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Utilize QFE not QNH.

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Know that when you report an altitude or are assigned an altitude, it will be in meters QFE.

11.11 VOR and GPS Position Updating in Russia
There are very few VOR/DME’s in the Northern part of Russian. This means that ground based radio position updating is not available for the aircraft’s navigation system until well within the heart of Russian airspace. Hence, formal waypoint passage and post position verification are required until within the range of VOR/DME facilities. Although part of this airspace is technically not class II since there are some NDBs, the ability to accurately confirm aircraft position by other than passing directly overhead the NDB, is not highly reliable due to normal NDB inaccuracies.
GPS position updating is available. However, the Russians use a different Datum when determining geographical coordinates than is used for the GPS system. This results in a slight disagreement in coordinates for any given location in Russia. This discrepancy could result in as much as a 365 meter or 1200 foot error in
Issue I 28.08.2007  Rev. 0

navigation accuracy. This amount of error is tolerable in an certainly could be meaningful on an instrument approach. The best solution in this situation, due to the lack of radio updating, is to continue GPS position updating while insuring that instrument approaches are always flown primarily with reference to ground based navigation radio signals. Utilize the Navigation Display map while observing the raw signal navigation needles. If there is a small disagreement between the map and raw data, then follow the raw data ILS, VOR or NDB as appropriate.