C/S G.003 - INTRODUCTION TO THE COSPAS-SARSAT SYSTEM Issue 7

Some of the GNSS that are used by the MEOSAR system support a Return Link Service (RLS); this service uses the navigation downlink signals to transmit messages or commands to the beacon. In the initial implementation, the Galileo system is used to send an automatic acknowledgement message to the beacon after the alert has been received and the position confirmed by the MCC; this does not guarantee that the alert has been received and acted on by the RCC.

 The performance requirements for the support of the return link message distribution are that the solution should be sent to the Return Link Service Provider (RLSP) within fifteen minutes after the beacon transmission. With a potential time of fifteen minutes for the RLSP to send the acknowledgement to the beacon, the total end-to-end capability is within thirty minutes. This requirement applies only to the MEOSAR and GEOSAR systems.