Modern-Aviation

Early service
The U.S. Army formally accepted its first production AH-64A in January 1984 and training of the first pilots began later that year. The first operational Apache unit, 7th Battalion, 17th Cavalry Brigade, began training on the AH-64A in April 1986 at Fort Hood, Texas. Two operational units with 68 AH-64s first deployed to Europe in September 1987 and took part in large military exercises there.
Upon fielding the Apache, capabilities such as using the FLIR for extensive night operations made it clear that it was capable of operating beyond the forward line of own troops (FLOT) to which previous attack helicopters were normally restricted. It was discovered that the Apache was coincidentally fitted with the Have Quick UHF radio system used by the U.S. Air Force, allowing inter-service coordination and joint operations such as the joint air attack teams (JAAT). The Apache have operated extensively with close air support (CAS) aircraft, such as the USAF's Fairchild Republic A-10 Thunderbolt II and the USMC's McDonnell Douglas AV-8B Harrier II, often acting as a target designator to conserve the Apache's own munitions. The Apache was first used in combat in 1989, during Operation Just Cause, the invasion of Panama. The AH-64 participated in over 240 hours of combat attacking various targets, mostly at night. General Carl Stiner, the commander of the operation, commented that: "You could fire that Hellfire missile through a window from four miles away at night".

Gulf War and Balkans
AH-64 during an extraction exercise at Camp Bondsteel, Kosovo in 2007 with a soldier on the avionics bay.
Nearly half of all U.S. Apaches were deployed to Saudi Arabia following Iraq's invasion of Kuwait. During Operation Desert Storm on 17 January 1991, eight AH-64As guided by four MH-53 Pave Low IIIs destroyed part of Iraq's radar network in the operation's first attack, allowing aircraft to evade detection. The Apaches each carried an asymmetric load of Hydra 70 flechette rockets, Hellfires, and one auxiliary fuel tank. During the 100-hour ground war a total of 277 AH-64s took part, destroying 278 tanks, numerous armored personnel carriers and other Iraqi vehicles. One AH-64 was lost in the war, to a rocket-propelled grenade (RPG) hit at close range, the Apache crashed but the crew survived.
While effective in combat, the AH-64 also presented serious logistical complications. Findings reported in 1990 stated "maintenance units could not keep up with the Apache's unexpectedly high work load..." To provide spare parts for combat operations, the U.S. Army unofficially grounded all other AH-64s worldwide; Apaches in the theater flew only one-fifth of the planned flight-hours. These problems were evident before the Gulf War.
The AH-64 played roles in the Balkans during separate conflicts in Bosnia and Kosovo in the 1990s. During Task Force Hawk, 24 Apaches were deployed to a land base in Albania in 1999 for combat in Kosovo. These required 26,000 tons of equipment to be transported over 550 C-17 flights, at a cost of US$480 million. During these deployments, the AH-64 encountered some problems, such as deficiencies in training, night vision equipment, fuel tanks, and survivability. On 27 April 1999, an Apache crashed during training in Albania due to a failure with the tail rotor, causing the fleet in the Balkans to be grounded in December 2000.
In 2000, Major General Dick Cody, 101st Airborne's commanding officer, wrote a strongly worded memo to the Chief of Staff about training and equipment failures. No pilots were qualified to fly with night vision goggles, preventing nighttime operations. The Washington Post printed a front-page article on the failures, commenting: "The vaunted helicopters came to symbolise everything wrong with the Army as it enters the 21st century: Its inability to move quickly, its resistance to change, its obsession with casualties, its post-Cold War identity crisis". No Apache combat missions took place in Kosovo due to fears of casualties.

