Small Aircraft
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 13.75
Confusion; Situational Awareness
Conflict NMAC; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Separated Traffic; Flight Crew Returned To Clearance
Aircraft
Aircraft X requested a westbound departure and was cleared for takeoff. There were three other aircraft in the south downwind: Aircraft Y (pattern work); followed by Aircraft Z; inbound from the west; and Aircraft A who was entering the pattern and departed ahead of Aircraft X.  On departure; Aircraft X turned a crosswind southbound instead of going westbound; which put him in the path of Aircraft Z.  At first I thought I confused Aircraft Z and Aircraft X; but I issued traffic immediately to Aircraft Z and watched as he had to maneuver to avoid Aircraft X.  I then issued traffic to Aircraft A as he was also going to be in conflict.  Aircraft X was not answering at first; and then when he responded; I asked his intentions; thinking that I misunderstood him. He decided that he would go to MZB VORTAC before turning north; which is contrary to what 99.99% of our pilots do. Though the aircraft is based here; I do not believe the pilot is based here; and he does not know the airspace and procedures. I thought he was going westbound; and I could not have anticipated his moves. I issue traffic normally on this situation; (westbound departures with inbounds from the west) and was in that process when he turned into the traffic. Aircraft Z pilot said 'That was pretty close.'  Then on the phone later; he described Aircraft X as 'That guy who tried to crash into me.'This pilot needs to be found and educated.
MYF Tower controller describes a NMAC caused by a pilot not familiar with the local procedures while airborne.