The Wireless Telecommunications Bureau (WTB) has announced that the FAA has released a new Advisory Circular for Obstruction Marking and Lighting (AC 70/7460-1L) for antenna structures replacing the previous circular (AC 70/7460-1K). This new Advisory Circular most notably makes changes to FAA Lighting Styles A (red obstruction light), E (medium intensity dual obstruction lights), and F (high intensity dual obstruction lights) by requiring that tower owners no longer employ L-810 steady-burning side lights; rather, such L-810 lights must flash. This change will apply to all new or altered towers over 350 feet above ground level (AGL) immediately. For all new or altered towers 151-350 feet AGL, this change will apply beginning on September 15, 2016. The FAA made this change to reduce the effects that antenna structures have on migratory birds because birds are more attracted to steady-burning side lights such as L-810 as opposed to flashing lights. The Bureau encourages owners of existing registered antenna structures to eliminate the use of L-810 steady-burning side lights; however, such change requires a new FAA no hazard determination under the new FAA advisory circular, and an amendment to the antenna structure registration in notification of the lighting change. Environmental notice will not be required as the lighting would change from a less preferred to a more preferred style.