Afghanistan and Iraq
AH-64D Apache flying over Baghdad, Iraq in 2007, on a reconnaissance mission
U.S. Apaches served in Operation Enduring Freedom in Afghanistan from 2001. The Apache was the only Army platform capable of providing accurate CAS duties for Operation Anaconda, regularly taking fire during the intense early fighting, they were typically repaired quickly. U.S. AH-64Ds typically flew in Afghanistan and Iraq without the Longbow Radar in the absence of armored threats. On 21 December 2009, a pair of U.S. Apaches attacked a British-held base in a friendly fire incident, killing one British soldier. In 2006, Thomas Adams noted that Apaches often fought in small teams with little autonomy to react to threats and opportunities, requiring lengthy dialogue with command structures in an effort to centrally micromanage each unit.
In 2003, the AH-64 participated in the invasion of Iraq during Operation Iraqi Freedom. On 24 March 2003, 31 Apaches were damaged, one shot down and its crew captured, in an unsuccessful attack on an Iraqi Republican Guard armored brigade near Karbala. Iraqi tank crews had set up a "flak trap" among terrain and effectively employed their guns. Iraqi officials claimed a farmer with a Brno rifle shot down the Apache, but the farmer denied involvement. The helicopter came down intact and both the pilot and co-pilot were captured.The AH-64D was destroyed via air strike the following day.
By the end of U.S. military operations in Iraq in December 2011, several Apache helicopters had been shot down by enemy fire, and others lost in accidents. In 2006, an Apache was downed by a Soviet-made Strela 2 (SA-7) in Iraq, despite the Apache being typically able to avoid such missiles.In 2007, four Apache helicopters were destroyed on the ground by insurgent mortar fire using web-published geotagged photographs taken by soldiers. Several AH-64s were lost to accidents in Afghanistan as of 2012. Most Apaches that took heavy damage were able to continue their missions and return safely.

Recent service
AH-64 Apache engaging Taliban insurgents over Afghanistan.
As of 2011, the U.S. Army Apache fleet had accumulated more than 3 million flight hours since the first prototype flew in 1975. A DOD audit released in May 2011, found that Boeing had significantly overcharged the U.S. Army on multiple occasions, ranging from 33.3 percent to 177,475 percent for routine spare parts in helicopters like the Apache.
On 21 February 2013, the 1st Battalion (Attack), 229th Aviation Regiment at Joint Base Lewis-McChord became the first U.S. Army unit to field the AH-64E Apache Guardian; a total of 24 AH-64E were received by mid-2013. On 27 November 2013, the AH-64E achieved initial operating capability (IOC). In March 2014, the 1st-229th Attack Reconnaissance Battalion deployed 24 AH-64Es to Afghanistan in the type's first combat deployment. From April through September 2014, AH-64Es in combat maintained an 88 percent readiness rate. The unit's deployment ended in November 2014, with the AH-64E accumulating 11,000 flight hours, each helicopter averaging 66 hours per month. The AH-64E flies 20 mph (32 km/h) faster than the AH-64D, cutting response time by 57 percent, and has better fuel efficiency, increasing time on station from 2.5-3 hours to 3-3.5 hours; Taliban forces, which were familiar with the AH-64D and based their tactics accordingly, were surprised by the AH-64E arriving and attacking sooner and for longer periods. AH-64Es also worked with medium and large unmanned aerial vehicles (UAVs) to find targets and maintain positive ID, conducting 60 percent of the unit's direct-fire engagements in conjunction with UAVs; Guardian pilots often controlled UAVs and accessed their video feeds to use their greater operating altitudes and endurance to see the battlespace from standoff ranges.
The Army is implementing a plan to move all Apaches from the Army Reserve and National Guard to the active Army to serve as scout helicopters to replace the OH-58 Kiowa. Using the AH-64 to scout would be less expensive than Kiowa upgrades or purchasing a new scout helicopter. AH-64Es can control UAVs like the MQ-1C Grey Eagle to perform aerial scouting missions; a 2010 study found the teaming of Apaches and UAVs was the most cost-effective alternative to a new helicopter and would meet 80 percent of reconnaissance requirements, compared to 20 percent with existing OH-58s and 50 percent with upgraded OH-58s. National Guard units, who would lose their attack helicopters, criticized the proposal. In March 2015, the first heavy attack reconnaissance unit was formed with 24 Apaches and 12 Shadow UAVs.
In July 2014, the Pentagon announced that Apaches had been dispatched to Baghdad to protect embassy personnel from Islamic State militant attacks. On 4 October 2014, Apaches began performing missions in Operation Inherent Resolve against Islamic State ground forces. In October 2014, U.S. Army AH-64s and Air Force fighters participated in four air strikes on Islamic State units northeast of Fallujah. In June 2016, Apaches were used in support of the Iraqi Army's Mosul offensive and provided support during the Battle of Mosul, sometimes flying night missions supporting Iraqi operations.

