Chinook - Still Hitting Back 3 (Merged)
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Mr B,
Yes, it is fairly damning (understatement of the month) but I'm not sure it implies crticism of the RAF flight safety system (ie IFS) per se, as I don't think IFS were responsible for SFI/AIL/ANA promulgation and monitoring. That was more the remit of Handling Sqn Boscombe Down who would send out SFIs to the world in a signal using an AIG. Action addressees (Gp tasking & op staffs/sqns/TPs etc - I would think) would be required to ack receipt (anyone know if that included IFS (RW) and Gp FS staff? I can't believe it didn't!).
Its likley that ANAs, AILs and ALs would be similar in origin but the releasing authority would probably be the relevant ProjO within DHP of MoD PE. So, IFS should have known - but responsibilty lay with MoD PE -even then, there was only so much that Handling Sqn/ProjO could do to check disemination.
Of course, the way these changes were seen by the crews was by the use of the 'reds/greens' signature cards on Sqn Ops Desks and checked at every crew out-brief. I often remember turning the aircrew signature cards to 'red' on receipt of ALs to FRCs, Aircrew Manuals or ODMs and, more occasionally, when ANAs & AILs hit my desk.
Ultimately, this is not about the fact the SFI(s) existed but that the BoI neither realised its signifigance nor investigated/commented further. Subsequently, this knowledge has almost been denied by MoD and their airships - especially when S/L Burke referred to UFCMs as a possible cause - one that would leave no evidence.
Damning of the RAF Flight Safety system? - Not massively.
Damning of the MoD's airworthiness process? - Most Definitely!
(It is also precisely what Mr Haddon-Cave found)
Yes, it is fairly damning (understatement of the month) but I'm not sure it implies crticism of the RAF flight safety system (ie IFS) per se, as I don't think IFS were responsible for SFI/AIL/ANA promulgation and monitoring. That was more the remit of Handling Sqn Boscombe Down who would send out SFIs to the world in a signal using an AIG. Action addressees (Gp tasking & op staffs/sqns/TPs etc - I would think) would be required to ack receipt (anyone know if that included IFS (RW) and Gp FS staff? I can't believe it didn't!).
Its likley that ANAs, AILs and ALs would be similar in origin but the releasing authority would probably be the relevant ProjO within DHP of MoD PE. So, IFS should have known - but responsibilty lay with MoD PE -even then, there was only so much that Handling Sqn/ProjO could do to check disemination.
Of course, the way these changes were seen by the crews was by the use of the 'reds/greens' signature cards on Sqn Ops Desks and checked at every crew out-brief. I often remember turning the aircrew signature cards to 'red' on receipt of ALs to FRCs, Aircrew Manuals or ODMs and, more occasionally, when ANAs & AILs hit my desk.
Ultimately, this is not about the fact the SFI(s) existed but that the BoI neither realised its signifigance nor investigated/commented further. Subsequently, this knowledge has almost been denied by MoD and their airships - especially when S/L Burke referred to UFCMs as a possible cause - one that would leave no evidence.
Damning of the RAF Flight Safety system? - Not massively.
Damning of the MoD's airworthiness process? - Most Definitely!
(It is also precisely what Mr Haddon-Cave found)
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John Blakeley
But these are your thoughts:
<<Assuming that ZD 576 exhibited similar vibration characteristics to the BD trials aircraft it seems to me as a "simple" engineer that the crew were very unlikely to have deliberately flown at some of the claimed speeds >>
I would have thought an engineer of your standing would by now be aware of the improvement in terms of vibration at speed of the HC2s and so I am indeed disappointed that you are disputing some claimed speeds – undermining, effectively, any dist/time analysis.
Oh, and please don't get hung up on “secret missions” - is it not enough at this stage to wonder why a significant piece of equipment has not been brought to the attention of the inquiries to date?
Do you not think any new inquiry should be informed?
Dalek
<<6. At some stage, very late in the flight there was a 25 - 30 kt speed increase. (Cable). This increase must have come very late, or the Average speed would have been higher.
