TCAS Event Leads to Injuries During Avoidance Maneuver Near Jeju Island

Casualties unknown • 99NM south of the Jeju Island， Korea/in the air, TW

A Boeing 757-200 flight experienced a TCAS Resolution Advisory near Korea, resulting in multiple passenger injuries during an aggressive descent.

What happened

On November 16, 2006, Far Eastern Air Transport flight EF306, a Boeing 757-200 with registration B-27015, was en route from Taipei to Jeju International Airport. While descending through 34,000 feet approximately 99 nautical miles south of Jeju Island, the aircraft's Traffic Alert and Collision Avoidance System (TCAS) issued a Traffic Advisory (TA) followed by a Resolution Advisory (RA) due to a conflict with Thai Airways International flight TG659, a Boeing 777-300.

In response to the TCAS "DESCEND" instruction, the flight crew initiated an avoidance maneuver. The maneuver involved an excessive high rate of descent, reaching a maximum rate of approximately 12,096 feet per minute. This rapid change in vertical speed induced negative G-forces within the cabin, resulting in 4 passengers seriously injured and 10 passengers and 6 cabin crew sustaining minor injuries. The aircraft interior also sustained minor damage.

The investigation

The Taiwan Transportation Safety Board (TTSB) conducted the investigation in coordination with the Korea Aviation & Railway Accident Investigation Board (KARAIB) and the US NTSB. The investigation examined flight data recorder (FDR) parameters, radar tracks from the Incheon Area Control Center (ACC), and TCAS performance. Investigators analyzed the communication between the aircraft and air traffic controllers, as well as the flight crew's adherence to standard operating procedures during the TCAS event.

Findings

  • Non-standard ATC communications: The Incheon ACC issued a confusing, non-standard instruction to EF306 during its descent through FL340. The flight crew failed to fully comprehend and confirm these instructions, which contributed to the TCAS event.
  • Improper avoidance maneuver: The EF306 flight crew did not follow standard TCAS RA procedures, instead executing an excessive descent rate that caused the passenger injuries.
  • Communication failures: Both the air traffic controllers and the flight crew failed to apply standard radiotelephony phraseology and procedures.
  • Risk factors: The investigation noted that the increasing air traffic density in the RVSM airspace near Jeju, combined with a lack of standard instrument arrival procedures for the area, increased the complexity of the sector.

Probable cause

The primary cause of the event was a combination of non-standard and confusing ATC instructions that led to a loss of situational awareness, followed by the flight crew's failure to adhere to standard TCAS Resolution Advisory procedures, resulting in an aggressive descent maneuver.

Frequently asked questions

What happened in the 2006-11-16 Boeing/B757-200 accident near 99NM south of the Jeju Island， Korea/in the air, TW?

A Boeing 757-200 flight experienced a TCAS Resolution Advisory near Korea, resulting in multiple passenger injuries during an aggressive descent.

What aircraft was involved and where did it happen?

The accident on 2006-11-16 involved a Boeing/B757-200, registration B-27015, at 99NM south of the Jeju Island， Korea/in the air, TW.

What was the probable cause of the accident?

The primary cause of the event was a combination of non-standard and confusing ATC instructions that led to a loss of situational awareness, followed by the flight crew's failure to adhere to standard TCAS Resolution Advisory procedures, resulting in an aggressive descent maneuver.

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