Israel
The Israeli Air Force (IAF) first received AH-64As in 1990, for a total fleet of 42. There was some controversy over the Air Force's choice to purchase Apaches over upgrading existing AH-1 Cobra attack helicopters. In 2000, Israel was interested in acquiring up to 48 AH-64Ds, but U.S. reluctance to share the software source code complicated the prospect. In April 2005, Boeing delivered the first AH-64D to the IAF. In 2001, the U.S. government was allegedly investigating misuse of the Apache and other US-supplied military equipment against Palestinian leaders and facilities. In 2009, an arranged sale of six AH-64Ds was reportedly blocked by the Obama Administration, pending interagency review, over concerns the helicopters may pose a threat to civilian Palestinians in Gaza. In IAF service, the AH-64A was named as the Peten (Hebrew: פתן‎‎, for Cobra), while the AH-64D was named Saraph (שרף, also as "Seraph", Hebrew for venomous/fiery winged serpent).

Israeli Air Force AH-64D "Saraph" during an exercise with the Hellenic Air Force in 2011
During the 1990s, Israeli AH-64As frequently attacked Hezbollah outposts in Lebanon. On 13 April 1996, during Operation Grapes of Wrath, an Apache fired two Hellfire missiles at an ambulance in Lebanon, killing six civilians. During the al-Aqsa Intifada in the 2000s, AH-64s were used to kill senior Hamas figures, such as Ahmed Yassin, Abed al-Aziz Rantissi, and Adnan al-Ghoul. On 24 May 2001, a privately owned Lebanese-registered Cessna 152 flew 15 minutes down the coast over Israeli airspace, refused to identify and respond to contact and a warning shot before it was shot down by an IAF AH-64A IAF Apaches played a prominent role in the 2006 Lebanon War, launching strikes into Lebanon targeting Hezbollah forces.
There have also been accidents involving the Apache helicopter in Israeli service. During the Lebanon War in 2006, two IAF AH-64A helicopters collided, killing one pilot and critically wounding three. In another incident in the conflict an IAF AH-64D crashed due to a malfunction in the main rotor, killing the two crew. In late 2007, the Israeli Air Force put further purchases and deliveries of AH-64Ds on hold during an investigation upon the aircraft's performance envelope. However, Israeli officials have since praised the Apache for its role in Operation Cast Lead in 2008, against Hamas in Gaza. In recent years, Israeli Apaches have been used to patrol the skies over Gaza; strike operations against insurgents using these helicopters has become a frequent occurrence.
Since recent orders of new AH-64Ds have been blocked, Israel has pursued upgrades to its AH-64A fleet. In June 2010, Israel decided not to upgrade all AH-64As to D configuration, due to funding constraints and lack of U.S. cooperation. In December 2010, the IAF was examining the adoption of a new missile system as a cheaper and lightweight complement to the Hellfire missile, either the American Hydra 70 or the Canadian CRV7. In 2013, Israeli AH-64As had been receiving a comprehensive upgrade of their avionics and electrical systems. The AH-64As are being upgraded to the AH-64Ai configuration, which is near the AH-64D standard.

