No mutt, the value I quoted was the published TAS for OEI at LRC.
Just as an example:
A/C Weight 70 Tonnes
FL230 (Max after driftdown)
IAS 235
TAS 332
.548M
Those values are straight out of the FCOM.
On Engine Failure I would expect to set MCT and reduce to Green Dot before drift down.
Green Dot at this weight is 230 IAS. Are you certain theres enough distance advantage gained during the deceleration at initial cruise level to get up to the 400NM range you refer to?
Even if it is so, I reckon its stretching the rules a lot to factor the decel phase in. I mean, how do I calculate that at the planning stage when trying to select a diversion field? Bit dodgy innit?