Narrative:

I was advised by management that they had received a public inquiry from the local flight school about a report from a flight school operator about a possible near midair collision.the pilot stated that while they were upwind; that another aircraft [aircraft X] that had departed from the south runway flew under them turning north bound.per managements investigation; it was determined that aircraft Y departed the south runway on an immediate take off clearance and made a turn to the north immediately off the departure end. The local controller at the time had failed to issue a straight out departure for the north runway traffic. They had also been training on local control at the time.I remember that day; the local two controller being confused when seeing the traffic upwind and talking to local control about it; but by the time I was fully aware of the situation; it was over and when I saw the aircraft; they appeared safe and clear. I asked the local controller if there was a problem or issue and he said that the pilot made no statements to the fact of a near midair collision and it just appeared that both aircraft drifted a bit in the upwind.there was a lot of training going on and some busy traffic; so I was paying attention to the final at the time of the supposed event.with our closely spaced parallels; it is imperative that local controllers issue restrictions to upwind traffic when the potential for local controller traffic conflicts exist. Also; due to visibility issues; it is very hard to tell when aircraft are lined up correctly in the upwind and on final for [different runways]. We need a taller more visible vantage point to help differentiate this.

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Original NASA ASRS Text

Title: HIO Tower Controller reported a Near Mid Air Collision occurred due to an early turn from an aircraft departing a parallel runway.

Narrative: I was advised by management that they had received a public inquiry from the local flight school about a report from a flight school operator about a possible NMAC.The pilot stated that while they were upwind; that another aircraft [Aircraft X] that had departed from the south runway flew under them turning north bound.Per managements investigation; it was determined that Aircraft Y departed the south runway on an immediate take off clearance and made a turn to the north immediately off the departure end. The local controller at the time had failed to issue a straight out departure for the north runway traffic. They had also been training on local control at the time.I remember that day; the local two controller being confused when seeing the traffic upwind and talking to local control about it; but by the time I was fully aware of the situation; it was over and when I saw the aircraft; they appeared safe and clear. I asked the Local controller if there was a problem or issue and he said that the pilot made no statements to the fact of a NMAC and it just appeared that both aircraft drifted a bit in the upwind.There was a lot of training going on and some busy traffic; so I was paying attention to the final at the time of the supposed event.With our closely spaced parallels; it is imperative that local controllers issue restrictions to upwind traffic when the potential for Local Controller traffic conflicts exist. Also; due to visibility issues; it is very hard to tell when aircraft are lined up correctly in the upwind and on final for [different runways]. We need a taller more visible vantage point to help differentiate this.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.