What is the maximum driving speed and altitude for LTE?

Question

Computer networks

I read somewhere that the maximum speed of the car at which the LTE Internet on the tablet will work correctly (that is, the telecom towers will have time to switch correctly) = 120km / h
But from my experience, the Internet works fine even at 160km / h. When I began to learn more, they explained to me that the towers themselves, unlike conventional communications, have a much larger area coverage and 120 km / h - only for situations when switching is in progress if two BSs have a small overlap area (i.e. coverage area in butt or with a small space)
As for the height - it's not clear at all.
When the plane lands, 3G seems to start receiving at about 1 km (well, mail arrives, etc.) if you are lucky
I will add: I am not interested in the theoretical side of the issue. I ask for the cause, it is the Russian reality and approximate thresholds that are of interest. I really want to hear from those who work for telecom operators on the technical side and can reveal the nuances on this topic.
I need to stream from a helicopter and, depending on the nuances, we will choose the route and speed.