Antennas used aboard aircraft to communicate with satellites or ground stations may have complex antenna patterns, which may vary as the aircraft moves throughout a given coverage area. Techniques are disclosed for dynamically adjusting the instantaneous power fed to an antenna system to ensure that the antenna transmits at the regulatory or coordinated effective isotropic radiated power (EIRP) spectral limit. The antenna may transmit, in accordance with aircraft location and attitude, steerable beam patterns at different scan and skew angle combinations, causing variations in antenna gain and fluctuations in the transmitted EIRP. Using on-board navigational data, an antenna gain and ESD limit may be calculated for a particular scan and skew angle, which may be used to adjust power fed to the antenna such that the antenna transmits substantially at maximum allowable EIRP as the steerable beam pattern is adjusted.