The social and economic impact of an aircraft disappearance depends on the timeliness to determine the causes of a disappearance and locate the aircraft. Moreover, whenever an accident occurs over water, save people in distress and recovery of flight recorders are particularly difficult. This document describes the characteristics of Remote Command via the SAR Return Link Service for ELT(DT) in particular for remote activation and deactivation capabilities for an Emergency Locator Transmitter. It is intended to be used for Service Providers and Users of the Return Link Service and focuses on high level concepts and typical functional interface user requirements. There are situations where a remote activation of an ELT for Distress Tracking (ELT(DT)) could offer the possibility to localize aircraft in-flight (e.g. in cases of a non-cooperative or incapacitated crew). This type of Service complements the automatic activation as recommended by the ICAO Global Aeronautical Distress & Safety System (GADSS). The pertinence of the remote activation and deactivation functionality by aircraft operators has been recognised and envisaged in the ICAO GADSS Concept of Operations. In addition, this document has relationship with ICAO documentation such as the Annex 11, Annex 12 or for example the DOC10054.