It seems if you've got crews on the gound using maps, then it is much easier to have everyone using those maps' datum - probably NAD27 on USGS topo maps. If the maps are setup for UTM then that is probably best, otherwise they'll have to use Lat/Long.

It seems much easier for GPS users in the air (or on ground) to convert to whatever datum & coordinate system than for a map user to change.

Just my $0.02.

Ken

BTW, I have sooo much respect for you SAR folks out there. You're heros in my book.