D2.5 Skier remote trigger in isolated location, estimated remote trigger on switch back while on uptrack. 3 skiers had descended (lookers left) 5-10 min prior to avalanche. Most likely failed on old Jan facets. This is the "Deep Persistent Slab" we have been talking about for weeks. Notice the sympathetic avalanche lookers left of the slab. Low probability/high consequence. Let's ask ourselves, "Is my safe zone really a safe zone?"