A newer addition to commercial airliners is seatback screens, that allow the passengers to watch movies, TV, and so forth. On most airlines, there is also a map, that shows you the aircraft's flight path, position, airspeed, and altitude.

I have noticed that the information displayed on the map screen only updates in roughly 15-second intervals. Is there any reason for this? I can't imagine that there would be any bandwidth limitation issue for such a small amount of text data (for example, I can drive a ton of data to my ForeFlight app with my relatively mid-range GA IFD), so I imagine there must be a safety or technical reason for it.

Seatback Map - JetBlue

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    $\begingroup$ Is it possible to zoom in on that map? If not, how many pixels would the icon move in 15 seconds? $\endgroup$ Nov 29 '18 at 15:19
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    $\begingroup$ It's possible that the source of the data is only updated every 15 seconds $\endgroup$ Nov 29 '18 at 15:46
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    $\begingroup$ Do most people really care? If there's no demand (and thus, requirement) for it, the 15~s interval may simply be an arbitrary software value on the airline or OEM's part that seems "about right." They could have simply decided on 2, 5 or 31s and it wouldn't have made any difference. (Okay, maybe 31s is a bit long.) $\endgroup$
    – aerobot
    Nov 29 '18 at 16:10
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    $\begingroup$ @aerobot As a pilot, it mattered to me. It also mattered to the other 8 pilots I was traveling with. It's not "needed" information, but it goes along the lines of, why do they give us fre snacks? We're not going to starve inflight, but it's still nice to have. Same applies to the information - it's nice information to know. $\endgroup$
    – M28
    Nov 29 '18 at 16:13
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    $\begingroup$ What possible reason is there for a passenger to see updates more frequently than that? The first question of an aviation system designer is going to be "why should we do this" rather than "why should we not do this". $\endgroup$ Nov 29 '18 at 16:52

If data is continually updated, nervous flyers will fixate on every minor change.

  • The altitude changed by 30 ft in one second?
    That is a descent rate of 1,800 FPM! Surely we're going to crash!

  • The speed changed from 480kts to 470kts in one second?
    At this rate, we will stall in less than a minute!

  • The plane was at 260kts at 9,800ft?
    This crazy pilot is breaking FAA regulations and must be reported!

By updating less frequently, there is a natural filtering and smoothing of the data to obscure tiny measurement changes due to instrument limitations or conditions like turbulence.

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    $\begingroup$ Definitely possible. Do you have any source to back it up though? $\endgroup$
    – M28
    Nov 29 '18 at 15:51
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    $\begingroup$ @CptReynolds yes, but it wouldn't stop some pax with too little knowledge from complaining! $\endgroup$
    – abelenky
    Nov 29 '18 at 19:16
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    $\begingroup$ @abelenky I was only nitpicking :) of course! Although actually the (relatively few) people I know who don’t get ground vs. indicated wouldn’t have any clue about 250 below 10. $\endgroup$ Nov 29 '18 at 20:56
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    $\begingroup$ @Matt I don't know if the channel 9 live ATC provided by some US airlines still exists, but there are plenty of stories of pax listening in and making complaints when they think the pilot did something wrong. This would be the same, there doesn't need to be a paper to confirm that. $\endgroup$
    – Ben
    Nov 29 '18 at 20:58
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    $\begingroup$ Actually, I've never seen a flight system that reports KIAS to the passengers. They always report ground speed (usually in kmph or mph), head / tail component of winds aloft, altitude and outside air temperature. One has to do some math to work out the KIAS. $\endgroup$
    – kevin
    Nov 30 '18 at 7:54

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