At the time of the crash, the Otter had flown 7,197 hours, and was properly maintained in accordance with its maintenance manual.

The flight landed in Siocon at 07:30, where the pilot was informed of unfavourable weather conditions en route and at his destination.

Heavy rain and squalls were around the western Mindanao coast which made conditions unfavourable for VFR flights.

[7] At approximately 08:10, the flight took off returning to Zamboanga due to the worsening weather conditions, with 10 passengers on board.

It was determined that the pilot continued to fly under VFR in unfavourable weather over the jagged shorelines with practically zero visibility due to heavy rain.

Shortly after the crash, the Civil Aviation Administration suspended the operation of Philippine Air Lines' Otters until they were fitted with automatic direction finders and more powerful high-frequency radios, and that they should exercise more supervision over pilots based at Zamboanga.

After the crash, the Otters were not returned to service, and the two surviving aircraft of the airline's fleet was used on charter flights before being sold.