Using gnomonic tracking chart WOXZC 5270, determine which of the following statements about a voyage from San Francisco to San Bernardino Strait (LAT 13°00'N, LONG 125°30'E) is TRUE.

Correct Answer: Option B — You will cross the Northern Hemisphere vertex at the approximate longitude of 159°W.

On a gnomonic chart, the great circle track is a straight line. By plotting the route from San Francisco to the San Bernardino Strait, the track line crosses the vertex of the great circle. The longitude of this vertex is approximately 159°W, which is a standard navigational reference point.