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Air carrier captain reported the terrain critical depressurization procedure conflicts with the ETOPS critical point on a specific transatlantic route.
| Attributes | |
| ACN | 1504383 |
| Time | |
| Date | 201712 |
| Environment | |
| Flight Conditions | VMC |
| Aircraft 1 | |
| Make Model Name | Widebody Transport |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Parked |
| Flight Plan | IFR |
| Person 1 | |
| Function | Captain Pilot Not Flying |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Total 6855 Flight Crew Type 2502 |
| Events | |
| Anomaly | Deviation - Procedural Published Material / Policy Inflight Event / Encounter Fuel Issue |
Narrative:
Flying [this leg] we are generally over the terrain critical depressurization procedure (tcdp) area of greenland. The tcdp is simple; if west of W040 descend to FL140 and proceed to the west coast of greenland; if east of W040 descend to FL140 and proceed to the east coast of greenland.for my flight; the original route had an ETOPS critical point (cp) west of W040 with an ETOPS alternate east of W040. Thus the ETOPS solution conflicted with the tcdp. I can find no guidance that says that an ETOPS solution can ignore tcdp requirements; nor does it say that an ETOPS solution must comply with a tcdp; however since both are in the manuals and both address the same contingency; a decompression; it seems a reasonable inference that an ETOPS solution should comply with a tcdp. From a practical standpoint it also seems reasonable.
Original NASA ASRS Text
Title: Air Carrier Captain reported the Terrain Critical Depressurization Procedure conflicts with the ETOPS Critical Point on a specific transatlantic route.
Narrative: Flying [this leg] we are generally over the Terrain Critical Depressurization Procedure (TCDP) area of Greenland. The TCDP is simple; if west of W040 descend to FL140 and proceed to the west coast of Greenland; if east of W040 descend to FL140 and proceed to the east coast of Greenland.For my flight; the original route had an ETOPS Critical Point (CP) west of W040 with an ETOPS alternate east of W040. Thus the ETOPS solution conflicted with the TCDP. I can find no guidance that says that an ETOPS solution can ignore TCDP requirements; nor does it say that an ETOPS solution must comply with a TCDP; however since both are in the manuals and both address the same contingency; a decompression; it seems a reasonable inference that an ETOPS solution should comply with a TCDP. From a practical standpoint it also seems reasonable.
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.