7. Some of this increase must have come from increased power.*
* Not backed by firm evidence, just strong circumstantial. >>
I refer you to Boeing's analysis of the available data (not the simulation) – the only decent effort at such analysis done by a body with authority – it has that the a/c slowed down in terms of airspeed as it approached the landmass but the increased wind there masked this leaving a net no change in groundspeed.
But these are your thoughts:
<<Assuming that ZD 576 exhibited similar vibration characteristics to the BD trials aircraft it seems to me as a "simple" engineer that the crew were very unlikely to have deliberately flown at some of the claimed speeds >>
I would have thought an engineer of your standing would by now be aware of the improvement in terms of vibration at speed of the HC2s and so I am indeed disappointed that you are disputing some claimed speeds – undermining, effectively, any dist/time analysis.
Oh, and please don't get hung up on “secret missions” - is it not enough at this stage to wonder why a significant piece of equipment has not been brought to the attention of the inquiries to date?
Do you not think any new inquiry should be informed?
Dalek
<<6. At some stage, very late in the flight there was a 25 - 30 kt speed increase. (Cable). This increase must have come very late, or the Average speed would have been higher.
7. Some of this increase must have come from increased power.*
* Not backed by firm evidence, just strong circumstantial. >>
I refer you to Boeing's analysis of the available data (not the simulation) – the only decent effort at such analysis done by a body with authority – it has that the a/c slowed down in terms of airspeed as it approached the landmass but the increased wind there masked this leaving a net no change in groundspeed.
I refer you to Boeing's analysis of the available data (not the simulation) – the only decent effort at such analysis done by a body with authority
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Walter,
I have said before, it is the word "available" makes this analysis incomplete.
Call me old fashioned, but I always thought that ADR / CVR was required to carry out meaningful analysis / simulation.
The Cable assessment of crash speeds is based on physical evidence.
The RACAL analysis, although possibly flawed, is based on information extracted from a physical piece of kit.
The Boeing analysis excludes evidence that was "not available."
Cable is right. RACAL and Boeing may or may not be.
I may be a cynic, but don't you think Boeing will "lean towards" any evidence that absolves their aircraft of blame.
I have said before, it is the word "available" makes this analysis incomplete.
Call me old fashioned, but I always thought that ADR / CVR was required to carry out meaningful analysis / simulation.
The Cable assessment of crash speeds is based on physical evidence.
The RACAL analysis, although possibly flawed, is based on information extracted from a physical piece of kit.
The Boeing analysis excludes evidence that was "not available."
Cable is right. RACAL and Boeing may or may not be.
I may be a cynic, but don't you think Boeing will "lean towards" any evidence that absolves their aircraft of blame.
Mr B
Indeed. Of course, MoD would say this is not new evidence as it was clearly "available" at the time. That the BoI did not dig deep enough into the evidence of UFCMs is bad enough. That someone knowingly withheld this relevant information and actively prevented the witness speaking is a breach of so many regs one doesn't know where to begin.
Still, Secy of State has promised ALL evidence will be reviewed, so that would (logically) include what the BoI considered, what the ROs ignored and that which was withheld. Good job Lord Philip was sent it last month, eh?
Crikey tuc, that stuff seems pretty damning of just the flight safety system, never mind this accident!
Still, Secy of State has promised ALL evidence will be reviewed, so that would (logically) include what the BoI considered, what the ROs ignored and that which was withheld. Good job Lord Philip was sent it last month, eh?
flipster, I apologise for my less than focussed use of the phrase "flight safety system". My intention was to refer to any system in place that would rapidly disseminate safety critical information to those likely to be 'at risk' if they didn't know about said information. UFCMs would certainly fit that requirement, but the 'system' screwed up, big time. That is ****e, and unforgiveable!
tuc, I don't doubt that MoD will be manouevring, obfuscating, and I-don't-know-what-all just to set up it's smoke and mirror show over this one. I pray that those in the know about the injustices in this case, come the reveiew, will have all their ducks in a neat and clear row such that they can calmly and patiently show how much of the MoD's 'case' is just the big lie that it is. And I want to see certain Airships take a fall - a huge, public, humiliating fall. If it involves legal proceedings against them, all the better. Wankers.
tuc, I don't doubt that MoD will be manouevring, obfuscating, and I-don't-know-what-all just to set up it's smoke and mirror show over this one. I pray that those in the know about the injustices in this case, come the reveiew, will have all their ducks in a neat and clear row such that they can calmly and patiently show how much of the MoD's 'case' is just the big lie that it is. And I want to see certain Airships take a fall - a huge, public, humiliating fall. If it involves legal proceedings against them, all the better. Wankers.
