FY 2018. The former head of the USAF Air Combat Command, Gen. Mike Hostage helped extend the U-2S to ensure commanders receive sufficient intelligence, surveillance and reconnaissance (ISR) coverage; stating "it will take eight years before the RQ-4 Global Hawk fleet can support 90% of the coverage of the U-2 fleet." In 2015, the RQ-4 was planned to replace the U-2 by 2019, though Lockheed states the U-2 can remain viable until 2050. As of January 2018, the U.S. Air Force budget for 2018 had indefinitely postponed the retirement of the U-2. In February 2020, the U.S. Air Force submitted budget documents with confusing language suggesting that it could begin retiring U-2s in 2025 but clarified afterwards that no retirement is planned. On 20 September 2016, a TU-2S trainer crashed upon takeoff from Beale Air Force Base, killing one pilot and injuring the other. In early August 2018, NASA flew two missions using infrared sensors to map the Mendocino Complex Fire. The flights used the Moderate Resolution Imaging Spectroradiometer (MODIS) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite instruments. In 2020, the U-2 made history as the first military aircraft to integrate Artificial Intelligence on a mission. The AI program, code-named ARTUµ, was developed by the U-2 Federal Laboratory. In the 2023 Chinese balloon incident, the U.S. Air Force used U-2 aircraft to monitor a Chinese balloon that crossed the United States and Canada. U-2 flights confirmed the balloon’s surveillance package was outfitted with multiple antennas capable of conducting signals intelligence collection operations and that the craft had large solar panels to power them."US Used U-2 to Gather Intelligence on Chinese Spy Balloon". Air & Space Forces Magazine, 9 February 2023. United Kingdom Bissell suggested bringing the British into the program to increase the number of overflights. Prime Minister Harold Macmillan agreed with the plan, and four RAF officers were sent to Laughlin Air Force Base in Texas for training in May 1958. On 8 July, the senior British pilot, Squadron Leader Christopher H. Walker, was killed when his U-2 malfunctioned and crashed near Wayside, Texas. This was the first death involving the U-2, and the circumstances were not disclosed for over 50 years. Another pilot was quickly selected and sent to replace Walker. After training, the group of RAF U-2 pilots arrived in Turkey in November 1958, shortly after the CIA's Detachment B from Adana provided valuable