Northwest flight 4422 was a non-scheduled charter flight en route from Shanghai-Lunghwa Airport to La Guardia Field. An intermediate stop was made at Anchorage. Take-off from Anchorage was accomplished at 20:12 and the DC-4 climbed to the cruising altitude of 11,000 feet. The last position report was at 21:03 when the flight reported being over the Gulkana radio range station. At that point the airway deflects to the north, its course being 23 degrees, to provide a safe lateral distance from Mt. Sanford which has an elevation of 16,208 feet. The DC-4 continued off the airway and flew into Mount Sanford. The wreckage slid down for about 3000 feet before coming to rest. The wreckage was spotted the day after the accident, but it took until July 24, 1999 before someone was able to reach the crash site.

PROBABLE CAUSE: "The Board determines that the probable cause of this accident was the pilot's failure to see Mt. Sanford, which was probably obscured by clouds or the aurora borealis or both while flying a course off the airway."