It was testified that at the time of takeoff, the aircraft was still airworthy and its gross weight and centre of gravity were within allowable limits.

He had flown the same route for nine years, some being on DC-3 and DHC-3 Otter aircraft, so he was familiar with the prevailing weather conditions and flight path.

The PAL radio operator at Davao had reported a visibility of 1–2 miles, 500–1,000 feet in overcast and wind speeds of 5–8 knots.

The probable flight path was reconstructed, and it was believed that the aircraft may had drifted inland due to eastern winds at about 10 knots.

The Board believed that the pilot was too confident of his position and flight experience that he did not take into account the crosswinds that drifted the aircraft off course.

Therefore, the probable cause was determined to be a navigational error, en-route and during descent, with contributing factors being the limited visibility and crosswind in the final stages of the flight.