I have a question based on flight track logs on https://flightaware.com.
In one of the logs I'm looking at, it says that at time 08:16:15 PM the altitude was 36,000 ft and plane speed was at 473 mph. At time 08:16:58 PM, the plane descended to 35,400 ft.
I did some rough calculations and realized that the speed 473 cannot be along the vertical plane. Then, what is this speed? Is it along the descent path? Also, what angle do planes make with the vertical plane when descending? Where can I get this information?