Chinook Helicopter Crash (1994)
Encyclopedia
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.
Around 18:00, Chinook ZD576 flew into a hillside in dense fog. The pilots were Flight Lieutenant
s 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".
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". 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.
with their known SA 7
surface-to-air missile
capability had been quickly ruled out by investigators. Two air marshal
s, on review of the evidence, found the two pilots guilty of gross negligence
by flying too fast and too low in thick fog. 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.
(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
. 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.
In December 2007, Defence Secretary Des Browne
agreed to conduct a fresh report into the crash. 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. 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. The 2011 Review concluded that criticism that the original board had not paid enough attention to maintenance and technical issues was unjustified.
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. 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.
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.
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.
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. On 2 June 1994, ZD576 crashed into a hillside, killing the four crew members and all passengers on board.
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.
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. 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.
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; if VFR conditions are lost an emergency climb must be immediately flown. 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.
If witness accounts of visibility are correct, the pilots should have transferred to Instrument Flight Rules; which would require the pilots to slow down the aircraft and climb to a safe altitude at the best climbing speed. 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. The height of the crash site of ZD576 was 810 feet, 1,600 feet below the minimum safe level. 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.
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."
(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.
The committee investigating the crash were satisfied that the destructive error in 1989 was not relevant to the 1994 crash. 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." 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.
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".
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". 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. 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.
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. The onboard Tactical Air Navigation System, which only retained the last measured altitude, gave an altitude reading of 468 feet. 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.
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 data greatly reduced the amount and quality of data available to subsequent investigations. 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.
Royal Air Force
The Royal Air Force is the aerial warfare service branch of the British Armed Forces. Formed on 1 April 1918, it is the oldest independent air force in the world...
(RAF) Chinook helicopter
Helicopter
A helicopter is a type of rotorcraft in which lift and thrust are supplied by one or more engine-driven rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forwards, backwards, and laterally...
(serial number
United Kingdom military aircraft serials
In the United Kingdom to identify individual aircraft, all military aircraft are allocated and display a unique serial number. A unified serial number system, maintained by the Air Ministry , and its successor the Ministry of Defence , is used for aircraft operated by the Royal Air Force , Fleet...
ZD576, callsign
Call sign
In broadcasting and radio communications, a call sign is a unique designation for a transmitting station. In North America they are used as names for broadcasting stations...
F4J40) crashed on the Mull of Kintyre
Mull of Kintyre
The Mull of Kintyre is the southwesternmost tip of the Kintyre Peninsula in southwest Scotland. From here, the Antrim coast is visible and an historic lighthouse, the second commissioned in Scotland, guides shipping in the intervening North Channel...
, Scotland, killing all twenty-five passengers and four crew on board. Among the passengers were almost all the United Kingdom's senior Northern Ireland
Northern Ireland
Northern Ireland is one of the four countries of the United Kingdom. Situated in the north-east of the island of Ireland, it shares a border with the Republic of Ireland to the south and west...
intelligence
Intelligence (information gathering)
Intelligence assessment is the development of forecasts of behaviour or recommended courses of action to the leadership of an organization, based on a wide range of available information sources both overt and covert. Assessments are developed in response to requirements declared by the leadership...
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.
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.Around 18:00, Chinook ZD576 flew into a hillside in dense fog. The pilots were Flight Lieutenant
Flight Lieutenant
Flight lieutenant is a junior commissioned rank in the Royal Air Force and the air forces of many Commonwealth countries. It ranks above flying officer and immediately below squadron leader. The name of the rank is the complete phrase; it is never shortened to "lieutenant"...
s 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
MI5
The Security Service, commonly known as MI5 , is the United Kingdom's internal counter-intelligence and security agency and is part of its core intelligence machinery alongside the Secret Intelligence Service focused on foreign threats, Government Communications Headquarters and the Defence...
, the Royal Ulster Constabulary
Royal Ulster Constabulary
The Royal Ulster Constabulary was the name of the police force in Northern Ireland from 1922 to 2000. Following the awarding of the George Cross in 2000, it was subsequently known as the Royal Ulster Constabulary GC. It was founded on 1 June 1922 out of the Royal Irish Constabulary...
and the British Army
British Army
The British Army is the land warfare branch of Her Majesty's Armed Forces in the United Kingdom. It came into being with the unification of the Kingdom of England and Scotland into the Kingdom of Great Britain in 1707. The new British Army incorporated Regiments that had already existed in England...
, from RAF Aldergrove
RAF Aldergrove
RAF Aldergrove was a Royal Air Force station situated northwest of Belfast. It adjoined Belfast International Airport, sometimes referred to simply as Aldergrove which is the name of the surrounding area...
(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".
