Page:NTSB Southern Airways Flight 932 report.pdf/37

 for altitude reference -- is not supported by sufficient evidence to be termed a causal factor in this accident.

One final matter, airport facilities, warrants comment. Many of the circumstances of this accident are typical of the approach/landing accidents that occur during nonprecision approaches. As a result, the Board examined the environmental conditions that existed in this case to determine what aids would have assisted the pilot in making a nonprecision approach.

The terrain under the approach path was irregular with numerous hills of varying heights. There were few lights along the approach path excepting those of the refinery which were to the right of the inbound track. The lower clouds were ragged and the restrictions to visibility included darkness, rain, fog, and smoke. The pilot had his barometric altimeter, vertical speed indicator, airspeed indicator, and radio altimeter to aid him in establishing the desired descent profile. However, the pilot had little, if any, information instantly available to him regarding the elevation and character of the terrain below the aircraft or the flightpath related thereto.

External navigational aids used to provide vertical guidance to a pilot during an instrument approach include Precision Approach Radar (PAR), ILS glide slope, and VASI system. There was no PAR installed at Huntington nor was the installation of one under consideration. The FAA policy was to provide VASI systems primarily where no other electronic guidance was either planned or available. Since Huntington had been actively negotiating for a glide slope since 1957 no VASI system was installed. In this case, the VASI system would have been useful if the pilot had been able to see the first 1,500 feet of the runway. However, if the pilot had not visually acquired contact with that much of the runway he would not have been able to use the VASI system for vertical guidance.

It is also possible that the nonstandard glide slope which was installed subsequent to the accident might have prevented this accident in that the pilot would have been provided with a primary electronic indication of his position relative to the desired glide path. This cross-check against the altimeter information available would have alerted the crew to any discrepancy between the intended and actual descent. Additionally, if the aircraft remained on the glide slope, it would have arrived at the MDA approximately 2,500 feet closer to the hill where initial impact occurred, and it would have had to descend at an unusually steep angle of about 10° to strike the trees from that point.