Runway LOS Elements Awareness & Score Evasive action Relative positions Speed communication No awareness by ATS or flight crew(s) of imminent collision Traffic alert (STCA or Aircraft positioning is Aircraft speed Collision impending TCAS RA) as last such that a collision dictates a high where evasive action is line of defence 15 with another aircraft, closure rate with taken or should have Loss of vehicle or person is another aircraft, been taken communications imminent vehicle or person (such as use of frequency or frequency congestion) Loss of situational awareness by ATS or flight crew(s) No positive runway are crossing, One aircraft high Ground based or separation reciprocal or the other at taxi aircraft traffic alert 10 converging (collision speed (collision not Critical conflict activation preventing not imminent but imminent but necessitating ATS or potential collision deemed critical) deemed flight crew action High traffic, frequency congestion Action required to Paths are crossing, One is aware of One aircraft separation reciprocal or the other either high/medium speed 5 standard (non-critical) or converging (collision visually and/or with the other party collision risk deemed risk deemed through external stopped or slowing non-threatening communication Both aircraft/vehicles travelling at low Paths are diverging, speed or one ATS and ground No risk of a collision 1 parallel or same stopped (actual parties aware of occurring track runway surface not each other infringed by one party) Appendix B: risk classification matrix A three-step method is used to assess the risk that each occurrence poses to aviation safety, and determine the ERC risk classification for that occurrence. Step 1 If this event had escalated into an accident, what would have been the most credible accident outcome?
Runway LOS Elements Score Evasive action Relative positions Speed Awareness & communication 15 Collision impending where evasive action is taken or should have been taken Aircraft positioning is such that a collision with another aircraft, vehicle or person is imminent Aircraft speed dictates a high closure rate with another aircraft, vehicle or person No awareness by ATS or flight crew(s) of imminent collision Traffic alert (STCA or TCAS RA) as last line of defence Loss of communications (such as use of frequency or frequency congestion) 10 No positive runway separation Critical conflict necessitating ATS or flight crew action are crossing, reciprocal or converging (collision not imminent but deemed critical) One aircraft high the other at taxi speed (collision not imminent but deemed Loss of situational awareness by ATS or flight crew(s) Ground based or aircraft traffic alert activation preventing potential collision High traffic, frequency congestion 5 Action required to separation standard (non-critical) or collision risk deemed non-threatening Paths are crossing, reciprocal or converging (collision risk deemed One aircraft high/medium speed with the other party stopped or slowing One is aware of the other either visually and/or through external communication 1 No risk of a collision occurring Paths are diverging, parallel or same track Both aircraft/vehicles travelling at low speed or one stopped (actual runway surface not infringed by one party) ATS and ground parties aware of each other Appendix B: risk classification matrix A three-step method is used to assess the risk that each occurrence poses to aviation safety, and determine the ERC risk classification for that occurrence. Step 1 If this event had escalated into an accident, what would have been the most credible accident outcome?
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