You are indeed right, there is a connection to the BUS that shares some information. You can also write back some of the information(flight number, flight leg etc.) back to it. However, rest of the things are read-only. So, no way to do weird things like modifying the altitude or ground speed etc.
Basically, the main computer is completely isolated from the infotainment system, except for the BUS emitting these minor information.
You can however, probably get near the main computer if you can get the jump seat ...
Disclaimer: Work in aviation tech.
Unless this is a one-way optical bus or similar, I'd be very skeptical of that claim.
From reading the Wikipedia article, they are indeed logically one-way (although the underlying protocol involves two-way communication). It has no security at all.
However, it seems that communication between any avionics systems and anything user-accessible goes through a Network Extension Device (NED). These are required to either be physically (not only logically) unidirectional _or_ have built-in security.
So it might be physically impermeable or it might be a buggy 10-year old firewall. Doesn't exactly inspire confidence given the subject of the article.
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.
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.
How do you get this list?
[1] https://play.google.com/store/apps/details?id=com.eclipsim.g...