Due to incorrect automatic direction finder ( ADF ) readings caused Causation by the thunderstorm , the plane strayed Motion 15 km ( 9.3 mi ) west from the procedural let-down track .

The investigation Criminal_investigation could not determine Deciding the exact reason for the accident Catastrophe , but suspected Suspicion the insufficient meteorological information given Giving to the crew , failure of the ground equipment , and the atmospheric effects on the ADF indicator .