Narrative:

Returning from guaymas, mexico and stopping at calexico, ca to refuel, I obtained a standard briefing and filed an IFR flight plan from calexico to sba. The forecast indicated moderate turbulence below FL180 and 30 KT winds out of the northwest. The storm front was to reach sba at about 6 pm local time. Cloud cover was 2000-5000' scattered and 15000' overcast. At 34 NM east of julian VOR at 8000', early pm, the aircraft indicated 115 KTS true and a DME ground speed of 65 KTS, representing a 60 KT headwind (aircraft cruise=125 KTS). I encountered sharp up and down drafts of 100'. I advised the controller and requested 10000'. I was initially cleared to 9000' due to traffic, then to 10000'. Due to a severe updraft the aircraft climbed at over 1500 FPM in mountain wave conditions, also reported at the same time by another aircraft in the vicinity. Over julian at X19, the aircraft began to sink at over 1000 FPM in moderate turbulence. I advised san approach 132.2 that I could not hold altitude and reported descent every few hundred ft. The controller asked if I could stop the descent at 8000' as we passed 8700'. I advised that I was at stall speed to try to control the descent rate and she said that she, 'could see that,' and that she was, 'declaring an emergency.' I was requested to turn to 210 degrees and maintain 7000' if possible. The aircraft began to recover and increase airspeed and I was given a heading of 270 degrees, maintaining 7000'. The turbulence subsided and at X26 pm we were cleared direct oceanside to maintain 6000'. The rest of the trip was uneventful. I am submitting this report due to the declaration of an emergency by the controller. I am aware that no written report to the FAA is required unless specifically requested and none has been. While I am experienced in and comfortable with mountain flying, this is the first time that I have experienced actual severe turbulence and rapid loss of nearly 2000' of altitude. I was careful to maintain my aircraft's maneuvering speed when necessary, to continuously report my flight conditions and comply with the controller's request insofar as possible. I believe that no errors were made either on my part or on the part of the controllers.

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Original NASA ASRS Text

Title: GA ACFT CAUGHT IN SEVERE UP AND DOWN DRAFT MOUNTAIN WAVE ACTIVITY. CTLR DECLARES AN EMERGENCY.

Narrative: RETURNING FROM GUAYMAS, MEXICO AND STOPPING AT CALEXICO, CA TO REFUEL, I OBTAINED A STANDARD BRIEFING AND FILED AN IFR FLT PLAN FROM CALEXICO TO SBA. THE FORECAST INDICATED MODERATE TURB BELOW FL180 AND 30 KT WINDS OUT OF THE NW. THE STORM FRONT WAS TO REACH SBA AT ABOUT 6 PM LCL TIME. CLOUD COVER WAS 2000-5000' SCATTERED AND 15000' OVCST. AT 34 NM E OF JULIAN VOR AT 8000', EARLY PM, THE ACFT INDICATED 115 KTS TRUE AND A DME GND SPD OF 65 KTS, REPRESENTING A 60 KT HEADWIND (ACFT CRUISE=125 KTS). I ENCOUNTERED SHARP UP AND DOWN DRAFTS OF 100'. I ADVISED THE CTLR AND REQUESTED 10000'. I WAS INITIALLY CLRED TO 9000' DUE TO TFC, THEN TO 10000'. DUE TO A SEVERE UPDRAFT THE ACFT CLBED AT OVER 1500 FPM IN MOUNTAIN WAVE CONDITIONS, ALSO RPTED AT THE SAME TIME BY ANOTHER ACFT IN THE VICINITY. OVER JULIAN AT X19, THE ACFT BEGAN TO SINK AT OVER 1000 FPM IN MODERATE TURB. I ADVISED SAN APCH 132.2 THAT I COULD NOT HOLD ALT AND RPTED DSNT EVERY FEW HUNDRED FT. THE CTLR ASKED IF I COULD STOP THE DSNT AT 8000' AS WE PASSED 8700'. I ADVISED THAT I WAS AT STALL SPD TO TRY TO CTL THE DSNT RATE AND SHE SAID THAT SHE, 'COULD SEE THAT,' AND THAT SHE WAS, 'DECLARING AN EMER.' I WAS REQUESTED TO TURN TO 210 DEGS AND MAINTAIN 7000' IF POSSIBLE. THE ACFT BEGAN TO RECOVER AND INCREASE AIRSPD AND I WAS GIVEN A HDG OF 270 DEGS, MAINTAINING 7000'. THE TURB SUBSIDED AND AT X26 PM WE WERE CLRED DIRECT OCEANSIDE TO MAINTAIN 6000'. THE REST OF THE TRIP WAS UNEVENTFUL. I AM SUBMITTING THIS RPT DUE TO THE DECLARATION OF AN EMER BY THE CTLR. I AM AWARE THAT NO WRITTEN RPT TO THE FAA IS REQUIRED UNLESS SPECIFICALLY REQUESTED AND NONE HAS BEEN. WHILE I AM EXPERIENCED IN AND COMFORTABLE WITH MOUNTAIN FLYING, THIS IS THE FIRST TIME THAT I HAVE EXPERIENCED ACTUAL SEVERE TURB AND RAPID LOSS OF NEARLY 2000' OF ALT. I WAS CAREFUL TO MAINTAIN MY ACFT'S MANEUVERING SPD WHEN NECESSARY, TO CONTINUOUSLY RPT MY FLT CONDITIONS AND COMPLY WITH THE CTLR'S REQUEST INSOFAR AS POSSIBLE. I BELIEVE THAT NO ERRORS WERE MADE EITHER ON MY PART OR ON THE PART OF THE CTLRS.

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.