Skyhawk 172/Cutlass 172
Air Traffic Control Fully Certified; Flight Crew Instrument
Air Traffic Control Time Certified In Pos 1 (yrs) 1
Situational Awareness
ATC Issue All Types; Conflict NMAC; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Executed Go Around / Missed Approach
Airspace Structure; Human Factors; Procedure; Weather
Aircraft X; a C172; departed and was instructed to make a left turn direct to the mid span of a bridge. Instead; Aircraft X made a left downwind departure becoming a conflict for arriving traffic. Aircraft Y was on final approach [when] Aircraft X made their unintended turn. When I recognized the conflict I issued traffic to both aircraft and they replied they were looking for traffic. When I realized greater action was required I turned Aircraft X 20 degrees left to avoid traffic; but the pilot did not comply. Aircraft Y never got traffic in sight and went around on approximately a two mile final. Aircraft X did advise they had Aircraft Y in sight. The radar display showed that the targets merged at 1000 feet. I should have turned Aircraft X earlier to avoid the conflict and the pilot of Aircraft X should have followed ATC instructions.
I took off for a short flight. It was the last leg of a 3+ hour cross country. Weather was Broken at 1000 feet; but visibility was good and sitting on the runway threshold I was able to see that the quadrant toward my destination was clear; hence I decided to go back VFR. I was cleared for takeoff for an enroute departure direct to a VFR waypoint. Right after departure the conditions in my destination quadrant changed making harder to visually acquire my target. While working on maintaining VFR and looking for my waypoint; I got the following instruction from the tower '<Callsign> it sounds like you are continuing North of runway 30; make left turn 20 degrees for traffic'. I was flying a southeasterly heading; close to the one that I was expecting my visual waypoint to be; and this instruction contributed to the task loading and inadvertently made me delay the turn demanded by ATC.Shortly after I got from ATC a traffic advisory to which I replied with 'Negative Contact' and the advisory was followed by the following instruction (as checked on LiveATC).'<Callsign> <garbled> turn LEFT; <garbled> actually turning RIGHT.' I understood and read back the instruction as 'TURN RIGHT' and I inverted my turn direction to the RIGHT. While in the turn I acquired the target visually and took evasive action which consisted of a LEFT turn. I heard on the frequency that the traffic initiated a go around. In the same exchange I overheard the B777 saying that the TCAS had been triggered.After the occurrence the controller gave me a turn to the right; toward my first waypoint that I acquired; I was given a frequency change shortly after and I landed safely. Analyzing the factors that contributed to what happened; I can definitely recognize Fatigue; Get-Home-Itis and Weather. It was the last leg of a few hours flight; after a whole day at work. The short flight and the will to get home soon made me make the incautious decision to conduct the flight under VFR while I could have just filed IFR and not have to worry about the weather. As a contributing factor I can also recognize the familiarity with the area and landmarks that made me underestimate the task loading I experienced while trying to acquire my waypoint.I also perceive the usage of non-standard phraseology from the controller as a contributing factor. For instance hearing two different directions in the same instruction was a big source confusion; as can be heard on the audio recording I interpreted that as an instruction to turn RIGHT while it was probably meant to be an instruction to turn to the LEFT.
OAK Tower Controller and pilot reported that the pilot did not comply with departure instructions causing them to fly into conflict with traffic inbound on an instrument approach.