Porterhouse...
"(say based on radar returns, I don't think they explained how)"
You put an edit in there !
Because that is the "bit" I couldn't work out.
Increased work (eg) increased speed (or lower altitude) equals shorter distance travelled.
They would have had to model various scenarios to move the whole SAR effort....or it was "other" information.
Well I hope they are right.
And from early indications (the latest P3 reports) they maybe correct.