This strenuous circuit-hike provides a great traverse of Carter Dome and Mount Hight in about 10.5 miles with around 3500' of elevation gain. It starts and ends at the Nineteen Mile Brook Trailhead on US16 in Pinkham Notch. See the main page for information on parking passes.
Start from the Nineteen Mile Brook Trailhead (see main page) and ascend the moderate, well-groomed trail along the brook of the same name. After 1.9 miles, you will reach a split and must make a decision. The left fork takes you to the remote Zeta Pass, the right to the more hospitable Carter Notch. Either way will work and you'll be back here eventually.
I'll describe the counter-clockwise loop (heading right to Carter Notch first): Continue up the Nineteen Mile Brook trail to Carter Notch in another 1.8 miles. You quickly break out of trees and pass a pair of very nice ponds on the north. Shortly thereafter you reach the Carter Notch Hut. It is a good place to catch your breath, grab some home-made goodies, and rest your feet (or don crampons if you're doing this in winter).
From the Hut, the Appalachian Trail heads north and south. South lies the killer ascent of Wildcat Mountain. North lies the only slightly less arduous climb up Carter Dome. Head north and climb the mile up to the summit of Carter Dome.
From the summit, you can continue north-east to the impressive summit of Mount Hight or bear left and start the descent. If you try for the second summit, be aware that the trail makes a 90-degree turn to the left at the summit and can be very tricky to find. You should be heading almost due west on leaving the bare summit of Mount Hight in order to regain the trail. There are blazes on the rocks, but this is worthless in the winter or in dense fog.
The trails rejoin shortly before you reach Zeta Pass (if ascending from Zeta Pass, bear left to reach Mount Hight); a small, densely-forested notch between the Carter Dome massif and the tripple-peaked ridge of North-Middle-South Carter. The AT continues northward while the Carter Dome Trail turns left and descends a stream valley to the southwest. This slope is especially prone to blowdowns in the winter and spring and very... interesting... detours may be neccessary to avoid them on the steep side-hills.
Regain the Nineteen Mile Brook Trail and hike out 1.9 miles to the TH.
This is a potentially brutal hike in the winter, but it's only a hike. Snowshoes and crampons may be neccessary in places. Turn back at Carter Notch if the weather looks bad.
Summer is conciderably friendlier but hikers may still encounter unexpectedly cold temperatures on the summits and the weather is famously fickle. Bring extra clothing, food and water. Sturdy hiking shoes/boots are a must.