View source for 1994 Mull of Kintyre Chinook crash

{{Short description|Helicopter crash in Scotland}}
{{Use British English|date=May 2011}}
{{Use dmy dates|date=December 2019}}
{{Infobox aircraft occurrence
|date            = {{Start date|1994|06|02|df=yes}}
|image           = ZD576 (15925406339).jpg
|caption         = ZD576, the aircraft involved in the accident, in 1987
|summary         = Crashed in fog; cause is disputed.
• [[Pilot error]] leading to [[CFIT]] ([[Royal_Air_Force|RAF]])
• Possible mechanical failure ([[FADEC]] software error) (Independent inquiry)
|occurrence_type = Accident
|site            = [[Mull of Kintyre]], Scotland
| coordinates    = {{coord|55|18|49|N|5|47|42|W|region:GB_type:event|display=it}}
|origin          = [[RAF Aldergrove]] (near [[Belfast]], Northern Ireland)
|destination     = [[Inverness]], Scotland
|occupants       = 29
|passengers      = 25
|crew            = 4
|injuries        = 
|fatalities      = 29
|survivors       = 0
|aircraft_type   = [[Boeing Chinook (UK variants)|Boeing Chinook]]
|operator        = [[Royal Air Force]]
|callsign        = F4J40
|tail_number     = ZD576
}}

On 2 June 1994, a [[Boeing Chinook (UK variants)|Chinook]] helicopter of the [[Royal Air Force]] (RAF), [[United Kingdom military aircraft serial numbers|serial number]] ''ZD576'', crashed on the [[Mull of Kintyre]], Scotland, in foggy conditions. The crash resulted in the deaths of all twenty-five passengers and four crew on board. Among the passengers were almost all the United Kingdom's senior [[Northern Ireland]] [[Intelligence (information gathering)|intelligence]] experts. The accident is the RAF's fourth-worst peacetime disaster.<ref>{{Cite news|title=31 Killed in R.A.F. Transport|work=The Times|location=London, England|date=16 October 1945|page=4; Issue 50274}}</ref><ref name=Times1>{{Cite newspaper The Times |title=41 Killed on Parachute Training Flight |date=7 July 1965 |page=10 |issue=56367 |column=C}}</ref><ref name="times58321">{{Cite newspaper The Times |title=RAF Plane crashed in Italy, killing 52 |author=Peter Nichols |date=10 November 1971 |page=1 |issue=58321 }}</ref>

In 1995, an RAF board of inquiry ruled that it was impossible to establish the exact cause of the accident. This ruling was overturned by two senior reviewing officers, who stated that the pilots were guilty of gross negligence for flying too fast and too low in thick fog. This finding proved to be controversial, especially in light of irregularities and technical issues surrounding the then-new Chinook HC2 variant which were uncovered, and in light of technical problems with the specific airframe involved in the weeks leading up to the crash. A Parliamentary inquiry conducted in 2001 found the previous verdict of gross negligence on the part of the crew to be 'unjustified'. In 2011, an [[Independent reviews in the United Kingdom|independent review]] of the crash cleared the crew of negligence and accepted that the RAF had falsely declared compliance with regulations in relation to the aircraft's authority to fly.

==Incident==

===Crash===
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Earlier on 2 June 1994, the helicopter and crew had carried out a trooping flight, as it was considered to be safer for British troops to fly around in certain parts of Northern Ireland at the time due to the threat posed by [[Provisional IRA]] attacks. This mission was safely accomplished and they returned to [[RAF Aldergrove]] (outside Belfast, Northern Ireland) at 15:20. They took off for Inverness at 17:42. Weather en route was forecast to be clear except in the [[Mull of Kintyre]] area. The crew made contact with military air traffic control (ATC) in Scotland at 17:55.<ref>Brookes 1996, p. 58</ref>

Around 18:00, Chinook ZD576 flew into a hillside in dense fog. The pilots were [[Flight Lieutenant]]s Jonathan Tapper, 28, and Richard Cook, 30, both [[United Kingdom Special Forces]] pilots. There were two other crew. The helicopter was carrying 25 British intelligence experts from [[MI5]], the [[Royal Ulster Constabulary]] and the [[British Army]], from Aldergrove to attend a conference at [[Fort George, Scotland|Fort George]] (near Inverness) in Scotland. At the time of the accident, [[Air Chief Marshal]] [[Bill Wratten|Sir William Wratten]] called it "the largest peacetime tragedy the RAF had suffered".<ref name='clear2002'>{{cite news |url = https://news.bbc.co.uk/1/hi/scotland/3710403.stm |title = 'Clear Chinook two' ex-PM urges |work = BBC News |date = 13 May 2004 |access-date = 11 September 2011}}</ref>

