; and (B) fix the basic pay of any individual appointed under subparagraph (A) at a rate of not more than level I of the Executive Schedule without regard to the civil service laws, except that the total annual compensation of the individual shall be at a rate of not more than the highest total annual compensation payable under section 104 of title 3, United States Code. (4) Merit principles The Administrator shall ensure that the exercise of the authority granted under paragraph (3) is consistent with the merit principles of section 2301 of title 5, United States Code. (b) Experts and consultants The Administrator may obtain the temporary or intermittent services of experts or consultants as authorized by section 3109 of title 5, United States Code. (c) Advisory committees (1) Establishment The Administrator may establish, in accordance with the Federal Advisory Committee Act (5 U.S.C. App.), such advisory committees as the Administrator may consider appropriate to assist in the performance of the functions of the Administrator. (2) Compensation A member of an advisory committee, other than a full-time employee of the Federal Government, may be allowed travel expenses, including per diem in lieu of subsistence, as authorized by section 5703 of title 5, United States Code, for individuals in the Government service without pay, while attending meetings of the advisory committee or otherwise serving away from the homes or regular place of business of the member at the request of the Administrator. 503. Offices (a) Principal office The principal office of the Administration shall be in or near the District of Columbia. (b) Field offices The Administrator may maintain such field offices as the Administrator considers necessary to carry out the functions of the Administrator. 504. Mission plan (a) In general The Administrator shall prepare a mission plan, which shall— (1) provide an informational basis sufficient to permit informed decisions to be made in carrying out the functions of the Administrator