That range ring example whilst mildly helpful, is still air.
Roughly, any westbound travel will have less range due headwinds encountered.
That's as may be, but the ring requested wanted KUL as the center point. To add winds into a poorly chosen datum (which I did not choose) would only introduce further error.
There's a process to determining search areas which involves reducing uncertainties. Starting with a ring centered about an airport isn't part of that process unless there is no other information available. I provided what was asked for without compounding the ~500nm error inherent in the request. Adding winds (which can only be guessed at without knowing altitudes) would have done just that. Without more data than appears to be available to the general public it is pretty unlikely that any individual or small group will settle upon a high probability search area.