line from the position of waypoint change to the position of initial impact was near as damn it 035M which just happened to be the course set on the handling pilot's HSI - and 8deg change is not insignificant.
Join Date: Oct 2006
Location: cornwall UK
Age: 80
Posts: 236
Likes: 0
Received 0 Likes
on
0 Posts
ShyTorque
Many thanks. I did not know that.
Can you tell me what the cloud base requirement is for a miltary helicopter flying at an airspeed greater than 140 knots?
Many thanks. I did not know that.
Can you tell me what the cloud base requirement is for a miltary helicopter flying at an airspeed greater than 140 knots?
Join Date: Aug 2000
Location: Liverpool based Geordie, so calm down, calm down kidda!!
Age: 60
Posts: 2,051
Likes: 0
Received 17 Likes
on
6 Posts
Please lets not split hairs here on the Chinook cruise speed. A wokka can exceed 140, but is not a comfortable ride at max speed, a bunch of VIP pax would soon get upset. The Puma did a 145 cruise at 15.5 degrees pitch on a good day, but we would not be staring at the ASI saying 'OK, 141 kts, different limits!!' It was accepted that the change of rules at 140 would not be required and that we didn't move into the next category. If you wish to hang me for this henious crime, asi accuracy taken in, I may have bust the 140 limit by oooooooohhhh, 1-2kts.
150kts, ok I would agree on a change.
150kts, ok I would agree on a change.
Join Date: Sep 2003
Location: Perth, Western Australia
Posts: 786
Likes: 0
Received 0 Likes
on
0 Posts
Hello again JB – thank you again for some decent constructive feedback. If only everyone would work through the detail likewise.
Here are my thoughts on the points you raised:
<< In a previous post you said that a witness at one of the Inquiries had said that the odds of a control jam in two channels were "billions to one" - please tell me who said this as I would like to see the basis for his calculations, especially given the AAIB comments on this area. They certainly do not dismiss a major control jam as "nonsense" - indeed they accept that it could not be ruled out - what do you base your judgement on?>>
I believe it was Flt Lt Ian MacFarlane who was a proponent of the control jam idea at the FAI. Steuart Campbell’s book, p67-69 on the questioning of Flt Lt Ian MacFarlane by Mr Dunlop at the FAI summarises quite well, I think:
<<Mac Farlane was questioned at length by Dunlop about his alternative explanation … After he had agreed that all the control channels were separate and designed to be very secure, it was pointed out to him that the expected rate of failure of a single channel was not more than once in a million flying hours. He was also informed that the probability of a failure of two channels simultaneously was one in 1,000 billion flying hours. He did not dispute these estimates and also accepted that the probability of both pitch and roll channels jamming simultaneously and then un-jamming simultaneously was “one in a million, billion, billion flying hours”. … It turned out that MacFarlane was unaware that Boeing had, from December 1994, discounted the probability of a loose article jamming the flight controls and had withdrawn a previous requirement for visual checks. … When it was pointed out that he had described his scenario as “probable”, he retracted that view and described it instead as “possible”.
<< Now if, as you contend, the crew planned to land on the field by the lighthouse, why did they change waypoints. They had a VFR flight plan and were VMC when they changed waypoints - at that point as current MOD operators have pointed out they would have expected an immediate course change, indeed geography would have dictated this as well - after the WP change the HSI would, I assume, have been showing the demanded course to WP B, but, of course, they continued on essentially the same course. Why would they take such an inconsistent set of actions?>>
Contemporary systems that interacted with personnel locator beacons fed the range and bearing to the HSI – perhaps this was the case here.
Perhaps someone familiar with the operation of such a system as fitted to the HC2 Chinooks in 1995 could comment (don’t hold your breath waiting for a reply on this one!).
In 47Ds each pilot could select a different source for nav data to his own HSI but if such information went via the CDU as some kind of temporary waypoint that had to be manually selected (as opposed to some hardwired alternative), then neither pilot could call upon waypoints A or B (‘coz there’s only one TANS CDU).
Had there been a PRC112 up the hill (near where the memorial now stands) when it was expected to be at the suggested LZ (the “green triangle” that I have described previously), everything fits (eg the 035M heading and the overshoot that I suggest was the problem).
Regarding the current discussion on weather minima:
If they thought they knew where the Mull was and (rightly) assumed that it had a thin coating of mist it would have been reasonable to assume that
Nothing would be flying out of it AND
THEREFORE they could be as close to it as they liked without breaking the VFR rules as it could (rightly) be regarded as a solid object – a terrain feature which they could in a low level flight approach closely – a fixed object – until the last few seconds, they could have had excellent vis in all directions including towards the Mull as far as the top of the ground hugging mist.
I say again, it was the visual judgment of distance off that was the problem; at a low level (lower than the orographic cloud at 8-900 ft as I believe was the case) they would have been able to see the lower slopes of the Mull from a considerable distance (all the way across from NI, probably) but sight of the actual ground/vegetation/features would have been sporadic as the thin, streaking mist obscured detail/texture.
Their problem was not one of flying inside cloud but one of avoiding a fixed, fuzzy object to which, for whatever reason, they appeared to intentionally approach closely.
