This thread seems to focus on errors in aeronautical decision making committed by "PPL's." One only need read a reasonable number of accident reports to observe that those with CPL and ATPL are having difficulties with ADM, not only with respect to IIMC, but many other issues as well (but hopefully to a lesser degree). At risk of being acused of thread creep (and possibly other serious transgressions), here is a link to a recent NTSB investigation which drives this home in a compelling way. This is a plank accident but, highly relevant when we are trying to better understand failures in ADM. The report is long and somewhat repetitive, but an education and then some. For those not inclined to read it, a brief summary:
1. the pilot held an ATP certificate, was ex-military and ex-airline, and had 2000+ hours in make/model (Pilatus PC-12). He had recent recurrent make/model training and an otherwise unblemished flying record over about 40 years.
2. He made a choice to operate the accident aircraft with 14 people on board (certified for a maximum of 11, and in this case, equipped with 10 seats/seat belts), at almost 600 lbs above max gross weight, and did not add fuel anti icing agent (FSII) as required by the AFM. Furthermore, the accident flight was not the first time he made these choices.
He killed himself an 13 others as a result of these decisions. I would agree with others here that pilots with limited experience often dont know what they dont know. This was not a case of not knowing better. Why did he choose the course of action that he did?
NTSB report here:
http://www.ntsb.gov/doclib/reports/2011/AAR1105.pdf