Date: 201412
Local time of day: 1201-1800
Location: SCT.TRACON, CA
Aircraft: Medium Large Transport
Operator: Air Carrier
Operating under: Part 91
Flight plan: IFR
Flight phase: Cruise
Airspace: Class B LAX; Class E ZLA
ATC / advisory: TRACON SCT
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Workload; Troubleshooting; Confusion; Communication Breakdown; Distraction
Second reporter function: Captain; Pilot Flying
Anomaly: ATC Issue All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Returned To Clearance
Contributing factors: Procedure; Human Factors
Primary problem: Procedure

Narrative: Prior to flying an unpressurized ferry flight to PHX today; we reviewed all pertinent procedures pertaining to our flight. We were restricted to a lower altitude as we were unpressurized and originally were filed for 9000 ft. As the copilot; I looked at our MEA's along our route of flight and determined that we would need higher; and eventually we coordinated that change with dispatch; who had filed us along a route of flight that brought us down way south so we could cross over the mountains to Phoenix on airways with lower MEA's due to our MEL restrictions.We spoke with the chief pilot and maintenance control about operating the aircraft at 11;000 ft which is legal per FAR part 91. We acknowledged that we could have gone higher but decided to stick with our final altitude of 11;000 which was coordinated through our chiefs and dispatch. Our PDC showed us re-routed so we contacted clearance and asked them to remain on our filed route; which they cleared us for. Our flight departed normally outside of the fact we were depressurized. Upon reaching our cruise altitude of 11;000 ft; center informed us of a re-route and we requested to remain on our present route due to our original planning and higher MORA's to the east. When we reached SoCal approach; they attempted to re-route us again and we once again requested to remain on our filed route; explaining that for operational reasons we needed to stay as filed. Our controller got very angry with us and said we needed to accept vectors as we were reaching Filmore VOR. He said to expect vectors to either Palmdale VOR or Ponoma VOR. We replied that we were unable. The MORA's out that way were too high for us down the road; though he was very certain that they weren't. The controller got very upset and told us that we were interrupting flights out of LAX and advised us that we had company traffic ahead of us restricted to lower as a result of our current route of flight; once again emphasizing how very upset he was with us.He switched us off and once again they tried to re-route us. In total it must have been 10 times; and each time we responded that we had to stay on our present route due to terrain in the area. This new controller gave us vectors and then re-joined us to the airway we were on; also giving us a descent to 7000 ft. He then gave us a phone number and said to contact them ASAP. After SoCal finally switched us over to center; we were climbed back up to 11000 ft and the flight proceeded normally. Upon landing and after a post flight inspection; we called [flight ops] and explained our situation. We then called the phone number given to us by SoCal and spoke with an ATC supervisor who advised us that we were not being recorded and this was not being submitted to the FAA.He reprimanded us for not coordinating with them prior to departing and for not trusting the controller's years of experience as a SoCal controller. I mentioned to him that his controller may know the airspace very well; but we did not and were relying on what our low-altitude enroute charts said. I also mentioned that we were more worried about airspace farther to the east where the MORA's were in the range of 12;900 ft and higher; well outside of SoCal's airspace. We agreed that prior coordination would have made this a non-issue and I held my tongue concerning that controller's less than friendly tone with us. We were trying to be as safe and conservative as possible and ended up getting into the way of a few arrivals/departures into LAX. I understand their frustration but am certain [the Captain] made the right call. I support and agree with his judgment on the matter.Prior to doing any abnormal routes or having any restrictions for our flights; we need to coordinate that with all ATC facilities along our route. Clearly SoCal had no idea why we needed to stay down low and remain on our current flight. We should be working together as a team; and need to change the mentality of 'us vs. them' with respect to controllers and pilots. Also; I would argue that we should never have received our original clearance out of ZZZ if it meant causing such an issue with SoCal down the road. Hope this helps and sorry for any inconvenience we may have caused today.


Second narrative: We were ferrying Aircraft X to PHX unpressurized.  Upon receipt of the dispatch release in; the first officer and I called dispatch to confirm that our route was compatible with non-pressurized flight.  Dispatch filed us a lengthy but viable and legal routing; and we confirmed with them that our intention was to stay on the route and not accept directs or shortcuts downline due to high grid MORA's along some of the route. Dispatch confirmed that they had co-ordinated this routing with the ATC and mentioned Oakland Center; specifically. We contacted Clearance and received a re-route with directs through the areas of high grid MORA's that concerned us. We asked them for the originally filed routing and it was granted and read back as our clearance. Departed and proceeded along the route.  We informed Departure and Oakland Center of our intentions to proceed as filed due to operational limitations and this was granted.  Upon checking in with SOCAL Approach; SOCAL had requested to give us multiple re-routes due to their traffic situation.  We reviewed the options given and felt that given the available arrivals to PHX; enroute MEA's; and grid MORA's; our best option was to remain on our filed route.  SOCAL Approach provided us a phone number to call them upon arrival to PHX to discuss how dispatch had coordinated our route; as they felt that they were not adequately informed of our operational need to stay with what we filed.  We proceeded along the route to PHX continuing to respect the aforementioned items and contacted SOCAL Approach upon arrival as requested. While not familiar with the inner workings of the ATC system; when an aircraft has an operational limitation; having this communicated to ATC facilities upon the route in advance would be helpful.


Synopsis: Pilots report of a ferry flight to PHX that had a route that was non-standard and low; which caused confusion further down the route.