36 CFR § 1002.17 - Aircraft and air delivery.
(a) Delivering or retrieving a person or object by parachute, helicopter, or other airborne means, except in emergencies involving public safety or serious property loss, or pursuant to the terms and conditions of a permit, is prohibited.
(b) The provisions of this section, other than paragraph (c) of this section, shall not be applicable to official business of the Federal government, or emergency rescues in accordance with the directions of the Executive Director, or to landings due to circumstances beyond the control of the operator.
(1) Except as provided in paragraph (c)(3) of this section, the owners of a downed aircraft shall remove the aircraft and all component parts thereof in accordance with procedures established by the Executive Director. In establishing removal procedures, the Executive Director is authorized to establish a reasonable date by which aircraft removal operations must be complete; determine times and means of access to and from the downed aircraft; and specify the manner or method of removal.
(2) Failure to comply with procedures and conditions established under paragraph (c)(1) of this section is prohibited.
(3) The Executive Director may waive the requirements of paragraph (c)(1) of this section or prohibit the removal of downed aircraft, upon a determination that the removal of downed aircraft would constitute an unacceptable risk to human life; the removal of a downed aircraft would result in extensive resource damage; or the removal of a downed aircraft is impracticable or impossible.
(e) The operation or use of hovercraft is prohibited.