USAF 965th Aircraft Early Warning and Control Squadron (552nd AEW&C Wing), pilot First Lieutenant Robert J. Springer, Jr, Tech. Sergeant. Herman L. Giles, and 16 other air crewmen, while on routine Airborne Operations Center radar early warning patrol over the Pacific aboard RC-121D aircraft (s/n 53-3400) were about 175 miles southwest of San Francisco. They detected a target on IFF Mode two transponder only. At 7:56 the IFF target became a direct radar "skin paint," at 8:02 the IFF equipment APX-6/APX-7 was turned off but target was still tracked on airborne radar. At 8:15 target was at two o'clock position ten miles range when aircraft started a right turn to reverse course putting target at dead ahead and target "suddenly" took off to the northwest at "very high" speed, disappearing at 58 miles range (within one to two minutes? at 1,800-3,600 mph?). Regained radar contact at 8:18 at one o'clock position 22 miles range moving right to left, crossed in front of aircraft again, closing distance to 8 miles at 11 o'clock position at 8:20 when target turned to head on parallel path. Lost contact at 8:24 at 7 o'clock position behind the plane at 15 miles, IFF remaining off, no visuals.

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