Eric Greenwell wrote:
And I'm still wondering if a PCAS in any or all of the aircraft could
have averted the disaster. $500 each would be cheap it would work in
that situation.

Just FYI, here's an article discussing the Traffic Avoidance Systems
commonly installed on many Cirrus aircraft:
http://www.theflightacademy.com/pres...lot_Nov_06.pdf

It is possible that the model involved had a TIS - which may not have been
helpful in this case.