Disappearance of C-123K Transport Aircraft 293

Flight Details and Mission Profile The C-123K transport aircraft, identified as 293, departed Udon Thani RTAFB (UTH) in Thailand on a mission referred to as a Peppergrinder flight. The objective was to load and dispatch mixed ordnance for use in Laos, with the destination being Ban Xieng Lom Airstrip (LS-69). The aircraft was carrying 12,892 pounds of mixed ordnance, which included 75 mm shells, 81 mm rounds, 222 caliber small arms ammunition, and white phosphorus smoke rounds. ## Navigation and Environmental Factors Based on computed crosswinds at 8,500 feet, the reported altitude of aircraft 293, investigators determined it was likely that the aircraft was positioned to the right of its desired track en route out of Udon Thani and traveling at a higher than normal ground speed. Although the pilot was reportedly well familiar with the route, the investigation suggested the pilot was likely flying an inadequate cross-wind correction heading while entering and exiting cloud bases. This navigation error could have placed the aircraft to the right of L-23 and, subsequently, well to the right and beyond LS-62, particularly because no navigational aids were available in the area. ## Tactical Situation and Probable Cause A valley similar to that of LS-62 is located just to the northeast of LS-62 and close to Route 46. Had the captain been positioned to the northeast of the reported position at LS-62 and initiated a descending left turn towards LS-69, the enemy reaction over Route 46 would have been immediate and violent. Large anti-aircraft guns were situated only 15 miles north of LS-62. The official investigation listed the cause of the disappearance of aircraft 293 as undetermined. However, the findings indicated that the aircraft probably strayed from course and, over exceedingly hostile country, was hit by enemy fire and rapidly destroyed.