HIGHFLY33,
The minimum gradients required in 25.111, 25.119 and 25.121 are still air gradients because 25.101(a) specifies:
(a) Unless otherwise prescribed, aeroplanes must meet the applicable performance requirements of this Subpart for ambient atmospheric conditions and still air.
The gradients specified in 25.115(b) are not still air because 25.1587(b) specifies:
(b) Each aeroplane Flight Manual must contain the performance information computed under the applicable provisions of this CS–25 (including CS 25.115, 25.123 and 25.125 for the weights, altitudes, temperatures, wind components, and runway gradients, as applicable) within the operational limits of the aeroplane, and (...)