Narrative:

On 1/wed/90 I obtained a standard WX briefing from sea FSS at XA45 Z, for a VFR flight from okanogan, wa to wenatchee, wa. At that time VFR conditions were predicted for all of eastern washington until XH00 Z that day, at which time conditions were to begin deteriorating. I departed okanogan at approximately XB00 Z and landed at wenatchee at XB40 Z. WX conditions during the flight had been as predicted. I was in wenatchee on business for 2 1/2 hours, and returned to the airport at approximately XE00 Z. I observed that the WX had changed to being an estimated 4000' MSL ceiling. I was concerned that the WX had started to deteriorate early. With WX briefing from wenatchee FSS, I learned that a cold front was moving into the area and that an hour old report from omak, wa gave its ceiling as 4000'. There were no pilot reports along my proposed route. I decided that since the ceilings at my present location and at my destination were the same, I would be able to fly to okanogan. Flying up the columbia river to orondo, I could see that the ceiling was lowering in the valley. I was at 350' MSL, so I could look to the east and see the town of waterville and the douglas county plateau. It looked clearer with better visibility than the river valley ahead. I turned east and flew to the town of waterville, then turned back north. I was still at 3500' and had a ceiling of about 4000'. The visibility was approximately 10 mi. Upon reaching the high voltage power lines connecting wells dam and chief joseph dam, the ceiling had lowered to 3500' MSL and I had descended to 3000' MSL. The visibility had also lowered to approximately 5 mi. I knew my altitude was too low to fly over dyer hill to my north, so I decided to turn east along the power line and fly to chief joseph dam, where I could fly the valley on north to okanogan. It began snowing and visibility was lowering. I decided a return to the waterville airport was needed. As I flew back west along the power line it was apparent the snowstorm was surrounding me from all sides. I knew getting back to waterville was out of the question. I was approaching a straight section of county road with a farmhouse a short distance away. I radioed wenatchee FSS of my intentions to land on a county road. There was a spur road off of the intersection, so I parked the plane there and tried to call FSS. I was unable to contact FSS, but they began calling jet traffic and having them monitor the frequency. I was able to contact a jet and he relayed a message to them that I was down and all right. After 1 hour, 2 county sheriff cars and a road department pickup showed up. The WX was improving. They helped me figure where I wanted to take off at and called on the radio for current WX at brewster airport, since it was closest. They blocked the road for me and I took off. I believe that lack of a good WX reporting station in the okanogan valley was a prime factor in leading to this situation. The reported 4000' ceiling in omak was one of the main reasons I made the decision to go. I also under-estimated the speed at which the cold front and low ceilings were moving into the area. To prevent a recurrence of this situation, the okanogan county pilots association has made plans to make up wallet-size cards, with all the local members phone #'south on it, so we can call home to each other and get a current and more accurate assessment of the valley WX.

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Original NASA ASRS Text

Title: GA SMA OFF ARPT LNDG WHEN DETERIORATING WX WAS ENCOUNTERED ENROUTE.