United Kingdom
UK Army Air Corps Westland WAH-64D Apache Longbow displays at a UK airshow
Main article: AgustaWestland Apache
The UK currently operates a modified version of the Apache Longbow; initially called the Westland WAH-64 Apache, it is designated the Apache AH1 by the British Army. Westland built 67 WAH-64 Apaches under license from Boeing, following a competition between the Eurocopter Tiger and the Apache for the British Army's new Attack Helicopter in 1995. Important deviations made by AgustaWestland from the U.S. Apache variants include changing to more powerful Rolls-Royce engines, and the addition of a folding blade assembly for use on naval ships.
On 11 July 2016, the UK Ministry of Defence confirmed a $2.3 billion order for 50 AH-64Es to be built in Mesa, Arizona. The purchase is via a Foreign Military Sales (FMS) agreement with the US government. Leonardo Helicopters in the UK is to maintain the current fleet of Apaches until 2023-2024, with a long-term plan for Leonardo and other UK companies to "do most of the work" on the new fleet. The deal includes an initial support contract for maintenance of the new helicopters, along with spare parts and training simulators for UK pilots. The first UK helicopters are due off the US production line in early 2020 and will begin entering service with the British Army in 2022. "To further guarantee value for money, systems from the current Apache fleet, such as the Modernised Target Acquisition & Designation System, and the Longbow Fire Control Radar, will be reused and incorporated into the new helicopters where possible."Approval for the re-manufacture of fifty of the UK's WAH-64 Mk 1 fleet to AH-64E Apache Guardian standard had been given by the Defense Security Cooperation Agency in August 2015. The aircraft will utilise the General Electric T700 engine rather than the Turbomeca RTM322 from the current fleet; the first off-the-shelf purchase of a GE engine by the UK MOD.

Netherlands
Royal Netherlands Air Force AH-64D at the Farnborough Airshow, 2006
The Dutch government initially showed an interest in acquiring Apache helicopters in the late 1980s, where it stated that it may purchase as many as 52. A competition held in 1994 against the Eurocopter Tiger and the Bell AH-1 SuperCobra led to the Royal Netherlands Air Force ordering 30 AH-64D Apaches in 1995Deliveries began in 1998 and ended in 2002. The RNLAF Apaches are equipped with the Apache Modular Aircraft Survivability Equipment (AMASE) self-protection system to counter infrared (IR) missile threats.
The RNLAF Apaches' first deployment was in 2001 to Djibouti, Africa. They were also deployed alongside U.S. AH-64s in support of NATO peacekeeping forces in Bosnia and Herzegovina. In 2004, six Dutch AH-64s were deployed as part of the Netherlands contribution to Multinational force in Iraq to support the Dutch ground forces. The Apaches performed close combat support and display of force missions, along with providing reconnaissance information to ground forces. In February 2006, the Netherlands contribution to NATO forces in Afghanistan was increased from 600 to 1,400 troops and 6 AH-64s were sent in support.

A Royal Netherlands Air Force AH-64D Apache from the Apache Solo Display Team
Shortly after Apaches were deployed to Hamid Karzai International Airport, as part of the Netherlands contribution to ISAF, on 10 April 2004, a pair of Dutch Apaches came under light gunfire close to the Kabul. On 17 December 2007, an RNLAF Apache flew into power lines during a night flying exercise in the Netherlands, forcing an emergency landing and causing a lengthy blackout in the region. On 17 March 2015, a RNLAF Apache crashed during a training mission in Mali. Both pilots died. The Ministry of Defense opened an investigation into the cause of the crash.

Saudi Arabia
Following the 1991 Gulf War, during which many U.S. Apaches operated from bases within Saudi territory, Saudi Arabia purchased twelve AH-64As for the Royal Saudi Land Force. It has been speculated that the Saudi purchase had motivated Israel to also procure the Apaches. In August 2006, the Saudi Arabian government began negotiations for Apache upgrades worth up to $400M, possibly remanufacturing their AH-64As to the AH-64D Longbow configuration. In September 2008, the U.S. Government approved the purchase of 12 AH-64Ds requested by Saudi Arabia. In October 2010, Saudi Arabia requested a further 70 AH-64Ds as part of a possible, massive arms deal.
In November 2009, the Royal Saudi Land Force, as part of a military effort against insurgent intrusions of the kingdom's border, started using the Apache in Operation Scorched Earth; this also involved launching air strikes against Houthi rebels operating inside neighboring Yemen. In January 2010 the rebels claimed to have shot down an Apache; this was denied by the Saudi military. In late January 2010, the leader of the Shiite rebels announced their withdrawal from Saudi territory, this announcement followed a key battle on 12 January when Saudi forces reportedly took control of the border village of Al Jabiri.
On 17 March 2017, an Apache[not in citation given] helicopter was reportedly involved in the attack on a Somali refugee boat in which 42 refugees were killed. Saudi Arabia denied involvement though it is the only military in the Yemeni Civil War.

