gunnery to deter the Japanese bombers was also influenced by unique circumstances. The HACS was originally designed with Atlantic conditions in mind and Prince of Waless AA FC radars had become unserviceable in the extreme heat and humidity in Malayan waters and her 2-pdr ammunition had deteriorated badly as well. The RN made the following claims for ship borne anti-aircraft fire against enemy aircraft, from September 1939 up to 28 March 1941: :Certain kills: 234, Probable kills: 116, Damage claims: 134 The RN made the following claims for ship borne anti-aircraft fire against enemy aircraft, from September 1939 up to 31 Dec 1942: Major warships (ships likely to have HACS or FKC fire control systems) Certain kills: 524 Probable kills: 183 Damage claims: 271 Minor warships and merchant vessels (most having no AA fire control systems) Certain kills: 216 Probable kills: 83 Damage claims: 177 Total kill claims: 740 Total probable claims: 266 Total damage claims: 448 Radar and the Mark VI Director HACS used various director towers that were generally equipped with Type 285 as it became available. This metric wavelength system employed six yagi antennas that could take ranges of targets, and take accurate readings of bearing using a technique known as "lobe switching" but only crude estimates of altitude. It could not, therefore, "lock on" to aerial targets and was unable to provide true blindfire capabilities, which no other navy was able to do until the USN developed advanced radars in 1944 using technology transfers from the UK. This situation was not remedied until the introduction of the HACS Mark VI director in 1944 that was fitted with centimetric Type 275 radar. Another improvement was the addition of Remote Power Control (RPC), in which the anti-aircraft guns automatically trained with the director tower, with the necessary changes in bearing and elevation to allow for convergent fire. Previously the gun crews had to follow mechanical pointers that indicated where the director tower wanted the guns to train. HACS systems in use or planned in August 1940 HACS Directors fitted to ships in a document dated as "revised Aug 1940": HACS III: ABC transmission, AV cradle for 15 ft HF/RF. Introduced Mk III table. HMS Ajax, Galatea, Arethusa, Coventry, HMAS Hobart, Sydney, Perth HACS III*: Similar to MarkIII but with larger windscreen and space for a rate officer. HMS Penelope, Southampton, Newcastle, Malaya, Hood*, Australia*, Nelson*, Royal Sovereign*, Barham*,