During the Korean War, AD Skyraiders were flown by only the U.S. Navy and U.S. Marine Corps and were normally painted in dark navy blue. It was called the "Blue Plane" by enemy troops. Marine Corps Skyraiders suffered heavy losses when used in low-level close-support missions. To allow low-level operations to continue without unacceptable losses, a package of additional armour was fitted, consisting of 0.25–0.5 inches (6.4–12.7 mm) thick external aluminium armour plates fitted to the underside and sides of the aircraft's fuselage. The armour package weighed a total of 618 pounds (280 kg) and had little effect on performance or handling. A total of 128 Navy and Marine AD Skyraiders were lost in the Korean War – 101 in combat and 27 to operational causes. Most operational losses were due to the tremendous power of the AD: ADs that were "waved-off" during carrier recovery operations were prone to performing a fatal torque roll into the sea or the deck of the aircraft carrier if the pilot mistakenly gave the AD too much throttle. The torque of the engine was so great that it would cause the aircraft to rotate about the propeller and slam into the sea or the carrier.