 Later, in October 1989, at the request of the Federal Emergency Management Agency, the wing flew U-2 photo missions over the San Francisco and Oakland areas after the strong Loma Prieta earthquake.A unique chapter of the 9th's history ended on 1 January 1990 when the SR-71 retired.High maintainability and operating costs and the availability of similar intelligence from other sources convinced Air Force officials the aircraft was no longer vital to the national defense.