Date: 201808
Local time of day: 1801-2400
Location: SNA.Airport, CA
Aircraft: Widebody; Low Wing; 2 Turbojet Eng
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb
Airspace: Class A ZLA
ATC / advisory: Center ZLA
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Communication Breakdown; Confusion
Anomaly: ATC Issue All Types; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Automation Air Traffic Control
When detected: In-flight
Result: Flight Crew Returned To Clearance
Contributing factors: Human Factors; Procedure
Primary problem: Procedure

Narrative: Flight release flight plan showed route as follows: PADRZ2 PADRZ DCT DINTY DCT ADUMM...etcRoute was loaded and verified prior to departure. Fixes shown in FMS legs page were identical to flight plan fixes (see attached flight plan excerpt)PDC received from ATC (attached) indicated clearance as follows: CLEARED TO ADUMM VIA ROUTE CLEARANCE DINTY+ LOAD NEW RTE TO ADUMM+ AFTER ADUMM CLEARED TO [ZZZ] ARPT AS FILEDPADRZ2.DINTY; CLIMB VIA SIDEXPECT FL360 10 MIN AFT DP […] CHECK ATIS FOR FLOW-----KSAN PADRZ2.DINTY ADUMM […].Our interpretation of this clearance was that there was no change. We had filed PADRZ2 PADRZ; direct to DINTY from PADRZ.The route clearance was exactly what we thought we had filed; so we made no changes to the FMS waypoints.We proceeded to fly the departure. While cleared to an intermediate altitude and sometime after passing PADRZ2 the controller asked what fix we were proceeding to. I advised we were proceeding to DINTY. He acknowledged and cleared us to FL360 and shortly afterward handed us to another controller. While I was 'off frequency' obtaining a call check; PF (Pilot Flying) was advised by ATC that we were supposed to be tracking to SXC; and that we had deviated from our clearance; and that we would need to call them after the flight via telephone. When I returned to the ATC frequency the PF advised me of what the controller had said. Apparently we had already been handed off again to another controller; this controller cleared us direct to GALIP then ADUMM; as filed.I called the ATC number after the flight and discussed it with an FAA specialist. At first they insisted that we had been cleared to fly from PADRZ2 to DINTY via SXC; and that we had deviated from our clearance and entered restricted airspace. I sent a copy of the PDC to the specialist; and after some additional discussion referencing our PDC; they acknowledged that there is a systemic problem with that particular departure routing (frequent deviations) and that they understood how we could interpret our clearance to be what we believed it to be.PF loaded FMS flight plan. While doing so they asked how to load PADRZ departure with PADRZ2 transition; as indicated on our flight release. I explained that we did not need to load any transition; that the departure procedure would simply terminate at PADRZ. This matched our flight plan; and our LEGS verification indicated that we would fly direct from PADRZ to DINTY; as filed.PDC included language 'NEW ROUTE TO ADUMM' but clearance appeared identical to what we had filed and loaded; so we made no changes. It is not uncommon to see the words 'NEW ROUTE' on a PDC clearance when in fact there is no change at all to the flight plan filed and expected by the flight crew; so this did not raise any red flag.Our interpretation of the PDC was that there was no change from the routing filed; expected and loaded.If there was an expectation for us to fly to DINTY via SXC; the PDC should have indicated this somewhere. Simply removing the PADRZ 'transition' as it was filed in our flight plan; left the 'new' clearance looking exactly like what was expected...PADRZ direct to DINTY direct to ADUMM direct to BARAZ.Additionally; the first ATC controller who inquired about our route after PADRZ did not indicate that there was any error; but simply acknowledged and cleared us to our cruise altitude. To tell us afterward that this was a deviation from our flight plan; rather than correcting the situation at the time does not make sense; and reinforced our assertion that we were flying the route we were cleared to fly.




Synopsis: Widebody Transport flight crew reported failing to recognize a change to their PDC clearance.