According to the video in the link, looks like the DC-3 (may) have suffered a radio compass failure which -may- have caused, or helped cause, a CFIT during IMC. The official verdict, way back when, gave the pilots 100% of the blame. Hopefully this recent find will shed some light on exactly what happened...
http://www.yahoo.com/news/video/man-...covers-70-old-plane-225014379.html
Article quote:
"A California man who spent months searching for the wreckage of an American Airlines plane that crashed in the San Diego mountains in 1946 has stumbled onto a key piece of history."