declaring a full emergency
As Flt Crew, we do not tend to declare "full" or "partial" emergencies, rather either "No" to declaring an Emergency, or Pan or Mayday...
I am led to believe that a "Full Emergency" might be an ATC term...
As stated above, a "cracked windscreen" from the Flt Crew / safety point of view is usually a non-event, but might require an airborne return.
NoD