Narrative:

I was working the tul approach control arrival radar west position combined on the local control east position in the tower cabin. All facility control positions were being operated by me from the local control east (lce) position (ground, local, arrival/departure radar east and west) as positions were combined just prior to the mid-watch. WX in the form of a line of severe thunderstorms extended from off my scope to the northeast to off scope southwest. Tul approach airspace is sfc--15000' and underlies ZKC, ZME and ZFW areas. ZFW handed off medium large transport X, cargo flight, inbound to tulsa from the south descending to 10000', but at FL190. The aircraft was about to enter the line of thunderstorms when initial contact was made I informed the pilot of X of the WX displayed to me on the tower BRITE radar and issued further descent to 6000'. (The WX line extended along the ZFW-ZKC boundary in that area.) aircraft X's immediate reply was his desire to climb out of the area. (It should be noted that X reported severe turbulence while I was considering my actions and immediately after his request to climb.) (the aircraft now was in the WX and almost on the center boundary, perhaps a mi south of the boundary.) I looked on radar in front of the aircraft based on his northbound track and saw nothing, so I issued a climb at pilot's discretion to FL230. Tul, by letter of agreement, climbs departures to FL230 if requesting higher to ZKC's airspace, so I felt I could at least work that out with ZKC if needed as I saw no traffic for X. Based on mode C indications, aircraft X had, in fact, started to climb prior to my clearing him to do so. In any case, I did coordinate with ZKC stillwater sector right after I issued the climb, and was told no traffic for X, pointout approved, etc, but ZFW might have traffic. By then X was in ZKC airspace climbing out of the storms and turbulence. Also, ZFW called while climb was being issued to X to ask why he was climbing, an indication he had already started before being cleared. It appeared ZFW had small transport aircraft Y at FL200, 4.6 mi northeast of aircraft X, swbnd in ZKC airspace and just on the northern edge of the WX. His target and data block were not visible to me due to the bright blooming of WX return on tower BRITE radar. On the approach control display in the TRACON, this target would have been visible to me. The 2 aircraft passed .9 mi/400' vertical from each other. My decision was a split second one based on what I could see and what information I had, but I still feel the odds were greater for structural failure than for a midair collision and I did what I felt was right under the circumstances.

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Original NASA ASRS Text

Title: LTSS BETWEEN SUPP CARGO CARRIER AND CORP SMT. OPERROR.

Narrative: I WAS WORKING THE TUL APCH CTL ARR RADAR W POS COMBINED ON THE LCL CTL E POS IN THE TWR CABIN. ALL FAC CTL POSITIONS WERE BEING OPERATED BY ME FROM THE LCL CTL E (LCE) POS (GND, LCL, ARR/DEP RADAR E AND W) AS POSITIONS WERE COMBINED JUST PRIOR TO THE MID-WATCH. WX IN THE FORM OF A LINE OF SEVERE TSTMS EXTENDED FROM OFF MY SCOPE TO THE NE TO OFF SCOPE SW. TUL APCH AIRSPACE IS SFC--15000' AND UNDERLIES ZKC, ZME AND ZFW AREAS. ZFW HANDED OFF MLG X, CARGO FLT, INBOUND TO TULSA FROM THE S DSNDING TO 10000', BUT AT FL190. THE ACFT WAS ABOUT TO ENTER THE LINE OF TSTMS WHEN INITIAL CONTACT WAS MADE I INFORMED THE PLT OF X OF THE WX DISPLAYED TO ME ON THE TWR BRITE RADAR AND ISSUED FURTHER DSCNT TO 6000'. (THE WX LINE EXTENDED ALONG THE ZFW-ZKC BOUNDARY IN THAT AREA.) ACFT X'S IMMEDIATE REPLY WAS HIS DESIRE TO CLB OUT OF THE AREA. (IT SHOULD BE NOTED THAT X RPTED SEVERE TURB WHILE I WAS CONSIDERING MY ACTIONS AND IMMEDIATELY AFTER HIS REQUEST TO CLB.) (THE ACFT NOW WAS IN THE WX AND ALMOST ON THE CENTER BOUNDARY, PERHAPS A MI S OF THE BOUNDARY.) I LOOKED ON RADAR IN FRONT OF THE ACFT BASED ON HIS NBOUND TRACK AND SAW NOTHING, SO I ISSUED A CLB AT PLT'S DISCRETION TO FL230. TUL, BY LETTER OF AGREEMENT, CLBS DEPS TO FL230 IF REQUESTING HIGHER TO ZKC'S AIRSPACE, SO I FELT I COULD AT LEAST WORK THAT OUT WITH ZKC IF NEEDED AS I SAW NO TFC FOR X. BASED ON MODE C INDICATIONS, ACFT X HAD, IN FACT, STARTED TO CLB PRIOR TO MY CLEARING HIM TO DO SO. IN ANY CASE, I DID COORDINATE WITH ZKC STILLWATER SECTOR RIGHT AFTER I ISSUED THE CLB, AND WAS TOLD NO TFC FOR X, POINTOUT APPROVED, ETC, BUT ZFW MIGHT HAVE TFC. BY THEN X WAS IN ZKC AIRSPACE CLBING OUT OF THE STORMS AND TURB. ALSO, ZFW CALLED WHILE CLB WAS BEING ISSUED TO X TO ASK WHY HE WAS CLBING, AN INDICATION HE HAD ALREADY STARTED BEFORE BEING CLRED. IT APPEARED ZFW HAD SMT ACFT Y AT FL200, 4.6 MI NE OF ACFT X, SWBND IN ZKC AIRSPACE AND JUST ON THE NORTHERN EDGE OF THE WX. HIS TARGET AND DATA BLOCK WERE NOT VISIBLE TO ME DUE TO THE BRIGHT BLOOMING OF WX RETURN ON TWR BRITE RADAR. ON THE APCH CTL DISPLAY IN THE TRACON, THIS TARGET WOULD HAVE BEEN VISIBLE TO ME. THE 2 ACFT PASSED .9 MI/400' VERT FROM EACH OTHER. MY DECISION WAS A SPLIT SECOND ONE BASED ON WHAT I COULD SEE AND WHAT INFO I HAD, BUT I STILL FEEL THE ODDS WERE GREATER FOR STRUCTURAL FAILURE THAN FOR A MIDAIR COLLISION AND I DID WHAT I FELT WAS RIGHT UNDER THE CIRCUMSTANCES.

Data retrieved from NASA's ASRS site as of August 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.