Type 21 frigate

The Royal Navy frigate HMS Arrow underway (circa 1982)
Class overview
Name	Type 21 Amazon
Builders	Yarrow Shipbuilders, Vosper Thornycroft
Operators	Royal Navy (historical) Pakistan Navy
Preceded by	Type 12I Leander
Succeeded by	Type 22 Broadsword
Subclasses	Niteroi class Alvand class Tariq class
Built	6 November 1969-20 November 1975
In commission	11 May 1974
Completed	8
Active	0
Lost	2
Retired	6
Preserved	1 (planned)
General characteristics
Type	Frigate
Displacement	As built: 2,750 tons (standard) 3,250 tons (full load) After strengthening: 2,860 tons (standard) 3,360 tons (full load)
Length	360 ft (110 m) (waterline) 384 ft (117 m) (overall)
Beam	41.8 ft (12.7 m)
Draught	19 ft (5.8 m)
Propulsion	COGOG on 2 shafts; 2 × Tyne cruise turbines: 8,500 shp (6,300 kW) 2 × Olympus boost turbines: 50,000 shp (37,000 kW)
Speed	32 knots (59 km/h; 37 mph) 37 knots burst speed (Olympus) 18 knots (33 km/h; 21 mph) (Tyne)
Range	4,000 nmi (7,400 km; 4,600 mi) at 17 knots (31 km/h; 20 mph) 3,500 nmi (6,500 km; 4,000 mi) at 18 knots (33 km/h; 21 mph) 1,200 nmi (2,200 km; 1,400 mi) at 30 knots (56 km/h; 35 mph)
Complement	13 officers, 164 ratings
Sensors & processing systems	1 × Radar Type 992Q low-level search 1 × Radar Type 978 navigation 2 × Radar Type 912 fire-control Sonar Type 184M and 162M
Armament	1 × 4.5 in (114 mm) Vickers Mark 8 gun 2 × 20 mm Oerlikon guns (later 4) 1 × 4-rail launcher for GWS-24 Sea Cat 2 × 8-barrelled Knebworth Corvus countermeasures launchers Later additions: 4 × launchers for MM38 Exocet surface-surface missiles 2 × 12.75 in (324 mm) 3-tube STWS-1 anti-submarine torpedo launchers Pakistani modifications: TKWA/MASS (Multi Ammunition Softkill System) 2 x 4-cell Harpoon missile launchers (3 ships) or 1 x 6-cell LY-60N Hunting Eagle SAM launcher (3 ships) 1 × Vulcan Phalanx 20mm CIWS
Aircraft carried	1 × Wasp or Lynx
Aviation facilities	Flight deck and hangar

The Type 21 frigate, or Amazon-class frigate, was a British Royal Navy general-purpose escort that was designed in the late 1960s, built in the 1970s, and that served into the 1990s.