The upgrade programme involves bringing the entire US Army fleet of AH-64As up to AH-64D standard, which will include the fitting of more powerful General Electric T700 GE701C turboshafts (1890shp), modern digital avionics, weapons and mast-mounted Longbow Fire Control Radar (FCR) giving a tenfold improvement in the Apache's combat effectiveness.

The Longbow millimetre-wave mast-mounted radar (FCR) and fire-and-forget RF seeker Hellfire missiles can track and lock-on to targets through fog, rain and smoke conditions in which normal FLIR and TV are ineffective. Under the Apache modernisation programme 227 of the US Army's 811 Apaches will be remanufactured to the AH-64D Longbow configuration and be fitted with the mast-mounted Fire Control Radar (FCR). The remaining fleet will be upgraded to a new AH-64D base-line configuration but without the FCR mission kit.

New digitised avionics, integrated cockpit, advanced navigation and communications, data-links and reliability improvements will provide the US Army with an all-weather battlefield helicopter capable of operating independently, or as part of a combined arms team undertaking multi-missions from engaging high value targets, to air combat, deep strike, joint air attack, aerial security, armed reconnaissance and fire support missions.

The digitisation of the AH-64D will allow the helicopter to operate and be integrated within the US Army's new digitised concept for operating in the 21st Century. They will be a key element in their new digital battlefield team and will be able to receive and transmit digitised targeting and tactical control information between aircraft and other compatible sources on the battlefield. The first of six Longbow Apache prototypes first flew in April 1992 with operational and test evaluations starting in January 1995. Partnered with GKN Westland Helicopters Ltd, McDonnell Douglas Helicopters are offering the Longbow Apache for the UK's new Army Attack helicopter.

P.Allen "The Helicopter", 1996

Current improvement programme of the AH-64 "Apache" based on Westinghouse mast-mounted Longbow millimetre-wave radar and Lockheed Martin Hellfire with RF seeker; includes more powerful GE T700-GE-701C engines, larger generators for 70 kVA peak loads, Plessey AN/ASN-157 Doppler navigation, MIL-STD-1553B databus allied to dual 1750A processors, and a vapour cycle cooling system for avionics; early user tests completed April 1990.

Full-scale development programme, lasting 4 years 3 months, authorised by Defense Acquisition Board August 1990, but airframe work extended in December 1990 to 5 years 10 months to coincide with missile development; supporting modifications being incorporated progressively; first flight of AH-64A (82-23356) with dummy Longbow radome 11 March 1991; first (89-0192) of six AH-64D prototypes flown 15 April 1992; second (89-0228) flew 13 November 1992; fitted with radar in mid-1993 and flown 20 August 1993; No 3 (85-25410) flown 30 June 1993; No 4 (90-0423) on 4 October 1993; No 5 (formerly AH-64C No 1) 19 January 1994 (first Apache with new Hamilton Standard lightweight flight management computer); No 6 flown 4 March 1994; last two mentioned converted from 85-25408 and 85-25477 and lack radar. First preproduction AH-64D flown 29 September 1995. Six AH-64Ds to fly 3,300 hour test programme; first remanufactured production aircraft flown 17 March 1997 and delivered to US Army 31 March 1997. IOC scheduled for June 1998. Initial AH-64D battalion (1-227 AvRgt) to be based at Fort Hood, Texas; second (3-101 AvRgt) at Fort Campbell, Kentucky.

Five year US$1.9 billion agreement for remanufacture signed 16 August 1996. The contract covers 232 AH-64Ds over a five year period, with the entire US Army fleet of 758 AH-64As to be upgraded in remanufacture programme lasting 10 years, although only the initial 232 to carry Longbow radar. Production rate to rise from one per month in 1997 to five per month in 1999. Contract also includes 227 Longbow radars (since increased to 500), 13,311 Hellfire missiles and 3,296 launchers.

Agreement reached with US Army for a US$2.3 billion contract to remanufacture a further 269 AH-64As to the AH-64D Apache Longbow configuration from FY2001, to bring total to 501 and programme to 2006. First flight of Apache with initial enhancements incorporating COTS technologies for reduced costs, and first of second 269 unit batch, made on 13 July 2001.

First flight of AH-64D with four new colour flat-panel MultiPurpose Displays (MPDs) 12 September 1997. Starting with the 27th production aircraft all Apache Longbows, including those ordered by the United Kingdom and the Netherlands, will be equipped with the Honeywell (AlliedSignal) Guidance and Control Systems MPDs.