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Apologies
Walter,
I had not realised you were also an expert on Chinook Mk2 aircraft dynamics - many apologies. However, you are not quite as "sharp" in reading my posts, and if you wish to quote my words to question my "waning" engineering capabilities please quote them in full - I actually said "but I will happily bow to more expert opinion" - I do not claim to be an expert on either helicopter dynamics or the Chinook Mk2. As a Chinook pilot, and hence an "expert opinion", I thought Boslandew with his post two days ago provided a very good explanation - however, perhaps you are aware of changes to the aircraft between the BD report of October 1993 and the accident which would have caused BD to modify their comment that "The vibration characteristics were similar to the Mk 1 and were unsatisfactory."
As I tried to explain in my second post I am not trying to use the BD reports to provide a possible cause for the accident - but to point out the failure of the BoI process to look at all these very relevant issues and hence highlight the further doubts these omissions raise on the "safety" of the verdict. In the wider sense they also further highlight the flaws in the RTS process and confirm the now very public doubts on the airworthiness of the Chinook at the time of the accident - similar flaws were, as we now know, present in other later accidents with the Nimrod loss leading directly to the H-C Inquiry and the formation of the MAA - an organisation which has not yet had time to prove its effectiveness and independence.
I have already acknowledged your "success" in pointing out that equipment was apparently fitted to the aircraft that the BoI does not mention, but if this was classified I would not expect it to be mentioned unless it could have relevance to the accident. Although I do not subscribe to your theory you believe it had, and in the sense that none of us know, I would not dispute your wish, indeed right, to raise the issue with the next Inquiry. Albeit I think MOD will provide TORs which are very restrictive as they will definitely not want most of the issues we now know a lot more about to be looked at again. I think MOD and the families will want to settle for clearing the pilots' names, and given that this is what this thread was originally all about that anyway needs to be the absolute priority - however, MOD is, I suggest, mistaken if they believe that reversing this unjust and unjustifed verdict, vital as that is, will be the end of the discussions as far as their airworthiness and RTS failings are concerned.
JB
I had not realised you were also an expert on Chinook Mk2 aircraft dynamics - many apologies. However, you are not quite as "sharp" in reading my posts, and if you wish to quote my words to question my "waning" engineering capabilities please quote them in full - I actually said "but I will happily bow to more expert opinion" - I do not claim to be an expert on either helicopter dynamics or the Chinook Mk2. As a Chinook pilot, and hence an "expert opinion", I thought Boslandew with his post two days ago provided a very good explanation - however, perhaps you are aware of changes to the aircraft between the BD report of October 1993 and the accident which would have caused BD to modify their comment that "The vibration characteristics were similar to the Mk 1 and were unsatisfactory."
As I tried to explain in my second post I am not trying to use the BD reports to provide a possible cause for the accident - but to point out the failure of the BoI process to look at all these very relevant issues and hence highlight the further doubts these omissions raise on the "safety" of the verdict. In the wider sense they also further highlight the flaws in the RTS process and confirm the now very public doubts on the airworthiness of the Chinook at the time of the accident - similar flaws were, as we now know, present in other later accidents with the Nimrod loss leading directly to the H-C Inquiry and the formation of the MAA - an organisation which has not yet had time to prove its effectiveness and independence.
I have already acknowledged your "success" in pointing out that equipment was apparently fitted to the aircraft that the BoI does not mention, but if this was classified I would not expect it to be mentioned unless it could have relevance to the accident. Although I do not subscribe to your theory you believe it had, and in the sense that none of us know, I would not dispute your wish, indeed right, to raise the issue with the next Inquiry. Albeit I think MOD will provide TORs which are very restrictive as they will definitely not want most of the issues we now know a lot more about to be looked at again. I think MOD and the families will want to settle for clearing the pilots' names, and given that this is what this thread was originally all about that anyway needs to be the absolute priority - however, MOD is, I suggest, mistaken if they believe that reversing this unjust and unjustifed verdict, vital as that is, will be the end of the discussions as far as their airworthiness and RTS failings are concerned.