Egypt
In 1995, the Egyptian Air Force placed an order for 36 AH-64A helicopters. These Apaches were delivered with most of the advanced avionics used on the U.S. fleet at that time, with the exception of localized radio equipment. In 2000, Boeing announced an order to remanufacture Egypt's existing Apache fleet to the AH-64D configuration. Notably, the AH-64D upgrade did not include the procurement of the Longbow radar, the supply of which had been refused by the U.S. government. Egypt requested a further 12 AH-64D Block II Apaches through a Foreign Military Sale in 2009.
In August 2012, the Egyptian Armed Forces undertook a large-scale military operation to regain control of the Sinai Peninsula from armed militants. Air cover throughout the operation was provided by the Egyptian Air Force's Apache helicopters; reportedly the Apaches destroyed three vehicles and killed at least 20 militants. Up to five Egyptian Apaches were temporarily stationed in the Sinai following an agreement between Egypt and Israel. In September 2015, an Egyptian Apache attacked a group of foreign tourists in the Western Desert, killing 12 people and injuring 10, they were mistaken for Islamist militants, the Egyptian Interior Ministry stated that the group were in a restricted area.

Other users
Republic of Singapore Air Force AH-64D on static display, note the swept wing tip on the main rotor blades
The United Arab Emirates purchased 30 AH-64A helicopters in 1991 and 1994, which they are now upgrading to AH-64D specification. In December 2016, the U.S. State Department approved a proposed sale of another 37 AH-64E helicopters and Congress was notified; this consist of 28 re-manufactured and nine new-build helicopters.
In 2005, Kuwait purchased 16 Longbow helicopters.
Greece received 20 AH-64As by 1995; another 12 AH-64Ds were ordered in September 2003.
Singapore purchased 20 AH-64Ds aircraft in two batches between 1999 and 2001; during October 2010 Apache training was suspended following the forced crash-landing of an Apache.[Japan ordered 50 AH-64Ds, which are being built under license by Fuji Heavy Industries, designated "AH-64DJP". The first helicopter was delivered to the JGSDF in early 2006.
Taiwan (Republic of China) reached an agreement with the U.S. to purchase 30 AH-64Es with weapons, and associated equipment in June 2011. On 5 November 2013, Taiwan received the first 6 AH-64s.[On 25 April 2014, a Taiwanese AH-64E crashed into a three-story building during a training flight in bad weather conditions, the first airframe loss of an AH-64E. An investigation ruled out mechanical failure and concluded human error as responsible, that the pilots descended too fast through clouds at low altitude without checking flight panels to maintain adequate height; the Army responded by stepping up simulator training for pilots. In October 2014, the fifth and final batch of AH-64Es was delivered to Taiwan, completing the order.
In 2009, South Korea showed interest in acquiring Apaches, potentially related to U.S. plans to withdraw many of its Apaches from the country. On 21 September 2012, the U.S. Congress was notified of the possible purchase of 36 AH-64D Block III Apaches, along with associated equipment and armament. The Apache competed against the Bell AH-1Z Viper and the TAI/AgustaWestland T-129; in April 2013, South Korea announced that it would purchase 36 AH-64Es. The first four AH-64Es were delivered in May 2016, and all 36 were deployed in January 2017.

