Contact the Federal Aviation Administration at 877-487-6867.
Provide the FAA during your call with the general location of the tower, its address, and if you know it, the nearest airport. If you're the owner of the tower, also provide the tower registration number, which is also known as the Antenna Structure Registration (ASR) number.
Repair the light outage as soon as possible, or notify station personnel to fix the light. The notice created for pilots lasts for 15 days, after which the FAA assumes the light has been repaired. If after 15 days the light is still not fixed, you should recontact the FAA to inform them of the situation.