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OBSTRUCTION IDENTIFICATION SURFACES
FEDERAL AVIATION REGULATIONS PART 77
DIM ITEM DIMENSIONAL STANDARDS (FEET)
VISUAL RUNWAY NON - PRECISION
INSTRUMENT RUNWAY		 PRECISION
INSTRUMENT
RUNWAY
A B A B
C D
A WIDTH OF PRIMARY SURFACE AND APPROACH SURFACE WIDTH AT INNER END 250 500 500 500 1,000 1,000
B RADIUS OF HORIZONTAL SURFACE 5,000 5,000 5,000 10,000 10,000 10,000


VISUAL
APPROACH		 NON - PRECISION
INSTRUMENT APPROACH		 PRECISION
INSTRUMENT
APPROACH
A B
A B C D
C APPROACH SURFACE WIDTH AT END 1,250 1,500 2,000 3,500 4,000 16,000
D APPROACH SURFACE LENGTH 5,000 5,000 5,000 10,000 10,000 *
E APPROACH SLOPE 20:1 20:1 20:1 34:1 34:1 *
  • A - UTILITY RUNWAYS
  • B - RUNWAYS LARGER THAN UTILITY
  • C - VISIBILITY MINIMUMS GREATER THAN 3/4 MILE
  • D - VISIBILITY MINIMUMS AS LOW AS 3/4 MILE
  • * - PRECISION INSTRUMENT APPROACH SLOPE IS 50:1 FOR INNER 10,000 FEET AND 40:1 FOR AN ADDITIONAL 40,000 FEET

    3D-Diagram of FAR Part-77 surfaces