{{quote|The initial point of impact was {{convert|810|ft|disp=sqbr}} above mean sea level and about 500&nbsp;metres east of the lighthouse, but the bulk of the aircraft remained airborne for a further 187&nbsp;metres horizontally north and {{convert|90|ft|disp=sqbr}} vertically before coming to rest in pieces. Fire broke out immediately. All those on board sustained injuries from which they must have died almost instantaneously. The points of impact were shrouded in local cloud with visibility reduced to a few metres, which prevented those witnesses who had heard the aircraft from seeing it.<ref name ='select2002'>[https://publications.parliament.uk/pa/ld200102/ldselect/ldchin/25/2504.htm#a9 "Select Committee on Chinook ZD 576, Part 3: Factual Background."] UK Parliament, 2002; retrieved: 3 November 2006.</ref>}}

In the immediate aftermath of the accident, one commentator stated that the loss of so many top level Northern Ireland intelligence officers in one stroke was a huge blow to the [[John Major]] government, "temporarily confounding" its campaign against the IRA.<ref>{{cite news |url = https://news.bbc.co.uk/2/hi/uk_news/scotland/1800804.stm |title = Q&A: Chinook crash inquiry |work = BBC News |date = 3 June 2004 |access-date = 3 November 2006}}</ref> That the crash killed so many British intelligence experts, without any witnesses in the foggy conditions, led to considerable speculation and [[conspiracy theory|conspiracy theories]] being devised regarding the potential of a [[cover-up]]. Among these were accusations that [[wake turbulence]] from a top-secret [[hypersonic]] US aircraft had been responsible for the crash,<ref>{{cite web |first = Andrew |last = Thomas |url = https://www.theregister.co.uk/2000/07/10/top_secret_us_plane_caused |title = Top Secret US plane 'caused Chinook crash' |publisher = The Register |date = 10 July 2000 |quote = But a third explanation for the crash has now come to light: that a top secret hypersonic US plane, codenamed [[Aurora (aircraft)|Aurora]] and which is reportedly capable of flying at up to 20 times the speed of sound, created a massive jet wake into which the helicopter flew, causing the crew to lose control. |access-date = 19 October 2005 |archive-url=https://web.archive.org/web/20050913140342/https://www.theregister.co.uk/2000/07/10/top_secret_us_plane_caused |archive-date = 13 September 2005 |url-status = live}}</ref> while another postulated that it was a deliberate assassination of the intelligence operatives on board in order to facilitate negotiations with [[Irish republicanism|republican factions]] during the then on-going [[Northern Ireland peace process]].<ref>{{cite news |first = John |last = O'Farrell |url = https://www.theguardian.com/uk/2000/jun/14/northernireland.comment |title = Dark rumours surround Chinook crash |work = The Guardian |date = 14 June 2000 |quote = But dark rumours abound. The loss of ten senior RUC intelligence officers, nine army intelligence officers and six MI5 officers on the eve of the 1994 IRA cessation was, for some, propitious. [...] Some loyalists believe that the intelligence officers were deliberately "taken out" for "knowing too much" about the people the government would have to deal with in a post-conflict Ulster. |access-date = 15 August 2011}}</ref><ref>{{cite news |first = Henry |last = McDonald |url = http://www.belfasttelegraph.co.uk/opinion/columnists/mull-of-kintyre-helicopter-crash-why-only-a-formal-apology-and-fresh-investigation-can-begin-to-assuage-this-wrong-30322860.html |title = Mull of Kintyre helicopter crash: Why only a formal apology and fresh investigation can begin to assuage this wrong |work = Belfast Telegraph|quote = Conspiracy theories from the right, preceding the wilder conspiracies of the 9/11 'Truthers', have tried to suggest that the crash was deliberate; that the Government somehow needed to weed out a number of hardline securocrats in the intelligence community who were opposed to doing a peace deal with the IRA. |date = 3 June 2014}}</ref>

