Date: 202001
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Aircraft: B777-200
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Other / Unknown
Second reporter function: First Officer; Relief Pilot
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural FAR
Detector: Person Dispatch
When detected: In-flight
Result: Flight Crew Returned To Departure Airport; Flight Crew Landed in Emergency Condition
Contributing factors: Human Factors; Logbook Entry
Primary problem: Human Factors

Narrative: During preflight planning discovered this was the third airplane assigned to the flight. Arrived at the aircraft and discussed two MEL (Minimum Equipment List) items which we reviewed together and called Maintenance out to clarify an item. All four pilots handled and reviewed the logbook during this discussion. We all briefed the ETOPS (Extended Twin Operations) signoff and agreed it was done and in the book. The boarding was slightly delayed so there was no pressure to get things done quickly. After about two hours into cruise Dispatch sent a message asking if the ETOPS signoff was in the logbook. I checked it and found that there was indeed an entry and it was the correct date but saw that the departure station was ZZZZ. This means that the signoff was for the previous leg which was the day before. The day before; in the other hemisphere. We all were looking for an ETOPS date and we all saw what we expected to see. At that point we were not in ETOPS airspace and worked out a routing with Dispatch that avoided ETOPS airspace entirely and secured the clearances with ATC (Air Traffic Control). Shortly after Dispatch told us that the maintenance department wanted us to return the airplane to ZZZ. We asked to divert to minimize the delay to the passengers but were told to return to ZZZ. The return to ZZZ required and overweight landing at 485;000 lbs (max landing weight is 460;000 lbs); so ATC was advised. All checklists were complete and an uneventful landing was made.I think all pilots expected to see an ETOPS signoff dated [the same day] and that is exactly what we saw. We should have reviewed the entry more carefully. There was no reason as we were not rushing to depart; we just missed the fact that the last leg originated in the other hemisphere.I need to inspect the logbook entries more carefully and make sure I know where the previous leg originated; especially when a change of equipment is involved. I never suspected the date line issue would cause such a problem but it happened.


Second narrative: Flight departing ZZZ to ZZZZ. Aircraft changed tail number two times before departure. Logbook was reviewed by Flight Crew and Maintenance was called to the aircraft to clarify an MEL (Minimum Equipment List) item. Flight crew incorrectly verified ETOPS (Extended twin Operations) signoff in the AML (Aircraft Maintenance Log). ETOPS was signed off on the correct date; however; the ETOPS was signed off in ZZZZ; not ZZZ.Lack of awareness that is was possible; although unusual; that an ETOPS could be signed off in ZZZZ and need an additional ETOPS sign off to go back to ZZZZ from ZZZ in the same day.I believe that awareness of this unusual event would prevent it from reoccurring.


Synopsis: B777-200 reported returning to departure airport after inadvertently departing without proper ETOPS sign-off in logbook.