Ac declaring an emergency (PAN or MAYDAY) should be notified by the relevant ATSU to D&D in order that D&D may alert the ARCC and take executive control of the incident, operational control remains with the ATSU. All civil crashes and major incidents (say a forced landing into a field) are reported by D&D to the SRG - or at least they were 4 years ago! Now whether or not all civil ATSUs notify D&D when an ac on their freq declares an emergency or not is another question. They should (instant comms access to ARCC and associated SAR assets, Police C2, ability to auto-triangulate/radar plot exact ac position etc), but don't!