1994 Scotland RAF Chinook crash

1994 Scotland RAF Chinook crash

The memorial on the Mull of Kintyre to the victims
Accident summary
Date	2 June 1994
Type	CFIT
Site	Mull of Kintyre, Scotland
Passengers	25
Crew	4
Fatalities	29 (all)
Survivors	0
Aircraft type	Boeing Chinook
Operator	Royal Air Force
Tail number	ZD576
Flight origin	RAF Aldergrove near Belfast, Northern Ireland
Destination	Inverness, Scotland

The 1994 Scotland RAF Chinook crash occurred on 2 June 1994 at about 18:00 hours when a Royal Air Force (RAF) Chinook helicopter (serial number ZD576, callsign F4J40) crashed on the Mull of Kintyre, Scotland, killing all twenty-five passengers and four crew on board. Among the passengers were almost all the United Kingdom's senior Northern Ireland intelligence experts. It was the RAF's worst peacetime disaster.

An RAF board of inquiry in 1995 ruled that the cause was pilot error; on 13 July 2011 a new report cleared both pilots.

Incident

Crash

Earlier on 2 June 1994 the helicopter and crew had carried out a trooping flight, as it was unsafe for British troops to move around in Northern Ireland using surface transport at the time. The mission was safely accomplished and they returned to Aldergrove 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 Scottish military ATC at 17:55.^[1]

Around 18:00, Chinook ZD576 flew into a hillside in dense fog. The pilots were Flight Lieutenants Jonathan Tapper, 28, and Rick Cook, 30; both of them pilots in the Special Forces. There were two other crew. The helicopter had been carrying 25 British intelligence experts from MI5, the Royal Ulster Constabulary and the British Army, from RAF Aldergrove (outside Belfast, Northern Ireland) to attend a conference at Fort George (near Inverness) in Scotland. At the time of the accident Air Chief Marshall Sir William Wratten called it "the largest peacetime tragedy the RAF had suffered".^[2]

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" an "anti-IRA campaign".^[3] The fact that the crash killed so many intelligence experts and that none of the witnesses saw the crash in the foggy conditions, encouraged speculation and conspiracy theories over a cover-up.^[4][5]

"The initial point of impact was 810 feet above mean sea level and about 500 metres east of the lighthouse, but the bulk of the aircraft remained airborne for a further 187 metres horizontally north and 90 feet 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."^[6]

Initial inquiry

In 1995, an RAF board of inquiry found 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 IRA with their known SA 7 surface-to-air missile capability had been quickly ruled out by investigators. Two air marshals, on review of the evidence, found the two pilots guilty of gross negligence by flying too fast and too low in thick fog.^[7] 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.^[8]

Subsequent inquiries

This ruling proved highly controversial. A subsequent Fatal Accident Inquiry (1996), House of Commons Defence Select Committee report (2000) and Commons 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 Defence Secretary Malcolm Rifkind.^[2][9] 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.^[10]

In December 2007, Defence Secretary Des Browne agreed to conduct a fresh report into the crash.^[11][12] It was announced on 8 December 2008 by Secretary of State for Defence John Hutton that "no new evidence" had been presented and the findings of gross negligence against the flight crew would stand.^[13] On 4 January 2010, doubts of the official explanation were raised again with the discovery that an internal MOD document, written 9 months before the incident, described the engine software as 'positively dangerous' as it could lead to failure of both engines.^[14] The 2011 Review concluded that criticism that the original board had not paid enough attention to maintenance and technical issues was unjustified.^[15]

On 10 July 2011, the BBC announced that an independent report, chaired by retired judge Lord Philip, was expected to exonerate the pilots of all blame.^[16] On 13 July 2011, 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 have now been cleared of any wrong doing.^[17]

ZD576's service history

Boeing CH-47C 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 1984.^[18]

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. On 10 May 1994, a post-flight fault inspection revealed a dislocated mounting bracket causing the collective lever to have restricted and restrictive movement. This resulted in a Serious Fault Signal 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 indicating the No.2 engine was about to fail.^[19][18]

On 31 May 1994, two days before the accident, two Chinook HC.1s were withdrawn from RAF Aldergrove and substituted for by a single HC.2, ZD576.^[20] On 2 June 1994, ZD576 crashed into a hillside, killing the four crew members and all passengers on board.

Possible causes

Pilot error

Author Andrew Brookes observed that although the true cause will never be known, pilot error induced by 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.^[21]

"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."

