Tower Controller at airport with significant foreign pilot training activity described pattern conflict event; alleging continued problems with students that are soloed too early; have language difficulties and are causing on going safety problems; noting suspected contractual pressure as possible causal factors.

Narrative

Aircraft 1 was entering the traffic pattern for Runway XXR from the southeast reporting point. Once Aircraft 1 reached this reporting point; Local Control (LC) told Aircraft 1 to enter base for XXR. Aircraft 1 did not turn base and continued to fly directly to the numbers; conflicting with a C172 on downwind. Local Control then told Aircraft 1 to 'fly westbound for a base to Runway XXR.' Aircraft 1 turned westbound; but continued through final for XXR and turned final for XXL. This conflicted with Aircraft 2 on downwind to base for XXL. Local Control immediately turned Aircraft 2 back to the downwind; and told Aircraft 1 he was lined up for the wrong runway and to go back to XXR. Aircraft 1 then flew east and joined final for XXR. Once Aircraft 1 was back at the ramp; I observed that he was a solo student pilot. A local flight school operate these aircraft and has a contract with a foreign airline to train their students to fly. Since the inception of this program; our ATCT has had extreme difficulty with issuing instructions to these students and ensuring that they understand what we are telling them and they will do it. I feel that these students are being allowed to fly solo too early; as they have a hard time understanding any instructions which are not part of the regular procedures (also due to English as a second language.) This results in multiple calls to the same aircraft; and no guarantee that they understand what we are tell them. In the past week; we have had two events from these students; on their first pattern solo; thus emphasizing the point that they are being allowed to solo too early. The lack of experience and the lack of instructor in the aircraft has lead to many dangerous situations; like the one above. If this student was given more time before soloing; the student would have learned the procedure ...... correctly and would have had more practice with ATC communications with the assistance of an instructor. I have talked to a few flight instructors and they indicated that they are under pressure from their bosses to solo the students at certain points; as that is one of the stipulations of the contract with the foreign airline. This lack of experience and the allowance of early solos to continue is a huge safety hazard for all users of this airport.