Aviation Communication & Surveillance Systems (ACSS)

Regarding the statement under “Discussion” of “This condition, if not corrected, could lead to possible loss of separation of air traffic and possible mid-air collision.” ACSS feels it significant to note that the calculated probability associated with such a possible event is very low (reference Section 2.3 of ACSS document 8008352-001,“ACSS Continuing Operational Safety Probability Assessment of the Interference Limiting Function”, included with this comment submittal), which corresponds to the fact that ACSS has never received any reports of such an operational anomaly from field operation. This analysis would indicate that the probability of such an event is low enough that an Airworthiness Directive to address the potential situation is unnecessary.