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
John Major
Sir John Major, is a British Conservative politician, who served as Prime Minister of the United Kingdom and Leader of the Conservative Party from 1990–1997...
government, "temporarily confounding" an "anti-IRA
Provisional Irish Republican Army
The Provisional Irish Republican Army is an Irish republican paramilitary organisation whose aim was to remove Northern Ireland from the United Kingdom and bring about a socialist republic within a united Ireland by force of arms and political persuasion...
campaign". 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.
"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."
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 IRAProvisional Irish Republican Army
The Provisional Irish Republican Army is an Irish republican paramilitary organisation whose aim was to remove Northern Ireland from the United Kingdom and bring about a socialist republic within a united Ireland by force of arms and political persuasion...
with their known SA 7
Strela 2
The 9K32 “Strela-2” is a man-portable, shoulder-fired, low-altitude surface-to-air missile system with a high explosive warhead and passive infrared homing guidance...
surface-to-air missile
Surface-to-air missile
A surface-to-air missile or ground-to-air missile is a missile designed to be launched from the ground to destroy aircraft or other missiles...
capability had been quickly ruled out by investigators. Two air marshal
Air Marshal
Air marshal is a three-star air-officer rank which originated in and continues to be used by the Royal Air Force...
s, on review of the evidence, found the two pilots guilty of gross negligence
Gross negligence
Gross negligence is a legal concept which means serious carelessness. Negligence is the opposite of diligence, or being careful. The standard of ordinary negligence is what conduct one expects from the proverbial "reasonable person"...
by flying too fast and too low in thick fog. 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.
Subsequent inquiries
This ruling proved highly controversial. A subsequent Fatal Accident InquiryFatal accident inquiry
A fatal accident inquiry is a Scottish judicial process which investigates and determines the circumstances of some deaths occurring in Scotland...
(1996), House of Commons Defence Select Committee
Defence Select Committee
The Defence Select Committee is one of the Select Committees of the British House of Commons, having been established in 1979. It oversees the operations of the Ministry of Defence and its associated public bodies, including the armed forces.-Membership:...
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
John Major
Sir John Major, is a British Conservative politician, who served as Prime Minister of the United Kingdom and Leader of the Conservative Party from 1990–1997...
and former Defence Secretary
Secretary of State for Defence
The Secretary of State for Defence, popularly known as the Defence Secretary, is the senior Government of the United Kingdom minister in charge of the Ministry of Defence, chairing the Defence Council. It is a Cabinet position...
Malcolm Rifkind
Malcolm Rifkind
Sir Malcolm Leslie Rifkind KCMG QC MP is a British Conservative Party politician and Member of Parliament for Kensington. He served in various roles as a cabinet minister under Prime Ministers Margaret Thatcher and John Major, including Secretary of State for Scotland , Defence Secretary and...
. The new inquiry took place in the House of Lords
House of Lords
The House of Lords is the upper house of the Parliament of the United Kingdom. Like the House of Commons, it meets in the Palace of Westminster....
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.
In December 2007, Defence Secretary Des Browne
Des Browne
Desmond Henry Browne, Baron Browne of Ladyton is a British Labour Party politician who was the Member of Parliament for Kilmarnock and Loudoun from 1997 to 2010...
agreed to conduct a fresh report into the crash. It was announced on 8 December 2008 by Secretary of State for Defence John Hutton
John Hutton (Labour MP)
John Matthew Patrick Hutton, Baron Hutton of Furness is a British Labour Party politician who was the Member of Parliament for Barrow and Furness in Cumbria from 1992 to 2010, and has served in a number of Cabinet offices, including Defence Secretary and Business Secretary...
that "no new evidence" had been presented and the findings of gross negligence against the flight crew would stand. 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. The 2011 Review concluded that criticism that the original board had not paid enough attention to maintenance and technical issues was unjustified.
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. 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.
ZD576's service history
BoeingBoeing Helicopters
Boeing Rotorcraft Systems is a US aircraft manufacturer, now part of Boeing Defense, Space & Security...
CH-47C Chinook
CH-47 Chinook
The Boeing CH-47 Chinook is an American twin-engine, tandem rotor heavy-lift helicopter. Its top speed of 170 knots is faster than contemporary utility and attack helicopters of the 1960s...
, construction number B-868, RAF serial number ZD576 was originally delivered to the Royal Air Force
Royal Air Force
The Royal Air Force is the aerial warfare service branch of the British Armed Forces. Formed on 1 April 1918, it is the oldest independent air force in the world...
as a Chinook HC.1 on 22 December 1984.
