Tech Center Supports Engineers at Atlanta Hartsfield International Airport

By Rodney C. Guishard

Technical Center Instrument Landing System (ILS) and navigation signal analysis experts Dave Lamb and Huy Dao were called by FAA Atlanta regional engineers to assist in identifying a source of interference to the ILS that supports the new 10-28 runway at Atlanta Hartsfield International Airport. The new airport cannot realize its full capacity unless the interference problem is solved.

Regional engineers were aware of the interference problem and had attributed its likely source to construction related reflecting surfaces. When these surfaces were removed, however, the interference persisted.

Technical Center personnel, along with colleagues from Ohio University were called to Atlanta to work with the FAA field engineers to review and execute a plan of action to identify and rectify the problem. Efforts involved trying to identify offending reflection sources, and where possible, removing or mitigating them.

If this had not been possible, alternative solutions included increasing the number of transmitting antenna array elements or modifying the structure of the reflecting surfaces. Technical Center engineers developed a math based computer model that can replicate expected ILS performance based upon siting characteristics, and is being used to help solve the problem.

As a result of the combined team effort, proximate electrical power lines were identified as the likely source of interference. Center engineers have returned from Atlanta and are currently conducting further analysis and corroborative work to validate the identified interference source.