Description of the Bowman Field Airport Area Safety Program
The LRAA's recent update of the Bowman Field Airport Layout Plan requires this planning document to reflect the traditional airspace protection surfaces established under FAA regulations regarding objects affecting navigable airspace (found at 14 Code of Federal Regulations Part 77). Additional airspace safety requirements - defined as "TERPS," Terminal Instrument Procedures - are also required by FAA to be evaluated in the updated planning process. TERPS are specified in FAA Order 8260.3B and are used to design airport-specific procedures for pilots when they use cockpit instruments (as opposed to visual observation) to fly into and from airports. TERPS is also applied in reverse, as in this case, to evaluate obstructions into airspace that might pose hazards to air navigation under existing or planned instrumentation procedures. The "ideal" minimum take-off gradient for aircraft departures under TERPS is to climb 200 feet for every 6,076 ft. (nautical mile). A 40:1 flight path ratio (flying 40 ft. of horizontal distance for every 1 ft. of vertical distance) from a departure runway end provides the obstruction clearance necessary to meet the 200 ft./nautical mile ideal. (See attached diagram: Airspace Surfaces Profile.) At this climb ratio, for example, at 0.5 miles (2,420 ft.) from a departure runway end, a tree that is more than 60-ft. high would intrude into the TERPS minimum take-off gradient, thus encroaching into the airspace sought to be protected during flights when pilots use cockpit instrumentation, such as low-visibility weather conditions. LRAA hired the Hanson Engineering consulting team in July 2012 to perform an airspace study to identify trees and human-made structures that intrude into airspace heights sought to be protected by TERPS. That study (Airspace Study) is expected to be submitted to the FAA for review in spring 2013. After completion of FAA's review in fall 2013, the FAA will determine which obstructions, if any, pose a "hazard" to air navigation. Then, in consultation with the FAA and the public, alternatives that "mitigate" any hazardous intrusions into the TERPS obstacle clearance surface (OCS) will be evaluated. Mitigation options could include complete removal of trees, tree trimming, marking or lighting, changing flight departure procedures, raising the height of the OCS, or seeking a waiver of the TERPS requirements from the FAA. See most recently published maps of affected areas and table of direct impact areas (cities, neighborhoods, streets, parks, golf courses): Maps of Affected Areas
Plea For The Trees rough estimate of schedule for Bowman Field Safety Program
Fall 2012: Hanson took aerial photography of the Bowman Field area, as part of the Airspace Study, on September 19; FAA approved after-the-fact Hanson's work plans for the survey.
May 2013: LRAA submit the Obstruction Study to FAA
July 2013: FAA issues a letter to LRAA regarding "obstruction areas" in Big Spring Country Club and giving LRAA the option of revising flight procedures or alternative warning measures. LRAA does not pursue these options.
Fall 2013: LRAA cuts trees in Big Spring Country Club.
First half 2014: FAA initiates the environmental and historic property review - IMPORTANT PUBLIC PARTICIPATION OPPORTUNITY.
Mid-Late 2014: FAA makes a final determination on the Bowman Field Safety Program (i.e., if any obstructions are hazards; if so, how they are mitigated)
Late 2014: LRAA attempts to negotiate mitigation (i.e., tree removal/cutting) and avigation easements with property owners.
For more info see the following links:
Decision makers regarding obstructions into airspace:
FAA, LRAA, and KY Airport Zoning Administrator
Bowman Field Letters to Neighbors:
LRAA issues RFQ (04-09-12); see Request for Qualifications (note: RFQ makes no reference to Section 106 Historic Landscape Review)
LRAA Commitment To Not Acquire Avigation Easements Until Required Studies Done
FAA brochure on "Wide Area Augmentation System" (WAAS)
Additional FAQ, Airspace Surface Diagram, and TERPS Departure Surface Boundaries
Bowman Field Airport Layout Plan (Map with Plan Overlay)
Flight Statistics for 2006-2009
NTSB Bowman Field Incidents Statistics
Tree height has not been a factor ("probable cause") in any of the 29 Bowman Field incidents investigated by the NTSB since 1982 (oldest available data through NTSB database).
Understanding Airspace, Objects, and Their Effects on Airports
(2010 Report Sponsored by FAA)
(This is a lengthy, but reader-friendly, explanation of FAA's multiple standards for airspace protection. Even if you read only the first 24 pages, you'll learn helpful info.)