I have a question about UCM, as I am studying it in my Physics course. I understand that Non-UCM experiences a tangential acceleration component, which is the result of changing speed along its circular path.

My textbook gives an example of this in the form of a pendulum, which is given tangential acceleration when it rotates in a vertical plane due to the acceleration from gravity.

This makes sense to me. However, what doesn't make sense to me is a scenario under UCM, in which gravity does not affect tangential acceleration - because in UCM, tangential acceleration must equal zero. So is UCM just a fictitious scenario, or can circular motion really appear on Earth and experience a tangential acceleration of zero?

Thanks.