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Computer-Related Incidents with Commercial Aircraft

British Airways/Korean Air near miss, Chinese airspace, 28 June 1999

28 June 1999

Synopsis British Airways Flight 27 and Korean Air Lines Flight 507 experienced a near miss over Chinese airspace. Both aircraft were equipped with the TCAS collision avoidance system. But one aircraft was transmitting faulty altitude data, confusing the TCAS resolution logic. The aircraft were thus drawn closer to each other through the TCAS Resolution Advisories, the exact opposite of what is intended to happen. The problem was traced to a physical anomaly in the TCAS kit, which led to a redesign. The incident is recounted in Section 3.1 of Ed Williams's paper Airborne Collision Avoidance System, presented at the Ninth Australian Workshop on Safety-Related Programmable Systems, Brisbane, August 2004, published in CRPIT Volume 47: Safety Critical Systems and Software 2004