Page:NTSB Southern Airways Flight 932 report.pdf/13

 marker and middle marker were located 4.6 and 0.6 miles, respectively, from the runway threshold. The Localizer was offset approximately 0.07° to the south of the runway centerline. The offset was accomplished to place the antenna on stable ground where the electronic signal would remain within tolerances. A flight check of the facilities was accomplished by the Federal Aviation Administration (FAA) on November 15, 1970, and all were found satisfactory.

An instrument landing system was scheduled for installation and commissioning at the Tri-State Airport in June 1958. The localizer, middle marker, and outer marker installations were completed at that time, but there was insufficient terrain to provide adequate reflecting surface for the glide-slope antenna, within the existing criteria. Three applications for runway extension, which would also provide suitable terrain for the glide-slope antenna, were submitted to the FAA in Fiscal Years 1967, 1970 and 1971. The 1967 and 1970 requests were not approved because the necessary "matching funds" from the sponsoring agency were not available, and consequently the Federal funds were not committed. The 1971 request was still under consideration at the time of the accident.

Subsequent to the accident, concurrent negotiations involving the FAA, West Virginia State Aeronautics Commission, Wilcox Electric Company, Inc., and the Tri-State Airport Authority, resulted in the installation of a nonstandard glide slope for Runway 11, paid for by Federal funds only. Prior to installation, the FAA estimated that there was a 50 percent probability of success with the glide slope. A Wilcox Mark I, Series 8020 transmitter was placed 1,211 feet south of the runway centerline and 960 feet west of the Runway 29 threshold. The elevation of the site was 805.2 feet m.s.l. and the antenna was rotated 13.5° to align with the middle marker. This offset was required to place the site on suitable terrain, and resulted in an unusable signal below 1,075 feet m.s.l. Consequently, there was no reduction in the minimum altitude authorized for the instrument approach. However, the signal generating capability of the facility to date has been as reliable as the standard systems.

1.9 Communications

There were no known difficulties with radio communications.

1.10 Aerodrome and Ground Facilities

The Tri-State Airport was located on a hilltop approximately 2.5 miles southwest of Huntington, West Virginia, at an elevation of 828 feet - 9 -