===Victims===
The crash resulted in the deaths of 29 people: four Royal Air Force crew members and 25 passengers from the British Army, Royal Ulster Constabulary, and the Security Service.<ref name="UKParliamentReport">https://publications.parliament.uk/pa/ld200102/ldselect/ldchin/25/25we21.htm</ref>

=== Royal Air Force crew ===
* Flight Lieutenant Jonathan Paul Tapper
* Flight Lieutenant Richard David Cook
* Master Air Loadmaster Graham William Forbes
* Sergeant Kevin Andrew Hardie

=== British Army ===

==== Intelligence Corps and attached units ====
* Lieutenant Colonel Richard Lawrence Gregory-Smith
* Lieutenant Colonel John Tobias MBE
* Lieutenant Colonel George Victor Alexander Williams MBE, QGM
* Colonel Christopher John Biles QGM, BEM
* Major Richard Allen (Royal Gloucestershire, Berkshire and Wiltshire Regiment)
* Major Christopher John Dockerty (Prince of Wales’s Own Regiment of Yorkshire)
* Major Anthony Robert Hornby MBE (Queen’s Lancashire Regiment)
* Major Roy Pugh MBE
* Major Gary Paul Sparks (Royal Artillery)

=== Royal Ulster Constabulary (Special Branch) ===
* Assistant Chief Constable John Charles Brian Fitzsimons MBE
* Detective Chief Superintendent Desmond Patrick Conroy QGM, BEM
* Detective Chief Superintendent Maurice McLaughlin Neilly
* Detective Superintendent Philip George Davidson
* Detective Superintendent Robert Patrick Foster
* Detective Superintendent John Turbitt Phoenix
* Detective Superintendent William Rutherford Gwilliam
* Detective Inspector Dennis Stanley Bunting
* Detective Inspector Kevin Michael Magee
* Detective Inspector Stephen Davidson

=== Security Service ===
* Martin George Dalton
* John Robert Deverell CB, MBE
* Anne Catherine Macdonald
* Michael Bruce Maltby
* Stephen Lewis Rickard
* John Stuart Haynes MBE

===Initial inquiry===
In 1995, an RAF board of inquiry that investigated the incident determined that there was no conclusive evidence to determine the cause of the crash. An immediate suspicion that the helicopter could have been shot down by the [[Provisional IRA]], with their known [[Strela 2]] [[surface-to-air missile]] capability, had been quickly ruled out by investigators. A review of the evidence, carried out by two Air Chief Marshals of the Royal Air Force, found the two pilots to have been guilty of [[gross negligence]] by flying too fast and too low in thick fog.<ref>{{cite news |url = https://news.bbc.co.uk/2/hi/uk_news/7660363.stm |work = BBC News |title = Campaigners want Chinook review |date = 9 October 2008 |access-date = 20 April 2010}}</ref> Both the incident and the first inquiry have been subject to controversy and dispute, primarily as to whether the crash had been caused by pilot error or by a mechanical failure. The 2011 Parliamentary report found the reviewing officers to have failed to correctly adhere to the standard of proof of "absolutely no doubt" in deciding the question of negligence.<ref>House of Commons 2011, p. 9.</ref>

==Subsequent inquiries==

[[File:1994 Chinook Crash Memorial.JPG|thumb|upright|Memorial on Mull of Kintyre to the crash victims]]The first inquiry and its conclusion proved to be highly controversial. A subsequent [[fatal accident inquiry]] (1996), [[House of Commons of the United Kingdom|House of Commons]] [[Defence Select Committee]] report (2000) and Commons [[Public Accounts Committee (United Kingdom)|Public Accounts Committee]] report have all either left open the question of blame or challenged the original conclusion. The campaign for a new inquiry was supported by the families of the pilots, and senior politicians, including former prime minister [[John Major]] and former [[Secretary of State for Defence|defence secretary]] [[Malcolm Rifkind]].<ref name='clear2002'/><ref>{{cite news |first = Ross |last = Lydall |url = http://www.thisislondon.co.uk/standard/article-23790759-sir-malcolm-rifkind-wrong-to-blame-crash-on-chinook-crew.do |title = Sir Malcolm Rifkind: Wrong to blame crash on Chinook crew |work = London Evening Standard |date = 4 January 2010 |access-date = 11 September 2011 |archive-url = https://web.archive.org/web/20101212101114/http://www.thisislondon.co.uk/standard/article-23790759-sir-malcolm-rifkind-wrong-to-blame-crash-on-chinook-crew.do |archive-date = 12 December 2010 }}</ref> The new inquiry took place in the [[House of Lords]] from September to November 2001. The findings were published on 31 January 2002, and found that the verdicts of gross negligence on the two pilots were unjustified.<ref>[https://publications.parliament.uk/pa/ld200102/ldselect/ldchin/25/2501.htm "Chinook ZD 576 – Report."] UK Parliament, 2002; retrieved 3 November 2006.</ref>