Future and possible users
India
In 2008, the Indian Air Force (IAF) released a tender for 22 attack helicopters; there were six contending submissions-Sikorsky's UH-60 Black Hawk, the AH-64D, Bell's AH-1 Super Cobra, Eurocopter's Tiger, Mil's Mi-28 and AgustaWestland's A129 Mangusta.[246] In October 2008, Boeing and Bell withdrew. In 2009, the competition was restarted. In December 2010, India requested the possible sale of 22 Apaches and associated equipment. On 5 October 2012, IAF Chief NAK Browne confirmed the Apache's selection. The IAF sought control of the 22 proposed Apaches for air combat missions, while the Army Aviation Corps argued that they would be better used in army operations. In April 2013, the Indian Ministry of Defence (MoD) decided that the IAF would receive the 22 AH-64s.
In May 2013, the Indian Army requested 11 AH-64Es; and has a requirement for 39 Apaches. The Indian Ministry of Defence approved the procurement in August 2014, as did India's Cabinet Committee on Security (CCS) in September 2015. On 28 September 2015, a contract was formally signed; the first helicopter is expected to be delivered to India in the next three to four years. India's Defence Acquisition Council approved procurement of 6 Apaches for the Indian Army in August 2017.

Others
On 26 August 2013, the U.S. and Indonesia formalized a $500 million deal for 8 AH-64E Apaches.
Iraq requested the sale of 24 AH-64s in April 2013; In January 2014, a sale, including the helicopters, associated parts, maintenance, and training, was cleared by Congress. However, the proposal was not accepted by the Iraqi government and expired in August 2014.
In July 2012, Qatar requested the sale of 24 AH-64D Apache Block III helicopters, with associated equipment, training, and support. The sale was approved on 27 March 2014.
In July 2016, the UK placed an order for 50 AH-64Es through the US Foreign Military Sales (FMS) programme instead of upgrading their Westland-built WAH-64s.

Variants
AH-64A
IAF AH-64A Peten
The AH-64A is the original production attack helicopter. The crew sit in tandem in an armored compartment. It is powered by two GE T700 turboshaft engines. The A-model was equipped with the −701 engine version until 1990 when the engines were switched to the more powerful −701C version.
U.S. Army AH-64As are being converted to AH-64Ds. The service's last AH-64A was taken out of service in July 2012 before conversion at Boeing's facility in Mesa, Arizona. On 25 September 2012, Boeing received a $136.8M contract to remanufacture the last 16 AH-64As into the AH-64D Block II version and this was forecast to be completed by December 2013.

AH-64B
In 1991, after Operation Desert Storm, the AH-64B was a proposed upgrade to 254 AH-64As. The upgrade would have included new rotor blades, a Global Positioning System (GPS), improved navigation systems and new radios. Congress approved $82M to begin the Apache B upgrade. The B program was canceled in 1992. The radio, navigation, and GPS modifications, were later installed on most A-model Apaches through other upgrades.

AH-64C
Additional funding from Congress in late 1991 resulted in a program to upgrade AH-64As to an AH-64B+ version. More funding changed the plan to upgrade to AH-64C. The C upgrade would include all changes to be included in the Longbow except for mast-mounted radar and newer −700C engine versions. However, the C designation was dropped after 1993. With AH-64As receiving the newer engine from 1990, the only difference between the C model and the radar-equipped D model was the radar, which could be moved from one aircraft to another; thus the decision was made to simply designate both versions "AH-64D".

AH-64D
Israeli AH-64D
The AH-64D Apache Longbow is equipped with a glass cockpit and advanced sensors, the most noticeable of which being the AN/APG-78 Longbow millimeter-wave fire-control radar (FCR) target acquisition system and the Radar Frequency Interferometer (RFI), housed in a dome located above the main rotor. The radome's raised position enables target detection while the helicopter is behind obstacles (e.g. terrain, trees or buildings). The AN/APG-78 is capable of simultaneously tracking up to 128 targets and engaging up to 16 at once, an attack can be initiated within 30 seconds. A radio modem integrated with the sensor suite allows data to be shared with ground units and other Apaches; allowing them to fire on targets detected by a single helicopter.
The aircraft is powered by a pair of uprated T700-GE-701C engines. The forward fuselage was expanded to accommodate new systems to improve survivability, navigation, and 'tactical internet' communications capabilities. In February 2003, the first Block II Apache was delivered to the U.S. Army, featuring digital communications upgrades. The Japanese Apache AH-64DJP variant is based on the AH-64D; it can be equipped with the AIM-92 Stinger air-to-air missiles for self-defense.

