Grand Turk is sequenced with Sultan Mountain. One-way mileage and elevation gain are measured from the summit of Sultan Mtn. Round-trip mileage and elevation gain assume completion of the sequence.
From the summit of Sultan Mountain, walk south down the ridge that connects over to Grand Turk. The saddle is indicated on the USGS map to be 12,776 ft. Beyond the saddle, the 372 feet of gain to the summit of Grand Turk is a simple walk-up. The entire traverse can be completed in about a half hour and passes over tundra, scree and rubble. Walking is not difficult. The true summit may not be apparent. We just hit both high points to be safe.
For the descent, here's what we did: For the return to the trailhead, we decided to cover some different ground by heading further south. For good measure, we climbed the 13,087 summit. It only required about an additional 15 minutes to do so and it was only as little as 13 ft. from counting. From the top of this summit, we descended the southeast ridge on small scree for a while until we reached more stable tundra, and then continued down the southeast ridge of the peak. At 12,600 ft., we could have contoured over into the basin just north of this ridge, but did not do so because we could not see clearly if we could descend all the way down the basin without contending with a cliff band. As it turned out, we could have done so with no problem, but instead, we hiked on down the southeast ridge until we dropped off it on the north side at 11,900 ft. This took us into a flat area of a basin that would have been flower-filled earlier in the summer, but now, they were all frostbitten.
From this basin, we skirted one group of trees to the north and hiked east-southeast on the grassy slopes down to Sultan Creek. At 10,500 ft., we contoured north, hiked a little north, then cut through or around the trees to the east, passing under the utility line and located the road used to begin the hike. Walk south on back to your vehicle.
Links to other information, routes & trip reports for this peak that may be helpful.