Narrative:

Merrill field (mri) has 2 runways, 6/24 and 15/33. The runways do not intersect, but the departure corridor for runway 24 intersects with the departure corridor for runway 33. I was working local combined with ground control. WX was VFR but turbulent. Air carrier X, a C150, had requested to taxi for departure on runway 33, and was instructed to taxi to that runway. Air carrier Y, a C172 operated as an air taxi, requested to taxi to runway 6. I told him the wind favored runway 24, and he asked, and I instructed him to taxi to runway 24. Air carrier Z, a C207, operated as an air taxi by the same company, requested to taxi to runway 6. I told him the wind favored runway 24, but he still wanted runway 6, so I instructed him to taxi to runway 6. Air carrier U, a C150, was doing touch and goes on runway 24. Air carrier X requested takeoff clearance on runway 33. I observed that air carrier X was on climb out, past the intersection, so I cleared air carrier Z for takeoff. Air carrier Z requested takeoff on runway 6, and I observed he would not be a factor for air carrier U, so I cleared him for takeoff on runway 6. Air carrier Y then requested takeoff on runway 24, and I told him to hold short for the opposing direction departure. I scanned the runway prior to air carrier Z's departure, and then watched him as he departed. As soon as he passed the intersection where air carrier Y was waiting, I cleared air carrier Y for takeoff, completely forgetting that air carrier X would be a factor. About 10 seconds later I realized the conflict, and told air carrier Y to cancel his takeoff. Just as I said that he lifted off and said 'say again?' I turned my head and observed air carrier X crossing the runway 24 departure path. Air carrier Y was about 2000 ft from the end of the runway. A few moments later I got relieved from position and reported the operational error. Contributing factors: I was working ground combined with local, when it was not necessary to do so. I was being too permissive in allowing the departures their requested runways. Air carrier X and air carrier Z simply requested the closest runway to their base. I didn't take the whole air traffic picture into account when clearing air carrier Y. I had 3 departures from 3 different runways, all at the same time. Human performance considerations: I was trying to do everything for everybody, alone. I was being an 'accommodator' instead of a 'controller.' my attention was spread too thin, over too many different things.

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Original NASA ASRS Text

Title: COMBINE GND AND LCL TWR CTLR MADE AN OPERROR WHEN HE CLRED A CESSNA 172 FOR TKOF WHEN A CESSNA 150 WAS XING THROUGH THE DEP PATH OF THE C172.

Narrative: MERRILL FIELD (MRI) HAS 2 RWYS, 6/24 AND 15/33. THE RWYS DO NOT INTERSECT, BUT THE DEP CORRIDOR FOR RWY 24 INTERSECTS WITH THE DEP CORRIDOR FOR RWY 33. I WAS WORKING LCL COMBINED WITH GND CTL. WX WAS VFR BUT TURBULENT. ACR X, A C150, HAD REQUESTED TO TAXI FOR DEP ON RWY 33, AND WAS INSTRUCTED TO TAXI TO THAT RWY. ACR Y, A C172 OPERATED AS AN AIR TAXI, REQUESTED TO TAXI TO RWY 6. I TOLD HIM THE WIND FAVORED RWY 24, AND HE ASKED, AND I INSTRUCTED HIM TO TAXI TO RWY 24. ACR Z, A C207, OPERATED AS AN AIR TAXI BY THE SAME COMPANY, REQUESTED TO TAXI TO RWY 6. I TOLD HIM THE WIND FAVORED RWY 24, BUT HE STILL WANTED RWY 6, SO I INSTRUCTED HIM TO TAXI TO RWY 6. ACR U, A C150, WAS DOING TOUCH AND GOES ON RWY 24. ACR X REQUESTED TKOF CLRNC ON RWY 33. I OBSERVED THAT ACR X WAS ON CLBOUT, PAST THE INTXN, SO I CLRED ACR Z FOR TKOF. ACR Z REQUESTED TKOF ON RWY 6, AND I OBSERVED HE WOULD NOT BE A FACTOR FOR ACR U, SO I CLRED HIM FOR TKOF ON RWY 6. ACR Y THEN REQUESTED TKOF ON RWY 24, AND I TOLD HIM TO HOLD SHORT FOR THE OPPOSING DIRECTION DEP. I SCANNED THE RWY PRIOR TO ACR Z'S DEP, AND THEN WATCHED HIM AS HE DEPARTED. AS SOON AS HE PASSED THE INTXN WHERE ACR Y WAS WAITING, I CLRED ACR Y FOR TKOF, COMPLETELY FORGETTING THAT ACR X WOULD BE A FACTOR. ABOUT 10 SECONDS LATER I REALIZED THE CONFLICT, AND TOLD ACR Y TO CANCEL HIS TKOF. JUST AS I SAID THAT HE LIFTED OFF AND SAID 'SAY AGAIN?' I TURNED MY HEAD AND OBSERVED ACR X XING THE RWY 24 DEP PATH. ACR Y WAS ABOUT 2000 FT FROM THE END OF THE RWY. A FEW MOMENTS LATER I GOT RELIEVED FROM POS AND RPTED THE OPERROR. CONTRIBUTING FACTORS: I WAS WORKING GND COMBINED WITH LCL, WHEN IT WAS NOT NECESSARY TO DO SO. I WAS BEING TOO PERMISSIVE IN ALLOWING THE DEPS THEIR REQUESTED RWYS. ACR X AND ACR Z SIMPLY REQUESTED THE CLOSEST RWY TO THEIR BASE. I DIDN'T TAKE THE WHOLE AIR TFC PICTURE INTO ACCOUNT WHEN CLRING ACR Y. I HAD 3 DEPS FROM 3 DIFFERENT RWYS, ALL AT THE SAME TIME. HUMAN PERFORMANCE CONSIDERATIONS: I WAS TRYING TO DO EVERYTHING FOR EVERYBODY, ALONE. I WAS BEING AN 'ACCOMMODATOR' INSTEAD OF A 'CTLR.' MY ATTN WAS SPREAD TOO THIN, OVER TOO MANY DIFFERENT THINGS.

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.