JB
Per Ardua ad Astraeus
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Originally Posted by JB
I think MOD and the families will want to settle for clearing the pilots' names, and given that this is what this thread was originally all about that anyway needs to be the absolute priority - however, MOD is, I suggest, mistaken if they believe that reversing this unjust and unjustified verdict, vital as that is, will be the end of the discussions as far as their airworthiness and RTS failings are concerned.
Mr Bernoulli:
In a very uncertain world that is one thing that we may all be certain of. As BOAC points out, if W&D hadn't started an upsurge of righteous indignation all those years ago by an unforgiveable and unsubstantiated attack on the reputations of two deceased junior officers none of the scandalous shenanigans of the MOD, as the UK Military Airworthiness Authority charged with assuring the airworthiness of the Chinook HC2 and every other UK Military Aircraft, might ever have emerged. It is for this reason that I make respectful challenge to JB's statement:
When this thread was started that of course was the only priority, but we didn't know then what we all know now. It seems to me that any Professional Aviator must put Flight Safety ahead of all other considerations, even those of sympathy and empathy with the bereaved. This has always been a matter of life and death, but now it is a matter of future deaths while such a criminal and reckless body, as is the MOD, has control over the airworthiness of UK Military Aircraft. To avoid those future deaths as much as possible that control must be removed forthwith. This can only be done by placing Airworthiness Provision, and for that matter Air Accident Investigation, into the hands of separate and independent bodies, both of each other and of the MOD. I call yet again for the establishment of such an MAA and an MAAIB. Until that happens we may rely on there continuing to be avoidable accidents to unairworthy UK Military Aircraft, many of them tragically will be fatal.
Self Regulation Never Works and in Aviation It Kills!
I don't doubt that MoD will be manouevring, obfuscating, and I-don't-know-what-all just to set up it's smoke and mirror show over this one.
......clearing the pilots' names, and given that this is what this thread was originally all about that anyway needs to be the absolute priority
Self Regulation Never Works and in Aviation It Kills!
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There is no doubt in my mind that the two pilots will eventually be cleared. And now it is out of the hands of the MoD how it is done. If the mandarins and retired officers had thought about it, the better option and least damaging to themselves and the MoD would have been to have cleared the pilots of negligence before the minute details of the acute lack of airworthiness became a matter of public consumption.
Now, however, it is a completely different story, I rather suspect the outrageously negligent implementation of airworthiness regulations will be central to the unfolding story.
I expect, that once again people will be named and shamed. After the Nimrod tragedy many were quietly "retired", moved along etc. Surely time has come for those responsible to appear before a separate court and answer for their actions. The MoD appears to be beyond learning the most important lessons.
Now, however, it is a completely different story, I rather suspect the outrageously negligent implementation of airworthiness regulations will be central to the unfolding story.
I expect, that once again people will be named and shamed. After the Nimrod tragedy many were quietly "retired", moved along etc. Surely time has come for those responsible to appear before a separate court and answer for their actions. The MoD appears to be beyond learning the most important lessons.
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Priorities
Chug,
I think we are in violent agreement - I agree entirely with the need for the flight safety and airworthiness issues to be followed up. However, given how long the families have waited, and the battles they have fought, I would not wish to see any delay to clearing their sons' and husband's names because pursuing the wider isssues will probably take longer. I certainly agree that these other issues are, in terms of the aviation community as whole, even more important in the longer term. Incidentally I think you will find the MAA is calling itself the Military Aviation Authority. Its remit is:
Defence Military Aviation Authority (MAA)
Enhancing the delivery of operational capability through continuous improvement in military Air Safety, associated culture, regulation and practice
The Military Aviation Authority (MAA) is the organisation that regulates, audits and assures all aspects of military aviation.
