ATM/ANS.OR.A.070 Contingency plans

MODE S INTERROGATOR CODES

(a)An air traffic service provider should assess the possible impact on air traffic services of interrogator code conflicts, and the corresponding potential loss of Mode S target surveillance data from the impacted Mode S interrogators, taking into account their operational requirements and available redundancy.

(b)Unless the potential loss of Mode S target surveillance data has been assessed to have no safety significance, the surveillance provider should:

(1)implement monitoring means to detect interrogator code conflicts caused by other Mode S interrogators impacting eligible Mode S interrogators that they operate on any operational interrogator code;

(2)ensure that the interrogator code conflict detection provided by the implemented monitoring means is achieved in a timely manner and within a coverage that satisfy their safety requirements;

(3)identify and implement as appropriate, a fallback mode of operation to mitigate the possible interrogator code conflict hazards on any operational code, identified in the assessment referred to in point (1);

(4)ensure that the implemented fallback mode of operation does not create any interrogator code conflict with other Mode S interrogators referred to in the interrogator code allocation plan.

GENERAL The contingency plan may include the definition of the measures, the coordination with other actors (i.e. the State, the competent authorities, possibly the other service providers, the insurance companies, aerodrome operators, as applicable) and alternative services needed in case of degradation or interruption of the services, while the applicability of emergency response planning may be attributable to or affected by an aviation safety occurrence.