Issued in February 2016. This document defines the minimum specification to be met for criteria which can be used to detect an in-flight aircraft distress event and to trigger the transmission of sufficient information for the purpose of locating an accident site. It only specifies characteristics that are relevant to the logic used for event detection and trigger activation/cancellation. These characteristics should be useful as guidance material to regulatory authorities, designers, installers, manufacturers, service providers and users of systems intended for operation. Compliance with these specifications is recommended as one means of assuring that the criteria will meet the intended function(s) satisfactorily under the specific conditions encountered in distress conditions, as well as under conditions normally encountered in routine aeronautical operations for the environments intended. The MASPS may be implemented by one or more regulatory documents and/or advisory documents (for example certifications, authorisations, approvals, commissioning, advisory circulars, notices) and may be implemented in part or in total. Any regulatory application of this document is the sole responsibility of appropriate governmental authorities.