Operation Igloo White - Pinball Wizards

Pinball Wizards

The sensor transmitters would relay their data to the second element of the system, an orbiting EC-121R aircraft of the Air Force's 553rd Reconnaissance Wing, based at Korat Royal Thai Air Force Base. The EC-121s would then relay the collected information to Nakhon Phanom. At Task Force Alpha, the last of the three components in the system, the intelligence data (from a variety of sources, not just the sensors) would be entered, collated, retrieved, and stored by two IBM 360/40 (later two 360/65) computers. Technicians at the center controlled the system from a variety of video displays that were also linked to the computers.

Analysts at the 200,000-square-foot (19,000 m2) center concentrated on such arcane topics as pathway predictions, delay intervals, route segments, and choke points. The computers analyzed sensor data and compiled intelligence information and then made predictions as to where and when a particular PAVN truck convoy would be geographically located. According to author John Prados, the system functioned "exactly like a pinball machine... in truth, the mavens of the electronic battlefield became pinball wizards".

The effectiveness of the system was determined not by how long a sensor would last in the field, but by the adequacy of coverage by a particular string of sensors. For instance, a well placed string with several failed sensors was more effective than a fully functional string placed in the wrong location. The electronic data was, however, only as good as the human analysts and operators at the ISC. The knack of timely sensor activation depended on careful study of device locations and the patterns of PAVN logistical behavior.

The sensors were delivered to the target areas by U.S. Navy OP-2 Neptunes of VO-67 or by U.S. Air Force helicopters, both based at Nakhon Phanom. Due to increasing PAVN anti-aircraft artillery defences encountered in southeastern Laos, delivery in high-risk areas of the trail system was handed over from the Neptunes to Air Force F-4 Phantom II fighter-bombers that had been specially equipped for the missions.

U.S. strike aircraft were directed to predicted target areas by a variety of means. The first was for the ISC to relay target information to an airborne battlefield command and control center (ABCCC), which then routed bombers to a forward air control aircraft (FAC). The FAC then led the strike to the target. During inclement weather or complete darkness, aircraft could still attack the trail by utilizing either MSQ-77 Combat Skyspot (a radar-directed system) or LORAN (a radio-directed navigational system).

As the program (and PAVN air defences) evolved, so did the relay aircraft. The EC-121Rs and their crews proved too vulnerable and were partly replaced in 1969 and 1970 by QU-22Bs (modified Beech A-36 Bonanzas) which were to be remotely piloted, and which had undergone primary mission equipment and PME flight tests at Eglin Air Force Base, Florida, in 1968. The aircraft suffered from mechanical difficulties, however, and were never flown during an operational mission without a pilot. They were replaced by C-130B models in December 1971.