Changes from the AH-64D include Rolls-Royce Turbomeca RTM322 engines, a new electronic defensive aids suite and a folding blade mechanism allowing the British version to operate from ships.

[3] Both the Tiger, Commanche and upgraded Cobra variant required more development, and thus risk, while the Apache was combat proven, though its performance in the First Gulf War was criticised by competitors.

Now we have taken the decision to buy the Apache, the Army must ensure that doctrine is developed to allow us to make the fullest possible use of its tremendous capability."

[12] When the requirement for the Apache had been formalised in the early 1990s, military doctrine assumed that a large conventional armoured assault from the Eastern Bloc was Britain's main threat.

[15] Prior to the Apache entering service in 2004, several development problems were noted, including a lack of the ability to securely communicate with other helicopters and a risk of damage to the tail rotor and airframe from firing its Hellfire missiles.

[8] These problems were corrected prior to entering service, a secure communications suite was installed and Hellfire missiles are routinely fired by Apaches.

[21] Various options were considered for maintaining the capability: In August 2015, the UK requested the upgrade of 50 of its Apaches to AH-64E standard through a US Foreign Military Sale.

[18] Compared to many helicopters used by coalition forces in Afghanistan, the Apache required less modification to serve in the region due to special filters incorporated into the engine design.

There were changes made to the sensor and avionics outfitting the craft as well; connectivity with the BOWMAN secure communications system to interact with other British military units being a significant one.

[38] There used to be a third type of warhead: the Multi-Purpose Sub Munition (MPSM), which was a controversial weapon as it has been classified as a cluster bomb;[39] each rocket contained nine M73 submunitions.

[46] A modem was interfaced into the Longbow radar and other sensor systems to relay information to other aircraft, this allowed other Apaches to fire on targets identified by only a single helicopter.

It had been suggested that advanced rotor blades and additional controls to improve the agility of the aircraft may have been fitted in a mid-life update of the fleet.

Unlike US versions, the Westland Apache had been partially navalised and for a time served aboard Royal Navy ships in addition to its land-based role.

[65] Unlike their American counterparts in Afghanistan, the Apache AH1 is deployed with its Longbow Fire Control Radar to enable the pilot to better manage traffic in their airspace.

[67] On 22 May 2006, a UK Apache operating in Afghanistan's Helmand province used a Hellfire missile to destroy an abandoned French vehicle to protect sensitive equipment.

On 13 January 2007, a 200-strong British force, led by Royal Marines, launched an operation to attack Jugroom Fort, a major Taliban base in southern Helmand Province.

[73] In May and June 2008, British and Afghan National Army forces conducted Operation Eagle's Eye, aimed at disrupting Taliban activities to the south of Musa Qaleh; a key portion of which was a major night-time helicopter raid, rapidly deploying members of 2nd Battalion, Parachute Regiment into the town.

[74] In June 2008, a British Apache fired a thermobaric Hellfire missile; the controversial usage of such weapons was approved after extensive legal and ethical evaluations within the MoD.

[75] In June 2008, a Taliban leader and several cell members were killed in Helmand Province by a Hellfire missile launched by an Apache of the 664 Army Air Corps.

[77] In September 2008, an Apache was seriously damaged by a crash shortly after takeoff in Helmand province; no loss of life occurred but the airframe was written off.

[79] During the summer of 2009, British Apaches were an integral component of Operation Panther's Claw, which was aimed at pushing insurgents out of civilian areas in the runup to the 2009 Afghan Elections.

[80] During the Summer 2009 operations, a senior Taliban leader, Mullah Mansur, and several accomplices were killed in a precision strike launched by an Apache.

[81] On 25 July 2011, the MoD announced that during a combat operation in the Nahr-e-Saraj district of Helmand province, several Afghan children had been injured from crossfire by an Apache; they were flown to Camp Bastion for medical treatment.

[85] In May 2011, the MoD announced that the Apache fleet had reached 100,000 hours flying time, and describing it as a "vital battlefield tool in Afghanistan".

[90] On 14 June 2011, reports of British preparation to evacuate Yemen emerged, involving Apache and Merlin helicopters operating from Royal Fleet Auxiliary vessels off the coast.

[91] On 4 June 2011, Apaches struck targets within Libya for the first time, destroying a radar site and an armed checkpoint near the town of Brega.

[92] Further precision strikes were launched by Apaches, typical targets were mobile air defenses, and were occasionally engaged by AK-47 fire from ground troops.