B747 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 60; Flight Crew Total 15000; Flight Crew Type 3000
Situational Awareness
Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Weather / Turbulence
Flight Crew Took Evasive Action
Company Policy; Human Factors; Weather
For some number of hours prior to departure there were multiple SIGMETS for severe turbulence in areas south of; over and east of Japan.  As well there was one volcano SIGMET in western Japan.  Multiple updates of applicable times were made; the SIGMETS did not expire.  Two SIGMETS were applicable to routes typically chosen by the company for minimum cost flight; one other would apply in event of diversion from cruise to suitable landing airports. One severe turbulence encounter was also found within the defined SIGMET area.  All SIGMET and PIREP discovery was on NOAA and other multiple World Meteorological Organization (WMO) format weather sites and on one personally contracted flight planning service provider products.Weather map features for cold upper level continental depression air flow from Mongolia-Siberia merging with warmer and higher pressure airflow from the India-China axis certainly had the general measure for possible turbulence over the Japan area.   Wind speed and temperature changes along the route also highly supported the possibility for higher levels of turbulence.Upon arrival in flight planning the crew cannot find any SIGMETS in the company provided flight planning paperwork for the flight.  I recheck other weather service providers and the SIGMETS are still there and applicable at takeoff time as well as one actual report of severe turbulence encountered in one of the forecast severe turbulence SIGMET areas.  As well the SIGMETS are available in map form from a high quality flight planning service I have on contract.  Times are applicable at and after scheduled takeoff time.  The dispatch chosen route and altitudes are well within the SIGMET K11 defined severe turbulence area.  SIGMET D03 for a volcano cloud of unknown intensity and flight level is directly under the chosen route.   SIGMET J16 for severe turbulence is applicable for flight from cruise altitude to enroute alternates in event of the need for diversion.  NONE OF THESE SIGMETS OR THE SEVERE TURBULENCE ENCOUNTER PIREP ARE PROVIDED BY DISPATCH.  The flight plan notes mention some occasional moderate turbulence in areas addressed by the SIGMETS but the applicable altitudes are incongruent with the SIGMET defined altitudes.  The flight plan notes show altitudes not having moderate turbulence that are included in the SIGMET as having possible severe turbulence.  The weather maps included in the flight planning paperwork also shows no severe forecast turbulence and no volcano.  This is typical of maps provided on many of my flights; they exclude severe turbulence forecast areas found on WMO format weather maps.  The maps provided today also exclude part of the route in the Pacific; a constant problem on Asia flights.  However; [the company] does have a current SIGMET chart on their web site that is congruent with the SIGMET text which was also on their web site and matched the SIGMETS provided by other flight planning service products.  None of this SIGMET data was provided in the flight planning paperwork; again a common issue in SABRE flight planning products sent by dispatch.  One must go on Easter Egg hunts and buy outside weather services in order to flight plan per FAA 121 requirements imposed on the PIC.The SIGMET situation was discussed with the dispatcher but we failed to reach an agreement on avoiding forecast severe turbulence areas and routes.  The dispatcher told me that the flight avoided these areas. The dispatch chosen route and altitudes were well within the SIGMET K11 severe turbulence areas and altitudes and the route was near directly the SIGMET D03 volcano of unknown height and intensity.  Our crew knew what to do to avoid the forecast severe turbulence areas and we flew the flight accordingly at altitudes to honor the SIGMET K11 and avoid severe forecast altitudes.  We had visual conditions approaching the SIGMET D03 volcano area and determined the course to be free of ash clouds at our altitudes.Multiple planes were heard to encounter moderate turbulence above us in the areas of SIGMET severe turbulence definition.  Dispatch sent a message of somebody encountering moderate within the areas defined in the SIGMET.  Our flight had little turbulence flying under the altitudes forecast for severe turbulence.  As a precaution we did have seatbelt signs on for lengthy periods and had flight attendants seated multiple times.  We spoke with an Airline crew behind us who were in possession of the SIGMETS provided by their airline dispatch office and they avoided the forecast severe turbulence flight levels as we were doing by flying under the dispatch chosen flight plan altitudes and under the base of the SIGMET severe turbulence forecast altitudes. Again the flight planning products are of questionable quality; especially since Sabre showed up things are much worse.  In today's case once again materials provided to our crew were well under the standard employed by other Airlines.  Quite often we hear other pilots speaking of SIGMETS and PIREPS in the Pacific and making adjustments to avoid those areas for which we have no knowledge so today's events and solution to get assistance from other airline crews is no surprise.  Seeking SIGMET data from ACARS once inflight yielded zero usable information today; a year's old problem never fixed.
An air carrier Captain notes that his company provided preflight weather package does not include several Sigmets that are available from other weather services. He believes that the weather service always understates significant weather elements provided to the crews by the company.