Maryland Code, Criminal Law § 3-807

(1) by an individual conducting research and development or flight testing for an aircraft manufacturer or the Federal Aviation Administration;

(2) by a member of the United States Department of Defense or the United States Department of Homeland Security acting in an official capacity during an activity related to research and development, flight testing, or training;

(3) by a law enforcement officer, as defined in § 1-101 of the Public Safety Article, acting in an official capacity;

(4) by an individual attempting to make the individual's location known; or

(5) by an individual attempting to give a warning signal.