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Comment by mschuster91 | Hacker News Reader

A 10$ GPS antenna can give you this information... just without the performance guarantees that come with glass cockpit equipment.

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I don’t know why you are getting downvoted. You are absolutely right. There is no need for any kind of connection to the system that flies the plane, even a read-only one. The entertainment network should be completely isolated and if one of the entertainment apps requires the aircraft’s location, they could use a separate GPS receiver and antenna.

A regular phone can also give you this information, just be seated at the window (I guess) for best reception of GPS data. The GPS test app is nice for this.

Can it though? The chips in 10$ AFAIK have hardware limitation built in to cut/fudge output on high (air traffic scale) speeds.

Coordinating Committee for Multilateral Export Controls (COCOM) limits is 1,000 knots (510 m/s) and/or at an altitude higher than 18,000 m (59,000 feet).

Commercial airliners usually have a service ceiling at about 40000 feet and a speed below the speed of sound (343 m/s). Even with a very strong jet stream of 100 m/s it's below the limit.

The Concorde had a service ceiling of 60000 feet and maximum speed of 605 m/s.

COCOM is technically AND, so you can buy some receivers which will work with one or the other condition.

You can use Open Street Maps to monitor the flight without the internet connection.

I often use it to watch how the plane speeds up for take off and slows down for landing.

Sometimes you have to keep the phone closer to the window. Luckily you get the list of currently connected GPS sats so you can debug whether hiccups are software/hardware related or poor GPS coverage.

It's lot of fun observing how early planes start going down in altitude before landing or trying to guess river and city names from up top.

> luckily you get the list of currently connected GPS sats

How do you get this list?

The almanac, which is part of every GPS transmission https://en.wikipedia.org/wiki/GPS_Almanac?wprov=sfla1

GPS really is amazing. It's hard to believe it works at all.

My favorite part about GPS is that it only works because we understand relativity, proving Einstein right.

It would work without an understanding of relativity, but the accuracy would drop by about a meter. https://physics.stackexchange.com/a/128951

Personally, I use GPS Toolbox. No idea about iPhones though.

[1] https://play.google.com/store/apps/details?id=com.eclipsim.g...

I have used Google's My Tracks (now defunct but apk still works) app, and Various GPS Speedometer apps at window seat to get the air speed and such for fun.

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