In December 2007, Defence Secretary [[Des Browne]] agreed to conduct a fresh report into the crash.<ref>{{cite news|author=Press Association |work=The Guardian |location=London |url=https://www.theguardian.com/uklatest/story/0,,-7132503,00.html |archive-url=https://web.archive.org/web/20080108132312/http://www.guardian.co.uk/uklatest/story/0%2C%2C-7132503%2C00.html |title=Chinook crash report to be examined |date=6 December 2007 |archive-date=8 January 2008 |author-link=Press Association }}</ref><ref>{{cite news |first = Sam |last = Lister |title = MoD to consider new Chinook claims |url = http://www.belfasttelegraph.co.uk/news/local-national/article3342423.ece |archive-url = https://archive.today/20080120153457/http://www.belfasttelegraph.co.uk/news/local-national/article3342423.ece |archive-date = 20 January 2008 |work = Belfast Telegraph |date = 16 January 2008 |access-date = 17 January 2008}}</ref> On 8 December 2008, Secretary of State for Defence [[John Hutton (Labour MP)|John Hutton]] announced that "no new evidence" had been presented and the verdicts of gross negligence against the flight crew would stand.<ref>{{cite news |url = https://news.bbc.co.uk/2/hi/uk_news/scotland/7772125.stm |title = Gross negligence verdicts to stand |work= BBC News |date=8 December 2008 |access-date = 8 December 2008 |archive-url = https://web.archive.org/web/20081210084043/http://news.bbc.co.uk/1/hi/scotland/7772125.stm |archive-date = 10 December 2008 |url-status=live}}</ref> On 4 January 2010, doubts of the official explanation were raised again with the discovery that an internal [[Ministry of Defence (United Kingdom)|Ministry of Defence]] (MOD) document, which had been written nine months prior to the incident, described the engine software as 'positively dangerous' as it could lead to failure of both engines.<ref>{{cite news |url = https://news.bbc.co.uk/2/hi/uk_news/8438659.stm |work = BBC News |title = Fresh doubts over Chinook crash |date = 4 January 2010 |access-date = 20 April 2010}}</ref><ref>Lewis, Page. [https://www.theregister.co.uk/2010/01/04/mull_of_kintyre_chinook_dead_horse/ "Please shut up about the Mull of Kintyre Chinook crash."] ''The Register'', 4 January 2010.</ref> The 2011 Review concluded that criticism that the original board had not paid enough attention to maintenance and technical issues was unjustified.<ref>House of Commons 2011, p. 8.</ref>

On 13 July 2011, the Defence Secretary [[Liam Fox]] outlined to MPs the findings of an independent review into the 1994 crash, which found that the two pilots who were blamed for the crash had been cleared of gross negligence.<ref name=bbc14130867>{{cite news |url = https://www.bbc.co.uk/news/uk-scotland-glasgow-west-14130867 |work = BBC News |title = Apology as Mull of Kintyre Chinook crash pilots cleared |date = 13 July 2011 |access-date = 13 April 2011}}</ref> In doing so, the Government accepted Lord Philip's confirmation that the [[Controller Aircraft]] Release was "mandated" upon the RAF. Issued in November 1993, the Controller Aircraft stated that the entire navigation and communications systems used on the Chinook HC2 were not to be relied upon in any way by the aircrew, and therefore it had no legitimate clearance to fly. Knowledge of this had been withheld from the pilots; by withholding this when issuing their Release to Service (RTS) (the authority to fly), the RAF had made a false declaration of compliance with regulations. In December 2012, the Minister for the Armed Forces, [[Andrew Robathan]], confirmed such a false declaration did not constitute "wrongdoing", despite it leading directly to deaths of servicemen.{{fact|date=June 2024}}