Established on 1 April 2010, the MAA is an independent and autonomous body that will execute, on behalf of the Secretary of State for Defence, an integrated suite of regulatory, surveillance, inspection and assurance functions across the Defence air operating and technical domains, to underpin the safe design and use of military air systems within the Defence operating context.
Like you I would like to see it completely independent of MOD, and we have yet to see if it can deliver on any or all of these fine and all embracing objectives in a reasonable timescale - possibly also like you, I have my doubts, and I would like to see the priority aims relating to the airworthiness and flight safety outcomes which are demonstrably needed being made much clearer, and the plan to achieve them in as short a timescale as possible. It is also not clear to me how the other independent function of a MAAIB can be achieved - but perhaps others could enlighten us.
JB
I think we are in violent agreement - I agree entirely with the need for the flight safety and airworthiness issues to be followed up. However, given how long the families have waited, and the battles they have fought, I would not wish to see any delay to clearing their sons' and husband's names because pursuing the wider isssues will probably take longer. I certainly agree that these other issues are, in terms of the aviation community as whole, even more important in the longer term. Incidentally I think you will find the MAA is calling itself the Military Aviation Authority. Its remit is:
Defence Military Aviation Authority (MAA)
Enhancing the delivery of operational capability through continuous improvement in military Air Safety, associated culture, regulation and practice
The Military Aviation Authority (MAA) is the organisation that regulates, audits and assures all aspects of military aviation.
Established on 1 April 2010, the MAA is an independent and autonomous body that will execute, on behalf of the Secretary of State for Defence, an integrated suite of regulatory, surveillance, inspection and assurance functions across the Defence air operating and technical domains, to underpin the safe design and use of military air systems within the Defence operating context.
Like you I would like to see it completely independent of MOD, and we have yet to see if it can deliver on any or all of these fine and all embracing objectives in a reasonable timescale - possibly also like you, I have my doubts, and I would like to see the priority aims relating to the airworthiness and flight safety outcomes which are demonstrably needed being made much clearer, and the plan to achieve them in as short a timescale as possible. It is also not clear to me how the other independent function of a MAAIB can be achieved - but perhaps others could enlighten us.
JB
If I may, I’d like to quote from the “Letter of Delegation – Engineering Authority” issued by the RAF’s Chief Engineer in January 1992. The postholder was Air Marshal Sir Michael Alcock (whom Mr Haddon-Cave said would have prevented any airworthiness problems before the post was disestablished in about 1998) and who is a vocal supporter of the Wratten/Day ruling.
On Chinook specifically, I would ask what the CE thought of the Boscombe statement of 30th September 1993 that the FADEC software was "positively dangerous" and what action he took.
If he was not aware, then (a) his senior staffs were negligent and failed in their duty and (b) he didn’t have the degree of control over his department one would expect of such a senior postholder/manager/leader. If he was aware, he demonstrably took no action during his tenure (1991-96), because Director Internal Audit reported to PUS in June 1996 that the problems, first mentioned in an audit in 1988, were still almost universal.
Again, submitted to Lord Philip.
“If you or your staff become aware of any circumstances, practice or procedure which casts doubt on the airworthiness or safety of any of the aircraft or engines for which you are responsible, you are to take immediate action to restore the situation. In addition, you are to keep me informed of any significant airworthiness or safety matter concerning the aircraft and engines under your authority”.
One assumes CE was aware of his Department’s policy of the day to waste hundreds of millions. And of the consequent policy to cancel/limit core airworthiness activities and divert the funding to replace that wasted. And the fact his senior staffs routinely sought disciplinary action against those who became aware of these “circumstances, practices and procedures” and duly met their obligation by reporting it to their line management (e.g. DGSM’s threat to sack civilian staffs in December 1992 if they did not stop highlighting the waste and increasing impact on airworthiness). On Chinook specifically, I would ask what the CE thought of the Boscombe statement of 30th September 1993 that the FADEC software was "positively dangerous" and what action he took.
If he was not aware, then (a) his senior staffs were negligent and failed in their duty and (b) he didn’t have the degree of control over his department one would expect of such a senior postholder/manager/leader. If he was aware, he demonstrably took no action during his tenure (1991-96), because Director Internal Audit reported to PUS in June 1996 that the problems, first mentioned in an audit in 1988, were still almost universal.
