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Comment by usrusr | Hacker News Reader

The moving map could easily be fed from a separated consumer grade GPS. Same for all other metrics that the median passenger would care about (height, speed over ground), except for the ever-impressive outside temperature.

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Outside temperature is pretty impressive indeed. The map also shows projected flight plan and ETA, which would not come purely from GPS.

Most/all international flights I've been on are really terrible at providing an accurate flight plan or ETA to the passengers via the entertainment system. I would not be surprised if it is already a manual update done when convenient by a member of the flight crew.

Could be! I can safely say that not all such entertainment systems work that way, but I reckon it's possible that some do.

They tend to use what's programmed in the FMS. Pilots will have the cleared route in there, even if they already know that they'll probably get several short cuts along the way.

I have never seen one that showed a flight plan. They only had a straight-line (well, a great circle route) to the destination. ETA was pretty clearly straight-line distance divided by (average?) speed.

Consumer grade GPS actually won't work at 30,000+ feet at speeds the plane would be flying. This is to prevent someone from using the GPS system to steer a ballistic missile.

The gps on my phone begs to differ. You can (sometimes) acquire enough gps locks to get a signal and subsequent gps data like speed, position, etc. Worth a shot trying because there's very few other times where you'd be able to see your gps sensor read 600mph. You're probably right though, it's just that the cutoff speed is higher than whatever a commercial jetliner speed is.

The ITAR/COCOM limits used to be (according to https://en.wikipedia.org/wiki/Coordinating_Committee_for_Mul...) "faster than 1,000 knots (1,900 km/h; 1,200 mph) at an altitude higher than 18,000 m (59,000 ft)".

They have been relaxed since then, but all current commercial jetliners would stay comfortably within both limits.

Clearly an exception could be made in this case. Systems that are part of a passenger jet could hardly be called consumer grade.

Incidentally, my GPS watch (Garmin) was working last time I was on a plane. It was bang on 700kph the whole time IIRC.

My cell phone GPS works at cruise on an airplane. I can't attest to how location accurate it is but the altitude and speed are usually right on with what the infotainment system says.

Data diodes are things that exist

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