==ZD576's service history==
[[File:Chinook.hc2.za677.arp.jpg|thumb|RAF Chinook HC2 (ZA677) similar to accident aircraft]]
[[Boeing Helicopters|Boeing]] CH-47C [[CH-47 Chinook|Chinook]], construction number B-868, RAF serial number ZD576 was originally delivered to the [[Royal Air Force]] as a Chinook HC.1 on 22 December 1983.<ref name ='teletimeline'>{{cite news |url = https://www.telegraph.co.uk/news/uknews/defence/5110232/Chinook-crash-timeline.html |title = Chinook crash – timeline |newspaper = The Daily Telegraph |location = London |date = 6 April 2009 |access-date = 11 September 2011}}</ref>

It was re-delivered to No 7 Squadron as a Chinook HC.2 on 21 April 1994. On arrival at [[RAF Odiham]], its No. 1 engine had to be replaced due to a [[FADEC]] incident.{{Clarify|date=June 2024|reason=what happened? should this be cited?}} Five days later, that same engine had to be replaced due to a second FADEC incident. On 10 May 1994, a post-flight fault inspection revealed a dislocated mounting bracket had caused the [[Helicopter flight controls#Collective|collective lever]] to have restricted and restrictive movement; this resulted in a "Serious Fault Signal"<ref>[https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/554613/20161002-LEGACY_JSP886-V3P315-FaultReport-FINAL-O.pdf "THE DEFENCE LOGISTICS SUPPORT CHAIN MANUAL JSP 886 VOLUME 3 SUPPLY CHAIN MANAGEMENT PART 315 FAULT REPORTING – SUPPLY PROCEDURES."] ''gov.uk'', 1 July 2008.</ref> being sent as a warning to other UK Chinook operating units. On 17 May 1994, emergency power warning lights flashed multiple times and the No.1 engine was again replaced. On 25 May 1994, a serious incident occurred which had indicated the imminent failure of the No.2 engine.<ref name ='teletimeline'/><ref name="McMullon, D 1998">McMullon 1998, {{page needed|date=September 2011}}</ref>

On 31 May 1994, two days before the accident, two Chinook HC.1s were withdrawn from RAF Aldergrove and replaced by a single HC.2, ZD576.<ref>House of Commons 2011, p. 16.</ref>

==Possible causes==

===Pilot error===
Aviation safety author [[Andrew Brookes]] wrote that the true cause will never be known, but that pilot error induced by [[Fatigue (physical)|fatigue]] is likely to have played a part; the crew had been on flight duty for 9 hours and 15 minutes, including 6 hours flying time, before they took off on the crash flight. Had they made it to Fort George, they would have needed special permission from a senior officer to fly back to Aldergrove.<ref>Brookes 1996, p. 59</ref>

{{Quote box|align=right|width=30%|quote="There is no evidence of any significant change of course and none of the decision, if any, that the crew made. When the crew released the computer from its fix on the Mull, the pilots knew how close to the Mull they were and, given the deteriorating weather and the strict visibility requirements under [[visual flight rules]] they should by that time already have chosen an alternative course. As they had not done so, they could, and, under the rules, should have either turned away from the Mull immediately or slowed down and climbed to a safe altitude."|source=[[Baroness Symons]], speaking on behalf of the Government in the House of Lords in 2000.<ref>{{cite web |url = https://publications.parliament.uk/pa/ld199900/ldhansrd/vo000712/text/00712w02.htm|title=Chinook Helicopter ZD576: Flight Plan |publisher = House of Lords |date = 12 July 2000 |access-date = 9 February 2006 |archive-url = https://web.archive.org/web/20060324224259/http://www.publications.parliament.uk/pa/ld199900/ldhansrd/vo000712/text/00712w02.htm |archive-date= 24 March 2006 |url-status = live}}</ref>}}

In his book, [[Steuart Campbell]] suggested that two errors by the pilots—failure to climb to a safe altitude upon entering cloud, and a navigational error made in the poor visibility (mistaking a fog signal station for a lighthouse)—together caused the crash.<ref>Campbell 2004, p. 197.</ref> The Board of Inquiry had identified that several factors may have sufficiently distracted the crew from turning away from the Mull, and upon entering cloud, failed to carry out the correct procedure for an emergency climb in a timely manner.<ref>House of Commons 2011, p. 24.</ref>

