Date: 201708
Local time of day: 0001-0600
Location: OAK.Airport, CA
Flight conditions: Marginal
Weather elements / visibility: 10
Light: Night
Aircraft: Skyhawk 172/Cutlass 172
Operator: Personal
Operating under: Part 91
Flight plan: VFR
Mission: Personal
Flight phase: Initial Climb
Airspace: Class C OAK
ATC / advisory: Tower OAK
Second aircraft: B777 Undifferentiated or Other Model
Reporter organization: Government
Reporter function: Local
Reporter qualification: Air Traffic Control Fully Certified; Flight Crew Instrument
Human factors: Situational Awareness
Second reporter function: Single Pilot
Anomaly: ATC Issue All Types; Conflict NMAC; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Detector: Automation Aircraft RA; Person Air Traffic Control
When detected: In-flight
Result: 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
Contributing factors: Airspace Structure; Human Factors; Procedure; Weather
Primary problem: Human Factors

Narrative: 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.


Second narrative: 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.


Synopsis: 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.