Narrative:

I was working local control, and had cleared small transport X to land when on left downwind to runway 34. Approach control had pointed out traffic flying over the airport from south to north. Small aircraft Y called ready for departure, and I concentrated on the tower D BRITE to determine if I should restrict small aircraft Y below the overflying traffic. I restr small aircraft Y and cleared him for takeoff. The pilot of small aircraft Y asked if he should hold for the traffic on short final, which I had forgotten. Small transport X was passing the end of the runway, so I told small aircraft Y affirmative, taxi into position and hold. In analyzing the situation, I believe the following human performance factors may have contributed. I had not worked local control for several days, so as not quite into the flow of things; I had just taken the position after lunch with 1 1/2 hours remaining in my shift and was not as alert as I should have been; I allowed myself to be distraction by other control decision of restriction for the overflt; small transport X beacon had dropped off from the scope, so that even though I was concentrating on the scope, I failed to be reminded by the primary target on short final; I failed to use my mental checklist (check scope, runway, final, note pad before clearing any aircraft). That has kept me out of trouble for many yrs. I am thankful that the system has checks and is able to absorb errors, and I am thankful to the alert small aircraft Y pilot.

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Original NASA ASRS Text

Title: LCL CTLR TECHNIQUE ATC COM FAILED TO INSURE STANDARD SEPARATION BETWEEN SMT X AND SMA Y. OPDEV.

Narrative: I WAS WORKING LCL CTL, AND HAD CLRED SMT X TO LAND WHEN ON L DOWNWIND TO RWY 34. APCH CTL HAD POINTED OUT TFC FLYING OVER THE ARPT FROM S TO N. SMA Y CALLED READY FOR DEP, AND I CONCENTRATED ON THE TWR D BRITE TO DETERMINE IF I SHOULD RESTRICT SMA Y BELOW THE OVERFLYING TFC. I RESTR SMA Y AND CLRED HIM FOR TKOF. THE PLT OF SMA Y ASKED IF HE SHOULD HOLD FOR THE TFC ON SHORT FINAL, WHICH I HAD FORGOTTEN. SMT X WAS PASSING THE END OF THE RWY, SO I TOLD SMA Y AFFIRMATIVE, TAXI INTO POS AND HOLD. IN ANALYZING THE SITUATION, I BELIEVE THE FOLLOWING HUMAN PERFORMANCE FACTORS MAY HAVE CONTRIBUTED. I HAD NOT WORKED LCL CTL FOR SEVERAL DAYS, SO AS NOT QUITE INTO THE FLOW OF THINGS; I HAD JUST TAKEN THE POS AFTER LUNCH WITH 1 1/2 HRS REMAINING IN MY SHIFT AND WAS NOT AS ALERT AS I SHOULD HAVE BEEN; I ALLOWED MYSELF TO BE DISTR BY OTHER CTL DECISION OF RESTRICTION FOR THE OVERFLT; SMT X BEACON HAD DROPPED OFF FROM THE SCOPE, SO THAT EVEN THOUGH I WAS CONCENTRATING ON THE SCOPE, I FAILED TO BE REMINDED BY THE PRIMARY TARGET ON SHORT FINAL; I FAILED TO USE MY MENTAL CHKLIST (CHK SCOPE, RWY, FINAL, NOTE PAD BEFORE CLRING ANY ACFT). THAT HAS KEPT ME OUT OF TROUBLE FOR MANY YRS. I AM THANKFUL THAT THE SYSTEM HAS CHKS AND IS ABLE TO ABSORB ERRORS, AND I AM THANKFUL TO THE ALERT SMA Y PLT.

Data retrieved from NASA's ASRS site as of July 2007 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.