LAX
The first answer is LAX. Trace LAX from row 2, column 7 straight down through row 3, column 7 and finish at row 4, column 7. The letters read L, A, X, and the route stays in column 7 for all three cells.
For a precise check, use this sequence: 1 at row 2, column 7; 2 at row 3, column 7; 3 at row 4, column 7. It has no turns, begins on an open cell with two open orthogonal neighbors, and ends on one with three.