Capt.Doug wrote:
Heard an E-6 Heavy (WTF I said to myself when I heard it) call Center for an
IFR clearance to RTB after performing 'due regard' over oceanic airspace.
What is 'due regard'?

Didn't know an E-6 could be a "heavy". See:

http://en.wikipedia.org/wiki/E-6_Mercury

"Due regard" for other airplanes' safety is what a military flight must
exhibit when it's operating outside of ATC. For example, when
conducting firing or carrier exercises in international waters, or
patroling for enemy (or drug-runner) craft.

The aircraft could start with an IFR clearance, then declare "due
regard" and go do its thing (perhaps surveil a suspect ship from afar)
and then come back and request an IFR clearance again to get back into
the normal system.

See section 5.3.2 in:

http://west.dtic.mil/whs/directives/...81/d45401p.pdf

Kev