This mist is a common phenomenon there, as I have tried to describe at length previously – with that strong wind, it would have followed the slope for several hundred feet until it merged with the orographic cloud formed as the bulk of the air mass reached its dew point – and it would have been unlikely to have been more than 50 ft thick. This is my opinion of the local weather based upon years of sea trials in the NW of Scotland, much coastal navigation, low level flights in those areas in similar conditions, much hill walking in those areas, and several visits to the Mull itself.
Strong on-shore wind against uniform slope in near/moderately saturated conditions (as was the case that day) guarantees such upslope mist – it is the lowest layer of the air mass that is compressed and goes faster than the bulk of the air mass (a phenomenon known as “speed-up”) suffering a reduction in pressure and therefore temperature and thus reaches its dew point well before the height that the bulk of the air mass rising up the hill does.
If you still don’t get it, check out research for wind farms.
Here are my thoughts on the points you raised:
<< In a previous post you said that a witness at one of the Inquiries had said that the odds of a control jam in two channels were "billions to one" - please tell me who said this as I would like to see the basis for his calculations, especially given the AAIB comments on this area. They certainly do not dismiss a major control jam as "nonsense" - indeed they accept that it could not be ruled out - what do you base your judgement on?>>
I believe it was Flt Lt Ian MacFarlane who was a proponent of the control jam idea at the FAI. Steuart Campbell’s book, p67-69 on the questioning of Flt Lt Ian MacFarlane by Mr Dunlop at the FAI summarises quite well, I think:
<<Mac Farlane was questioned at length by Dunlop about his alternative explanation … After he had agreed that all the control channels were separate and designed to be very secure, it was pointed out to him that the expected rate of failure of a single channel was not more than once in a million flying hours. He was also informed that the probability of a failure of two channels simultaneously was one in 1,000 billion flying hours. He did not dispute these estimates and also accepted that the probability of both pitch and roll channels jamming simultaneously and then un-jamming simultaneously was “one in a million, billion, billion flying hours”. … It turned out that MacFarlane was unaware that Boeing had, from December 1994, discounted the probability of a loose article jamming the flight controls and had withdrawn a previous requirement for visual checks. … When it was pointed out that he had described his scenario as “probable”, he retracted that view and described it instead as “possible”.
<< Now if, as you contend, the crew planned to land on the field by the lighthouse, why did they change waypoints. They had a VFR flight plan and were VMC when they changed waypoints - at that point as current MOD operators have pointed out they would have expected an immediate course change, indeed geography would have dictated this as well - after the WP change the HSI would, I assume, have been showing the demanded course to WP B, but, of course, they continued on essentially the same course. Why would they take such an inconsistent set of actions?>>
Contemporary systems that interacted with personnel locator beacons fed the range and bearing to the HSI – perhaps this was the case here.
Perhaps someone familiar with the operation of such a system as fitted to the HC2 Chinooks in 1995 could comment (don’t hold your breath waiting for a reply on this one!).
In 47Ds each pilot could select a different source for nav data to his own HSI but if such information went via the CDU as some kind of temporary waypoint that had to be manually selected (as opposed to some hardwired alternative), then neither pilot could call upon waypoints A or B (‘coz there’s only one TANS CDU).
Had there been a PRC112 up the hill (near where the memorial now stands) when it was expected to be at the suggested LZ (the “green triangle” that I have described previously), everything fits (eg the 035M heading and the overshoot that I suggest was the problem).
Regarding the current discussion on weather minima:
If they thought they knew where the Mull was and (rightly) assumed that it had a thin coating of mist it would have been reasonable to assume that
Nothing would be flying out of it AND
THEREFORE they could be as close to it as they liked without breaking the VFR rules as it could (rightly) be regarded as a solid object – a terrain feature which they could in a low level flight approach closely – a fixed object – until the last few seconds, they could have had excellent vis in all directions including towards the Mull as far as the top of the ground hugging mist.
I say again, it was the visual judgment of distance off that was the problem; at a low level (lower than the orographic cloud at 8-900 ft as I believe was the case) they would have been able to see the lower slopes of the Mull from a considerable distance (all the way across from NI, probably) but sight of the actual ground/vegetation/features would have been sporadic as the thin, streaking mist obscured detail/texture.
Their problem was not one of flying inside cloud but one of avoiding a fixed, fuzzy object to which, for whatever reason, they appeared to intentionally approach closely.
This mist is a common phenomenon there, as I have tried to describe at length previously – with that strong wind, it would have followed the slope for several hundred feet until it merged with the orographic cloud formed as the bulk of the air mass reached its dew point – and it would have been unlikely to have been more than 50 ft thick. This is my opinion of the local weather based upon years of sea trials in the NW of Scotland, much coastal navigation, low level flights in those areas in similar conditions, much hill walking in those areas, and several visits to the Mull itself.
Strong on-shore wind against uniform slope in near/moderately saturated conditions (as was the case that day) guarantees such upslope mist – it is the lowest layer of the air mass that is compressed and goes faster than the bulk of the air mass (a phenomenon known as “speed-up”) suffering a reduction in pressure and therefore temperature and thus reaches its dew point well before the height that the bulk of the air mass rising up the hill does.
If you still don’t get it, check out research for wind farms.