RAF Visual Flight Rules (VFR) require the crew to have a minimum visibility of 5.5 kilometres above {{convert|140|kn|km/h}}, or minimum visibility of one kilometre travelling below 140 knots;<ref>House of Commons 2011, p. 78.</ref> if VFR conditions are lost an emergency climb must be immediately flown.<ref>House of Lords 2002, p. 4.</ref> Nine out of ten witnesses interviewed in the inquiry reported visibility at ground level in the fog as being as low as ten to one hundred metres at the time of the crash; in-flight visibility may have been more or less than this. The tenth witness, a yachtsman who was offshore, reported it as being {{convert|1|mi|spell=in}}, though he is regarded as a less reliable witness as he changed his testimony.<ref name='lord7'/>

If witness accounts of visibility are correct, the pilots should have transferred to Instrument Flight Rules,<ref name='lord10'>House of Lords 2002, p. 10.</ref> which would require the pilots to slow the aircraft and climb to a safe altitude at the best climbing speed.<ref>House of Commons 2011, pp. 78–79.</ref> In the area around the Mull of Kintyre, the safe altitude would be {{convert|2400|ft}} above sea level, {{convert|1000|ft}} above the highest point of the terrain.<ref>House of Commons 2011, p. 76.</ref> The height of the crash site of ZD576 was {{convert|810 |ft}} above sea level i.e. {{convert|1600|ft}} below the minimum safe level.<ref name ='select2002'/> The Board of Inquiry into the accident recommended formal procedures for transition from Visual Flight Rules to Instrument Flight Rules in mid-flight be developed, and the RAF has since integrated such practices into standard pilot training.<ref>House of Commons 2011, p. 72.</ref>

Regarding negligence on the part of the pilots, the 2011 Report said "the possibility that there had been gross negligence could not be ruled out, but there were many grounds for doubt and the pilots were entitled to the benefit of it... [T]he Reviewing Officers had failed to take account of the high calibre of two Special Forces pilots who had no reputation for recklessness."<ref>House of Commons 2011, p. 69.</ref>

===FADEC problems===
{{Quote box|align=right|width=30%|quote="The chances are that if software caused any of these accidents, we would never know. This is because when software fails, or it contains coding or design flaws... only the manufacturer will understand its system well enough to identify any flaws... Step forward the vulnerable equipment operators: the pilots... who cannot prove their innocence. That is why the loss of Chinook ZD576 is so much more than a helicopter crash. To accept the verdict against the pilots is to accept that it is reasonable to blame the operators if the cause of a disaster is not known." |source = Karl Schneider, Editor of ''[[Computer Weekly]]'', 2002<ref>{{cite web|url=http://www.computerweekly.com/Articles/2002/02/07/185089/Clear-and-present-danger-why-CW-refused-to-give-up-on.htm |title = Clear and present danger: why CW refused to give up on Chinook |publisher = Computer Weekly |date = 7 February 2002 |access-date = 11 September 2011}}</ref>}}

At the time of the crash, new [[FADEC]] (Full Authority Digital Engine Control) equipment was being integrated into all RAF Chinooks, as part of an upgrade from the Chinook HC.1 standard to the newer Chinook HC.2 variant. The [[Ministry of Defence (United Kingdom)|Ministry of Defence]] was given a £3&nbsp;million settlement from [[Textron]], the manufacturers of the system, after a ground test of the FADEC systems on a Chinook in 1989 resulted in severe airframe damage. Contractors, including Textron, had agreed that FADEC had been the cause of the 1989 incident and that the system needed to be redesigned.<ref>{{cite web |url = http://www.computerweekly.com/Articles/2000/06/29/174615/Defence-Minister-misleads-MPs-over-Chinook-accident.htm |title = Defence Minister misleads MPs over Chinook accident |publisher = Computer Weekly |date= 29 June 2000 |access-date = 11 September 2011}}</ref>

The committee investigating the crash were satisfied that the destructive error in 1989 was not relevant to the 1994 crash.<ref name ='lord7'>House of Lords 2002, p. 7.</ref> Information provided from Boeing to the investigation led to the following conclusion regarding FADEC performance: "Data from the Digital Electronics Unit (DECU) of the second engine showed no evidence of torque or temperature exceedance and the matched power conditions of the engines post-impact indicate that there was no sustained emergency power demand. No other evidence indicated any FADEC or engine faults."<ref name='lord23'>House of Lords 2002, p. 23.</ref> It was expected that in a FADEC engine runaway, engine power would become asynchronous and mismatched. The investigation found the engines at the crash to have matched settings, decreasing the likelihood of a FADEC malfunction being involved.<ref>{{cite web |url = https://publications.parliament.uk/pa/ld200102/ldselect/ldchin/25/25m06.htm |title = Mull of Kintyre |publisher = House of Lords |date = 12 July 2000 |access-date = 11 September 2011}}</ref>

