What the ASR is
The Antenna Structure Registration is the FCC's database of antenna structures that could affect aircraft. Owners must register a structure if it is more than 200 feet above ground, or if it is near an airport and the FAA must be notified about it. Each registration gets a seven-digit number, and the owner must display that number at the base of the structure where it can be seen.
Before registering, the owner files with the FAA, which studies whether the structure is a hazard and specifies any painting and lighting. That is why tall towers are painted in bands of aviation orange and white or carry red or white lights: the FAA's marking and lighting rules, set out in its advisory circular 70/7460-1, apply.
What the registration shows
- Location: latitude and longitude, street address, city, county and state.
- Height: height of the structure, overall height above ground including antennas, and height above sea level.
- Structure type: monopole, lattice, guyed, building, tank and so on.
- Owner: the registered owner and a contact.
- Status: granted, constructed, dismantled, and the relevant dates.
- FAA study: the FAA study number and the painting and lighting requirements.
How we use it
Every tower in our finder with an ASR number comes from this registry. We include structures marked as constructed that have not been reported dismantled, and we skip AM radio arrays. We add the owner, height and type straight from the filing, and we add carrier tags where the owner is a carrier or where a carrier's cellular licence names that ASR number as a transmitter site.
Looking up a tower yourself
Copy the ASR number from a result, or read it off the sign at the tower base, and search it in the FCC's ASR registration search, part of its Universal Licensing System. The full record includes the application history, which shows when the tower was built and whether ownership has changed.
What the ASR does not tell you
For those, see why towers are missing from the map and who owns cell towers.
- Which carriers rent space on the tower. Registrations name the owner, not tenants.
- Which frequencies or technologies (4G, 5G) are used there.
- Anything about structures under 200 feet away from airports, which are not registered.