Thermals are so dynamic that detecting them beyond a 1000 meters or so
won't be terribly useful. *They'll just dissipate before you can get
there. *You can play this game in Condor Competition Flight Simulator
but setting the thermal visibility to various ranges. *Heading off for
a thermal in the distance doesn't work.

??? 1000 meters is less than a minute away. I haven't flown many
places, but the thermals in the desert southwest hang around long
enough that a kilometer range would be quite useful. I think longer
would be better.