On 15 August your 0512 zone time position was LAT 29°18.0'N, LONG 57°24.0'W. Your vessel was steaming on course 262°T at a speed of 20.0 knots. An observation of the Sun's lower limb was made at 0824 ZT. The chronometer read 00h 22m 24s and was slow 01m 34s. The observed altitude (Ho) was 38°16.7'. LAN occurred at 1204 zone time. The observed altitude (Ho) was 74°58.0'. What was the longitude of your 1204 zone time running fix?

Question

On 15 August your 0512 zone time position was LAT 29&deg;18.0'N, LONG 57&deg;24.0'W. Your vessel was steaming on course 262&deg;T at a speed of 20.0 knots. An observation of the Sun's lower limb was made at 0824 ZT. The chronometer read 00h 22m 24s and was slow 01m 34s. The observed altitude (Ho) was 38&deg;16.7'. LAN occurred at 1204 zone time. The observed altitude (Ho) was 74&deg;58.0'. What was the longitude of your 1204 zone time running fix?

Accepted Answer

Option C: LONG 59&deg;58.5'W. Running fix longitude combines dead reckoning advance with celestial line of position intercepts. Time elapsed between the morning sight and LAN, multiplied by vessel speed and adjusted for course, establishes the precise meridian passage longitude.