Baroness Symons, speaking on behalf of the Government in the House of Lords in 2000.^[22]

Although the potential for engine control problems caused by a recent upgrade has been widely debated, it is hard to see how that on its own could have made two experienced flight crew fly a helicopter full of VIPs into a known cliff face at over 150 mph. 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.^[23] The board had identified that a number of 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.^[24]

RAF Visual Flight Rules (VFR) require the crew to have a minimum visibility of 5.5 kilometres above 140 knots, or minimum visibility of one kilometre travelling below 140 knots;^[25] if VFR conditions are lost an emergency climb must be immediately flown.^[26] Nine out of ten witnesses interviewed in the inquiry reported visibility in the fog as being as low as ten to one hundred metres at the time of the crash. The tenth witness, a yachtsman who was offshore, reported it as being 1 mile, though he is regarded as a less reliable witness as he changed his testimony.^[27]

If witness accounts of visibility are correct, the pilots should have transferred to Instrument Flight Rules;^[28] which would require the pilots to slow down the aircraft and climb to a safe altitude at the best climbing speed.^[29] In the area around the Mull of Kintyre, the safe altitude would be 2,400 feet above sea level, 1,000 feet above the highest point of the terrain.^[30] The height of the crash site of ZD576 was 810 feet, 1,600 feet below the minimum safe level.^[6] 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.^[31]

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... The Reviewing Officers had failed to take account of the high calibre of two Special Forces pilots who had no reputation for recklessness."^[32]

FADEC problems

"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."

Karl Schneider, Editor of Computer Weekly, 2002^[33]

At the time of the crash, new FADEC (Full Authority Digital Engine Control) equipment was being integrated onto 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 was given a £3 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.^[34]

The committee investigating the crash were satisfied that the destructive error in 1989 was not relevant to the 1994 crash.^[27] 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."^[35] It was expected that in a FADEC engine runaway, engine power would become asynchronous and mismatched; yet the investigation found the engines at the crash to have matched settings, decreasing the likelihood of a FADEC malfunction being involved.^[36]

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".^[6]

Tests upon the Chinooks performed by the MOD at Boscombe Down in 1994 reported the FADEC software to be "unverifiable and ... therefore unsuitable for its purpose".^[6] 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.^[19] 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.^[37]

Other factors

It is possible that the helicopter was headed for RAF Machrihanish rather than towards Inverness (as claimed by the MoD), and that the navigation system failed, leading the helicopter to become lost in the poor visibility.^[38] The onboard Tactical Air Navigation System, which only retained the last measured altitude, gave an altitude reading of 468 feet.^[39] The investigation also observed that it was possible for some of the avionics systems to interfere with the Chinook's VHF radio, potentially disrupting communications.^[40]

Flight data recorders and cockpit voice recorders were not fitted to all RAF Chinooks at the time of the accident. The absence of data greatly reduced the amount and quality of data available to subsequent investigations.^[41] Information on speed and height were derived from the position of cockpit dials in the wreckage, and the wreckage's condition. The RAF had begun to fit these recording devices across the Chinook HC.2 fleet in 1994, prior to the accident; this process was completed in 2002.^[42]

