Skyhawk 172/Cutlass 172
Flight Crew Commercial; Flight Crew Instrument
Flight Crew Last 90 Days 83; Flight Crew Total 564; Flight Crew Type 400
Confusion; Fatigue; Situational Awareness
Conflict NMAC; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued Advisory / Alert; Flight Crew Took Evasive Action
Human Factors
ATC issued a vector of 010 for traffic and ATC immediately issued a traffic advisory of a Citation on approach at my '3 o'clock.' I mistakenly turned to 100. A few seconds later I saw the Citation coming directly at me (not at my 3 o'clock) at the same altitude less than 1 NM away. Quickly evaluated which direction the Citation was flying and took an evasive descending left turn and reported to ATC 'Citation in sight we are making an evasive left turn.' ATC did not respond. During my turn the Citation initiated a climbing left turn and reported to ATC that they 'Received a Resolution Warning and that was way too close' ATC asked if they were abandoning the approach but the Citation decided to continue and contacted ZZZ tower. Later ATC clarified with me that he had issued 010 and I had flown a 100 heading. Fatigue was most likely a factor in the mistake; since we were 10 minutes away from the end of a 3.5 hour morning shift.
A Traffic Watch pilot reported a near-mid-air-collision with a Cessna Citation after making a heading deviation likely due to fatigue.