A Cessna 500 Citation I corporate jet was destroyed when it crashed near Santiago de Compostela Airport (SCQ), Spain. Both pilots were killed in the accident. They had flown a transplant organ to Porto that night and were returning to Santiago de Compostela, leaving Oviedo Airport at 05:45. Ten minutes later, the crew contacted approach control and was then authorized to make the ILS approach to runway 17 at Santiago de Compostela. The visibility at the airport was suitable for landing. At 06:15 hours the crew contacted Tower Control and was cleared to land. Two minutes later the aircraft impacted wooded terrain, 200 meters before the VOR of Santiago, about 1 mile before the threshold of runway 17. Causes The ultimate cause of the accident could not be determined. In light of the hypothesis considered in the analysis, the most likely scenario is that the crew made a non-standard precision approach in manual based primarily on distances. The ILS frequency set incorrectly in the first officer’s equipment and the faulty position indicated on the DME switch would have resulted in the distance being shown on the captain’s HSI as corresponding to the VOR and not to the runway threshold. The crew shortened the approach maneuver and proceeded to a point by which the aircraft should already have been established on the localizer, thus increasing the crew’s workload. The crew then probably lost visual contact with the ground when the aircraft entered a fog bank in the valleys near the airport and did not realize they were making an approach to the VOR and not to the runway. The contributing factors were: – The lack of operational procedures of an aircraft authorized to be operated by a single pilot operated by a crew with two members. – The overall condition of the aircraft and the instruments and the crew’s mistrust of the onboard instruments. – The fatigue built up over the course of working at a time when they should have been sleeping after an unplanned duty period. – The concern with having to divert to the alternate without sufficient fuel combined with the complacency arising from finally reaching their destination.