I believe some avionics engineers at ERAU in Florida did some research into this a few years back. I'll see if I can locate anything about it and post a link here if I do.
Didn't find quite what I was looking for, but here is a page with some interesting reading-including a couple of very telling in-flight occurences. A professor Helfrick at ERAU is named, so I guess thats what I was remembering.
http://www.airnig.co.uk/emi.htm
I'll have another look when I have more time.