Again, submitted to Lord Philip.
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Well, we have all been here before, just as soon as someone gets contact details of the members assigned to the review team, please post them up on the thread. Remember in the initial stages of Haddon-Cave an MoD stooge tried to intercept comms to H-C, at least until Tuc side-stepped the predictable attempt at interfering with the inquiry.
Glad, they are welcoming evidence from interested parties. Haddon-Cave widened his remit last time, I fully expect that when the avalanche of info starts piling in, the review will be widened, deepened and lengthened..
Glad, they are welcoming evidence from interested parties. Haddon-Cave widened his remit last time, I fully expect that when the avalanche of info starts piling in, the review will be widened, deepened and lengthened..
JB:
Well neither would I, but even more so would I not wish to see another thread started within this forum dedicated to yet another Airworthiness related fatal accident. God forbid, but that could happen at any time. There is no "longer term" in this respect for time is very definitely of the essence.
As to the MAA, whatever else that stands for it is not an independent military airworthiness authority and never will be while being part of the MOD. It is part of the misinformation dolled out in cubic metres by the MOD to suggest that it ever could be independent while being so constituted.
As to the campaign to restore the reputations to the two pilots of ZD576 there is no reason why that should await any such necessary reorganisation of these arrangements. That merely awaits the Royal Air Force. It was their senior Air Officers that sullied both their reputations and that of the RAF itself. In repudiating their actions it will start on the path of restoring its own tarnished record. Seems to me to be a job for the Chief of the Air Staff, who is supposed to have a care for that.
I would not wish to see any delay to clearing their sons' and husband's names because pursuing the wider isssues will probably take longer.
As to the MAA, whatever else that stands for it is not an independent military airworthiness authority and never will be while being part of the MOD. It is part of the misinformation dolled out in cubic metres by the MOD to suggest that it ever could be independent while being so constituted.
As to the campaign to restore the reputations to the two pilots of ZD576 there is no reason why that should await any such necessary reorganisation of these arrangements. That merely awaits the Royal Air Force. It was their senior Air Officers that sullied both their reputations and that of the RAF itself. In repudiating their actions it will start on the path of restoring its own tarnished record. Seems to me to be a job for the Chief of the Air Staff, who is supposed to have a care for that.
BTW, the News Letter has already been asked to clarify the "thick fog" comment, given the evidence of at least one witness who, at the precise time of the crash, stated she had 500 yards visibility across the hill and saw the immediate aftermath of the impact. That does not mean the other witnesses who had less visibility were wrong, but this first hand evidence deserves consideration alongside MoD's unsubstantiated opinion as to visibility both from the hill and the cockpit.
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more on time distance and speed......
..in the Excel spreadsheet below the fatal route is split into four legs...
...and allows one to adjust the speed for each leg....the point being to end up with 59.6 minutes in the box D13 ( this equates to 59 minutes 36 seconds , the calculations are done with decimal parts of minutes)...
..it takes the lift-off time from the HOL report......the zone boundary call time is for the first call......the boundary itself 10NM from the centre of the field ......uses the most probable route to Carnlough passing Ballymena ..........shows that a higher speed over the water can make up for the slower sections......the "delta" lines are the times for each leg.....
........when you change the distance (over the ground) for the first leg it will show the speed required to reach the point reported....
....for the next two legs changing the speed ripples down and corrects the arrival time.....
.the last leg is set to 151 kt GS for two minutes as per RACAL ........
..you can download a copy from here ...it is only small...there is also a readme file at the same link , with a more detailed explanation.....
rgds Robin.....
...and allows one to adjust the speed for each leg....the point being to end up with 59.6 minutes in the box D13 ( this equates to 59 minutes 36 seconds , the calculations are done with decimal parts of minutes)...
..it takes the lift-off time from the HOL report......the zone boundary call time is for the first call......the boundary itself 10NM from the centre of the field ......uses the most probable route to Carnlough passing Ballymena ..........shows that a higher speed over the water can make up for the slower sections......the "delta" lines are the times for each leg.....
