Gents,
I've been flying 604's for a while now, its very important to understand that it does NOT have a 4000nm range..............
Dubai to London (3200nms) against the wind is about as good as it gets, or London to KTEB. If you want sensible reserves then beware of this basic fact, also the additional issue is the tank capacity. Theoretically you should be able to load 20,000lbs of fuel, so far, in well over two years I've never been able to do this, despite following all the advice of pumping the aux tanks slowly and getting the plane 1 degree nose down etc. The high level shut-offs cut out well before 20,000lbs, at VERY best you'll get 19,500 in a cold place. Most times you'll be lucky to get 18,800. Before anyone says I'm flying a dog, this is my experience on three different 604's and is a known problem. Otherwise its a great aircraft, the pax always love the wide cabin.
The last thing to mention is of course the icing, NEVER accept ice on the wing AT ALL, it will kill you on a take-off.............
If you want anythinmg else just PM me.
Best regards,
SF