Narrative:

I was working hobby final. Hobby was landing runway 30L ILS. I had vectored several aircraft to the final without incident. A BE90 was in line and was too close to preceding large aircraft so I had to pull him out and re sequence. Shortly thereafter another aircraft was vectored to final; cleared for approach and shipped to tower. I continued to vector aircraft to final. Without warning and without ever changing to tower frequency; the aircraft turned on to the final made a very abrupt maneuver and ended up turning towards efd airport and eventually out toward hobby final. I cancelled the approach clearance for several air carrier jets on final and turned them out away from the lost aircraft. Eventually the lost flight contacted hobby tower and was given help by the tower to land successfully. I had three air carrier aircraft on my frequency that I had 'given up' my vertical separation since they had already been cleared for an approach once; and the BE90. I vectored the aircraft in trail with each other they were all on the exact same heading. While I was waiting for the lost aircraft situation to be resolved; I had to take the first air carrier across the localizer for spacing. The BE90 was first in the sequence and landed without incident. I vectored the first air carrier across the localizer on a 040 heading and then turned it left to 260 to get back toward the localizer and outside the approach gate. I eventually turned the aircraft to 280 to join and cleared for the ILS. I had to take the number two and three aircraft on the exact same routing; in trail with each other. When I turned the aircraft 140 degrees left I ended up 40 degrees off the reciprocal of the succeeding aircraft when 45 degrees is required. For two 'hits' tarp (traffic analysis and review program) determined that I did not have proper lateral separation between aircraft one and two. The same situation occurred between aircraft two and three. With the wind factored in; tarp determined that aircraft one and two were two 'hits' insufficient lateral separation by five degrees; and for aircraft two and three there were again two 'hits' insufficient lateral separation but with wind I was eight degrees short. I need the same tools to maintain separation as tarp uses to find errors. I use five mile range marks and my eyesight to keep aircraft moving in a fluid manner. Tarp measures thousands of a second and hundredths of a mile to try to 'catch' me. There was no safety issue involved. All three air carrier aircraft landed successfully and with proper separation. After the fact I was greeted with this 'random audit' operational error. Less overtime would be helpful in maintaining a good perspective on work. Here at I90 we are assigned overtime in conjunction with our prime time which makes it difficult to go anywhere for a week on your vacation. Additionally; I am assigned multiple overtime shifts per pay period and work hold over overtime on top of that.

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Original NASA ASRS Text

Title: I90 Controller described a loss of separation event that was discovered with automation. The event was initiated when an aircraft was vectored onto the ILS for HOU and unexpectedly turned off the localizer which in turn required vectors of four following aircraft already established on the final.

Narrative: I was working Hobby final. Hobby was landing Runway 30L ILS. I had vectored several aircraft to the final without incident. A BE90 was in line and was too close to preceding large aircraft so I had to pull him out and re sequence. Shortly thereafter another aircraft was vectored to final; cleared for approach and shipped to Tower. I continued to vector aircraft to final. Without warning and without ever changing to Tower frequency; the aircraft turned on to the final made a very abrupt maneuver and ended up turning towards EFD airport and eventually out toward Hobby final. I cancelled the approach clearance for several air carrier jets on final and turned them out away from the lost aircraft. Eventually the lost flight contacted Hobby Tower and was given help by the Tower to land successfully. I had three air carrier aircraft on my frequency that I had 'given up' my vertical separation since they had already been cleared for an approach once; and the BE90. I vectored the aircraft in trail with each other they were all on the exact same heading. While I was waiting for the lost aircraft situation to be resolved; I had to take the first air carrier across the localizer for spacing. The BE90 was first in the sequence and landed without incident. I vectored the first air carrier across the localizer on a 040 heading and then turned it left to 260 to get back toward the localizer and outside the approach gate. I eventually turned the aircraft to 280 to join and cleared for the ILS. I had to take the number two and three aircraft on the exact same routing; in trail with each other. When I turned the aircraft 140 degrees left I ended up 40 degrees off the reciprocal of the succeeding aircraft when 45 degrees is required. For two 'hits' TARP (Traffic Analysis and Review Program) determined that I did not have proper lateral separation between aircraft one and two. The same situation occurred between aircraft two and three. With the wind factored in; TARP determined that aircraft one and two were two 'hits' insufficient lateral separation by five degrees; and for aircraft two and three there were again two 'hits' insufficient lateral separation but with wind I was eight degrees short. I need the same tools to maintain separation as TARP uses to find errors. I use five mile range marks and my eyesight to keep aircraft moving in a fluid manner. TARP measures thousands of a second and hundredths of a mile to try to 'catch' me. There was no safety issue involved. All three air carrier aircraft landed successfully and with proper separation. After the fact I was greeted with this 'random audit' operational error. Less overtime would be helpful in maintaining a good perspective on work. Here at I90 we are assigned overtime in conjunction with our prime time which makes it difficult to go anywhere for a week on your vacation. Additionally; I am assigned multiple overtime shifts per pay period and work hold over overtime on top of that.

Data retrieved from NASA's ASRS site as of April 2012 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.