Some cheap android device + sat phone. Duct tape those two devices anywhere on the plane where you can feed then 5V.
Problem solved. I understand the safety precautions etc, but streaming critical data would not be a huge data stream, and we solved that problem with very small devices a long time ago. Building a device with a GPS module, accelerometer and satphone chipset would be enough to give basic positional and attitudinal data and would be completely isolated from the rest of the plane's systems except for the 5V feed.
You do NOT need a $100k contractor sourced device to add "tracking of last resort" functionality t a plane.