Page:CAB Accident Report, Southeast Airlines Flight 308.pdf/11

- 11 - Several other factors have been considered by the Board as equally important in the analysis of this accident. First, company regulations specifically require an operable ADF for all flights dispatched in accordance with instrument flight rules. Next, the operations specifications issued by the Administrator, Federal Aviation Agency, clearly set out the equipment requirements for an ILS approach procedure: "... (a) An ILS instrument approach procedure for the purpose of conducting a straight-in approach to the ILS runway is authorised if (1) no more than one component of the ILS (other than the localizer) is inoperative or the signals therefrom cannot be received (2) all other components of the ILS and related airborne equipment are in normal operation ... (b) an ILS instrument approach procedure for the purpose of conducting a straight-in approach to the ILS runway is authorized if (1) the localizer and either the outer marker or outer compass locator and related airborne equipment are in normal operation...

It is impossible to rationalize the pilot's thoughts concerning the absence of outer marker and glide slope indications. He may have believed either of the facilities (including ground or airborne equipment) inoperable. The Operations Specifications issued by the Administrator of the Federal Aviation Agency clearly limit the use of the ILS to facilities in which both functions are operable. Accordingly, it would have been necessary that the approach be abandoned. On the other hand, had he considered that both functions were operating satisfactorily he had no alternative but to conclude he was too far east of the outer marker to have used the minimum altitude specified for a procedure turn within 5 miles of the outer marker.

Conclusions

On the basis of all the evidence, the Board concludes that the radio compass (ADF) was inoperative and could not be used either for navigation along the low frequency radio range or receive the compass locators associated with the ILS. Further, the Board believes this condition was known to the crew at Nashville. It is also obvious that they did not use the other low frequency receiver aboard the aircraft because the flight was not on Green Airway 5 as it neared Tri-City. As stated before, the Board believes that the 65-degree radial of the Knoxville VOR was used to navigate to Tri-City and was also used to locate Gray intersection. It is concluded that the flight was east of its intended course and reported as being over Gray when it was actually several miles east of Gray. This conclusion is inescapable in view of all the known facts.

The Board further concludes that the crew, without realizing their actual position, followed the usual procedure for intercepting the localiser and in so doing passed to the south and east of the outer marker. After missing the outer marker, the only way position along the localizer could have been determined was by means of the Tri-City VOR. It is evident that the crew did not use this facility as an aid in the procedure.

A faulty indication or malfunction of equipment could not be used to mitigate the pilot's responsibility in these circumstances. Several additional facilities were available for a cross-check if in his mind he thought the outer marker or the marker beacon receiver was inoperative.

One of the provisions in the operations specifications issued to the company by the FAA clearly establishes the conditions under which an ILS can