Additional engines don't prevent CFIT, never will.
Additional crew helps a lot, provided there is no steep gradient in the cockpit between you and an indigenous air race world champion holding a CPL(A), CPL(H) (rated for AS350, BO105,R66) and entitled to NVFR.
Following applicatble regulations/permits would have prevented this 100%:
The off airfield takeoff and landing permit was issued for
- a maximum of 3 takeoffs and landings between 2016-07-15 and 2016-09-15
- at that mountain hut only
- and valid only between 07:30 and 14:00(!).
So the nightly departure (1h past ECET) was unauthorized. Specifying a bogus departure location on the flight plan further adds some sour taste, sounding like conserving on remaining allowed rides to the hut.
Especially sad, as there was time enough to take off before 14:00 lct, thereby complying with all regs. and avoiding mountain NVFR.