Fare paying passengers can not be carried on training flights.
Incorrect, line training??
On a training flight the instructor has to hold an appropriate rating i.e. TRI / TRE.
What about line trainers without TRI/TRE?
Line training using Training Captains who are not TRIs or TREs with fare paying passengers onboard can only be done if the pilot being "trained" is legally qualified to fly the aircraft in that situation.
When does somebody become legally qualified? Once they have finished their line training?
Or are we saying that this flight wasn't line training but was base training?