Line A

A line spanning from Washington State to Maine which approximates the border between the United States and Canada. The exact position of the line with respect to the border varies, however in most places it is about 75 miles/ 120 km from the border.

Applications from stations which operate in Part 90 (business and public safety) are sent by the FCC to Industry Canada for review against their TAFL database records. If the proposed application's -148 dBW signal signal (for VHF, -146 dBW for UHF) touches a Canadian licensee, a "NOTICE OF RETURN FOR CANADIAN OBJECTIONS" is generated. This Canadian objection letter usually states that harmful interference is anticipated ("HIA") and provides specific information against which the proposed system may be disputed. The dispute is usually settled by providing a detailed engineering study indicating the signal does not impinge on Canadian operations. The engineering study may, however, indicate that the proposed system will impinge on Canadian operations, thus requiring the selection of another frequency, reduction in power, or reduction in height above average terrain.

Line A is complemented by Line B, which is a similar line within Canada. Stations south of Line B must coordinate with the United States, as well.

A Line C exists in Alaska and a complementary Line D exists in Canada bordering Alaska.

The Industry Canada TAFL database contains information which has been protected for Canadian national security reasons. This information is unavailable through Industry Canada's search features. It is, therefore, possible to receive a Canadian objection with no information provided by the FCC. These objections are based on harmful interference anticipated to the protected operations.