Figure: RKPK ILS/DME 36L, from Korea Aviation Accident Investigation Board Report, Figure 1-10.

Eddie Sez:

There is a lot of blame to go around here, not all of it apparent in the official accident report. The Air China manual classified this Boeing 767 as Category C for straight in approaches and Category D for circling. The crew briefed and began the only available instrument approach: ILS 36L. When the runway was changed to 18R the controller asked the crew for their Approach Category and they responded "Charlie." During their maneuvering they were recorded at 160 knots, well above the Category C maximum speed.

  • They thought they were a Category C aircraft but were not. They were cleared the approach based on Category C minimums, but they flew Category D speeds.

  • They did not apply an adequate heading offset to fly a downwind with enough offset to allow for a base turn to final, and they did not apply wind drift correction to the downwind heading.

  • The captain delayed his base turn 20 seconds beyond what a normal circling maneuver technique would call for.

  • They failed to execute the missed approach once losing sight of the runway.

All of those items are noted in the accident report. But if you really want to trace the causes of an aviation mishap, look at the corrective action taken as a result. The job here, after all, is to prevent recurrence. The circling minimums were based on U.S. TERPS which, back then, were much tighter than ICAO standards. Having to maneuver a Boeing 767 within 2.3 nm under Category D minimums is foolhardy. Doing so within 1.7 nm under Category C minimums, in this case, was fatal to most of the passengers on board.

The FAA acknowledged this in 2009, seven years later, by revising TERPS Circling Approach Area criteria. While most U.S. circling approaches are still, as of April 2013, based on the tighter criteria, charts designed after 2011 should be closer to the ICAO standard.

The approach plate in front of you is probably based on the smaller area. You as the pilot can improve your odds by upping your personal visibility minimums. Mine? Three miles gets me to the ICAO minimums and revised TERPS standards. What about your minimum ceiling to circle? We require a go around if outside of Stabilized Approach criteria at 1,000 feet when IMC. If your ceiling minimums are lower than 1,000 feet, you can't do this. We also require a go around if you are not stabilized below 500 feet on a visual or circling approach. If you are fully banked turning on final two miles from the runway, you can't do this.

What follows are quotes from the sources listed below, as well as my comments in blue.


Accident Report


Narrative

[Korea AAR F0201, page 25]


Probable Cause

Figure: Circling Approach Radar Track, from Korea Aviation Accident Investigation Board Report, Figure 1-7.

[Korea AAR F0201, page 17]

  1. The flight crew of flight 129 performed the circling approach, not being aware of the weather minima of wide-body aircraft (B767-200) for landing, and in the approach briefing, did not include the missed approach, etc., among the items specified in Air China's operations and training manuals.

  2. The flight crew exercised poor crew resource management and lost situational awareness during the circling approach to runway 18R, which led them to fly outside of the circling approach area, delaying the base turn, contrary to the captain's intention to make a timely base turn.
  3. The approach was designed under older TERPS criteria with a 1.7 NM radius for Category C and 2.3 NM radius for Category D aircraft. The aircraft crashed at a point about 2.48 NM from the threshold of runway 18R. Had the approach been designed under ICAO rules, or under newer TERPS rules, the radius would have been much wider but so would the visibility required to fly the circling approach. All of that notwithstanding. the downwind was flown too close to the runway to make the turn even under optimal conditions.

  4. The flight crew did not execute a missed approach when they lost sight of the runway during the circling approach to runway 18R, which led them to strike high terrain (mountain) near the airport.

  5. When the first officer advised the captain to execute a missed approach about 5 seconds before impact, the captain did not react, nor did the first officer initiate the missed approach himself.

Other findings

[Korea AAR F0201, page 18]

  • Instrument approach chart used by the flight crew of flight 129 did not depict the high terrain north of the airport.

  • Flight 129 was flown between 150 and 160 kt on the downwind leg, which exceeded the maximum speed of 140 kt of Gimhae airport's circling approach category "C," and the width of the downwind leg was narrower than normal, for which corrective actions were inappropriate.

  • The differences between the ICAO and Korean criteria for the flight procedure establishment of Gimhae airport were not described in the ROK AIP effective at the time of the accident.

See Also:


References

Korea Aviation Accident Investigation Board Report, AAR F0201, Controlled Flight Into Terrain, Air China International Flight 129, B767-200ER, B2552, Mountain Dotdae, Gimhae, April 15, 2002