4,000 A D 7:1 7:1 A C 7:1 E 7:1 B 50:1 7:1 7:1 7:1 E 7:1 7:1 7:1 HORIZONTAL SURFACE 150 FEET ABOVE ESTABLISHED AIRPORT ELEVATION 20-1 CONICAL SURFACE 40:1 7:1 FAR part 77 imaginary surfaces. 7:1 40:1 7:1 7:1 FIGURE 6-25 5,000 A 16,000 5,000 219