Tête du Tronc - Cabane des Aiguilles Rouges - Glacier de Vouasson (3300m)

Summary

Length: 23km
Height difference: 1400m
Duration: Up to 10h depending on conditions
Difficulty: T2 up to the cabane, from then depending on conditions: T2 Maintain trail if no snow, T3 - Challenging mountain hike in snow + Last part T4 Alpine trail - Alpine F (glacier)
Gear: Crampons and hiking poles are needed. Ice axe obligatory.
Directions: Arolla - direction of Cabane des Aiguilles Rouges - Tête du Tronc - Cabane des Aiguilles Rouges - unmarked territory (return along same route)

Notes

A very challenging mountain hike, not only because of the length of the trail but also the height and difficult terrain you encounter. Be sure to start this very early in the morning so you'll have time for the steep ascent to the glacier. 
Along the trail we'll go for an extra summit Tête du Tronc (2554m) before heading towards the Cabane des Aiguilles Rouges (2800m), from the cabane it's climbing untill an unnamed col to rach the glacier.
Optional ascend of the Pointe de Vouasson (T4 - Alpine F glacier trail). 
Optional as a two day hike if you want more time to enjoy everything. Day 1 up to Cabane des Aiguilles Rouges, Day 2 up to the col and back to Arolla. Be sure to make reservation at the hut in this case.

Warnings

Do NOT perform this hike in bad weather conditions, because of the length and altitude of the hike, geting in bad weather can be very dangerous! 
Do NOT try this hike without proper equipment! Crampons and hiking poles/ice axe are a must.
ONLY for experienced hikers with some Alpine experience.

Route

We start at the center of Arolla, we won't follow the normal route along the Kurhaus (we'll do that when we return). Go straight towards Hotel Du Glacier and take the ascending path at your left. After a building go straight ahead into the forest, at the next junction keep left along an ascending trail. A bit further we take a sharp left turn along the grassy slope up the mountain, keep ascending untill you'll reach a junction where we go right. The trail will join the main trail of the normal route, we go right here further ascending. We are almost at Tête du Tronc, a nice little summit with a nice view over Satarma and the valley; it's an optional part of the trail, you can continue towards the Cabane or get a great view. The trail now gets somewhat more rough, we cross two streams and the trail further ascends to the Cabane Des Aiguulles Rouges at an altitude of 2800m. We'll be returning to the cabine, so it's better to keep going and don't lose too much time here. Keep on the trail that goes from the Cabane in northwars direction untill you cross a bridge over a stream. We'll be going left and not the obvious route right that goes down to Lac Bliue, you'll find white/blue/white markings that indicate the start of the Alpine trail in Alpine territory. The trail goes along a maraine ridge and ascends reletively steep up the mountain. The markings will stop when you reach a mountain lake around 3100m altitude. At your left you'll see the Glacier Supèrieure Des Aiguilles Rouges at the same altitude, great views from here. Depending on conditions, the trail turns into snow and ice, get your crampons out before proceeding. Even if the slope isn't covered with snow, there is no markings anymore! If enough hikers have passed through, you'll see the trail in the fine rubble. The glacier where we go to can't be seen untill we reach the unnamed col. In snowy conditions, watch your GPS to stay on trail, sometimes making your own trail through the snow. The col can be easely found so it's easy to keep track on the destination. Because of the altitude, the relatively steep slope makes it a breathtaking climb towards the col, but once you'll reach the col the view gets great. From the col the big Glacier de Vouasson lies in front of you and looks pretty impressive. The less experienced hiker stops here, the more experienced hiker can read further.
From the col go left up the icy tongue of the glacier and go up and keep going in northwestward direction, this trail is also unmarked and maybe there are footsteps visible in the snow. But be aware, you are walking on a glacier! The glacier has minor crevasses and can can be covered with snow. Be very cautious up here. If all goes well, you'll reach the summit of Pointe de Vouasson (3490m) but that's only for true alpine hikers with experience in this terrain.
The return is along the same trail, first back to the col, from the col back to the Cabane and make sure to rest a bit at the cabane before heading back toward Arolla. From the cabane, keep following the signs in the direction of Arolla.