Release GE791 Accident Investigation factual report
On December 21,2002, at 0152 Taipei local time, TransAsia Airways (TNA) freighter GE791, aircraft type ATR 72-200, registration No.B22708, encountered severe icing in cruising altitude of 18,000ft and crashed into Taiwan strait 17 kilometers southwest of Makung Islands. Two pilots on board GE791 were missing.
After 10 months of factual data collection, the investigation team held a 5 days Technical Review meeting, all factual data had been verified by the investigation team members and approved by the Council during the 60th & 61st Council Meeting, The Aviation Safety Council held a press conference on October 28, 2003 and published the factual report on the ASC web site (http://www.asc.gov.tw/)
The investigation teams were organized into the following groups: Systems, Flight Operations, Structure, Flight Recorders, Maintenance Records, ATC /Weather. The investigation team also includes the Accredited Representative team – BEA, France and their advisors from ATR. Other participants are CAA of ROC, and TransAsia Airways with a total of 47 team members.
The factual report contains 342 pages and 130 attachments.
Following are the highlight of the factual report:
The investigation team had tentatively ruled out Air Traffic Control and communication as the potential causal factors of this accident, and found no relative evidences of fire, smoke, and security.
The ground temperature was 20°C when GE791 departed from CKS International Airport and the temperature at 18,000 ft altitude of the accident area was -9°C
According to the SIGMETs valid from 12/20 0600UTC to 1000UTC and 12/20 2030UTC to 12/21 0030UTC by Taipei Aeronautical Meteorological Center, there was no severe icing observed or forecasted on the route of GE791.
According to the SIGWX chart for FL100-FL250 issued by Taipei Aeronautical Meteorological Center, there was no icing and turbulence indicated on the route of GE791.Moderate icing above FL120 and turbulence under FL220 were indicated on the route (Taipei-Penghu) of GE791 from the SIGWX chart issued by Hong Kong Observatory. Moderate icing from FL120 to FL240 and moderate turbulence from FL20 to FL380 were indicated around the northeast airspace to Taiwan island and the north part of Taiwan issued by Tokyo Aviation Weather Service Center.
Between 12/21 0134~0137 and 0141~0152 (FDR stopped recording), airframe de-icing were activated
Between 0152:11 to 0152:51 (CVR stopped recording), various warnings sounded.
According to FDR record, GE791 reached its lowest indicated air speed of 157kts at 0150:42, from 0152:23.till the stop of FDR, pitch angle exceeded 50 degrees, the maximum vertical acceleration was +4.2G at 0152:45, highest speed was 436kts at 0152:50 (when the FDR stopped recording)
Between 1994 and 2002, ATR 42/ 72 had 8 icing related occurrences.
ASC issued an Interim Flight Safety Bulletin on Jan 24,2003 recommending all operators with turboprop aircraft review their training programs to ensure the program contains the necessary training for pilots to recognize and effectively respond to all levels of "Icing Conditions." It also recommended that the operators should emphasize additional training in pilot′s situation awareness of icing conditions
The analysis process including Flight Operations, Weather, Systems, Performance and Maintenance Record will commence immediately after the release of the factual data report. It is expected that the final draft report will be finished in Sept. 2004., and the final report be finished near the end of 2004
For more information, please contact:
Flight Safety Investigator: Tracy Jen
Tel: 2547-5200 ext 167