Airport Obstruction Chart (OC Series)Map cabinet 4, drawers 2-11. Not cataloged - unfolded/flat - no barcodes. 1:12,000-scale graphics showing airport obstruction information, FAR Part 77 surfaces, runways, taxiways and apron areas, air navigation facilities, and selected planimetric details. The AOC provides data for computing maximum take-off and landing weights, for establishing instrument approach and departure procedures, for engineering studies relative to obstruction clearance and improvements in airport facilities. Sudoc C 55.411/3: date