[[Electronic Data Systems|EDS]]-SCICON was given the task of independently evaluating the software on the Chinook HC.2 in 1993. According to the House of Commons report: "After examining only 18 per cent of the code they found 486 anomalies and stopped the review... intermittent engine failure captions were being regularly experienced by aircrew of Chinook Mk 2s and there were instances of uncommanded run-up and run-down of the engines and undemanded flight control movements".<ref name='select2002'/>

Tests on the Chinooks performed by the MOD at [[MoD Boscombe Down|Boscombe Down]] in 1994 reported the FADEC software to be "unverifiable and ... therefore unsuitable for its purpose".<ref name='select2002'/> In June 1994, the MoD test pilots at Boscombe Down had refused to fly the Chinook HC.2 until the engines, engine control systems and [[FADEC]] software had undergone revision.<ref name="McMullon, D 1998"/> In October 2001, ''[[Computer Weekly]]'' reported that three fellows of the [[Royal Aeronautical Society]] had said that issues with either control or FADEC systems could have led to the crash.<ref>{{cite web |first = Tony |last = Collins |url = http://www.computerweekly.com/Articles/2001/10/25/183320/Top-Chinook-test-pilot-reveals-unease-over-engine-software.htm |title = Top Chinook test pilot reveals unease over engine software |publisher = Computer Weekly |date = 25 October 2001 |access-date = 11 September 2011}}</ref>

The main submission to [[Alexander Philip, Lord Philip|Lord Philip]] (see above) revealed that the FADEC Safety Critical software did not have a Certificate of Design, and was therefore not cleared to be fitted to Chinook HC2.  It further revealed that [[John Spellar]] MP had been wrong when claiming the software was not Safety Critical, providing the original policy document governing this definition to Lord Philip.{{fact|date=June 2024}}

===Other factors===
The onboard SuperTANS navigation computer, which retained only the last measured altitude, gave an altitude reading of {{convert|468|ft}}.<ref>House of Commons 2011, p. 22.</ref> The investigation observed that it was possible for some of the avionics systems to interfere with the Chinook's VHF radio, potentially disrupting communications.<ref>House of Commons 2011, p. 71.</ref>

[[Flight data recorder]]s and [[cockpit voice recorder]]s were not fitted to all RAF Chinooks at the time of the accident. The absence of these data greatly reduced the amount and quality of data available to subsequent investigations.<ref>House of Commons 2011, pp. 7–8.</ref> Information on speed and height were derived from the position of cockpit dials in the wreckage and the condition of the wreckage. During 1994, the RAF had begun to fit these recording devices across the Chinook HC.2 fleet before the accident; this process was completed in 2002.<ref>House of Commons 2011, pp. 71, 84–85.</ref>

The aircraft had not been classified as airworthy. It was mandated upon the RAF that it was "not to be relied upon in any way".<ref>Hill, David. ''Their Greatest Disgrace – The Campaign to Clear the Chinook ZD576 Pilots''. Nemesis Books, 2016. {{ISBN|1-52620-446-0}}.</ref>

