Overview
On a government flight from Rome, Italy to Belgrade, Yugoslavia, a Yemeni aircraft carrying the Under Secretary of Foreign Affairs of Yemen crashed on the western slopes of Monte Porretta. All four crew members and four passengers were killed, and the aircraft was destroyed.
Flight History
The flight departed Ciampino Airport at 1645Z under an IFR flight plan, routing via Viterbo, Pescara, and Split to Belgrade. At 1729Z, Ciampino Tower, noting an impossible estimate for the aircraft's ETA over Viterbo, notified the flight that it was on a bearing of 315°, indicating a position west of Viterbo. At 1736Z, YE-AAB reported being over the Viterbo NDB and gave an ETA for Pescara of 1817Z. At 1738Z, the tower cleared the aircraft to climb from 8,500 to 13,000 feet and requested a transfer from VHF to HF for further en route navigation messages. The flight acknowledged, marking the last effective radio contact.
Accident Sequence
At approximately 1800Z, the aircraft crashed on the western slopes of Monte Porretta at an elevation of 2,690 feet. The impact killed all eight occupants and destroyed the aircraft.
Investigation and Probable Cause
The official investigation determined that the accident was due to faulty conduct of the flight. Contributing factors included: inadequately trained crew; faulty use of the radio compass; failure to request assistance of D/F facilities; erroneous estimates; the pilot-in-command and crew had inadequate knowledge of Italian and English phraseology for radio communications; erroneous assessment of adverse weather conditions, particularly at destination, given the lack of adequate facilities; errors in flight plan compilation, including a 12-minute error in the Rome-Viterbo segment; inaccurate indication of available frequencies (specifically, the Rome ACC control frequency of 120.1 Kc was not available); and inadequacy of route charts, as no chart of Europe was on board and the flight guide found in the wreckage was out of date.