In the weather condition you see on that pic (sunny, a litle snow blowing,) We often get what we call snow blind, That is when we canīt tell the differense between snow and the sky (you just see white) sometimes this happens suddenly and you donīt realise it untill the truck is in the air. We are werry often driving on 60-80 km/prh so when this happens in these contisions things like this often happen. I belive that is what happened there......
This was just an accident.