The Military Auxiliary Radio System, or MARS, is composed mostly of amateur radio operators but conducts its day-to-day operations on frequencies just outside the amateur bands. However, the 60-meter (5-MHz) band is shared between hams and the federal government and MARS is scheduling occasional operations on 60 meters to demonstrate and practice interoperability with the broader amateur radio community. According to the ARRL, these sessions may be scheduled for several days at a time and will occur at least once a month through this October. Exercises will include exchange of voice messages as well as passing of ICS-213 (Incident Command System) messages using both voice and digital modes. Some of this year's dates coincide with quarterly Department of Defense "COMEX" communications exercises.
The 2021 schedule, according to Army MARS Chief Paul English, WD8DBY, is as follows: February 23-27 (COMEX), March 1-7, April 3-10, April 30-May 6 (COMEX), May 7-8 (Armed Forces Day Cross-Band Test), June 1-6, July 5-10, July 20-22 (COMEX), August 2-8, September 1-6 and October 1-31 (COMEX).