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After reporting Rochelle and turning to the southwest heading it is likely that both pilots believed the aircraft was describing a groundpath west of, but only a short distance west of, the normal track from Rochelle to the Charlottesville homer. It is the Board's opinion that at this time the flight was, in fact, 13 miles northwest of Rochelle. While this position was only two to three miles farther than Rochelle from the Casanova omni, the position placed the southwest course of the flight eight to nine miles west of the specified track. The location also positioned the flight about 10 miles farther from the homer facilities than from the Rochelle intersection.
It is believed that this latter factor could work to obscure the lateral error which existed during the southwest portion of the flightpath. The greater distance from the Signal source would reduce the angular displacement of the ADF presentation. Thus, if the aircraft was pos1tioned 10 miles farther from the Signal source than it was believed to be by its pilots, the angular deflection of the ADF presentation caused by the lateral course error could be obscured considerably by the greater distance. For example, the ADF presentation 2h miles from.the Signal source and eight to nine miles west of track is not alarmingly different than the presentation 12 miles from the Signal source and three miles west of the prescribed track. Similarly, the ADF presentation 19 miles from the Signal source and eight to nine miles west of track is not alarmingly different than the presentation seven miles from the Signal source and three miles west of the track desired. In addition, as the flight progressed toward the facilities but from a greater distance than believed by the pilots, the increa51ng angular displacement of the ADF needles showing lateral error could be interpreted as a closure on the Signal source. The Board believes the foregoing discussion to be a valid consideration in the reason that the pilots were not alerted early in the approach to the large lateral track error.
On the other hand, the Board 15 aware that as the flight proceeded on the southwest course the rate of progression of the ADF needles to the left 90—degree steam indication would have been much slower as the result of the greater distance and time to be flown. At the 90—degree position the angular spread between the needles would.have been much narrower 9 to 10 Miles west of the homers than three to four miles west of the homers. Further, 90 degrees abeam of the Signal source, a 20-degree relative bearing change on a flightpath three to four miles west of the homer, would take 30 to ho seconds as contrasted to approximately 1—1/2 minutes on a flightpath about nine miles West of the homer. In addition, the ADF presentation during the period the flight turned from the southwest heading until it struck the mountain would have been incompatible with a close-in position. The Board believes that these factors should have served to alert an attentive pilot that the lateral course error Was of considerable magnitude.
During the course of the investigation the aeronautical history of Captain Lavrinc was reviewed. His training, qualifications, and proficiency reports were satisfactory. His history showed that he had progressed normally to captain and had served in that capacity Since may 1957. It also showed that he had flown in and out of Charlottesville and over the route involved for several years on a regular basis. Captain Lavrinc had flown a total of 5,101 hours, of which 4,77l were in DC—3 aircraft.
