"Generally, would an ATC directed deviation from a flight plan generate any automatic ACARS transmissions from an aircraft of a major carrier?"
No there will be no automated ACARS messages caused by ATC deviations (to my knowledge).
The automated ACARS messages are triggered by the (previously by the airline) defined messsage-windows, like engine start, climb, stable cruise, descend etc...
It really depends on the definition of the ACARS message windows, what and when an automatic message will be triggered.
This SW is installed in the ACARS management-unit and can be modified by qualified technicians according to the special needs of the airline operations.
I hope this answers your question.
Last edited by flighttest-engineer; 18th Feb 2009 at 16:33.
Reason: added reference post