Pilot of C210 on an IFR flight plan; descended without clearance to get out of severe turbulence.

Attributes
ACN	702396
Time
Date	200602
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : zzz.bcstn
State Reference	US
Altitude	msl bound lower : 7000 msl bound upper : 9000
Environment
Flight Conditions	Mixed
Weather Elements	Turbulence Rain
Light	Daylight
Aircraft 1
Operator	general aviation : personal
Make Model Name	Cessna 210 Centurion / Turbo Centurion 210C 210D
Operating Under FAR Part	Part 91
Navigation In Use	Other
Flight Phase	cruise : enroute altitude change
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Function	flight crew : single pilot
Qualification	pilot : cfi pilot : instrument pilot : multi engine pilot : commercial
Experience	flight time last 90 days : 12 flight time total : 4100 flight time type : 10
ASRS Report	702396
Person 2
Affiliation	government : faa
Function	controller : radar
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter : turbulence inflight encounter : weather non adherence : published procedure non adherence : far non adherence : clearance
Independent Detector	other controllera other controllerb
Resolutory Action	controller : issued new clearance flight crew : exited adverse environment
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	Flight Crew Human Performance Weather ATC Human Performance Environmental Factor
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

IMC in cloud at 7000 ft cruise; ftw center control. Slight to moderate turbulence. General conditions: scattered with bases +/-4700 ft. Scattered rain; light to moderate; tops +/-10000 ft to much higher with a few larger cells. These conditions developing progressively from my departure (mkn) at noon. I was in and out of clouds then later almost entirely in cloud. Turbulence increasing. I requested climb to 10000 ft; thinking I would top most of the build-ups and be able to circumnav visually; as aircraft has no radar or storm scope. Center cleared me to climb to 10000 ft. Before reaching 10K; turbulence became severe. Pens and charts flying around. My head banging top of cabin; aircraft very hard to control. Told center I had to descend. Center advised they had to 'coordinate' with someone. I did not understand; or question. My hands were full trying to keep aircraft under control. Climb continued even as I reduced throttle to 15 inches manifold pressure. I said 'unable; I'm descending now' or words to that effect. Descended very quickly; broke out; clear +/-4500 ft and leveled at 4000 ft -- no obvious damage to aircraft (confirmed later on postflt). Center controller advised contact ZME chief of operations when on the ground; which I did. The center chief had listened/reviewed tapes which confirmed my 'unauthorized' descent. He then asked me for my side of the story. After listening to me he asked if I had advised the controller or turbulence. I said that I did not prior to descent; but did when out of turbulence at 4000 ft. Center chief thanked me and said that was all he needed; and concluded the call. I think the entire call to ZME was recorded (I heard intermittent beeps). In retrospect; I should have: 1) not tried to climb above the growing cumulus; especially not while in the cloud. 2) declared an emergency descent; or clearly stated my need to descend immediately. In my opinion; there was danger of aircraft damage or complete loss of control. I should have made that clear. Note: I was aware of the airmet/SIGMET for the area and was/am keenly aware of thunderstorm avoidance. I was not in any thunderstorm prior to the incident. I think I got into a building/ developing storm.

Original NASA ASRS Text

Title: PLT OF C210 ON AN IFR FLT PLAN; DSNDED WITHOUT CLRNC TO GET OUT OF SEVERE TURB.

Narrative: IMC IN CLOUD AT 7000 FT CRUISE; FTW CTR CTL. SLIGHT TO MODERATE TURB. GENERAL CONDITIONS: SCATTERED WITH BASES +/-4700 FT. SCATTERED RAIN; LIGHT TO MODERATE; TOPS +/-10000 FT TO MUCH HIGHER WITH A FEW LARGER CELLS. THESE CONDITIONS DEVELOPING PROGRESSIVELY FROM MY DEP (MKN) AT NOON. I WAS IN AND OUT OF CLOUDS THEN LATER ALMOST ENTIRELY IN CLOUD. TURB INCREASING. I REQUESTED CLB TO 10000 FT; THINKING I WOULD TOP MOST OF THE BUILD-UPS AND BE ABLE TO CIRCUMNAV VISUALLY; AS ACFT HAS NO RADAR OR STORM SCOPE. CTR CLRED ME TO CLB TO 10000 FT. BEFORE REACHING 10K; TURB BECAME SEVERE. PENS AND CHARTS FLYING AROUND. MY HEAD BANGING TOP OF CABIN; ACFT VERY HARD TO CTL. TOLD CTR I HAD TO DSND. CTR ADVISED THEY HAD TO 'COORDINATE' WITH SOMEONE. I DID NOT UNDERSTAND; OR QUESTION. MY HANDS WERE FULL TRYING TO KEEP ACFT UNDER CTL. CLB CONTINUED EVEN AS I REDUCED THROTTLE TO 15 INCHES MANIFOLD PRESSURE. I SAID 'UNABLE; I'M DSNDING NOW' OR WORDS TO THAT EFFECT. DSNDED VERY QUICKLY; BROKE OUT; CLR +/-4500 FT AND LEVELED AT 4000 FT -- NO OBVIOUS DAMAGE TO ACFT (CONFIRMED LATER ON POSTFLT). CTR CTLR ADVISED CONTACT ZME CHIEF OF OPS WHEN ON THE GND; WHICH I DID. THE CTR CHIEF HAD LISTENED/REVIEWED TAPES WHICH CONFIRMED MY 'UNAUTH' DSCNT. HE THEN ASKED ME FOR MY SIDE OF THE STORY. AFTER LISTENING TO ME HE ASKED IF I HAD ADVISED THE CTLR OR TURB. I SAID THAT I DID NOT PRIOR TO DSCNT; BUT DID WHEN OUT OF TURB AT 4000 FT. CTR CHIEF THANKED ME AND SAID THAT WAS ALL HE NEEDED; AND CONCLUDED THE CALL. I THINK THE ENTIRE CALL TO ZME WAS RECORDED (I HEARD INTERMITTENT BEEPS). IN RETROSPECT; I SHOULD HAVE: 1) NOT TRIED TO CLB ABOVE THE GROWING CUMULUS; ESPECIALLY NOT WHILE IN THE CLOUD. 2) DECLARED AN EMER DSCNT; OR CLRLY STATED MY NEED TO DSND IMMEDIATELY. IN MY OPINION; THERE WAS DANGER OF ACFT DAMAGE OR COMPLETE LOSS OF CTL. I SHOULD HAVE MADE THAT CLR. NOTE: I WAS AWARE OF THE AIRMET/SIGMET FOR THE AREA AND WAS/AM KEENLY AWARE OF TSTM AVOIDANCE. I WAS NOT IN ANY TSTM PRIOR TO THE INCIDENT. I THINK I GOT INTO A BUILDING/ DEVELOPING STORM.

Data retrieved from NASA's ASRS site as of January 2009 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.