Desert thermals cause deviation from assigned altitude by C182RG aircraft.

Attributes
ACN	445340
Time
Date	199908
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : bxk.vortac
State Reference	AZ
Altitude	msl bound lower : 9600 msl bound upper : 1000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zab.artcc
Operator	general aviation : personal
Make Model Name	Skylane 182/RG Turbo Skylane/RG
Operating Under FAR Part	Part 91
Navigation In Use	other vortac
Flight Phase	cruise : level
Route In Use	enroute airway : v16.airway
Flight Plan	IFR
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : multi engine pilot : instrument pilot : private
Experience	flight time last 90 days : 20 flight time total : 1020 flight time type : 600
ASRS Report	445340
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter : turbulence inflight encounter : weather non adherence : clearance
Resolutory Action	flight crew : returned to assigned altitude
Supplementary
Problem Areas	Weather Flight Crew Human Performance Environmental Factor
Primary Problem	Weather

Narrative:

I was flying west on V16. It was hot (august) over the desert. I encountered moderate to severe thermal downdrafts and quickly lost 300-400 ft from my assigned altitude. I reconfigured the plane to climb power. It took approximately 5-10 seconds to arrest the descent rate and another 20-30 seconds to climb back to my assigned altitude. No conversation from ATC occurred. To the best of my knowledge, no conflict occurred. My response and attitude flying were appropriate. After stabilizing in cruise at my assigned altitude, no further significant turbulence occurred. I could have made a report to ATC/FSS regarding the thermal draft but did not do so since it seemed to be an isolated event. Other than avoiding desert/summertime flying, I can't suggest any preventive alternative.

Original NASA ASRS Text

Title: DESERT THERMALS CAUSE DEV FROM ASSIGNED ALT BY C182RG ACFT.

Narrative: I WAS FLYING W ON V16. IT WAS HOT (AUGUST) OVER THE DESERT. I ENCOUNTERED MODERATE TO SEVERE THERMAL DOWNDRAFTS AND QUICKLY LOST 300-400 FT FROM MY ASSIGNED ALT. I RECONFIGURED THE PLANE TO CLB PWR. IT TOOK APPROX 5-10 SECONDS TO ARREST THE DSCNT RATE AND ANOTHER 20-30 SECONDS TO CLB BACK TO MY ASSIGNED ALT. NO CONVERSATION FROM ATC OCCURRED. TO THE BEST OF MY KNOWLEDGE, NO CONFLICT OCCURRED. MY RESPONSE AND ATTITUDE FLYING WERE APPROPRIATE. AFTER STABILIZING IN CRUISE AT MY ASSIGNED ALT, NO FURTHER SIGNIFICANT TURB OCCURRED. I COULD HAVE MADE A RPT TO ATC/FSS REGARDING THE THERMAL DRAFT BUT DID NOT DO SO SINCE IT SEEMED TO BE AN ISOLATED EVENT. OTHER THAN AVOIDING DESERT/SUMMERTIME FLYING, I CAN'T SUGGEST ANY PREVENTIVE ALTERNATIVE.

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.