14 CFR § 93.375

No person may operate a helicopter or powered-lift operating in the vertical-lift flight mode in the Ronald Reagan Washington National Airport Flight Restrictions Area unless the person is conducting an essential operation as provided in paragraph (b) of this section.

Essential operations are operations conducted for the following purposes:

Lifesaving medical;

Active law enforcement involving responses to ongoing criminal activity;

Active national security directly involving national defense or counterintelligence;

Continuity activities for the Federal government to ensure the continued operation of essential governmental functions under a broad range of circumstances, including all-hazard emergencies; or

Transportation of the President or Vice President of the United States.

Proficiency evaluation flights, other transportation of personnel not directly involved in an essential operation, and routine training operations are not essential operations as provided for in paragraph (b) of this section.