To learn from this ...
... I'm not sure if it is something generally taught or even talked about, but something I was told very early on; always cross wires at a pylon.
Of course in this incident they may not have seen the power lines or pylons. In the vid linked to below, from 1:00 the Director of Firemen tells us that it was the third time they had flown that route.
Four dead in helicopter crash near Mt. Signal - KYMA