About flight 138:

The aircraft departed Surabaya at 12:03 UTC for a hadj flight to Jeddah with a planned intermediate stop at Colombo. Around 16:30 UTC Colombo Control cleared the flight down from FL350 to FL150. At 16:38, when the flight was 50 nm from Colombo the air traffic controller cleared the flight further down to 5000 feet and to report reaching 8000 feet. At 16:44 Colombo Approach Control then cleared the flight down to 2000 feet and told them to expect a runway 04 approach. The crew were then to report overhead the KAT NDB or when the airfield was in sight. The crew continued their descent until the airplane crashed into the Anjimalai Mountain at an altitude of 4355 feet, about 40 nm East of Colombo.

PROBABLE CAUSE: "Collision with rising terrain as the crew descended the aircraft below safe altitude owing to incorrect identification of their position vis-a-vis the airport. The investigation is of the opinion that this was the result of dependence on Doppler and Weather Radar Systems on board PH-MBH which left room for misinterpretation."

ASN report were here:https://asn.flightsafety.org/wikibase/329765