49 CFR 501.4 - Succession to Administrator.
(a) The Deputy Administrator is the “first assistant” to the Administrator for purposes of the Federal Vacancies Reform Act of 1998 (5 U.S.C. 3345-3349d), and shall, in the event the Administrator dies, resigns, or is otherwise unable to perform the functions and duties of the office, serve as the Acting Administrator, subject to the limitations in the Federal Vacancies Reform Act of 1998.
(b) In the event of the absence or disability of both the Administrator and the Deputy Administrator, or in the event that both positions are vacant, the following officials, in the order indicated, shall serve as Acting Deputy Administrator and shall perform the functions and duties of the Administrator, except for any non-delegable statutory and/or regulatory functions and duties:
(1) Chief Counsel;
(2) Senior Associate Administrator for Vehicle Safety;
(3) Senior Associate Administrator for Traffic Injury Control;
(4) Senior Associate Administrator for Policy and Operations.
(c) In order to qualify for the line of succession, officials must be encumbered in their position on a permanent basis.