PURPOSE AND SCOPE This document contains the Minimum Aviation System Performance Standards (MASPS) for a C21 Link System connecting a Control Station (CS) and an Unmanned Aircraft (UA).2 It covers UA operations requiring a C2 Link System3 that allows the UA to operate within visual line of sight (VLOS) and beyond visual line-of-sight (BVLOS) of a CS. The types of information that are exchanged over the C2 Link System include both: The commands from the remote pilot@4 i.e.@ the telecommands sent over a forward link from the CS to the UA@ and The status and annunciations from a UA@ i.e.@ the telemetry data sent over a return link from the UA to the CS@ that are associated with all of the activities the remote pilot is required to perform to safely execute the flight plan. These safety-of-flight5 related information exchanges do not include normal payload information@ i.e.@ the information associated with the UA mission payloads. A more complete description of those information exchanges and the associated requirements on the C2 Link System are given within this MASPS. 1 Note: When the term ??C2?? is used as part of the name of a system@ i.e.@ C2 Link System@ the term ??C2?? is used as a noun and not as an abbreviation of the words ??command and control??. Where it is used not as part of a name@ then it would be an abbreviation for command and control. 2 An Unmanned Aircraft (UA) is the physical aircraft that a remote pilot is operating. 3 A C2 Link System is the logical connection used for the exchange of information between a CS and an UA@ to enable the remote pilot to safely operate the UA in the authorized U.S. airspace. 4 A remote pilot is the person who is operating an aircraft but is not physically on that aircraft. Within this document@ this term is used instead of Pilot in Command (PIC) since PIC represents a legal responsibility not necessarily the pilot operating the aircraft. 5 Safety-of-flight information is any information/data sent to or received from the UA that is necessary to ensure the UAS is operated/operating in a manner that protects people and/or property from harm due to unintentional events.