The Central Intelligence Agency and Overhead Reconnaissance; the U-2 and Oxcart Programs, 1954-1974

Secret NOFORN
Chapter 4

hours on the ground. Originally scheduled for Thursday, 28 April, GRAND SLAM was canceled because of bad weather over the northern Soviet Union. This had been the case for the past several weeks. When this flight was canceled, the U-2 returned to Adana before sunrise. That evening the U-2 flew back to Peshawar for another attempt to stage the mission early on the 29th, but bad weather again forced cancellation of the mission, and the U-2 returned to Adana. Because of continued bad weather over the target areas, no mission was planned for Saturday, 30 April. $ ^{26} $

Meanwhile, the plane ferried to Peshawar on 27 and 28 April had accumulated so many hours of flight time that it had to be removed from service for periodic maintenance. A different aircraft was, therefore, ferried to Peshawar on Saturday night, 30 April. This aircraft, article 360, had made a crash landing in Japan during the previous September (see chapter 5). Although it had been refurbished by Lockheed and now had the more powerful J75 engine that would give it greater altitude, pilots did not completely trust this aircraft and considered it a "hangar queen." As Powers noted in his memoirs, "Its current idiosyncrasy was one of the fuel tanks, which wouldn't feed all its fuel." $ ^{27} $ The aircraft was equipped with a B-model camera, a System-VI electronic intelligence unit, and a System-IXB device, which generated false-angle information in response to the radar pulses used by some Soviet airborne-missile fire-control systems.

Operation GRAND SLAM, mission 4154 and the 24th deep-penetration overflight of the Soviet Union, began almost 30 minutes late on Sunday, 1 May 1960, a delay due to difficulty in getting takeoff approval from Washington. This delay was caused by communications problems that are typical at sunrise and sunset during spring and autumn, when the ionosphere will not support reliable communications. In attempting to relay the authorization message, the radio operator in Adana was unable to reach the base in Peshawar, whose codename was HBJARGON. Realizing that neither the prearranged nighttime nor daytime frequencies were working, the operator began sending a message in the clear, using one of the guard frequencies in the transition area between the daytime and nighttime frequencies. The radio operators at Peshawar kept hearing the Morse