The Euroair night time mail flight was cleared for a runway 24 departure from Inverness Airport (INV), Scotland, followed by a left turn onto track and continue direct to Edinburgh at FL95. The aircraft took off at 20:55 returned over the field to follow the 175deg. radial of the Inverness VOR and continued below the cloud base. The aircraft soon impacted a hill and broke up. A post-impact fire erupted and the pilot was killed. The accident happened near Saddle Hill, at an elevation of 1600 feet. Minimum altitude at that point is 4800 feet. CONCLUSION: “Although various hypotheses could be formulated to fit these flight profiles, there is no evidence which would enable a determination as to the cause of the accident to be made with any degree of certainty.”