THE METEOROLOGICAL PREPARATION (OR RATHER THE UNPREPARATION).
Given the many uncertainties and complications during the preparation of the expedition, which was almost abandoned a few weeks before departure, we set off rather unprepared to go “fighting the volcanic thermals”, however taking two precautions: check the ground winds in Calama and reach an agreement with Matthew Scutter, “Mister” SkySight.
The figure below shows the wind rose at Calama Airport for the month of November 2018. October and December are similar. The east wind is the descending breeze from 10 pm to 10 am and the west wind is the rising breeze from 10 am to 10 pm. I was expecting that 20 to 25 kt of wind for half the day could suggest interesting dynamic systems if this breeze reached volcanoes, 120 km apart.
On the other hand, the morning downward breeze would have forced us to take off in the upward direction, with 60 m height difference along the runway. Given the altitude (2,300 m MSL), our small Limbach carburetor engine and the fact that the thermal activity was not yet established, we gave up and always waited for the west breeze. On the other hand, the 25-30 kt breeze was there against us every evening when we returned back home and the rule to maintain 25 L/D on the final glide saved us a lot of fright because the last 100 kilometers are totally unlandable, photo below.
On the final glide 100 km from home, Calama. Terrain neither landable nor crashable, so do not start with more than 25 L/D required. Otherwise it will be San Pedro nearby.