Capability exists to convert any AH-64D to Apache Longbow configuration in 4 to 8 hours; this potential was demonstrated in June 1994 when army personnel removed Longbow radar, associated equipment and T700-GE-701C engines from AH-64D prototype and installed them on second (non-radar) aircraft, which was then test flown for 30 minutes. AH-64D to equip 26 battalions; company strength to be three with radar plus five without; three companies per battalion. Longbow can track flying targets and see through rain, fog and smoke that defeat FLIR and TV; RF Hellfire can operate at shorter ranges; it can lock on before launch or launch on co-ordinates and lock on in flight; Longbow scans through 360° for aerial targets or scans over 270° in 90° sectors for ground targets; mast-mounted rotating antenna weighs 113kg. Production of RF Hellfire by Longbow LLC, a joint venture between Lockheed Martin and Northrop Grumman. Initial limited-rate production contract awarded in December 1995 for 352 missiles, of which first delivered to US Army Missile Command in November 1996.

Further 1,056 missiles and 203 launchers subject of US$233.7 million LRIP contract awarded in 1996. Further modifications include 'manprint' cockpit with large colour flat-panel MultiPurpose Displays (MPDs) replacing standard monochrome MultiFunction Displays (MFDs), air-to-air missiles, digital autostabiliser, integrated GPS/Doppler/INS/air data/laser/radar altimeter navigation system, digital communications, faster target hand-off system, and enhanced fault detection with data transfer and recording. AH-64D No 1 made first Hellfire launch on 21 May 1993; first RF Hellfire launch 4 June 1994; first demonstration of digital air-to-ground data communications with Symetrics Industries improved data modem, 8 December 1993.

Training of US Army instructors began summer 1994, in anticipation of Force Development Test and Experimentation (FDT&E) trial, using three prototypes, starting October 1994; followed by Initial Operational Test and Evaluation (IOT&E) January to March 1995. Successful completion of FDT&E and IOT&E precursor to start of modification programme in 1996; long-lead contract awarded to McDonnell Douglas December 1994 covering start-up funds for initial batch of remanufactured Apaches.

Test successes of 1994 include June trial in which Apache Longbow tracked moving ground target with radar and scored direct hit with RF Hellfire; communication of digital data with Joint-STARS and UH-60 Black Hawk via improved data modem in September; demonstration of new tri-service embedded GPS/INS in October; and RF Hellfire ripple-launch capability in November, when single Apache scored hits on three targets at close, medium and long range with three missiles; time of engagement, from detection to target impacts, less than 30 seconds.

Initial Operational Test and Evaluation exercises at Fort Hunter, California, in 1995 pitted six AH-64Ds against eight AH-64As. Test results indicated 400 per cent more lethality (hitting more targets) and 720 per cent higher survivability than the AH-64A; demonstrated ability to use Target Acquisition Designation Sight (TADS) or fire-control radar as targeting sight; detected, classified, displayed, prioritised more than 1,000 targets and initiated precision attack in less than 30 seconds; met or exceeded Army's situational awareness requirements (classified); available 91 per cent of time. Hit moving and stationary targets on smoky battlefield from 7.25 km (4.5 miles) away during test at China Lake, California.

AH-64D deliveries to US Army began 31 March 1997.

Initial AH-64D battalion (1-227 AvRgt) at Fort Hood, Texas fully equipped by end July 1998 and attained combat ready status on 19 November 1998, after eight month training programme at company and battalion level which included four live fire exercises and more than 2,500 flight hours. Second unit is 2-101 AvRgt at Fort Campbell, Kentucky; third will be 1-2 AvRgt in South Korea.

First flight with Rolls-Royce Turbomeca RTM 322 turboshaft engines 29 May 1998.

Jane's Helicopter Markets and Systems

- The AH-64D first entered service with the 1-227 Aviation Battalion, US Army at Fort Hood, Texas, in July 1998.

- Development of the AH-64D was initiated following experience in the Gulf War.

- Future operations will see the AH-64D operate alongside F-15E Eagles.

- Longbow is actually the name of the sophisticated radar system installed on the Apache.

- The six Longbow test Apaches have amassed over 5,000 flying hours.

- The first overseas deployment of US Longbows is likely to be in South Korea.