 On 29 March 1999, the second prototype fell out of the sky over the US Navy China Lake military training area in California and was destroyed.The third prototype was badly damaged during a landing on 6 December 1999 when a software bug told the aircraft to taxi at 290 km/h (180 mph), leading to the grounding of the survivors for three months.The Global Hawk was scheduled to reach operational service in late 2001, and this timeframe coincided with the US intervention in Afghanistan.