; (C) engages in, or is in training leading to, frequent and regular performance of operational flying duty or proficiency flying duty; (D) engages in or remains in aviation service for a specified period; and (E) meets such other criteria as the Secretary concerned determines appropriate. (2) Enlisted members not currently engaged in flying duty The Secretary concerned may pay aviation incentive pay under this section to an enlisted member who is otherwise qualified for such pay but who is not currently engaged in the performance of operational flying duty or proficiency flying duty if the Secretary determines, under regulations prescribed under section 374 of this title, that payment of aviation pay to that enlisted member is in the best interests of the service. (b) Aviation bonus The Secretary concerned may pay an aviation bonus under this section to an enlisted member in a regular or reserve component of a uniformed service who— (1) is entitled to aviation incentive pay under subsection (a); (2) is within one year of completing the member’s enlistment; (3) reenlists or voluntarily extends the member’s enlistment for a period of at least one year or, in the case of an enlisted member serving pursuant to an indefinite reenlistment, executes a written agreement to remain on active duty for a period of at least one year or to remain in an active status in a reserve component for a period of at least one year; and (4) meets such other criteria as the Secretary concerned determines appropriate. (c) Maximum amount and method of payment (1) Maximum amount The Secretary concerned shall determine the amount of a bonus or incentive pay to be paid under this section, except that— (A) aviation incentive pay under subsection (a) shall be paid at a monthly rate not to exceed $1,000 per month