This (partial) listing of U-2 missions conducted in 1971 by the 35th Sq. clearly shows that there was a three-month hiatus between Mission C-261C and C-301C. I don’t have any declassified stand-down order document that helps explain this long break. But I don’t need one either: On July 15, 1971, United States Prisident Richard Nixon announced that he would visit China the following year. The three-month stand-down was obviously a good-will gesture to China. Foreign Relations, 1969-1976, Vol. XVII, China, 1969-1972 has the following footnote on p. 323:
Although Detachment H resumed coastal reconnaissance mission on October, it was not the same anymore. The “high authority” ordered that all mission routes remain at least 25 NM offshore and at least 12 NM from any Chinese-held island on August 5:
But mission planners actually re-routed the missions 28 NM offshore to make room for navigation errors:
The result is that some mission were actually flown 30 to 45 NM offshore!
(To be continued)