Narrative:

En route in marginal VFR, circumnaving rain east of dallas, while deviating to the west of the rain, I attempted to contact regional approach, but frequency congestion apparently kept ATC from answering. The closer I got to dallas, the less certain I was off my exact position, since the plane was not equipped with DME. While trying to get a position fix by 2 VOR stations, I noticed I was close to love field and the addison air traffic area. I phoned addison tower for permission to transit, which was granted, along with flight following squawking 1200. Northwest of addison airport, it was clear I would need to deviate further west because of a thunderstorm between addison and sherman (destination). ATC asked if I could see a certain lake, which was not possible based on the terminal area chart, since recent floods had turned everything north of dallas into a lake. ATC cautioned me about going farther west because of the dfw TCA. Since I couldn't confidently avoid the TCA, I requested to land at addison. Human performance considerations: preflight briefings gave conflicting reports. 2 1/2 hours before the flight, no severe WX was noted. 1 hour before takeoff, brief commented on storms from abilene to dallas, but cloud bases on sequence reports were VFR. 15 mins before takeoff, storm information was reported as scattered, with some lower ceilings. Actual en route WX near dallas was barely VFR, even well away from any rain showers. The only lightning seen was in the 1 cell between addison and sherman. 2 observations: in MVFR, every arrival into a TCA will be IFR, and this will effectively deny use of the ATC frequency to transient VFR traffic. Also, unless the pilot is very familiar with all quadrants of the TCA in question, DME is vital to comfortable navigation.

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Original NASA ASRS Text

Title: SMA PLT DIVERTING FOR WX LANDS SHORT OF DESTINATION TO AVOID TCA PENETRATION.

Narrative: ENRTE IN MARGINAL VFR, CIRCUMNAVING RAIN E OF DALLAS, WHILE DEVIATING TO THE W OF THE RAIN, I ATTEMPTED TO CONTACT REGIONAL APCH, BUT FREQ CONGESTION APPARENTLY KEPT ATC FROM ANSWERING. THE CLOSER I GOT TO DALLAS, THE LESS CERTAIN I WAS OFF MY EXACT POS, SINCE THE PLANE WAS NOT EQUIPPED WITH DME. WHILE TRYING TO GET A POS FIX BY 2 VOR STATIONS, I NOTICED I WAS CLOSE TO LOVE FIELD AND THE ADDISON ATA. I PHONED ADDISON TWR FOR PERMISSION TO TRANSIT, WHICH WAS GRANTED, ALONG WITH FLT FOLLOWING SQUAWKING 1200. NW OF ADDISON ARPT, IT WAS CLR I WOULD NEED TO DEVIATE FURTHER W BECAUSE OF A TSTM BTWN ADDISON AND SHERMAN (DEST). ATC ASKED IF I COULD SEE A CERTAIN LAKE, WHICH WAS NOT POSSIBLE BASED ON THE TERMINAL AREA CHART, SINCE RECENT FLOODS HAD TURNED EVERYTHING N OF DALLAS INTO A LAKE. ATC CAUTIONED ME ABOUT GOING FARTHER W BECAUSE OF THE DFW TCA. SINCE I COULDN'T CONFIDENTLY AVOID THE TCA, I REQUESTED TO LAND AT ADDISON. HUMAN PERFORMANCE CONSIDERATIONS: PREFLT BRIEFINGS GAVE CONFLICTING RPTS. 2 1/2 HRS BEFORE THE FLT, NO SEVERE WX WAS NOTED. 1 HR BEFORE TKOF, BRIEF COMMENTED ON STORMS FROM ABILENE TO DALLAS, BUT CLOUD BASES ON SEQUENCE RPTS WERE VFR. 15 MINS BEFORE TKOF, STORM INFO WAS RPTED AS SCATTERED, WITH SOME LOWER CEILINGS. ACTUAL ENRTE WX NEAR DALLAS WAS BARELY VFR, EVEN WELL AWAY FROM ANY RAIN SHOWERS. THE ONLY LIGHTNING SEEN WAS IN THE 1 CELL BTWN ADDISON AND SHERMAN. 2 OBSERVATIONS: IN MVFR, EVERY ARR INTO A TCA WILL BE IFR, AND THIS WILL EFFECTIVELY DENY USE OF THE ATC FREQ TO TRANSIENT VFR TFC. ALSO, UNLESS THE PLT IS VERY FAMILIAR WITH ALL QUADRANTS OF THE TCA IN QUESTION, DME IS VITAL TO COMFORTABLE NAV.

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.