........when you change the distance (over the ground) for the first leg it will show the speed required to reach the point reported....
....for the next two legs changing the speed ripples down and corrects the arrival time.....
.the last leg is set to 151 kt GS for two minutes as per RACAL ........
..you can download a copy from here ...it is only small...there is also a readme file at the same link , with a more detailed explanation.....
rgds Robin.....
Last edited by Robin Clark; 21st Sep 2010 at 11:46. Reason: Readme added....
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Dist/Time calculations
Whether you would regard an analysis done by Boeing as likely to be biased or not, the following document lays out its calculations and you can use it as an aide memoir to help you:
Mull of Kintyre -Analysis of Available Data
8-7D20-DS S-03 06, Enclosure 4
James Mitchell of the Boeing company
Section 3.2 “Aircraft Velocity Assessment” is not a bad effort.
The assumptions therein about wind speed are based upon the forecasts and, of course, what is known from measurements at the light house – the (significantly) increased wind speed on the Mull itself is what you would expect with an on-shore wind pushing against the slope and reference to wind farm studies should assure those who may be surprised at how much it would increase.
What is most relevant, I suggest, is that the gist of what the Boeing analysis is saying is that the a/c would have to have been doing the top end of cruise speed for the whole way until near the Mull (to have got where it did by when it did): it couldn't have averaged any slower up until that area – and, as this would have been up to the limit for passenger and crew comfort, it could hardly have gone any faster to make up for any slower periods – thus we can reasonably assume that they had not deviated from a straight track at the high average calculated for that long leg from NI to the Mull - that is, in simple terms, they had flown in a straight line at constant speed until close to the Mull – they could not have done anything else.
On the final leg from the position of way point change to the point of impact Mitchell uses the speed from the last steering calculation (over ground on the slopes) together with the strong wind there to deduce that the a/c had slowed down in terms of airspeed but that this had been masked by the increase in wind such that the ground speed had remained constant.
I add that the engine states (matched and not at the level to be expected for maintaining the high cruise speed over the preceding long passage) were consistent with an intended reduction in speed (say, coasting in) – the matched state (nor for that matter the power level) was not consistent with any kind of emergency situation and the last second manoeuvre apparently initiated was too sudden for the engines to have been disturbed from this matched state indicating the pilots being surprised at their proximity to the ground.
Whether you would regard an analysis done by Boeing as likely to be biased or not, the following document lays out its calculations and you can use it as an aide memoir to help you:
Mull of Kintyre -Analysis of Available Data
8-7D20-DS S-03 06, Enclosure 4
James Mitchell of the Boeing company
Section 3.2 “Aircraft Velocity Assessment” is not a bad effort.
The assumptions therein about wind speed are based upon the forecasts and, of course, what is known from measurements at the light house – the (significantly) increased wind speed on the Mull itself is what you would expect with an on-shore wind pushing against the slope and reference to wind farm studies should assure those who may be surprised at how much it would increase.
What is most relevant, I suggest, is that the gist of what the Boeing analysis is saying is that the a/c would have to have been doing the top end of cruise speed for the whole way until near the Mull (to have got where it did by when it did): it couldn't have averaged any slower up until that area – and, as this would have been up to the limit for passenger and crew comfort, it could hardly have gone any faster to make up for any slower periods – thus we can reasonably assume that they had not deviated from a straight track at the high average calculated for that long leg from NI to the Mull - that is, in simple terms, they had flown in a straight line at constant speed until close to the Mull – they could not have done anything else.
On the final leg from the position of way point change to the point of impact Mitchell uses the speed from the last steering calculation (over ground on the slopes) together with the strong wind there to deduce that the a/c had slowed down in terms of airspeed but that this had been masked by the increase in wind such that the ground speed had remained constant.
I add that the engine states (matched and not at the level to be expected for maintaining the high cruise speed over the preceding long passage) were consistent with an intended reduction in speed (say, coasting in) – the matched state (nor for that matter the power level) was not consistent with any kind of emergency situation and the last second manoeuvre apparently initiated was too sudden for the engines to have been disturbed from this matched state indicating the pilots being surprised at their proximity to the ground.