It was re-delivered to No 7 Squadron as a Chinook HC.2 on 21 April 1994. On arrival at RAF Odiham
RAF Odiham
RAF Odiham is a Royal Air Force station situated a little to the south of the historic small village of Odiham in Hampshire, England. It is the home of the Royal Air Force's heavy lift helicopter, the Chinook HC2, HC2A and HC3...
, 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.
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. On 2 June 1994, ZD576 crashed into a hillside, killing the four crew members and all passengers on board.
Pilot error
Author Andrew BrookesAndrew Brookes
Andrew Brookes is an English aerospace analyst, author of aviation books and aviation journalist.He is a former Royal Air Force pilot, and flew 3,500 hours on strategic reconnaissance Victors and Canberras, and also the Vulcan bomber...
observed that although the true cause will never be known, pilot error induced by fatigue
Fatigue (physical)
Fatigue is a state of awareness describing a range of afflictions, usually associated with physical and/or mental weakness, though varying from a general state of lethargy to a specific work-induced burning sensation within one's muscles...
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.
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
Steuart Campbell
Steuart Campbell is an Edinburgh-based sceptic and investigative science writer born in Birmingham. Campbell trained as an architect and worked as one until the mid-1970s. He then gained a degree in mathematics and science from the Open University .He has written books on science and...
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. 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.
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; if VFR conditions are lost an emergency climb must be immediately flown. 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.
If witness accounts of visibility are correct, the pilots should have transferred to Instrument Flight Rules; which would require the pilots to slow down the aircraft and climb to a safe altitude at the best climbing speed. 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. The height of the crash site of ZD576 was 810 feet, 1,600 feet below the minimum safe level. 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.
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."
FADEC problems
At the time of the crash, new FADECFADEC
Full Authority Digital Engine Control is a system consisting of a digital computer, called an electronic engine controller or engine control unit , and its related accessories that control all aspects of aircraft engine performance...
(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
Ministry of Defence (United Kingdom)
The Ministry of Defence is the United Kingdom government department responsible for implementation of government defence policy and is the headquarters of the British Armed Forces....
was given a £3 million settlement from Textron
Textron
Textron is a conglomerate that includes Bell Helicopter, E-Z-GO, Cessna Aircraft Company, and Greenlee, among others. It was founded by Royal Little in 1923 as the Special Yarns Company, and is headquartered at the Textron Tower in Providence, Rhode Island, United States.With total revenues of...
, 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.
The committee investigating the crash were satisfied that the destructive error in 1989 was not relevant to the 1994 crash. 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." 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.
EDS
EDS
- Education :* Educational specialist , a terminal academic degree in the U.S.* Episcopal Divinity School, an Episcopal Seminary in Cambridge, Massachusetts* Evansville Day School, an independent college-prep school in Evansville, Indiana- Politics :...
-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".
Tests upon the Chinooks performed by the MOD at Boscombe Down
MoD Boscombe Down
MoD Boscombe Down is an aircraft testing site located at Idmiston, south of Amesbury, in Wiltshire, England. It is run and managed by QinetiQ, the company created as part of the breakup of the Defence Evaluation and Research Agency in 2001 by the UK Ministry of Defence...
in 1994 reported the FADEC software to be "unverifiable and ... therefore unsuitable for its purpose". 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
FADEC
Full Authority Digital Engine Control is a system consisting of a digital computer, called an electronic engine controller or engine control unit , and its related accessories that control all aspects of aircraft engine performance...
software had undergone revision. In October 2001, Computer Weekly reported that three fellows of the Royal Aeronautical Society
Royal Aeronautical Society
The Royal Aeronautical Society, also known as the RAeS, is a multidisciplinary professional institution dedicated to the global aerospace community.-Function:...
had said that issues with either control or FADEC systems could have led to the crash.
Other factors
It is possible that the helicopter was headed for RAF MachrihanishRAF Machrihanish
RAF Machrihanish is a former Royal Air Force station located west of Campbeltown at the tip of Kintyre. It is now known as MoD Machrihanish and also incorporates Campbeltown Airport which has commercial flights to Glasgow, operated by Loganair....
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. The onboard Tactical Air Navigation System, which only retained the last measured altitude, gave an altitude reading of 468 feet. 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.
Flight data recorder
Flight data recorder
A flight data recorder is an electronic device employed to record any instructions sent to any electronic systems on an aircraft. It is a device used to record specific aircraft performance parameters...
s and cockpit voice recorder
Cockpit voice recorder
A cockpit voice recorder , often referred to as a "black box", is a flight recorder used to record the audio environment in the flight deck of an aircraft for the purpose of investigation of accidents and incidents...
s 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. 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.
External links
- BBC timeline of events
- Simon Rogerson's article, from IMIS Journal
- Computer Weekly publications
- House of Lords select committee publications
- chinook-justice.org (campaign website)