Incident Details
A cargo flight originating from Singapore-Changi Airport was en route to Kayell for an NDB approach to runway 33. The aircraft carried a load of textiles, computer software, and mail, along with four crew members. While on a direct routing, the crew received an ATC clearance to 'descend two four zero zero' (2,400 feet), which they mistakenly interpreted as 'to 400'. Consequently, they continued descending below the minimum descent altitude of 2,400 feet. The aircraft subsequently struck trees and crashed on a wooded slope near the village of Puchong, approximately 14 kilometers from the airport. The impact totally destroyed the aircraft and claimed the lives of all four crew members.
Investigation Findings
The official investigation reported several contributing factors. The Ground Proximity Warning System (GPWS) alarm activated in the cockpit, but the crew failed to respond appropriately. Additionally, the crew did not adhere to published approach procedures and the approach checklist. Poor crew coordination was noted, and the lack of visibility further compromised situational awareness. Non-standard phraseology used by ATC led the crew to misinterpret the descent clearance.