I followed these threads back in December and posted something similar much earlier which is probably lost in the conversation and more details have emerged since then including Dan Colegate's dossier which does give a lot of detail. I am struck by his high level of confidence in her abilities and given his close relationship with her and her experience it is hard to argue that this is correct but experience can also lead to actions/behaviour outside of what others would feel is a comfortable level of risk.
He says that if she had left the area of no mobile signal (near Pic de Sauvegarde) without problems she would have contacted someone on 23rd November, the day after she last made contact on 22nd November. His dossier also gives an estimate of the extent of mobile phone signal, presumably from his observations (though I would not rely on this too precisely as UHF cellular phone signal propagation is affected by things that vary day to day and minute-to-minute such as weather/humidity). In any case, she had been walking at that point for several days and it is perfectly plausible her battery pack was low or it might have even run out on the night of 22nd November making communication on 23rd impossible. Phone batteries and battery packs are notoriously problematic in cold weather. Given that the Pic de Sauvegarde area, and the area around the Refuge de Venasque was very closely searched (perhaps with the exception of the water in the lakes), it is less likely she is there though not impossible. Foul play ( in that area )seems unlikely as she would have probably have been found.
It seems likely that ED planned to descend towards the Hospice de France direction (North by North East) from the Refuge de Venasque at some point and it is perfectly plausible to me given her high level of fitness that on descending from the Pic de Sauvegarde on 22nd she reached the Refuge de Venasque quite early in the evening on 22nd and may have decided to progress further and camp further down near Hospice de France that same evening. Perhaps she just didn't fancy staying the night in the mountains on her own (I certainly wouldn't) or became unnerved by lack of phone signal at the Refuge de Venasque- bear in mind it was late November.
In any case, whether she stayed at the Refuge de Venasque (no sign reported of this) or camped lower down, it is perfectly plausible that she was up early on 23rd near the Hospice de France and ready to join the Chemin de 'Impeatrice in a generally Westward direction. This area is well described on this link including photos of the route:
Chemin de l'impératrice entre l'hospice de France et le cirque de la Glère AA - ONVQF.over-blog.com (over-blog.com) . This blog contains a very detailed map of the area, and I note terrain on the Chemin is very steep to each side and the blog makes reference to various places where trips/falls are a risk including at some point ropes having been deployed to hold on. There are also some waterfalls near the start of the Chemin. Perhaps she set off early on the 23rd and had an accident on the Chemin de l'Impeatrice before she turned on her phone and touched base with Dan Colegate or her family. Although his dossier says this area was searched, I find it hard to believe that this area further down was searched in detail given that limited time available before the snow started and also the fact that it is a wooded and the steep area means it would be very easy to miss someone. The helicopters used in the search would have been of limited use in this area. Furthermore, the Chemin de L'Impeatrice is quite a long walk to Port de Glere through at least 1600m of wooded area so the search area is quite extensive and I think cannot have been completed to date.
My hypothesis is that she had an accident further along her planned path, perhaps in the area above but there are other possibilities like like foul play or a fall into water at the Refuge de Venasque etc which seem less likely.
