On 11 February 1990, an active service unit of the Provisional IRA East Tyrone Brigade shot down a British Army Gazelle helicopter (serial number ZB687) along the border between Northern Ireland and the Republic of Ireland. It took place between Augher in County Tyrone and Derrygorry in County Monaghan. The helicopter was hit several times by heavy machine-gun fire and crash-landed on an open field, injuring three members of its crew of four. Background Since early December 1989, the British Army had been on alert in and around County Tyrone after a credible threat was made by a suspected member of the IRA about an imminent attack. On 13 December, a major assault took place when an IRA team, riding on an improvised armoured truck, raided a permanent vehicle checkpoint manned by members of the King's Own Scottish Borderers (KOSB) regiment near Derryard, County Fermanagh, a few yards from the border with the Republic. Two soldiers were killed in an attack that involved the use of machine guns, rocket-propelled grenades and a flamethrower. While British officials focused on members of the IRA from County Monaghan, in the Republic, supported by others from Clogher, County Tyrone, author Ed Moloney asserts that the culprit was a flying column made up of IRA volunteers from different brigades, commanded by the East Tyrone Brigade's Michael "Pete" Ryan, who himself was shot dead in 1991 in the Coagh ambush. The execution of hit-and-run raids by the IRA was "professional" and "calculating", according to British military sources. Shootdown incident On 11 February 1990, a patrol of the King's Own Scottish Borderers was sent to investigate a suspicious column of vehicles close to the border with the support of an unarmed Gazelle helicopter from the 656 Squadron, Army Air Corps. The motorcade was actually a diversionary manoeuvre set up by the East Tyrone Brigade to lure the troops into an ambush. As usual during the KOSB tour in Northern Ireland, the soldiers would be backed up by a helicopter. The main mission of the helicopters was to airlift patrols to different locations during a single day. Another key role was to scan the terrain for potential enemy ambushes and to block the IRA getaway by landing reinforcements on their escape route. It was never determined whether the Provisionals had previously planned the shooting of the Gazelle or the helicopter became a target of opportunity. At 16:30, a