The way up AKA where the Fire Warden meets the AT
The first couple miles are a pretty easy grade amongst a mix of beautiful deciduous trees. There are a few bog bridges over mud and small run off water crossings. Careful as they are slick.
After 1.6 miles the Fire Warden Trail splits. You can continue on the Fire Warden Trail for another 3.0 miles up to the col between West Peak & Avery or you can take the Horns Pond Trail 2.5 miles up and arrive just west of West Peak by .6 miles on the AT. I've not traveled the Horns Pond Trail.
After this junction the trail will begin to climb after about a mile or so. There are beautiful stone "staircases" with water trickling all down them. When you are about a mile from reaching the col there will be tent platforms Moose Falls Tentsite. To the left there will be a small sign that reads "water" but there will be blue blazes that accompany. The blue blazes do not indicate that the trail goes that way - it leads into the alpine area. I've encountered people lost up there before!
Once you reach the col you are now on the Appalachian Trail & the blazes now turn white. To the right you can head up to Avery just .4 miles away. From here are excellent views of the rest of the Bigelow Reserve, Sugarloaf, Flagstaff Lake and on a clear day even Ktaadn! There is a stone building if you keep heading east down the range just a bit.