[exleardriver]

on the subject of a 'slant/u' or 'slant/a' aircraft, they may be cleared 'direct' to a navaid by the following verbiage, and in fact may request as follows: 'xyz center, cessna abc requests def vor when able'. this can cut some time off of your long victor airway routing if the def vor is a good ways away. atc would respond, 'cessna abc, fly heading xxx, direct def when able'. this is a vector clearance permitting a non-slant/g a/c to fly direct once within the working service volume and receiving the navaid morse code ident with no nav flag. just how far away along your route that the controller is willing to 'vector you direct' to a navaid may be dependent upon what agreement that center controller has with further center controllers in whose airspace you're requesting the 'heading direct when able' clearance.