Subject to paragraph (2) of this subsection, subsections (a), (b), (c), and (d) of this section shall not apply to any annuitant receiving an annuity from the Fund while such annuitant is employed, during any period described in
section 5532(f)(2) of this title (as in effect before the repeal of that section by
[section 651(a) of Public Law 106–65]) or any portion thereof, under the administrative authority of the Administrator, Federal Aviation Administration, or the Secretary of Defense to perform duties in the operation of the air traffic control system or to train other individuals to perform such duties:
Provided, however, That the amount such an annuitant may receive in pay, excluding premium pay, in any pay period when aggregated with the annuity payable during that same period shall not exceed the rate payable for level V of the Executive Schedule.