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Publish Far Eastern Air Transport Flight EF306 and Thai Airways International Public Company Ltd Flight TG659 a TCAS Event in Narrow Collision Avoidance occurrence report

Publication Date 2008-08-15
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On Nov.16, 2006, Far Eastern Air Transport Flight EF306, a Boeing 757-200 type aircraft with registration number B-27015, departed Tao Yuan international airport at 0841 Taipei local time and bound for Jeju International Airport, Korea. On the way to the destination, about 99 NM south of Jeju Island, over the open sea area during its descent to FL 310 from FL390 following the instruction of the Incheon (ICN)area control center (Incheon ACC), the Traffic Alert and Collision Avoidance System (TCAS) issued the Traffic Advisory (TA)/Resolution Advisory (RA) warning. The crew manipulated the aircraft to descend for an avoidance maneuver following the TCAS RA ‘DESCEND’ warning. During the avoidance maneuver, 4 passengers were seriously injured, 10 passengers and 6 cabin crew sustained minor injury, and the interior of the aircraft sustained minor damage.


The Aviation Safety Council (ASC), immediately launched a team to conduct the investigation of this occurrence under the concurrence of KARAIB (Korea Aviation & Railway Accident Investigation Board). The investigation team included members from the USA NTSB, KARAIB, Boeing Company, ROC Civil Aeronautical Administration (CAA) and Far Eastern Air Transport (FEA).

The Factual Data Collection Report was published on Jul. 31, 2007 and an Interim Flight Safety Bulletin on Aug. 01, 2007.The final report was reviewed by the Aviation Safety Council Board meeting and released on Aug. 15,2008.

Based upon the analysis by the Safety Council, the following are the findings relate to probable cause of the EF306 occurrence investigation:

ICN control made a non-standard call and gave a confusing instruction to the EF306 during its descent when passing FL340. EF306 flight crew did not fully comprehend the ATC instructions, failed to confirm the instructions and stopped descending at 33,800 ft. Both parties did not apply standard radiotelephony procedures and phraseologies. These anomalies contributed to the TCAS event between EF306 and TG659. The EF306 flight crew did not complete the TCAS RA standard operation procedures and commenced an excessive high rate descent. The induced negative G-force resulted in the occupants’ injury.

There are other 8 findings related to risk which include : The EF306 flight crew did not adequately exhibit good CRM performance in this occurrence, South Sector Radar Control(SSRC) momentarily missed monitoring the approaching situations developed between EF306 and TG659 while concentrating on the radar identification of other aircraft, SSRC did not comply with ATC/TCAS operating procedures and the limited human capability during a sudden occurrence of abnormal situation who was paying attention continuously to a large number of aircraft in a relatively broad service area which was B576 that applying Reduced Vertical Separation Method(RVSM) operations. In addition, most of the injured passenger did not have their seat belts fastened and lost their protection while the fasten seat best sign was still on, the cabin crewmembers did not provide timely injury information to the flight crew, that would have allowed the flight crew to request sufficient medical assistance before landing and the controllers did not aware the importance of the number of injuries and the need for more ambulances to meet the flight upon landing. This caused the necessary number of ambulances to arrive at the airport with delay.

There are 19 other findings for informational, and safety awareness, education, and improvement purposes. (Refer to complete investigation report)

The ASC issued 4 safety recommendations to Civil Aviation Safety Authority, Korea as: Improve the sectorization and staffing standards of Incheon ACC, Improve ATC proficiency training on TCAS procedures, communication procedures, phraseology, and language command capability, improve the sectorization and staffing standards of Incheon ACC, establish standard instrument arrival procedures for Jeju airport and enhance the controller’s procedures and training in emergency response.

Four other safety recommendations were issued to Far Eastern Air Transport which include: Improve pilot proficiency training on communication procedures, phraseology, and language command capability, especially the reconfirmation of the information issued from ATC; Ensure that flight crews follow the standard TCAS operation procedures, not visually conduct the avoidance maneuverings, and use good CRM practices during TCAS maneuverings; Enhance procedure and training to make sure that cockpit crews and cabin crews communicate and collect sufficient injury information timely, and that they notify the control authorities as soon as possible for airport’s emergency rescue preparation during mass injury situations; Enhance procedure and training regarding cabin chief’s leadership, decision making, communication and cabin crew’s first aid knowledge for emergency response during mass injury situations.

The ASC’ Managing Director Dr. Young emphasized the following safety issues during the investigation as improve pilot proficiency training especially the reconfirmation of the information issued from ATC and ensure that flight crews follow the standard TCAS operation procedures and cabin safety. On behalf of the ASC, Dr. Young expressed his appreciation to ARAIB for their assistance during the investigation. In conclusion, Dr. Young noted that flight safety needs commitment and cooperation of government, regulator, operator and everyone. It is ASC’s continuous goal to enhance safety and prevent the reoccurrence through investigation.

The complete report can be downloaded at

Safety Investigator: Tracy Jen
Tel: 89127388-310 

Last updated 2019-08-08
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