The Boeing CH-47 Chinook is an American twin-engine, tandem rotor heavy-lift helicopter. With a top speed of 170 knots (196 mph, 315 km/h) it is faster than contemporary utility and attack helicopters of the 1960s. The CH-47 is one of the few aircraft of that era that is still in production and front line service, with over 1,179 built to date. Its primary roles include troop movement, artillery emplacement and battlefield resupply. It has a wide loading ramp at the rear of the fuselage and three external-cargo hooks.