PA-28 Cherokee/Archer/Dakota/Pillan/Warrior
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 18.0
Training / Qualification; Communication Breakdown
ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Separated Traffic; Air Traffic Control Issued New Clearance; Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Executed Go Around / Missed Approach
Human Factors; Procedure
I was working on local control with moderate traffic and a fair amount of frequency congestion.  Aircraft Y was number one and cleared to land on a 2 mile final.  An aircraft called for departure.  I told Aircraft Y 'cancel landing clearance; traffic holding in position' Aircraft Y responded 'you want us to cancel landing clearance'  I said affirmative and then immediately told my other aircraft to line up and wait; traffic on two mile final.  I then observed Aircraft Y breaking off the final northbound.  Aircraft X was in the right traffic pattern approximately midfield downwind with Aircraft Y about a mile ahead of him northbound. Observing the aircraft out the window it appeared that they were separated and diverging.  I called the traffic for Aircraft X letting him know traffic was ahead northbound.  He said looking and then I have him in sight.  I informed the pilot of Aircraft Y that cancel landing clearance does not mean to break off the final; only that we cannot issue a landing clearance with traffic in position and that he should expect his landing clearance on short final.  He apologized; and then without instruction or clearance made an immediate southbound turn back into the north downwind coming in close proximity to Aircraft X who said 'that was close'.  Aircraft Y was given further instruction and landed without further incident and was given a brasher warning by ground control.  He called on the phone and apologized saying he didn't know why he broke off the approach and later turned into the downwind.  He stated he could not give us his license number since it is a temporary license he's only had for a week.I have never seen this occur before after cancelling an aircraft's landing clearance.  I think it's obvious that pilot inexperience added confusion to a sometimes already confusing procedure using lineup and wait.  Perhaps more pilot education as to why a landing clearance must sometimes be withheld or cancelled when using the procedure would be appropriate.
An aircraft on final approach was informed its landing clearance was cancelled. The aircraft misunderstood this transmission as to be an instruction to go-around. The aircraft initiated a go-around on their own and entered right downwind for the runway without receiving any instructions to do so from the Controller. There was another aircraft in the pattern on a right downwind. The Controller issued traffic to the aircraft. The aircraft established on the right downwind saw the go-around traffic and stated it was close to them.