As always, these are only my personal thoughts and are not to be used in any legal manner whatsoever.
Having an interest in air accidents, after having fallen out of the sky many years ago myself, attention was turned to an article in a morning paper (Metro, London edition, Pg1, 16th April 2002). It read.....
That Boeing 767 was somehow too low, and neither the radar chap nor the pilot appeared to know this, or if they did the pilot reportedly only told the passengers to "buckle up" and not assume the brace position. If anything, this substantiates the fact the pilot was not aware of his dangerous altitude (or lack thereof!), or at least until the very last moment.
Is it possible something interfered with the aircraft avionics? Such as a cellphone?
The question foremost in my mind is: How could this guy make a call within such a short time of crashing? Would he not have had to turn the phone on, wait for it to find a basestation to register with (as well as sorting out which one to register with as there would have been plenty to choose from at that altitude!), then locate his mate's number - either by dialling or phone book, and still have a 15 to 20 second conversation. I reckoned he would have needed at least 90 seconds before the call got answered.....
...... unless the phone was already on or, worse still, he was already chatting to his mate!?
I don't know what band they operate in the area, but is it possible it was close to, or a sub-harmonic of a critical piece of radio equipment? Believe me, if I was in his shoes the last thing I would have done is made known that I was party to a cellphone call in mid-air - especially true for the fact everyone knows it's illegal when off the ground!
I have it on good authority that the investigation is looking into possible interference between cellphones and the aircraft's avionic systems. It appears to now be a basic element in all accident investigations since the widespread use of cellphones.
This is not one of those "how do we reduce our network loading" pranks. If there is only one lesson that comes out of this it is while flying make sure your cellphone is off from the moment the doors are shut, and remains that way, until the aircraft is firmly at its parking spot!