On 2 June 1994, a Chinook helicopter of the Royal Air Force (RAF), 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 experts. The accident is the RAF's fourth-worst peacetime disaster.

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 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

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.Brookes 1996, p. 58

Around 18:00, Chinook ZD576 flew into a hillside in dense fog. The pilots were Flight Lieutenants 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 (near Inverness) in Scotland. At the time of the accident, Air Chief Marshal Sir William Wratten called it "the largest peacetime tragedy the RAF had suffered".

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. That the crash killed so many British intelligence experts, without any witnesses in the foggy conditions, led to considerable speculation and 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, while another postulated that it was a deliberate assassination of the intelligence operatives on board in order to facilitate negotiations with republican factions during the then on-going Northern Ireland peace process.

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.

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. 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.House of Commons 2011, p. 9.

Subsequent inquiries

The first inquiry and its conclusion proved to be 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. 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."Chinook ZD 576 – Report." UK Parliament, 2002; retrieved 3 November 2006.

In December 2007, Defence Secretary Des Browne agreed to conduct a fresh report into the crash. On 8 December 2008, Secretary of State for Defence John Hutton announced that "no new evidence" had been presented and the verdicts 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 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.Lewis, Page. "Please shut up about the Mull of Kintyre Chinook crash." The Register, 4 January 2010. The 2011 Review concluded that criticism that the original board had not paid enough attention to maintenance and technical issues was unjustified.House of Commons 2011, p. 8.

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. 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. Families campaign In 2025, families of the victims continued to campaign for a full release of documents relating to the crash, which the Ministry of Defence has sealed for 100 years, and for a fresh inquiry to examine this evidence. In July 2026, the families urged incoming Prime Minister Andy Burnham to order an independent review into the disaster with full access to all relevant information relating to the airworthiness of the helicopter and the circumstances leading up to the crash.

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 1983.

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. 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 collective lever to have restricted and restrictive movement; this resulted in a "Serious Fault Signal""THE DEFENCE LOGISTICS SUPPORT CHAIN MANUAL JSP 886 VOLUME 3 SUPPLY CHAIN MANAGEMENT PART 315 FAULT REPORTING – SUPPLY PROCEDURES." gov.uk, 1 July 2008. 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.McMullon 1998,

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.House of Commons 2011, p. 16.

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 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.Brookes 1996, p. 59

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.Campbell 2004, p. 197. 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.House of Commons 2011, p. 24.

RAF Visual Flight Rules (VFR) require the crew to have a minimum visibility of 5.5 kilometres above , or minimum visibility of one kilometre travelling below 140 knots;House of Commons 2011, p. 78. if VFR conditions are lost an emergency climb must be immediately flown.House of Lords 2002, p. 4. 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 , though he is regarded as a less reliable witness as he changed his testimony.