GETTING THERE: Vail is 85 miles, and Aspen 160 miles, west of Denver. Both are served by Rocky Mountain Airways operating as Continental Express. Aspen Airways, operating as United Express, also serves its namesake.

Bus service to both from the Denver airport is provided by several companies, including Airport Transportation Service (1-800-247-7074) and Colorado Ground Transportation Center (1-800-824-1104).

WHERE TO STAY: Since Aspen and Vail are major resort centers, both have a vast array of lodging. The Aspen Resort Association (1-303-925-1940) and the Vail Resort Association (1-800-525-3875 or 1-303-476-5677) can provide information.

We stayed at a place not included in the Aspen listings, the T-Lazy-7 Ranch (1-303-925-7254), a delightful, inexpensive and totally unpretentious place a few miles up Maroon Creek. Rates range from $50 (for one person) to $175 (for 10) per night.

INFORMATION AND RESERVATIONS: The Tenth Mountain Trail Association (1280 Ute Ave., Aspen, Colo. 81611, 1-303-925-5775) operates the hut system. Huts cost $14, and the inn $18, per person per night. The hut season runs from Thanksgiving Day through April.

Space at the huts and the privately operated Polar Star Inn must be reserved in advance through the association. For the first time this year, the association is accepting reservations for future seasons.

Many weekend and holiday periods are already booked for this season, but various guide services have blocks of time set aside for them. And plenty of weekday space -- and some weekend time, particularly during December and April -- is available.

The TMTA also has detailed maps of the routes available.

Hours: 8 a.m. to noon, Monday through Saturday.

The Diamond J Guest Ranch (26604 Frying Pan Rd., Meredith, Colo. 81642, 1-303-927-3222) is the usual overnight stop between Margy's hut and the Gates hut. It has nine rooms in a lodge, five cabins that sleep six and three cabins that sleep two. Lodging is $18 per person if you use your own sleeping bag, with a pillowcase and towels furnished, or $22 with all linen furnished. There is a four-person or a two-person minimum charge for the cabins.

Buffet meals are available and the large cabins have cooking facilities.

Arrangements can be made to have small amounts of equipment or food taken between the ranch and Glenwood Springs, a town between Aspen and Vail, reducing what you have to carry on the trail itself.

GUIDES: Among the companies that provide guide services to the huts:

Ute Mountaineer, 308 South Mill St., Aspen, Colo. 81611, 1-303-925-2849. Provides guide service for one- to seven-day trips for clients who want to do more on their own at somewhat lower cost.

Food is not included, and clients must carry their own sleeping bags.

The cost of a guide for a one-day, one-way trip is $125 for a group of up to seven people, not including the cost of the hut. With the hut included, the price for a two-day, one-night trip is $205 for one person, $260 for two and $100 per person for three or more, up to a maximum of seven. The cost of its longest trip, seven days and six nights, is $960 for one, $1,050 for two and $385 each for three or more.

Ute Mountaineer has scheduled five four-day, two six-day and two seven-day trips. The cost of lodging and food at the Diamond J Ranch is included in the above figures for trips that utilize it.

Guides are available at other times if you have your own hut reservations. Transportation is provided back to the starting point. Rental equipment, including skis, boots, poles, packs and sleeping bags, is available.

Paragon Guides, P.O. Box 130, Vail, Colo. 81658, 1-303-949-4272. Provides three- to six-day trips, including food and sleeping bags already at the huts, so that clients can carry lighter, smaller packs on the way.

A three-day trip costs $360 per person and does not vary with the size of the party. Five-day trips are $620 per person and six-day trips $770, all including the cost of the huts and the Diamond J Ranch. There are six three-day, four five-day and 14 six-day trips scheduled.

The costs of trips held early and late in the season are reduced by 15 percent.

Transportation is provided back to the starting point. Rental equipment, including skis, boots, poles, packs and sleeping bags, is available.

Rocky Mountain Climbing School, P.O. Box 2432, Aspen, Colo. 81611, 1-303-925-7625. Specializes in providing guides for individually arranged trips, including a one-way guiding to a hut. However, it also has a few scheduled group trips.

Its fees cover the guide, food, lodging and transportation.

Diamond J Guest Ranch, 26604 Frying Pan Rd., Meredith, Colo. 81642, 1-303-927-3222. The Diamond J has one three-day, one four-day and one six-day trip scheduled, at a per-person cost, respectively, of $250, $325 and $420. It also has weekend cross-country ski clinics in December and February for $125 per person, including food and lodging at the ranch. Their guide also is available for other individually arranged trips.

BOOKS: The following books are available from Recreational Equipment Inc. in College Park, 982-9681.

"Colorado High Routes," by Louis W. Dawson II, published by The Mountaineers in Seattle, provides maps and detailed description of the Tenth Mountain Trail, plus dozens of other routes in the vicinity of Crested Butte, Aspen and Vail. It also has a useful chapter on skier safety and equipment for back-country trips.

"Avalanche Safety for Skiers & Climbers," by Tony Daffern, published by Alpenbooks in Seattle, is a highly readable and essential book for anyone venturing into the mountains in winter. It describes snow in its myriad forms, what happens to it once it is on the ground and just how much of a threat it can be to an unwary back-country traveler when it starts to slide. Even a tiny avalanche can trap a skier who, if not killed outright, is unlikely to survive buried for more than half an hour. The book tells you what to watch for and how to minimize the danger -- including turning back if necessary.