This detailed answer to your question about inflight ground take-over and automated recovery of a hijacked flight was mounted on 12 Sep 01 and includes some assessments by automated flight-control experts whose resumes are also on the site (same page).
See
here and
here
The concept was discussed briefly on these Pprune threads:
http://www.pprune.org/cgibin/ultimat...1&t=015428&p=5 Skymarshall Now.......
and
http://www.pprune.org/cgibin/ultimat...3&t=002473&p=2 cockpit security - doors
and
http://www.pprune.org/cgibin/ultimat...1&t=015460&p=3 [cockpit doors/access]