Page:Aviation Accident Report, United Air Lines Flight 4.pdf/12

- 11 - Trips from the east approaching on instruments tune to the Salt Lake Range while approaching Ogden Range Station in order to check the alignment of the north leg of Salt Lake Range. After completing a shuttle on the north leg of the Ogden Range, the approach into Salt Lake is started using the north leg of the Salt Lake Range southbound. Constant back bearings are taken with the ADF tuned to the Ogden Range. At the Layton marker the north Leg of the Salt Lake Range and the south of the Ogden Range are compared. If they coincide, both receivers are tuned to Salt Lake for the remainder of the approach.

It is apparent from the foregoing that whether the approach is started over Salt Lake or over Ogden, the procedure during the latter portion, i.e., from the Layton marker to completion, is the same.

Once the final approach is under way, it is not likely that a pilot deviate in the slightest from the on course signal before becoming contact because of the high terrain which lies to the east. It is almost certain, therefore, that at least until about 10:56 when Trip 4 reported that it had become contact, the airplane was on the north leg of the Salt Lake Range. The apparent normality of the radio contacts up to that time tends to substantiate that conclusion. The north leg of the Salt Lake Range has a magnetic bearing of 150 degrees toward the station. The marks on the ground at the scene of the crash indicated that the airplane's course, at the time of first impact, was about 124 degrees magnetic. In view of the foregoing and of the witnesses' testimony that the airplane appeared to be traveling in a straight line to the southeast, it appears highly probable the course of the airplane was altered by at least 25 degrees to the left very shortly after the trip became contact. The marks on the ground at the scene of the crash indicated that the airplane might have been