References

Citations

1. ^ Brookes 1996, p. 58
2. ^ ^{a b} "'Clear Chinook two' ex-PM urges". BBC News. 13 May 2004. http://news.bbc.co.uk/1/hi/scotland/3710403.stm. 
3. ^ "Q&A: Chinook crash inquiry". BBC News. 3 June 2004. http://news.bbc.co.uk/1/hi/scotland/1800804.stm. Retrieved 3 November 2006. 
4. ^ O'Farrell, John (14 June 2000). "Dark rumours surround Chinook crash". The Guardian. http://www.guardian.co.uk/uk/2000/jun/14/northernireland.comment. "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." 
5. ^ Thomas, Andrew (10 July 2000). "Top Secret US plane ‘caused Chinook crash’". The Register. http://www.theregister.co.uk/2000/07/10/top_secret_us_plane_caused/. "a third explanation for the crash has now come to light: that a top secret hypersonic US plane, codenamed 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." 
6. ^ ^{a b c d} Select Committee on Chinook ZD 576, Part 3: Factual Background UK Parliament, 2002. Retrieved 3 November 2006.
7. ^ "Campaigners want Chinook review". BBC News. 9 October 2008. http://news.bbc.co.uk/1/hi/uk/7660363.stm. Retrieved 20 April 2010. 
8. ^ House of Commons 2011, p. 9.
9. ^ Lydall, Ross (4 January 2010). "Sir Malcolm Rifkind: Wrong to blame crash on Chinook crew". London Evening Standard. http://www.thisislondon.co.uk/standard/article-23790759-sir-malcolm-rifkind-wrong-to-blame-crash-on-chinook-crew.do. 
10. ^ Chinook ZD 576 – Report UK Parliament, 2002. Retrieved 3 November 2006.
11. ^ Press Association (6 December 2007). "Chinook crash report to be examined". The Guardian. Archived from the original on 8 January 2008. http://web.archive.org/web/20080108132312/http://www.guardian.co.uk/uklatest/story/0,,-7132503,00.html. 
12. ^ Lister, Sam (16 January 2008). "MoD to consider new Chinook claims". Belfast Telegraph. http://www.belfasttelegraph.co.uk/news/local-national/article3342423.ece. 
13. ^ "Gross negligence verdicts to stand". BBC News. 8 December 2008. http://news.bbc.co.uk/1/hi/scotland/7772125.stm. 
14. ^ "Fresh doubts over Chinook crash". BBC News. 4 January 2010. http://news.bbc.co.uk/1/hi/uk/8438659.stm. Retrieved 20 April 2010. 
15. ^ House of Commons 2011, p. 8.
16. ^ Reid, Tim (10 July 2011). "Mull of Kintyre Chinook crash report 'clears pilots'". BBC News. http://www.bbc.co.uk/news/uk-scotland-14093592. Retrieved 10 July 2011. 
17. ^ "Apology as Mull of Kintyre Chinook crash pilots cleared". BBC News. 13 July 2011. http://www.bbc.co.uk/news/uk-scotland-glasgow-west-14130867. Retrieved 13 April 2011. 
18. ^ ^{a b} "Chinook crash - timeline". The Telegraph. 6 April 2009. http://www.telegraph.co.uk/news/uknews/defence/5110232/Chinook-crash-timeline.html. 
19. ^ ^{a b} McMullon 1998,^{[page needed]}
20. ^ House of Commons 2011, p. 16.
21. ^ Brookes 1996, p. 59
22. ^ "Chinook Helicopter ZD576: Flight Plan". House of Lords. 12 July 2000. http://www.publications.parliament.uk/pa/ld199900/ldhansrd/vo000712/text/00712w02.htm. 
23. ^ Campbell 2004, p. 197.
24. ^ House of Commons 2011, p. 24.
25. ^ House of Commons 2011, p. 78.
26. ^ House of Lords 2002, p. 4.
27. ^ ^{a b} House of Lords 2002, p. 7.
28. ^ House of Lords 2002, p. 10.
29. ^ House of Commons 2011, pp. 78-79.
30. ^ House of Commons 2011, p. 76.
31. ^ House of Commons 2011, p. 72.
32. ^ House of Commons 2011, p. 69.
33. ^ "Clear and present danger: why CW refused to give up on Chinook". Computer Weekly. 7 February 2002. http://www.computerweekly.com/Articles/2002/02/07/185089/Clear-and-present-danger-why-CW-refused-to-give-up-on.htm. 
34. ^ "Defence Minister misleads MPs over Chinook accident". Computer Weekly. 29 June 2000. http://www.computerweekly.com/Articles/2000/06/29/174615/Defence-Minister-misleads-MPs-over-Chinook-accident.htm. 
35. ^ House of Lords 2002, p. 23.
36. ^ "Mull of Kintyre". House of Lords. 12 July 2000. http://www.publications.parliament.uk/pa/ld200102/ldselect/ldchin/25/25m06.htm. 
37. ^ Collins, Tony (25 October 2001). "Top Chinook test pilot reveals unease over engine software". Computer Weekly. http://www.computerweekly.com/Articles/2001/10/25/183320/Top-Chinook-test-pilot-reveals-unease-over-engine-software.htm. 
38. ^ "The last mile to justice". Sunday Herald. 19 January 2008. http://www.sundayherald.com/news/heraldnews/display.var.1979187.0.the_last_mile_to_justice.php. 
39. ^ House of Commons 2011, p. 22.
40. ^ House of Commons 2011, p. 71.
41. ^ House of Commons 2011, pp. 7-8.
42. ^ House of Commons 2011, pp. 71, 84-85.

Bibliography

• Brookes, Andrew (1996). Flights to Disaster. Ian Allan. ISBN 0711024758. 
• Campbell, Steuart (2004). Chinook Crash. Pen & Sword Aviation. ISBN 9781844150748. 
• House of Commons (13 July 2011). "The Mull of Kintyre Review". The Stationary Office. http://www.mullofkintyrereview.org.uk/sites/default/files/Mull%20of%20Kintyre%20Review%20Report.pdf. 
• House of Lords (22 July 2002). "Government's Response to the Chinook ZD 567 Report". Ministry of Defense. http://www.mod.uk/NR/rdonlyres/AE81D0D3-8025-4567-A658-47B561CC6F83/0/chinook_response.pdf. 
• McMullon, David (1999). Chinook!: The Special Forces Flight in War and Peace. Simon & Schuster. ISBN 9780671015992. 

External links

• BBC timeline of events
• Simon Rogerson's article, from IMIS Journal
• Computer Weekly publications
  • MPs Boost Chinook Fight 2000
  • Chinook report slams flawed MoD procurement methods 2000
• House of Lords select committee publications
  • Written evidence
  • Report
  • Conclusions
• chinook-justice.org (campaign website)

Coordinates: 55°18′48″N 5°47′37″W / 55.31333°N 5.79361°W / 55.31333; -5.79361