VH I don't believe you're asking anything more than the obvious but as usual it is too early to tell and it would be unwise for someone to answer on them at a so early stage
I just got some more info. on the incidents:
No night flight was involved.
The 2 a/c departed IFR from LGKO, destination LGKR.
4XCWO near Korinthos reported urgency and asked permission to return and land in Athens LGAV International which was done with success.
4XCWN continued, and managed to cross Peloponnese with inclement weather conditions though. When CWN was in the area of Kefalonia, it was decided to return and land at Zakinthos LGZA due to weather.
After an hour though the aircraft departed VFR for the 120nm flight to Kerkira LGKR. The departure was at 16.44Z radio contact was lost 7 minutes later and the crash site is some 30nm NW of LGZA inside a ravine of Kefalonia's ~5,600ft high Ainos mountain which rises steeply up from the seashore
Ainos mountain is right on the LGZA-LGKR (direct) route.
Kefalonia has also other rising terrain (of lower peaks) that can "trap" you if you go inland scud running below low cloud on a bad weather day and don't stay over the sea. Even with a route above the sea, but close to the island, there are still terrain traps because of the large Argostoli bay and Ithaka island to the east.
http://www.kefalonia-ithaca-hotels.g..._Map_final.jpg
The weather yesterday was comprising of a NE moving front from SW.
The humidity of the Ionian sea rises on the mountains of the islands, cools and hence brings adverse effects both on the windward & leeward sides.
Greece from above yesterday:
MODIS Rapid Response System Subset - Europe_3_03: 2009/118 - 04/28/09 The front can be clearly seen to the NW over the Ionian sea.
Something else ...
LGZA had the following operations hours for Tuesday 28/4:
03:30-04:30, 07:30-09:00 & 15:00-17:30 UTC
I can only guess that a "contributing factor" for the pilot to depart Zakinthos LGZA is that he did not want to get stranded there because the next day (today) LGZA is open only between 15:30-17:00z (18:30-20:00L) whereas Kerkira LGKR is H24.