All,

What's the difference between "Air Taxi" and Charter or Part 135
operations? While tracking some flights via FlightAware, I notice that
some planes fly under their tail numbers most of the time, but at times
there is a "T" prefixed to the tail number in the system. I read that
this signifies an "air taxi" operation.

How is this different from charter or 135? If they are the same, they
why are all 135 ops not prefixed with the "T" identifier?

Thanks,
Dan