Flight crew reported exceeding allowed crew day hours due to unrealistic expectations.

Attributes
ACN	1688438
Time
Date	201909
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	FO
Environment
Flight Conditions	VMC
Aircraft 1
Make Model Name	Heavy Transport
Operating Under FAR Part	Part 121
Flight Phase	Parked
Flight Plan	IFR
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Instrument Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 155 Flight Crew Total 2854
Person 2
Function	First Officer Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 160 Flight Crew Total 7531 Flight Crew Type 677
Events
Anomaly	Deviation - Procedural Published Material / Policy Deviation - Procedural FAR

Narrative:

We had a crew duty day limit of xe:30 before showing for flight ZZZ-nrt. Scheduled departure was xa:05 local ZZZ time. We departed the hotel as scheduled however after arriving at the gate we were told that departure was delayed until xd:00. I spoke with scheduling and told them that I did not believe that we would be able to fly the return flight because I believed we would exceed our crew duty day and inquired as to why we were not notified before leaving the hotel. I was told that this would be addressed upon arrival in nrt. We block in at nrt and were informed of our [out of duty] time. Both myself and my first officer (first officer) questioned the validity of this time. I obtained the flight plan and saw that we have a scheduled flight time of 2:59 at .85 mach! Nrt operations turns the aircraft in only 52 minutes! We block out and are airborne 13 minutes before the [out of duty] time. We fly the leg back to ZZZ with a total block time of only 3:20! Well below the historical block time for the leg. With the scheduled debriefing time we exceeded our max duty day by 19 minutes. In my opinion it was mathematically impossible to operate the segment without exceeding our duty day of xe:30 and that the [out of duty] time we received in nrt was fictitious.

Original NASA ASRS Text

Title: Flight crew reported exceeding allowed crew day hours due to unrealistic expectations.

Narrative: We had a crew duty day limit of XE:30 before showing for flight ZZZ-NRT. Scheduled departure was XA:05 local ZZZ time. We departed the hotel as scheduled however after arriving at the gate we were told that departure was delayed until XD:00. I spoke with scheduling and told them that I did not believe that we would be able to fly the return flight because I believed we would exceed our crew duty day and inquired as to why we were not notified before leaving the hotel. I was told that this would be addressed upon arrival in NRT. We block in at NRT and were informed of our [Out of Duty] time. Both myself and my FO (First Officer) questioned the validity of this time. I obtained the flight plan and saw that we have a scheduled flight time of 2:59 at .85 Mach! NRT operations turns the aircraft in only 52 minutes! We block out and are airborne 13 minutes before the [Out of Duty] time. We fly the leg back to ZZZ with a total block time of only 3:20! Well below the historical block time for the leg. With the scheduled debriefing time we exceeded our max duty day by 19 minutes. In my opinion it was mathematically impossible to operate the segment without exceeding our duty day of XE:30 and that the [Out of Duty] time we received in NRT was fictitious.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.