sentences:  Upon introduction, they were assigned to the 402 Squadron and used as a step-up trainer for their future F-5 Freedom Fighter pilots.The step-up characteristic of the Fantrainer is generally one of its main advantages; the abilities of the Fantrainer in a training capacity is such to almost fully cover a pilot's entire syllabus, only needing to be supplemented by an Advanced Trainer for the purpose of building direct experience with high performance jets.The first four aircraft were constructed in Germany while the remaining aircraft were assembled in Thailand from kits shipped from RFB, which were assembled at a peak rate of six Fantrainers per month.