==References==
===Citations===
{{Reflist|30em}}

===Bibliography===
{{Refbegin}}
* {{cite book |first=Andrew |last=Brookes |author-link=Andrew Brookes |title=Flights to Disaster |publisher=Ian Allan |year=1996 |isbn=0-7110-2475-8}}
* {{cite book |first=Steuart |last=Campbell |author-link=Steuart Campbell |title=Chinook Crash |publisher=Pen & Sword Aviation |year=2004 |isbn=978-1-84415-074-8}}
* {{cite book |author-link=Alexander Philip, Lord Philip |url=http://www.mullofkintyrereview.org.uk/sites/default/files/Mull%20of%20Kintyre%20Review%20Report.pdf |title=The Mull of Kintyre Review |author=Philip |first1=Alexander |last2=Forsyth |first2=Michael |author-link2=Michael Forsyth, Baron Forsyth of Drumlean |last3=Liddell |first3=Helen |author-link3=Helen Liddell |last4=Bruce |first4=Malcolm |author-link4=Malcolm Bruce |publisher=[[The Stationery Office]] |date=13 July 2011 |access-date=13 July 2011 |isbn=978-0-1029-5237-7 |archive-url=https://web.archive.org/web/20160531215132/http://www.mullofkintyrereview.org.uk/sites/default/files/Mull%20of%20Kintyre%20Review%20Report.pdf |archive-date=31 May 2016}}
* {{cite web |agency=[[House of Lords]] |url=http://www.mod.uk/NR/rdonlyres/AE81D0D3-8025-4567-A658-47B561CC6F83/0/chinook_response.pdf |title=Government's Response to the Chinook ZD 567 Report |publisher=Ministry of Defense |date=22 July 2002 |access-date=27 October 2011 |archive-url=http://webarchive.nationalarchives.gov.uk/20121018173232/http://www.mod.uk/NR/rdonlyres/AE81D0D3-8025-4567-A658-47B561CC6F83/0/chinook_response.pdf |archive-date=18 October 2012}}
* {{cite book |first=David |last=Hill |title=Their Greatest Disgrace |publisher=Nemesis Books |year=2016 |isbn=978-1-5262-0446-2}}{{Self-published inline|date=July 2024}}
* {{cite book |title=Phoenix: Policing the Shadows |publisher=Hodder & Stoughton |author2=Susan Phoenix |author1=Holland, Jack |author-link=Jack Holland (writer) |year=1996 |isbn=978-0-3406-6634-0 |url-access=registration |url=https://archive.org/details/phoenixpolicings0000holl}}
* {{cite book |first=David |last=McMullon |title=Chinook!: The Special Forces Flight in War and Peace |publisher=Simon & Schuster |year=1999 |isbn=978-0-671-01599-2}}
{{Refend}}

==External links==
{{Portal|Scotland|Aviation|1990s}}
* [https://news.bbc.co.uk/2/hi/uk_news/scotland/1800727.stm BBC timeline of events]
* [https://web.archive.org/web/20120717021641/http://www.ccsr.cse.dmu.ac.uk/resources/general/ethicol/Ecv12no2.html Simon Rogerson's article], from [[Irish Military Intelligence Service|IMIS]] Journal
* Computer Weekly publications
** [http://www.computerweekly.com/Articles/2000/11/30/174561/mps-boost-chinook-fight.htm MPs Boost Chinook Fight 2000]
** [http://www.computerweekly.com/Articles/2000/11/30/177569/chinook-report-slams-flawed-mod-procurement-methods.htm Chinook report slams flawed MoD procurement methods 2000]
* House of Lords select committee publications
** [https://publications.parliament.uk/pa/ld200102/ldselect/ldchin/25/25we01.htm Written evidence]
** [https://publications.parliament.uk/pa/ld/ldchin.htm Report]
** [https://publications.parliament.uk/pa/ld200102/ldselect/ldchin/25/2507.htm Conclusions]
* [https://archives.parliament.uk/collections/getrecord/GB61_HL_PO_CO_CH The records of the House of Lords Committee to Review Chinook ZD576 Crash are held by the UK Parliamentary Archives]
* [https://www.chinookjusticecampaign.co.uk/ Chinook Justice Campaign]

{{Aviation accidents and incidents in 1994}}
{{Aviation accidents and incidents in the United Kingdom in the 1990s}}
{{CH-47 Chinook family}}

{{Authority control}}

{{DEFAULTSORT:Mull of Kintyre Raf Chinook Crash}}
[[Category:1994 disasters in the United Kingdom]]
[[Category:1994 in Northern Ireland]]
[[Category:1994 in Scotland]]
[[Category:Aviation accidents and incidents in Scotland]]
[[Category:Aviation accidents and incidents involving controlled flight into terrain]]
[[Category:Aviation accidents and incidents in 1994]]
[[Category:Accidents and incidents involving Royal Air Force aircraft]]
[[Category:Accidents and incidents involving the Boeing Chinook]]
[[Category:Aviation accidents and incidents involving fog]]
[[Category:Fatal accident inquiries]]
[[Category:June 1994 in the United Kingdom]]
[[Category:Software bugs]]
[[Category:Accidents and incidents involving military helicopters]]