AH-64E
AH-64E Apache Guardian
Formerly known as AH-64D Block III, in 2012, it was redesignated as AH-64E Guardian to represent its increased capabilities.The AH-64E features improved digital connectivity, the Joint Tactical Information Distribution System, more powerful T700-GE-701D engines with upgraded face gear transmission to accommodate more power, capability to control unmanned aerial vehicle (UAVs), full IFR capability, and improved landing gear. New composite rotor blades, which successfully completed testing in 2004, increase cruise speed, climb rate, and payload capacity. Deliveries began in November 2011. Full-rate production was approved on 24 October 2012, with 634 AH-64Ds to be upgraded to AH-64E standard and production of 56 new-build AH-64Es to start in 2019/20. Changes in production lots 4 through 6 shall include a cognitive decision aiding system and new self-diagnostic abilities. The updated Longbow radar has an oversea capacity, potentially enabling naval strikes; an AESA radar is under consideration. The E model is to be fit for maritime operations. The Army has expressed a desire to add extended-range fuel tanks to the AH-64E to further increase range and endurance. AH-64Es are to have the L-3 Communications MUM-TX datalink installed in place of two previous counterparts, communicating on C, D, L, and Ku frequency bands to transmit and receive data and video with all Army UAVs. Lots 5 and 6 will be equipped with Link 16 data-links.

AH-64F
In 2014, Boeing conceptualized an Apache upgrade prior to the introduction of the U.S. Army's anticipated attack version of the Future Vertical Lift aircraft, forecast to replace the Apache by 2040. The conceptual AH-64F would have greater speed via a new 3,000 shp turboshaft engine from the improved turbine engine program, retractable landing gear, stub wings to offload lift from the main rotor during cruise, and a tail rotor that can articulate 90 degrees to provide forward thrust. In October 2016, the Army revealed they would not pursue another Apache upgrade to focus on funding the FVL; the Army will continue buying the Apache through the 2020s until Boeing's production line ends in 2026, then FVL is slated to come online in 2030.

Sea Apache
A U.S. Army AH-64A Apache aboard USS Nassau during Joint Shipboard Weapons and Ordnance training
During the 1980s naval versions of the AH-64A for the United States Marine Corps and Navy were examined. Multiple concepts were studied with altered landing gear arrangements, improved avionics and weapons. The USMC was very interested and conducted a two-week evaluation of the Apache in September 1981, including shipboard operation tests.
Funding for a naval version was not provided; the Marine Corps continued to use the AH-1. The Canadian Forces Maritime Command also examined a naval Apache. In 2004, British Army AgustaWestland Apaches were deployed upon the Royal Navy's HMS Ocean, a Landing Platform Helicopter, for suitability testing; there was U.S. interest in the trials.
During the 2011 military intervention in Libya, the British Army extensively used Apaches from HMS Ocean. In 2013, U.S. 36th Combat Aviation Brigade AH-64Ds were tested on a variety of U.S. Navy ships.

Export Apaches
Several models have been derived from both AH-64A and AH-64D for export. The British-built AgustaWestland Apache (assembled from kits purchased from Boeing) is based on the AH-64D Block I with several different systems, including more powerful engines, folding rotor blades, and other modifications for operation from Royal Navy vessels.
Block modification
While a major change in design or role will cause the type designator suffix to change, for example from AH-64D to AH-64E, the helicopters are also subject to block modification. Block modification is the combining of equipment changes into blocks of modification work orders, the modifications in the block (sometimes called a block package) are all done to the helicopter at the same time.