The Federal Aviation Regulation Part 77, abbreviated as FAR Part 77 “establishes standards for determining obstructions in navigable airspace” (FAA 1). This includes the evaluation of the impact of alteration or construction on operating procedures, the determination of potential hazardous impact of proposed construction or alteration on air navigation, the identification of mitigation measures to ensure safe air navigation and charting of new objects. The Airport Operations conducts daily inspections to ensure that every imaginary surface has specific orientations and dimensions, to look for new construction, cranes etc, and to pilot expectations to trust and safety. Thus, FAR Part 77 allows the “Federal Aviation Administration (FAA) to identify possible aeronautical hazards prior, in order to minimize or prevent the adverse effects to the efficient and safe use of navigable airspace” (FAA 1).
The various imaginary surfaces include primary, approach, transitional, horizontal and conical. Primary protects the runway surface and its dimensions are 1000 feet wide and 200 feet beyond the threshold bars of each side of the runway. Approach protects the approach end of the runway and its dimensions are either a 50:1 or 20:1 slope depending on the type of runway. This can either be precision or non-precision. Transitional protects the downwind/upwind sides of the runway and has a 7:1 slope outward from the runway centerline. Horizontal protects the airspace above the runway and surrounding areas and its dimensions are 150 feet above the ground and 10,000 foot diameter circles above both runway thresholds with a line connecting both tangents. This is illustrated in the diagram below. Conical protects a larger surrounding area in the airspace above and around the runway, and it is a 20:1 surface that sits on top of the Horizontal surface (FAA 1).
Usually, obstructions can penetrate a Part 77 surface. An object constitutes an obstruction to navigation if: it is 200 feet above ground level or 200 feet above the airport elevation, up to 3 miles from the airport (this increases 100 feet every mile up to 500 feet at 6 miles from the airport reference point); it is 500 feet or more above ground level at the object site; it penetrates an imaginary surface and; it penetrates the terminal obstacle clearance area. Before the start date of a proposed construction or alteration, the Notice of Proposed Construction or Alteration, also called Form 7460-1, must be submitted 45 days before this start date. This form records details such as: the company name and project location; whether it is a new construction, alteration or existing; the duration of construction; the type of construction e.g. antenna tower, building of crane; marking and lighting of obstruction; GPS coordinates; MSL of site location; total structure height and; description of project. After the submission of this form, the FAA studies and reviews the impact on the surrounding areas (FAA 1).
NOTAM is an acronym that stands for a Notice to Airmen. NOTAMs contain information that concerns the condition, establishment or change in any component, the timely knowledge of which is critical to personnel involved with flight operations. Usually, this information is not sufficiently known in advance and thus it is crucial in alerting pilots of any possible hazards along a certain flight route that can have an impact on the flight’s safety. According to Chambers (1), certain reasons warrant NOTAMs: hazards such as parachute jumps, rocket launches, kite flying and air shows; flights by important people such as presidents; closed runways; military exercises; inoperable radio navigation aids; inoperable lights on tall obstructions; passage of flocks of birds through the airspace and; temporary obstacle erection near airfields. As such, there are different types of NOTAMs.
Works Cited
Chambers, Dan. What is a NOTAM? Aviator, 12 Feb. 2010. Web. 31 May 2013.
Federal Aviation Administration. Obstruction Evaluation/Airport Airspace Analysis. FAA, 18 Jan. 2011. Web. 31 May 2013.
