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be executed. Those specifications make it clear that an ILS approach may not be commenced if more than one component of the ILS is inoperative or the signals cannot be received. Here N 18941 could not receive the compass locators and did not receive the outer marker. Although it may have received the glide slope signal it is obvious the crew did not or could not understand the indications.
The foregoing procedures are contained in the operations specifications issued to the carrier by the Administrator of the Federal Aviation Agency in accordance with Part 40.18 of the Civil Air Regulations. This regulation prohibits any operation in violation of these specifications. Part 40.364, moreover, fortifies this provision by requiring that the ILS procedures authorized in these operations specifications be adhered to. A determination as to when a procedure turn may be conducted at Tri-City east of the outer marker within 5 miles cannot be made without identifying the outer marker in passing.
The Board cannot conceive of any justification for the manner in which this flight was conducted. The purpose of the company regulation requiring an operable ADF for IFR flight is to prevent just this type of accident. The Board concludes that the malfunctioning ADF should have been noted in the aircraft log. Ample facilities were available at Nashville and Knoxville for corrective action to be taken before takeoff.
When Captain Gollmier chose to continue the flight in violation of company regulations it would have been expected that he use all other radio equipment available to him. This was not done.
All the radio aids in the Tri-City area are maintained by the Federal Government for the use of all pilots. While the use of all radios may not be mandatory for IFR flight, good operating practices dictate a maximum cross-check of all available facilities. If Flight 308 had utilized either the low frequency receiver on the Tri-City range or the No. 2 navigation receiver on the VOR, this accident would in all probability have been avoided.
Probable Cause
The Board determines the probable cause of this accident was the failure of the pilot to identify Gray intersection properly and his decision to continue on an ILS approach contrary to company and regulatory procedures.
BY THE CIVIL AERONAUTICS BOARD:
/s/ JAMES R. DURFEE
/s/ CHAN GURNEY
/s/ HARMAR D. DENNY
/s/ G. JOSEPH MINETTI
/s/ LOUIS J. HECTOR
