Nima Wangdi 

Ministry of Infrastructure and Transport asked Drukair Helicopter Services to “ground” the pilot involved in the helicopter crash killing a mother and her infant at Wachey, Lunana in Gasa on March 3.

The order comes after the ministry’s air crash investigation team completed its preliminary investigation of the crash.

The pilot is not allowed to fly until further notice.

The team retrieved critical equipment like Engine Data Recorder (EDR), Vehicle and Engine Multifunction Display (VEMD), Engine Control Unit (ECU), and V2-track from the wreckage. The retrieved components will be sent to the French Bureau of Enquiry and Analysis for examination and readout according to the team’s investigation report.

The report also stated that the results of the examinations will be included in the final investigation report.

The ECU performs fuel regulation, engine parameters management, and engine data recordings while EDR is a light recorder and exclusively records engine parameters and malfunctions during flights sent by ECU. The VEMD records system failure information, flight reports, and over-limit reports associated with flight parameters and it communicates with ECU.  

The report stated that the helicopter is normally equipped with Vision 1000, which was not present on board on the day of the accident. It was found to have been removed on March 1, for maintenance, and declared inoperative MEL category D.

The vision 1000 device collects inertial and positioning data, ambient acoustic data, and cockpit imagery, which are stored on a crash-hardened memory module, as well as a removable secure digital card. It is also critical in supporting accident investigations.

The report stated that the helicopter has a flight tracker device (V2-track) that tracks and records the flight path every 15 seconds of the interval during its flight path. “However, it was found that the V2-track had failed to record the final moments of the A5-BHT flight path two minutes before the crash.”

The report stated that the team examined the accident site and wreckage, interviewed survivors, eyewitnesses, and locals, collected meteorological data, aircraft maintenance, and pilot records, and obtained flight tracking data.

The report, when the investigation is complete, will include pilot records and medical information, aircraft maintenance and flight records, readouts of the V2-Trac, EDR, VEMD, and ECU data, witness and survivor interviews, and meteorological data.

The wreckage was found at the base of two trees with the tail boom separated from the main body and one of the main rotor blades separated about three meters above.

The ministry formed the aircraft accident investigation team on March 8 as per the Civil Aviation Act of Bhutan.

The helicopter crashed during the fourth flight to Wachey carrying a family of four.

The report quoted the pilot saying that it crashed about 200 meters northeast of the landing ground in Wachey at 2:25 PM.

The report stated that generally, the operator gathers weather information from the prescribed Windy TV App, weather forecast provided by the National Center for Hydrology and Meteorology (NCHM), and visual information collected from locals and these are all assessed by the pilots and ground staff before the aircraft departs from Paro base.

NCHM forecasted partly cloudy weather for Gasa District on that day. Since there were no adverse weather conditions that day, NCHM did not issue any weather warnings or alerts. The locals also reported fine weather at Wachey with no winds on the day of the crash.

The pilot told the investigation team, on March 3, the weather en route to Wachey was acceptable with a high cloud base, broken or scattered clouds, and suitable wind conditions.

The pilot also reported good visibility of more than 10km during the approach to Wachey and the recorded temperature was seven-degree celsius based on the previous flight reading.