Federal Aviation Administration, DOT Section 171.313 (1) Horizontally within a sector plus or minus 40 degrees about the runway centerline originating at the datum point and extending in the direction of the approach to 20 nautical miles from the runway threshold. The minimum proportional guidance sector must be plus or minus 10 degrees about the run- way centerline. Clearance signals must be used to provide the balance of the required coverage, where the proportional sector is less than plus or minus 40 degrees. When intervening obstacles prevent full coverage, the Section40Section guidance sector can be reduced as required. For systems providing Section60Section lateral guidance VerDate Sep<11>2014 08:20 May 17, 2019 Jkt 247048 PO 00000 Frm 00877 Fmt 8010 Sfmt 8010 Y:\SGML\247048.XXX 247048 EC15SE91.014 867