Air Traffic Control Developmental
Training / Qualification; Situational Awareness; Confusion
ATC Issue All Types; Conflict Airborne Conflict; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued New Clearance; Air Traffic Control Provided Assistance; Air Traffic Control Separated Traffic; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Became Reoriented; Flight Crew Executed Go Around / Missed Approach
Airspace Structure; Procedure; Human Factors; Chart Or Publication
Aircraft X requested one turn in holding at VECKI prior to one practice ILS 17 approach into KOA with the alternate missed approach followed by a clearance to [a different airport]. I was the D-Side so I coordinated the holding at VECKI; ILS 17; followed by the alternate missed approach climbing to 5;000. The holding and approach into KOA were accomplished with no issues. When Aircraft X checked back in with us on the missed approach he was observed making a right hand turn northbound. I notified the R-side and he asked Aircraft X what his intentions were. Aircraft X said he was on the alternate missed approach making a right hand turn to WERAK. WERAK is south of KOA at 174 degree radial 11.8 DME. While Aircraft X was northbound Aircraft Y was cleared for a visual approach Runway 17. Aircraft Z was cleared for a visual approach to follow Aircraft Y. The R-side proceeded to turn Aircraft X southwest bound away from the traffic and obstructions towards the ocean and safety below the Minimum IFR Altitude (MIA). Separation between aircraft was never lost. Aircraft X was clearly confused of what the alternate missed approach procedure entailed. Upon looking at the approach plate; the alternate missed approach is not depicted in the best manner and there is no written description to clarify the diagram.I would suggest the ILS 17 to KOA approach plate be revised to have a better description of the alternate missed approach procedure. In the diagram; there is nothing showing where the airport is and no written description of the procedure. This could be easily misinterpreted as shown in the event that was shown.
HCF TRACON trainee reported observing an aircraft deviate from the expected missed approach procedure below the minimum IFR altitude and towards arriving traffic.