The Mode S Interrogator Code Conflict Alerter (MICCA) has been brought into operation by the Romanian Air Traffic Services Administration (ROMATSA).

The application was developed by German air navigation service provider (ANSP) DFS Deutsche Flugsicherung to identify interrogator code conflicts of Mode S radar stations. Such conflicts may result in aircraft not being fully detected by one or more Mode S sensors.

MICCA allows system monitoring staff to simultaneously overview interrogator code conflicts at all Mode S facilities, to quickly identify affected sensors and to analyse the conflicts. Reconfiguring the affected radar station is one of the possible solutions to such a problem.

This alerting system can process live radar data from up to 32 Mode S radar stations and displays target acquisition problems graphically in real time. For example, the number of conflicts for each Mode S sensor can be represented on a time axis. Another feature is the ability to show where aircraft experienced a delay in radar detection or where they were not detected at all. As soon as specific adjustable thresholds are reached, the system sets off a visual and audible alert.

DFS has been using this in-house development to monitor Mode S facilities since 2010. The Latvian ANSP Latvijas Gaisa Satiksme (LGS) has employed this DFS tool since 2013.

A European Commission regulation has been in place since 2009 that requires Mode S operators to implement monitoring means to detect interrogator code conflicts (Regulation 262 / 2009, Article 7).