Obstruction Analysis & Airport Airspace Analysis
Airspace Protected Surfaces
FAR Part 77 - Safe, Efficient Use, and Preservation of the Navigable Airspace
77.9 Construction or Alteration Requiring Notice
77.17 Obstruction Standards
77.19 Civil Airport Imaginary Surfaces
77.19 (a) Horizontal Surface: Horizontal plane 150 ft. above the established airport elevation. Constructed by swinging arcs around the end of the primary surface.
77.19 (b) Conical Surface: 20:1 slope surface extending beyond the horizontal surface.
77.19 (c) Primary Surface: Aligned longitudinally with each runway and extends 200 ft. from each runway end.
77.19 (d) Approach Surface: Longitudinally centered with the runway and extends beyond the primary surface.
77.19 (c) Transitional Surface: Constructed to join approach and horizontal or approach and transitional surfaces.
77.21 Department of Defense (DOD) Airport Imaginary Surfaces
77.21 (a) (1) Inner Horizontal Surface: Horizontal plane 150 ft. above the established airport elevation, constructed by swinging arcs around the end of the primary surface.
77.21 (a) (2) Conical Surface: 20:1 slope surface extending beyond the horizontal surface.
77.21 (a) (3) Outer Horizontal Surface: Horizontal plane 500 ft. above the established airport elevation, constructed by swinging arcs around the end of the conical surface.
77.21 (b) (1) Primary Surface: Aligned longitudinally with each runway with a width of 2,000 ft.
77.21 (b) (2) Clear Zone Surface: A surface located on the ground or water at each end of the primary surface, with a length of 1,000 feet and the same width as the primary surface.
77.21 (b) (3) Approach Clearance Surface: Longitudinally centered with the runway and extends beyond the primary surface.
77.21 (b) (4) Transitional Surface: Constructed to join approach and horizontal or approach and transitional surfaces.
77.23 Heliport Imaginary Surfaces
77.23 (a) Primary Surface: The area of the primary surface coincides in size and shape with the designated take-off and landing area.
77.23 (b) Approach Surface: The approach surface begins at each end of the heliport primary surface with the same width as the primary surface, and extends outward and upward.
77.23 (c) Transitional Surface: These surfaces extend outward and upward from the lateral boundaries of the primary surface and from the approach surfaces.
Terminal Instrument Procedures (TERPS)
The purpose of the United States Standard for Terminal Instrument Procedures is to prescribe the criteria for the formulation, review, approval, and publishing of procedures for IFR (Instrument Flight Rules) operations to and from civil and military airports.
TERPS criteria have been established for the following Instrument Procedures: Precision Approach (PAR, ILS, MLS), Non-Precision Approach (VOR, TACAN, LNAV, NDB, ASR), Approach with Vertical Guidance (LDA, LPV, VNAV), Required Navigation Performance (RNP) and for Departure Procedures (DP).
The key considerations for developing Terminal Instrument Approach and Departure Procedures include but are not limited to, existing obstructions, ground/satellite-based equipment, lighting, and aircraft category.
TERPS criteria specify the minimum measure of obstacle clearance that is considered by the Federal Aviation Administration (FAA) to supply a satisfactory level of vertical protection from obstructions and are predicated on normal aircraft operations.
Understanding the complexities of Terminal Instrument Procedures is difficult since it is a highly specialized field requiring directed study and/or experience in its applications.
An individual or company that has a requirement for outside expertise in this arena should engage an aviation consultant who has extensive expertise in developing innovative and workable solutions in the TERPS area of expertise.
Our Consultants has successfully received favorable determinations from the FAA for our clients who had previously received a Notice of Presumed Hazard or a Determination of Hazard due to IFR impacts.