Narrative: ON 1/WED/90 I OBTAINED A STANDARD WX BRIEFING FROM SEA FSS AT XA45 Z, FOR A VFR FLT FROM OKANOGAN, WA TO WENATCHEE, WA. AT THAT TIME VFR CONDITIONS WERE PREDICTED FOR ALL OF EASTERN WASHINGTON UNTIL XH00 Z THAT DAY, AT WHICH TIME CONDITIONS WERE TO BEGIN DETERIORATING. I DEPARTED OKANOGAN AT APPROX XB00 Z AND LANDED AT WENATCHEE AT XB40 Z. WX CONDITIONS DURING THE FLT HAD BEEN AS PREDICTED. I WAS IN WENATCHEE ON BUSINESS FOR 2 1/2 HRS, AND RETURNED TO THE ARPT AT APPROX XE00 Z. I OBSERVED THAT THE WX HAD CHANGED TO BEING AN ESTIMATED 4000' MSL CEILING. I WAS CONCERNED THAT THE WX HAD STARTED TO DETERIORATE EARLY. WITH WX BRIEFING FROM WENATCHEE FSS, I LEARNED THAT A COLD FRONT WAS MOVING INTO THE AREA AND THAT AN HR OLD RPT FROM OMAK, WA GAVE ITS CEILING AS 4000'. THERE WERE NO PLT RPTS ALONG MY PROPOSED RTE. I DECIDED THAT SINCE THE CEILINGS AT MY PRESENT LOCATION AND AT MY DEST WERE THE SAME, I WOULD BE ABLE TO FLY TO OKANOGAN. FLYING UP THE COLUMBIA RIVER TO ORONDO, I COULD SEE THAT THE CEILING WAS LOWERING IN THE VALLEY. I WAS AT 350' MSL, SO I COULD LOOK TO THE E AND SEE THE TOWN OF WATERVILLE AND THE DOUGLAS COUNTY PLATEAU. IT LOOKED CLEARER WITH BETTER VISIBILITY THAN THE RIVER VALLEY AHEAD. I TURNED E AND FLEW TO THE TOWN OF WATERVILLE, THEN TURNED BACK N. I WAS STILL AT 3500' AND HAD A CEILING OF ABOUT 4000'. THE VISIBILITY WAS APPROX 10 MI. UPON REACHING THE HIGH VOLTAGE PWR LINES CONNECTING WELLS DAM AND CHIEF JOSEPH DAM, THE CEILING HAD LOWERED TO 3500' MSL AND I HAD DSNDED TO 3000' MSL. THE VISIBILITY HAD ALSO LOWERED TO APPROX 5 MI. I KNEW MY ALT WAS TOO LOW TO FLY OVER DYER HILL TO MY N, SO I DECIDED TO TURN E ALONG THE PWR LINE AND FLY TO CHIEF JOSEPH DAM, WHERE I COULD FLY THE VALLEY ON N TO OKANOGAN. IT BEGAN SNOWING AND VISIBILITY WAS LOWERING. I DECIDED A RETURN TO THE WATERVILLE ARPT WAS NEEDED. AS I FLEW BACK W ALONG THE PWR LINE IT WAS APPARENT THE SNOWSTORM WAS SURROUNDING ME FROM ALL SIDES. I KNEW GETTING BACK TO WATERVILLE WAS OUT OF THE QUESTION. I WAS APCHING A STRAIGHT SECTION OF COUNTY ROAD WITH A FARMHOUSE A SHORT DISTANCE AWAY. I RADIOED WENATCHEE FSS OF MY INTENTIONS TO LAND ON A COUNTY ROAD. THERE WAS A SPUR ROAD OFF OF THE INTXN, SO I PARKED THE PLANE THERE AND TRIED TO CALL FSS. I WAS UNABLE TO CONTACT FSS, BUT THEY BEGAN CALLING JET TFC AND HAVING THEM MONITOR THE FREQ. I WAS ABLE TO CONTACT A JET AND HE RELAYED A MESSAGE TO THEM THAT I WAS DOWN AND ALL RIGHT. AFTER 1 HR, 2 COUNTY SHERIFF CARS AND A ROAD DEPT PICKUP SHOWED UP. THE WX WAS IMPROVING. THEY HELPED ME FIGURE WHERE I WANTED TO TAKE OFF AT AND CALLED ON THE RADIO FOR CURRENT WX AT BREWSTER ARPT, SINCE IT WAS CLOSEST. THEY BLOCKED THE ROAD FOR ME AND I TOOK OFF. I BELIEVE THAT LACK OF A GOOD WX RPTING STATION IN THE OKANOGAN VALLEY WAS A PRIME FACTOR IN LEADING TO THIS SITUATION. THE RPTED 4000' CEILING IN OMAK WAS ONE OF THE MAIN REASONS I MADE THE DECISION TO GO. I ALSO UNDER-ESTIMATED THE SPD AT WHICH THE COLD FRONT AND LOW CEILINGS WERE MOVING INTO THE AREA. TO PREVENT A RECURRENCE OF THIS SITUATION, THE OKANOGAN COUNTY PLTS ASSOCIATION HAS MADE PLANS TO MAKE UP WALLET-SIZE CARDS, WITH ALL THE LCL MEMBERS PHONE #'S ON IT, SO WE CAN CALL HOME TO EACH OTHER AND GET A CURRENT AND MORE ACCURATE ASSESSMENT OF THE VALLEY WX.

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.