2
$\begingroup$

This question already has an answer here:

Given that there is no need now for one to swith off their cellphone midflight, inflight wifi is now a norm and common, Is it possible for me to measure the velocity and altitude of an aircraft using my personal car GPS speed indicator or cellphone app in the case of speed and altitude as a passenger?

$\endgroup$

marked as duplicate by Pondlife, fooot, mins, David Richerby, Ralph J Aug 3 '17 at 21:43

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

  • $\begingroup$ Would GPS signals be detected inside the body of an airliner? Non-composite ones would seem to make a pretty good Faraday cage. $\endgroup$ – jamesqf Aug 3 '17 at 18:39
3
$\begingroup$

Depending on the reliability of the sensors in your phone, yes that sounds completely possible. Most modern aircraft use GNSS for navigation, and your phone relies on the exact same technology.

Be aware that you will get the ground speed - see this question for further details: Why is there a difference between GPS Speed and Indicator speed?

$\endgroup$
  • $\begingroup$ Theoretically there are legal limits to use a GPS receiver on moving vehicles (did I say missiles?): 1,000 kt and 18,000 m, and US GPS receivers should enforce these limits. This is compatible with today airliners, but in some cases this creates problems. $\endgroup$ – mins Aug 3 '17 at 18:32
  • $\begingroup$ Similar to speed, the altitude that the gps reads is not pressure altitude. $\endgroup$ – Gürkan Çetin Aug 3 '17 at 18:50
  • 1
    $\begingroup$ @mins I had never heard of that before. That's completely silly. If someone is capable of engineering a high speed, high altitude GPS guided missile I'm sure they're not using a cell phone for guidance $\endgroup$ – TomMcW Aug 3 '17 at 18:50
  • $\begingroup$ @TomMcW: But they might well buy an off-the-shelf GPS reciever module that is manufactured by the millions (hence cheap) for use in cell phones. E.g. digikey.com/products/en/uncategorized/miscellaneous/49?k=gps or sparkfun.com/search/results?term=gps $\endgroup$ – jamesqf Aug 4 '17 at 6:39
3
$\begingroup$

Yes. Airplane mode generally only includes transmitters, and GPS is receive-only. The below is a screenshot I made with a speedometer app, on an Airbus A320. I had to hold the phone near the window to get GPS coverage. (Units: km/h groundspeed)

enter image description here

On a more recent flight, I could even get GPS coverage away from the window, in a Boeing 737-200 (although I was seated next to the overwing exit).

Note that some altimeter apps may use the phone's barometer, which will only give you the cabin altitude.

$\endgroup$
  • 2
    $\begingroup$ I was confused for a minute until I realised your average speedometer app obviously does not use knots ... $\endgroup$ – J. Hougaard Aug 3 '17 at 19:49
  • 2
    $\begingroup$ @J.Hougaard I was just about to submit an edit when I got a call. It's indeed km/h, from an app called DigiHUD which I used in a car with a dodgy speedometer (it can do a mirror image to get that F-16 HUD feel on your windscreen until you corner too tightly and have your phone fly of off the dashboard) $\endgroup$ – Sanchises Aug 3 '17 at 20:09

Not the answer you're looking for? Browse other questions tagged or ask your own question.