Narrative:

I previously submitted a report on this flight/issue; but one of my main concerns was completely ignored; thus this second report. At issue was planning an ETOPS flight over a terrain critical depressurization procedure (tcdp) area where the ETOPS solution did not comply with the tcdp requirements. Though the previous answer addressed the lack of functionality of the sabre terrain solver; it completely failed to address the legality of a dispatch where an ETOPS alternate fuel computation does not include that necessary to comply with a tcdp. On our flight the critical point was west of 040W. With the ETOPS alternate being bikf; east of 040W. While the tcdp requires a flight experiencing a depressurization prior to (west of) 040W to remain west of 040W and to proceed to the west coast of greenland; in the opposite direction of the ETOPS alternate. As decompression was the issue that was driving the ETOPS fuel computation; both the ETOPS [and] tcdp address the exact same scenario. I can find nowhere in the fars; the operations specifications nor our fom where it specifically states that an ETOPS solution can ignore a tcdp. As both the ETOPS procedures and tcdp are in our flight operations manual it seems a reasonable inference that both must be complied with during flight planning. If this is not the case; I would like a specific far or operations specifications reference so stating and would suggest that the flight operations manual be amended to address this situation and the legality. Though the previous response stated that there was sufficient fuel; how do they know as once a flight in such a condition reaches the coast of greenland; if no suitable alternate exists to the west; a circumnavigation of greenland at 10;000 ft could be a significant fuel burn. Please address the legality of this type of dispatch with either an far or an operations specifications reference if it is legal.

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Original NASA ASRS Text

Title: B777 Captain questioned the validity of a trans-Atlantic ETOPS dispatch release that in his opinion did not comply with fuel considerations if a terrain critical depressurization procedure became necessary.

Narrative: I previously submitted a report on this flight/issue; but one of my main concerns was completely ignored; thus this second report. At issue was planning an ETOPS flight over a Terrain Critical Depressurization Procedure (TCDP) area where the ETOPS solution did not comply with the TCDP requirements. Though the previous answer addressed the lack of functionality of the Sabre terrain solver; it completely failed to address the legality of a dispatch where an ETOPS alternate fuel computation does not include that necessary to comply with a TCDP. On our flight the critical point was west of 040W. With the ETOPS alternate being BIKF; east of 040W. While the TCDP requires a flight experiencing a depressurization prior to (west of) 040W to remain west of 040W and to proceed to the west coast of Greenland; in the opposite direction of the ETOPS alternate. As decompression was the issue that was driving the ETOPS fuel computation; both the ETOPS [and] TCDP address the exact same scenario. I can find nowhere in the FARs; the Operations Specifications nor our FOM where it specifically states that an ETOPS solution can ignore a TCDP. As both the ETOPS procedures and TCDP are in our Flight Operations Manual it seems a reasonable inference that both must be complied with during flight planning. If this is not the case; I would like a specific FAR or Operations Specifications reference so stating and would suggest that the Flight Operations Manual be amended to address this situation and the legality. Though the previous response stated that there was sufficient fuel; how do they know as once a flight in such a condition reaches the coast of Greenland; if no suitable alternate exists to the west; a circumnavigation of Greenland at 10;000 ft could be a significant fuel burn. Please address the legality of this type of dispatch with either an FAR or an Operations Specifications reference if it is legal.

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.