If the airspace around centrally located airports were restricted to commercial airliners and only those private planes equipped with radar, most of the private-plane traffic would be forced to sue outlying airfields. Such a reduction in the amount of private-plane traffic would reduce the risk of midair collision around the centrally located airports.
The conclusion drawn in the first sentence depends on which of the following assumptions?
I meant commerical airliners and private planes cannot be the same thing, so the condition that "most of the private-plane are not commericial airliners" will be a restatement of the obvious, not an assumption that one has to make.