This exit variant simplifies the climb of the last third of the South wall.
From the “Upper Glacier”, instead of going to the right in search of the base of the spur that the French followed in 1954, take a clear left of the visual vertical of the northern peak. In the direction of the “Guanaco” pass that extends between the two peaks of the mountain.
Climb the slopes of ice and snow that lead to an obvious rocky fringe. Slopes from 50° to 55°. The rocky strip is climbed in an ascending traverse to the left, 5 or 6 pitches of mixed terrain, (IV) and some passage of (V). Belay possibilities on natural ledges, poor quality rock. The start, depending on the general snow conditions, can be on very dangerous frozen mud.
The beginning of the slope of ice and terminal snow is thus gained. This large, very open terminal channel has an average slope of 50°. It is dominated to the left by a large hanging serac that is threatening and dangerous in the event of landslides.
Go straight up the great channel to a small rocky barrier (6,700 m), go around it to the left and continue until you reach the “guanaco” crest or summit ridge. From the “Upper Glacier” to the crest about 8-12 hours. It is possible to bivouac in the lateral cracks of the hanging serac (6,650 m). From the starting point to the top there are about 2 hours.
When the conditions of the wall are unfavorable (excessive accumulation of recent snow or, on the contrary, a winter with few snowfalls), the Messner variant is dangerous; Therefore, the original exit/54 is advisable, technically more difficult, but exposed to fewer objective dangers. If the snow is abundant, the dangers of being swept away by an avalanche in the “Messner Canal” are very great. Likewise, when there is little consistent snow that fixes the rocks of the top edge and other upper areas, the channel collects the constant falls of fast projectiles.
Beyond difficulties and dangers, the Messner/74 route is the most elegant route on the southern wall of Aconcagua, after the Slovenian route/82, direct to the southern peak. Plaza Argentina is located at 4,100 meters and is a good place to camp. To access this place, you start from the town of Punta de Vacas (2,400 m) and go up the “de las Vacas” river to the north. There is water and firewood throughout the creek, the path is well marked.
On the orographic right bank of the «de las Vacas» river, 15 km away is the «Casa de las Leñas» refuge (2,350 m). At 31 km (from Punta de Vacas) you cross the river of Las Vacas. Finally, and on the orographic left bank of the same river, rises the small shelter «Casa de piedra» (3,060 m), 47 km from the starting point, just in front of the mouth of the «de los Relinchos» ravine. This small shelter blends in with the landscape and is difficult to find, there is water in the area.