Date: 201908
Local time of day: 0001-0600
Location: ZZZZ.ARTCC, FO
Flight conditions: Mixed
Light: Night
Aircraft: B767-300 and 300 ER
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Cargo / Freight / Delivery
Flight phase: Cruise
ATC / advisory: Center ZZZZ
Reporter organization: Air Carrier
Reporter function: Relief Pilot; First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness; Human-Machine Interface; Communication Breakdown
Second reporter function: Pilot Flying; Captain
Anomaly: ATC Issue All Types; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: I had just finished my break as IRO (International Relief Officer) and gotten into the FO (First Officer) seat to relieve him for his break as we were approaching our 030W waypoint. I had been briefed by the Captain and our Oceanic Clearance was as filed. In the process of way point passage; we realized that our next way point in the FMC was X1N040W when the oceanic clearance had been X2N040W. We immediately entered the proper coordinate in the FMC with no idea how it was changed and began navigating to it. Within a very short period of time; we were queried by Center as to what our next way point was. We stated the X2N040W coordinate and were told to proceed to X1N040W. Neither myself nor the Captain had been aware of any route change before this occurred. To my knowledge; any deviation was very minor and did not conflict with other traffic.


Second narrative: I was Captain for this flight; pilot flying; and was assisted by my regular FO (First Officer); and an IRO (International Relief Officer). The flight departed normally; a few minutes early. We had a deferred APU air system and had to coordinate for a ground source of air and cross bleed start. We worked well as a crew handling this non normal. We departed and climbed to our cruise altitude of FL320. 90 minutes prior to oceanic entry; we requested our oceanic clearance. It was received very quickly and was for exactly as filed; no changes. 90 minutes later; just as we were crossing our oceanic entry point; everything was nominal; the FO (IRO was on break); CPDLC was signed in. [2 minutes later]; we got a CPDLC message saying 'Cleared to [exit point] via route clearance' to which I thought it was our normal; but differently stated verify route message. I said accept; and the IRO hit 'load' (I thought it was an 'accept' prompt) and execute before I noticed it was a load button and I never saw the execute action it was so quickly done. Then we got 5 different CPDLC messages; some of them repeats; about verifying route etc. [for the next 10 minutes]. It was somewhat confusing so many messages. At no time; did any of the messages say there was a change to our clearance. In verbal communications with ATC; no one emphasized; let alone mentioned; there was a change to our clearance. None of us knew this. As we crossed 30West; in ATC with a squawk and VHF communications; we also had a swap out of FO's and one's break was over; and the next one was about to begin. My regular FO took the FO's seat. I was PF (Pilot Flying); and I use a technique I learned on my OE crossing experience of having copied the route in the blocks to RTE 2; I then modify RTE 2 to add my 2 degree check points to display on my ND. At 30W; the 32W check point didn't align with the magenta line. FO and I started to scramble to solve this problem. He went to the flight plan; and the points in it didn't match what was in the FMC. We thought the FO on break might have made a mistake in key entry (even though it was all verified properly before). All I knew was I didn't think I was where I was supposed to be. I turned the plane towards the path I thought we should be on; what was in the flight plan. The FMC was 'corrected' to the mental model of what we thought it should be. It was at about this time Oceanic control on VHF said to us; it appeared we weren't flying to our proper point; and cleared us direct to it; X1N040W. The flight plan and what our oceanic clearance was for X2N040W. We told him this was different for us from our flight plan and clearance. He said it was a change; but it was news to us. It was only going through the log of CPDLC we found the error. On the [earlier ACARS] message; on the green screen; I doesn't say what the points are; or that this is a change; but when you print it out; you see the points and because it was executed so quickly (again; I thought it was an 'accept'); I didn't realize it was loading these new points. Once we got the FMC aligned with the new and proper clearance (again; never were we told with anyone we were communicating with this was a change to our original and filed clearance); I called the dispatcher on the SAT phone to see if he knew of this change. He looked; and didn't see any evidence of change. I gave him the new points; he ran the numbers through [the FMS]. As for the actual transgression; I don't think we deviated more than a few miles for either course; and there was never any conflicts with any other aircraft (there weren't any around). Oceanic control didn't seem to have an issue; and cleared us direct to the way point we needed to go to. I don't know if we were indeed in Radar contact; but we had the makings of it.


Synopsis: B767 flight crew reported a communications breakdown between flight crew and ATC resulted in deviation from assigned ATC clearance.