A couple of points:

With phased array radars, once one has located an aircraft to within 3000 meters (1000 khz radar), you could then flood the zone with higher frequency, and hence more accurate, radars.

Second, if you get multiple readings over time, and one has sufficient computational power, one can get a more accurate fix using statistical techniques.

If, for example, you had a shipping container full of processors, you could likely get a fairly accurate fix in a fairly short time.