Earlier in the summer I bought the Garmin Topo Alaska Enhanced map card ($100) from Accupoint in Anchorage and plugged it into my Garmin Oregon 450 (thanks Ken!). A few weeks ago, while on Denali's Whale Tail, I had a chance to test it out.
I have a love/hate relationship with GPS units. I think they detract from geophysical mountain skills of map, altimeter and compass. On the other hand I need every advantage when guiding. Also, it's nice to make progress in a whiteout. After purchasing Alaska Enhanced my question became: could the GPS map take the place of a 1:63,360-scale map printed by the USGS? (Alaska's most detailed maps are 1:63,360.)
I imagined using Alaska Enhanced for tour planning, while in the tent in the backcountry, by creating waypoints on the GPS before heading out into low visibility. The problem was I had too much good weather in Alaska this summer. I did find a whiteout on Mount Logan, but that's in Canada. There I followed waypoints that I entered while on the trail during the ascent.
Then a couple weeks ago we woke to fog soaking our camp on the Whale's Tail. In Alaska. Yes! Sometimes I am so stoked for whiteouts.
During our foggy day on the Whale's Tail we followed a ridgeline for 10 miles with 5,000 feet of ascent. Ridgelines in zero viz are not straightforward. They split, they broaden and become indistinct. All day I kept the GPS hanging around my neck, referring to it constantly to keep us on the ridge. Alaska Enhanced made the day almost a no-brainer and kept our group on the move.
Late August in Alaska means winter is close and termination dust coats the mountains. Termination dust is Alaskan for first snow of the season that terminates summer.
During the day I did go back to my paper map. Part of the ridge was too craggy for hiking and we traversed steep tundra slopes along the side. A cliff appeared in the fog and I consulted the GPS map at right - no cliff. The cliff did show up on the 1:63,360 USGS map with 100 foot contours (left).
When micro-route finding, those minute map details make a huge difference. While Alaska Enhanced is worth every cent, I found it doesn't take the place of the USGS-printed map for complex terrain.