2sticks has posted just below re Paraguayan accident, perhaps the threads could be combined. In any event here is a quote from the article he linked to it. Sums this thread up quite nicely.
One report from neighbouring Argentina says that the planned departure time for the R44 of 7.15pm was put back to 9.00pm and that the pilot had raised two objections to flying - firstly that the R44 was not suitably equipped for night flight, and secondly that there was an approaching storm front between the departure point at Concepcion and the intended destination at Asuncion. The report goes on to say that Oviedo insisted that the flight went ahead. The wreckage was found the following day.