Seventeen months before the Bashkirian Airlines-DHL collision there had already been another incident involving confusion between conflicting TCAS and ATC commands . In 2001 , two Japanese airliners nearly collided with each other in Japanese skies . One of the aircraft had received conflicting orders from TCAS and ATC ; one pilot followed the instructions of TCAS while the other did not . A collision was only averted because one of the pilots made evasive maneuvers based on a visual judgement . The aircraft missed each other by about , and the abrupt maneuver necessary to avert disaster left 100 occupants injured on one aircraft , some seriously . In its report , published eleven days after the Überlingen accident , Japan called on the International Civil Aviation Organization ( ICAO ) to make it clear that TCAS advisories should always take precedence over ATC instructions . ICAO accepted this recommendation and amended its regulations in November 2003
nearly collided
2001 Japan Airlines mid-air incident
2002 Überlingen mid-air collision