Flying the DC-9-21/-41 and the -33F in SAS,we used 2400 kgs/hr as a rule of thumb when flight planning.600 kgs/15 mins holding and 700 kgs for an approach from 3000 feet followed by a go-around to 3000 feet again.
Thanks for your that, FBU_4EVER, as you drew my attention to me not making myself clear in my first post! 4050 kg/hr is for "max. cruise", while about 2400 kg/hr is for economical cruise. Sorry for the confusion!