The three echoes are not in line (relative bearings 282°, 283° and 270°): the CPA depends on which echoes you use (about 0.45 M with the first two, 1.69 M with the first and last, 2.49 M with the last two). Here the first and last echoes are used.
Head Up display, 10-mile range scale. Your ship steers 355° at 20 knots. A target appears at 2050 at 9.2 M, relative bearing 282°; at 2056 at 6.8 M, 283°; at 2102 at 4.4 M, 270°. What is the CPA and when is it reached? What are the target's course and speed?
- Display
- Head Up, own heading 355°, 20 kn
- Echo at 2050
- 9.2 NM, 282° relative
- Echo at 2056
- 6.8 NM, 283° relative
- Echo at 2102
- 4.4 NM, 270° relative
Solution worked out by us from the course material: to be checked by the instructor.