Still don't really see how they both lost their lives, from the description sounded like a suitable landing site where a landing could have been made where perhaps they could have walked away with minor injuries, or possibly serious injury, but fatal injury is very unexpected in this circumstance.
Sounds like the landing was attempted on quite a steep up-slope. I've never done it, but I read that landing at some strips in the Alps is a whole new experience as the aircraft has to be flared uphill (and likely under power) to effect a controlled landing.
Sadly this accident appears to be a stark reminder of the need to be attentive to in-flight checks.