IMHO the backpack was big and heavily loaded because she carried a sleeping bag, sleeping pad and a tent, plus food to stay overnight in the mountains. On their blog, there are pictures of the sleeping bag during the previous days, it is big, it looks comfy and makes me wonder how one rolls it up.
The key to what happened may be in the fact that she asked the Spanish hikers for a piece of fruit. This could be an indication that her glycogen levels were getting low, causing fatigue and loss of energy. Also known as hitting the wall, or the man with the hammer. If so, everything wasn't going as well as it should have been, and she better would have taken a rest, eaten some food and then gone back.
Instead she continued for an hour and 20 minutes (estimate of the Spanish hiker) and stretched herself. Perhaps too much.
This scenario could well lead to an accident, probably a fall. Depending where she was, she might have gone into the water / under the ice with full gear. That's how she never reached the Refuge in France. If she had set up her tent and camped nearby, the tent would have been found.
It sounds like there are some questions in here along with some great points, so let me try to clarify.
-regarding the "big backpack". This could be a confusing observation because backpack size can be in the eyes of the beholder and it can also depend on the build of the person wearing it. In the scheme of things, ED doesn't have an especially large overnight backpack, and it's not a heavy model. Size is not noteworthy, in other words. It would just be a signifier of staying out overnight and not a day hike.
-it looked to me that she had an ultralight sleeping bag (yellow and black). I know it's in that category, because you can see the down fluff balls through they yellow fabric. Very expensive! This sleeping bag would compress very small. It would weigh, max, 2 lbs at a rating suitable for that location and date. I reckon it would stuff down to a 10"-11" tube of 6" diameter. The tube would be lying horizontally in the bottom of her pack.
-the pad ED has is a Cascade Designs ultralight inflatable. There are several models, and they pack up tiny. A tube 5" long x2" diameter may be about right.
-she evidently owned a tent, but she might not have had it with her if she was planning to stay at a refuge
-hopefully, she had long underwear, raingear, spare socks, and some extra layers in the pack. I get nervous when I see yoga pants for hiking, because there's no insulation or wind break.
ED's pack seems to be 58 liters. All the stuff I've mentioned here, plus food, water, water treatment, stove, pot, gas, would be <40 liters
The pack is not heavy. I can tell by how it works on her back. It's not making her stoop. It only weighs 20-25lbs. IMO
Is there a pool of water on the way down to the Refuge? I'm thinking she might have fallen in while trying to fill a water bottle.
