Medium Large Transport
Flight Crew Air Transport Pilot (ATP)
ATC Issue All Types
Procedure
We departed 16L and tower was fairly busy. However; we had to ask for a frequency change since it was not given at about the normal time on the LEETZ departure. This is not inherently a big deal. We continued on the departure and were given a; 'delete the speed' clearance. Shortly after; another clearance; climb and maintain FL230 came as well. At about ZEETA intersection; we were given the clearance 'cleared direct UPJAR' intersection. We agreed that this would be in conflict with our drift down since we were only about 6000 feet above the terrain and we would have to take responsibility for terrain clearance. So; we requested to stay on route since that is the safest and most conservative. We were approved to stay on course. We were then handed over to another controller. This controller; the second departure controller on the LEETZ departure issued the clearance 'Direct EKR (MEEKR).' There was an exchange back and forth between us and the controller in which we attempted to communicate we wanted to stay on the route for drift down alternate planning. We were not far from the original course. But; the end result of the conversation was what seemed to be a very strong-willed controller not taking into consideration what we were trying to convey in our radio communications. This being that our route is most conservatively flown in this aircraft using the drift down procedures dispatched with us. The controllers should be educated on exactly why drift down is important to our operations. Also; this communication should include the importance of not clearing us to fixes directly; taking us off our route. It is equally important for controllers to listen to the pilots and planes they are monitoring. Our reasoning may be in conflict with their need to expedite traffic out of their sectors; but safety is always in mind.
Air carrier Captain reported being given direct routings in mountainous terrain and repeatedly having to explain to ATC controllers that he wanted to remain on his filed route due to drift down considerations.