The CH-47D Chinook is a heavy-lift helicopter ideal for battlefield transportation manufactured by Boeing Helicopters. The CH-47D Chinook carries out transportation of troops, artillery, supplies and equipment to the battlefield. Other roles include medical evacuation, aircraft recovery, parachute drop, search and rescue, disaster relief, fire-fighting and heavy construction. The CH-47D is equipped with a two 3-bladed contra-rotating rotors and no tail rotor. The rotor blades are fabricated from composite materials and are resistant to AAA (anti-aircraft artillery) fire up to 23mm. The basic crew compliment for the CH-47D is three; pilot, co-pilot, and crew chief. Over 1,000 Chinooks are operational worldwide. Boeing has delivered more than 480 CH-47D Chinooks to the US Army and National Guard. Boeing has also exported the helicopter to military and commercial operators in Argentina, Australia, Canada, Japan, Norway, Spain, the UK and three Far East countries. Like most US Army helicopters, the Chinook has advanced avionics and electronics, including the Global Positioning System. The CH-47D saw wide use in Operation Enduring Freedom in Afghanistan and Operation Iraqi Freedom in Iraq. The Chinook was used in air assault missions, inserting troops into fire bases and later bringing food, water, and ammunition. It is typically escorted by attack helicopters such as the Apache for protection. The CH-47D was particularly useful in the mountainous terrain of Afghanistan where high altitudes and temperatures limited the use of the Black Hawk. The CH-47D is currently in service as the Army's primary heavy lift and transportation helicopter.