2010-04 · NASA ASRS report 883546
CRP Controller described a minimal separation event when using lateral separation between an arrival and departure aircraft. Observing Supervisor questioned the developing event and suggested the issuance of turns. The Controller discounted the recommendation.
I was working approach. I had just assumed the position. The previous Controller had released Aircraft X from HRL on a heading of 090; climbing to 8;000. There was an area of moderate weather approximately 15 miles in diameter about 17 miles northeast of HRL. I had cleared Aircraft Y for an ILS approach when he was about 18 or 20 miles north of HRL. He had captured the localizer and was flying inbound. I switched him to the Tower. Meanwhile; Aircraft X departed. I let him fly east for a bit then turned him northeast. The plan was to not force him to fly 18 or 20 miles east to get around the weather. If he turned north; he could stay west of it. I gave him a heading which would take him west of the weather; and in my judgment; keep him at least three miles east of Aircraft Y; as he tracked inbound on the localizer. The Supervisor looked at the RADAR and told me he thought I should turn Aircraft X. I gave Aircraft X a ten degree turn to the right. I asked the Supervisor what he was concerned about and he did not think I would have the required three miles as the two aircraft passed. I certainly would not have altitude; as Aircraft X was climbing extremely slowly. I used the STARS equipment to measure the distance between the two and had over 4 miles. The distance did seem to be narrowing a bit; but I never thought the two would get to be less than three miles. I watched; using the measuring equipment in STARS and never saw anything less than 3.4 miles between the two aircraft. The Supervisor later went and checked the tapes and recorded data information and told me that; in his judgment; the two planes did; in fact; get closer than 3 miles. I never observed any such loss of separation; but evidently I was mistaken; as the Supervisor informed me of such. It is my opinion that I never lost three miles; however; when the Supervisor told me I was wrong; he suggested I file this report. In the future; however; I will absolutely ensure that no two airplanes ever get this close together. Recommendation; my only recommendation to prevent a re-occurrence of this event is for me to strive harder to ensure that I never let any two airplanes get anywhere near three miles from each other.
An IFR Small Transport was on the ILS approach to Runway 17R. An IFR Small Aircraft departed opposite direction (Runway 35R) and turned eastbound (H090). The Departure Controller turned the Small Aircraft northbound prematurely (H010). I was monitoring the operation from the South Radar position when I heard the Controller comment on how slow the Small Aircraft was climbing. I used the STARS 'MIN' function and saw that the aircraft were predicted to pass with less than 3 NM. I then asked the Controller if the Small Aircraft was IFR. When he replied that it was; I told him he needed to turn the Small Aircraft eastbound because there was not going to be enough separation (At this point; the aircraft where a little over 4 miles apart). Rather than do this; the Controller questioned why he should turn the aircraft. I reiterated that there wasn't going to be enough separation. The Controller did take action just before separation was lost; but it was too little - too late. Recommendation; the Controller was 'betting' on having altitude separation between the departure and the arrival and was unwilling to change his plan; even though it wasn't going to work. To prevent a situation like this; positive separation should be applied. Also; when someone on the Radar Team (whether a controller or supervisor) suggests an alternate course of action; be willing to take action. There just isn't enough time to have full discussion about how and why separation is about to be lost.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.
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