Flight and Weather
The C-141 departed Athens for a night-time flight to Madrid, the first leg of a return flight to McGuire Air Force Base. The crew was cleared for an instrument landing system (ILS) approach to Torrejón's runway 23. Weather conditions were reported as a 20,000-foot overcast ceiling with 10 nautical miles visibility.
Crew Actions and Descent
During the descent, the crew did not use the Descent Checklist, resulting in a failure to set the altimeters from the standard setting of 29.92 inches of mercury to the local altimeter setting of 30.17 inches. The radar altimeter was also not turned on. While at flight level 60, the crew received a clearance to a lower altitude, but due to heavy radio traffic, the clearance was garbled. Unsure whether the controller cleared them to 5,000 or 3,000 feet, they agreed it must have been 3,000 feet and read back "three thousand feet," but the controller did not notice the error. When reporting "passing 5000 for 3000" to another controller, the mistake again went unnoticed.
Approaching 3,000 feet, the navigator observed a hill ahead and above their altitude. The pilot reassured him that "everything looks clear ahead," noting the lights of the air base visible in the valley below.
Impact and Aftermath
At an altitude of 3,050 feet and a speed of 250 knots, the airplane impacted terrain near the edge of a plateau, approximately 40 kilometers east of Torrejón Air Force Base. It became airborne again, rolled over, and disintegrated in a field. The navigator survived, while 24 other occupants were killed. The crew included Captain Clinton Clifford Corbin, pilot; Captain Thomas R. Dietz, pilot; First Lieutenant William A. Kuhn, copilot; Technical Sergeant Edward Peter Babcock, flight engineer; Technical Sergeant Donald R. Wells, flight engineer; Major Friedrich Hugo Lamers, navigator; First Lieutenant William Haskel Ray, navigator; and Technical Sergeant Sidney Nathaniel Hillsman, load master. Passengers included Corporal Edward Anthony Fanelli, Lieutenant Colonel Austin Frederick Balkman, Teresa Ann Wilcox, and others.
Probable Cause
The official investigation found no technical anomalies in the airplane and its components, equipment, and instruments. The flying crew failed to follow approach procedures and descended to an unsafe altitude following a misinterpretation of the ATC clearance. Contributing factors included a lack of crew coordination, a wrong planned approach, and crew fatigue (eight hours of rest during the last 60 hours).