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This question which claims that an altitude of 55,000 ft. was observed on a passenger's in-flight entertainment system on an Emirates B777 made me wonder: What are the normal sources of information for the flight data displayed on passenger IFE systems?

Of particular interest are the common sources for the following information:

  • Altitude (Is this a pressure altitude? Indicated altitude? A GPS-measured altitude? A radio-altimeter-measured absolute altitude?)
  • Speed (This seems to typically be true ground speed, which I'd assume comes from GPS, but any further insight would be appreciated)
  • Latitude/Longitude position (Is this from GPS? INS? radionav? some combination?)
  • Wind speed
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    $\begingroup$ There is no other source than the air data system of the aircraft. However, the data is filtered before it is displayed. The 55,000 ft altitude is not credible for several reasons. $\endgroup$ – Peter Kämpf Jan 1 '15 at 22:42
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I work on these panels which get the data (both IFE and cockpit display panels for a big OEM and there are very few in the world :)). This is all Air data systems which are providing all the data. We get this data from various sensors placed inside the cockpit or on aircraft exterior including wings and tail. Their are different kind of data transmission buses like ARINC which transmit that data then the required data is fed to IFE system through a protocol but most crucial data like data coming from Weather Radar etc is kept for Pilot usage and is displayed on the cockpit display panels.

For your question Altitude, elevation. azimuth there are some radars in the aircraft which gives that data and some of these radars measure and send this data using CAN protocol with very high speed varying from 40ms to 100ms.

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    $\begingroup$ Interesting, thanks! Can you elaborate on which particular data sources are used for the IFEs? For instance, as my question mentioned, the air data systems have several different sources that measure altitude in different ways (radar altimeter for altitude above terrain, GPS/INS for absolute altitude above sea level, pitot-static system for pressure altitude, etc.) I was curious which of these gets piped to the IFE systems. $\endgroup$ – reirab Jan 2 '15 at 14:48
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After a brief search I found an old US patent that states:

The video display system of the aircraft is directed by the present invention to automatically display aircraft ground speed, outside temperature, and altitude, among other information of interest, as sensed by the aircraft's navigation and air data systems.

Hence I believe the information comes from same system that the pilots use, though the actual implementation may not be known to any of us outside companies that produce those IFEs.

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My experience on a 757-200 owned by Icelandair this week was interesting. The Lat/Long DD:MM data displayed on the seat back display was OK for Latitude but wrong for Longitude. The aircraft Track was roughly NNW with a westerly component but showed the following bizarre series of positions:

18:02W 18:01W 19:00W 19:59W 19:58W ........... 19:03W 19:02W 19:01W 20:00W 20:59W etc

The degrees increment as expected, while the minutes decrement strangely.
Same bug observed on the return trip. The degrees W decrement as expected, while the minutes increment. Clearly this data is not a direct display of raw GPS data, but is being generated by the in-flight software presumably based on GPS input

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