Narrative:

Kdk is the home of a coast guard air station. Fixed wing and rotary wing mlt training is common. The coast guard also has a flying club which has a moderate amount of activity. The winters are usually slow, but on this day a fixed wing mlt, a rotary wing mlt and a flying climb small aircraft were in the pattern for touch and go's to runway 10. The base leg for left traffic is in a valley surrounded by mountains. The crosswind is over water (a large bay). Even though state airport has 3 crossing runways, I was putting everyone on runway 10 because of the terrain, the training and the wind. An atx small aircraft Y called up from the mountain pass west of the airport wanting to land. I told him to make a straight-in for runway 10 and call a reporting point for sequencing. He was already over my suggested point and this presented a problem for me. Analyzing my pattern I decided to give him runway 25 (his original request). So this was my picture: small aircraft Y on right downwind runway 25, fixed wing mlt on wide left downwind runway 10, another small aircraft in position on the #south runway 10, and mlt X holding on runway 10 west of runway 25 intersection. My plan: short approach the small aircraft Y and get him out of the way, early turn to the left for the mlt X, clear the small aircraft for takeoff, then clear the fixed wing mlt for the option. To save time, I instructed the mlt X, 'upon departure, make a short, early turn out.' the mlt X replied, that he would. I was watching the small aircraft Y turning final when I saw the mlt X taking off. I gave him instructions to avoid the landing small aircraft Y. This placed him in front of another small aircraft on downwind to runway 10, following the fixed wing mlt. The small aircraft Y made an s-turn to avoid the mlt X and return to final. Recordings indicate that I did not give the mlt X the landing traffic. I did not repeat his hold instruction after I gave departure instructions. I also did not clear him for takeoff. Normally, this is a quite tower. However, there was a lot going on at the time of the incident. This required an increase in awareness in all concerned. While the mlt X did not have a takeoff clearance, the heat of the moment left enough doubt for him to believe that he did. If I had described the situation better, the mlt X would have no doubt about what was wanted from him.

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Original NASA ASRS Text

Title: MULTIPLE RWY OPERATION AND TWR CTLR HAS MLT DEPART WITHOUT TKOF CLRNC. RESULT WAS NMAC WITH SMA ON FINAL TO RWY.

Narrative: KDK IS THE HOME OF A COAST GUARD AIR STATION. FIXED WING AND ROTARY WING MLT TRNING IS COMMON. THE COAST GUARD ALSO HAS A FLYING CLUB WHICH HAS A MODERATE AMOUNT OF ACTIVITY. THE WINTERS ARE USUALLY SLOW, BUT ON THIS DAY A FIXED WING MLT, A ROTARY WING MLT AND A FLYING CLB SMA WERE IN THE PATTERN FOR TOUCH AND GO'S TO RWY 10. THE BASE LEG FOR LEFT TFC IS IN A VALLEY SURROUNDED BY MOUNTAINS. THE XWIND IS OVER WATER (A LARGE BAY). EVEN THOUGH STATE ARPT HAS 3 XING RWYS, I WAS PUTTING EVERYONE ON RWY 10 BECAUSE OF THE TERRAIN, THE TRNING AND THE WIND. AN ATX SMA Y CALLED UP FROM THE MOUNTAIN PASS W OF THE ARPT WANTING TO LAND. I TOLD HIM TO MAKE A STRAIGHT-IN FOR RWY 10 AND CALL A RPTING POINT FOR SEQUENCING. HE WAS ALREADY OVER MY SUGGESTED POINT AND THIS PRESENTED A PROB FOR ME. ANALYZING MY PATTERN I DECIDED TO GIVE HIM RWY 25 (HIS ORIGINAL REQUEST). SO THIS WAS MY PICTURE: SMA Y ON RIGHT DOWNWIND RWY 25, FIXED WING MLT ON WIDE LEFT DOWNWIND RWY 10, ANOTHER SMA IN POS ON THE #S RWY 10, AND MLT X HOLDING ON RWY 10 W OF RWY 25 INTXN. MY PLAN: SHORT APCH THE SMA Y AND GET HIM OUT OF THE WAY, EARLY TURN TO THE LEFT FOR THE MLT X, CLR THE SMA FOR TKOF, THEN CLR THE FIXED WING MLT FOR THE OPTION. TO SAVE TIME, I INSTRUCTED THE MLT X, 'UPON DEP, MAKE A SHORT, EARLY TURN OUT.' THE MLT X REPLIED, THAT HE WOULD. I WAS WATCHING THE SMA Y TURNING FINAL WHEN I SAW THE MLT X TAKING OFF. I GAVE HIM INSTRUCTIONS TO AVOID THE LNDG SMA Y. THIS PLACED HIM IN FRONT OF ANOTHER SMA ON DOWNWIND TO RWY 10, FOLLOWING THE FIXED WING MLT. THE SMA Y MADE AN S-TURN TO AVOID THE MLT X AND RETURN TO FINAL. RECORDINGS INDICATE THAT I DID NOT GIVE THE MLT X THE LNDG TFC. I DID NOT REPEAT HIS HOLD INSTRUCTION AFTER I GAVE DEP INSTRUCTIONS. I ALSO DID NOT CLR HIM FOR TKOF. NORMALLY, THIS IS A QUITE TWR. HOWEVER, THERE WAS A LOT GOING ON AT THE TIME OF THE INCIDENT. THIS REQUIRED AN INCREASE IN AWARENESS IN ALL CONCERNED. WHILE THE MLT X DID NOT HAVE A TKOF CLRNC, THE HEAT OF THE MOMENT LEFT ENOUGH DOUBT FOR HIM TO BELIEVE THAT HE DID. IF I HAD DESCRIBED THE SITUATION BETTER, THE MLT X WOULD HAVE NO DOUBT ABOUT WHAT WAS WANTED FROM HIM.

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.