> Are there any public, open, comprehensive datasets on flights?
Airlines and commercial aviation operators schedule their own flights.
That is a dynamic schedulle. So, perhaps there is no "comprehensive data set".
However, FlightAware makes publicly available scheduled and completed flight data over many routes in the USA. You can search by route and get a list of flights.
Flight information includes filed departure time, route of flight, and speed. For completed flights actual time, altitude, and route is shown. For example,
a search on the route Dallas/Fort Worth to Austin lists 45 flights.
