Small Aircraft; High Wing; 1 Eng; Fixed Gear
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 3.5
Communication Breakdown; Confusion; Situational Awareness; Workload
ATC Issue All Types; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Ground Incursion Taxiway
Air Traffic Control Provided Assistance
Human Factors; Procedure
Aircraft X initially called from the NW with just his callsign and nothing else. I told him to enter left downwind for Runway 35L; [and] say type landing. He responded '35L; [type aircraft].'I watched him the best I could; but it appeared he was entering the downwind. I had just asked for a local assist. Local 2 already had a local assist. The traffic volume was extremely high.[Four minutes later]; Aircraft X was opposite direction over the top of [RWY] 35L.I told him to turn west immediately and that he was over the runway. No readback; but he turned west.I then told him to turn south into the downwind. No readback; but he turned south.I sequenced him and cleared him to land. He read back; 'Traffic in sight' and nothing else.I then had to tell him to turn base. No readback; but he turned base.[Two minutes later] I told him to 'Turn right A4; contact Ground 124.57.' He responded 'A4.'This pilot should not be in an airplane. He was opposite direction over a runway in a completely saturated airspace. He does not understand how radio communication and read backs are supposed to work. I was not in position at the time; but when he was ready to leave the airport; he taxied to the runway without talking to ATC because the guy who filled his airplane with fuel said he 'was good to go.'This pilot is an accident waiting to happen.
GFK Tower Controller reported an unsafe pilot; who in the reporter's mind; should not be flying.