With all the modern tech (gps, sattelites, tracking equipment, radar), how is it even possible for a plane (Boeing 737) to just go missing?

Question

Not to make light of the situation but wouldn’t that Boeing 737 make the best spy plane then?

In: Technology

Answer 1

“normal” tech stops working at certain altitude.

Plane tracking relies on pings back and forth between the plane and transmitting stations on the ground (and not satellites).