We used to do that at Colgan all the time between IAH and Beaumont or Lake Charles... Flight is severely delayed, all pax on other flights, call out reserver crew, Vmo there, shut down left engine and grab paperwork through the whiskey hatch, start #1, Vmo all the way back.

Funny thing is, every time we knew we were doing an empty run both ways, DX and Ops would have to call Continental directly to see if we could cancel it. Mainline says no do it anyway, so we go. Stupid thing is that it was at-risk flying!