For those unfamiliar with fire behaviour, the basic prediction tool developed by the CSIRO is the McArthur Fire Danger Meter. It is used to develop the fire danger indices so beloved of the media.
An online copy is available here.
Calculating Forest FDI's
I suggest that you go to the site, and start plugging in your own figures. A really bad day will have temperatures in excess of 40C, RH below 10% and wind in excess of 60KPH.
I suggest that you start at T=38C RH=25% and Wind=30kph. Drought factor of 9-10 and fuel load of 15-20 tons per ha.
Have a look at the expected spotting distance.
Now play around and work out how much you have to back off the conditions before the spotting distance is less than the 90m quoted as the effective width of the retardant line produced by the DC10.
Regards..... Peter