The propeller blades entered a fine-pitch configuration which caused a loss in lift and extremely high drag resulting in a loss of aircraft control.
The investigation revealed that the most likely cause of the propeller entering this mode, which is only used for taxiing, was a failure of the throttle cable system.
The purpose of an accident investigation report is to determine, as far as possible, the precise cause of the accident and to recommend measures to prevent a re-
occurrence.
In this case, having identified the most likely cause of the accident, the report contains nine safety recommendations. Six of these recommendations are for improvements to operational and maintenance procedures by the aircraft operator, Pelita Air Service; two of the recommendations concern the aircraft manufacturer's advice to aircraft operators on emergency procedures and the type of throttle cables to be used; the other recommendation is for Hong Kong Air Traffic Management to ensure that its emergency alerting list is up-to-date.
The report notes that most of the safety recommendations have been implemented by those concerned.
When the aircraft crashed it was returning to its base in Indonesia having earlier completed two flights from Hong Kong to Hanoi carrying a total of 66 Vietnamese who were being returned to Vietnam under the Orderly Repatriation Programme.
Although at the time of the crash, the aircraft was not carrying passengers, questions were asked in the media and by Legislative Councillors as to whether it was properly equipped and authorised for the carriage of passengers on the preceding flights.
At subsequent meetings of the Legislative Council Panel on Economic Services, Government officials explained that aircraft of the type which crashed had completed a total of 31 flights to repatriate Vietnamese migrants between 1991 and 1994, and that before the series of flights began, the Government had received written confirmation from the Indonesian authorities that the aircraft were approved for international passenger transportation.
The Indonesian Minister of Communications had also reconfirmed in writing that the aircraft in question was indeed approved and certified properly for international carriage of passengers under Indonesian Civil Aviation Regulations.