HMS Active (F171)

	HMS Active
History
United Kingdom
Name	HMS Active
Builder	Vosper Thornycroft
Laid down	23 July 1971
Launched	23 November 1972
Commissioned	19 July 1977
Decommissioned	23 September 1994
Identification	Pennant number: F171
Motto	Festina lente; (Latin: "Hasten slowly");
Fate	Transferred to Pakistan Navy
Pakistan
Name	PNS Shah Jahan
Acquired	23 September 1994
Fate	Sunk as Target on 12 January 2021
General characteristics
Class & type	Type 21 frigate
Displacement	3,250 tons full load
Length	384 ft (117 m)
Beam	41 ft 9 in (12.73 m)
Draught	19 ft 6 in (5.94 m)
Propulsion	COGOG:; 2 × Rolls-Royce Olympus gas turbines; 2 × Rolls-Royce Tyne RM1A gas turbines for cruising;
Speed	32 knots (59 km/h; 37 mph)
Range	4,000 nautical miles at 17 knots (7,400 km at 31 km/h); 1,200 nautical miles at 30 knots (2,220 km at 56 km/h);
Complement	177
Armament	RN:; 1 × 4.5 inch (114 mm) Mark 8 naval gun; 4 × Oerlikon 20 mm cannon; 4 × MM38 Exocet missiles; 1 × quadruple Sea Cat SAMs; 2 × triple ASW torpedo tubes; 2 × Corvus chaff launchers; 1 × Type 182 towed decoy; Pakistan:; 1 × 4.5 inch (114 mm) Mark 8 naval gun; 2 × Oerlikon 20 mm cannon; 1 × Phalanx CIWS; 2 × 4-cell Harpoon SSM launchers; 2 × triple STWS-1 torpedo launchers (for Mk 46 torpedoes); 2 × Mark 36 SRBOC chaff launchers; 1 × Type 182 towed decoy;
Aircraft carried	1 × Westland Wasp helicopter, later refitted for 1 × Lynx

HMS Active was a Type 21-class frigate of the Royal Navy, built by Vosper Thornycroft at Southampton, England. She was the first of the class completed with Exocet missile launchers installed in the 'B' position, located forward of the ship’s superstructure. This upgrade significantly enhanced her anti-ship capabilities compared to earlier Type 21s, which were originally designed without missile launchers.

The class was conceived during the 1960s as a fast, lightly armed frigate, built to commercial standards to reduce costs and improve speed. Vosper Thornycroft was responsible for constructing all Type 21 frigates, with the shipyard at Southampton chosen for its expertise in producing smaller warships, enabling rapid construction and delivery.

Early in her career, Active undertook a range of peacetime duties including fleet exercises, patrols, and showing the flag missions. Her wartime service during the Falklands conflict later confirmed her value in frontline operations.