On April 15, 1999, a South Korean cargo plane crashed due to a confusion over units. After takeoff, the first officer was instructed by the Shanghai tower to climb to 1500 m and maintain that altitude. The captain, after reaching 1450 m, twice asked the first officer at what altitude they should fly. Each time, the first officer replied incorrectly that they were to fly at 1500 ft. The captain started a steep descent; the plane could not recover from the dive and crashed. How far above the correct altitude were they when they started the rapid descent?