Pilot of an small aircraft sel momentarily lost control of the aircraft during descent in icing cond...

Attributes
ACN	301408
Time
Date	199504
Place
Locale Reference	atc facility : s5o airport : sea
State Reference	WA
Altitude	msl bound lower : 5700 msl bound upper : 6000
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Operator	general aviation : corporate
Make Model Name	PA-32 Cherokee Six/Lance/Saratoga
Operating Under FAR Part	Part 91
Flight Phase	descent other
Route In Use	enroute airway : v2
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : cfi pilot : atp
Experience	flight time last 90 days : 50 flight time total : 7000 flight time type : 790
ASRS Report	301408
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude inflight encounter : weather non adherence : far other anomaly other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : exited adverse environment flight crew : regained aircraft control flight crew : overcame equipment problem
Consequence	Other
Supplementary
Primary Problem	Weather
Air Traffic Incident	other

Narrative:

While initiating and executing descent from 11000 ft to 6000 ft and on vectors slightly left of V2 for a VFR letdown to S-50, and on an IFR flight plan in actual night conditions (IFR), encountered moderate rime icing at about 8000 ft. The airspeed indicated 160 KTS, the GPS indicated 94 KTS. The DME indicated 95 KTS. I had a crab angle of 15 degrees left to maintain present heading. Light to moderate turbulence and a moderate buildup of ice on airframe. Upslope icing was in forecast. Cold front located on windward side of cascades where I was. I attempted to arrest 2000 ft a minute descent rate at 7000 ft for a slower rate to 6000 ft. As I was attempting to raise the nose (attitude) on the attitude bar of attitude indicator to 0 degrees which I did, I think the moderate icing blocked the piper PA32T heated pitot (which was on as I have a light on the panel) indicating it was on. The vsi, the altimeter and the airspeed momentarily dumped about 600 ft backwards, then forward. The airspeed I was not looking at it, as I was sorting out which instruments were right. I hit the alternate air lever which stabilized the altimeter and the vsi. The controller came on asking me if I had a problem. I did not answer. (I 'blew' through altitude about 300 ft lower.) when I had the plane under control, I climbed back to 6000 ft and told the controller 'I had a little icing problem.' the rest of the flight went normal and I lost the ice at about 5000 ft, broke out of the clouds at 4000 ft, then on to S-50, 10 mi to the west. Moral of the story: don't fly on the upslope of the cascades with a cold front 'camping out' there with a 'no ice protection' airplane. This was a dumb move -- I asked for it.

Original NASA ASRS Text

Title: PLT OF AN SMA SEL MOMENTARILY LOST CTL OF THE ACFT DURING DSCNT IN ICING CONDITIONS DUE TO THE PITOT STATIC SYS ICING UP CAUSING LOSS OF BASIC FLT INSTS.

Narrative: WHILE INITIATING AND EXECUTING DSCNT FROM 11000 FT TO 6000 FT AND ON VECTORS SLIGHTLY L OF V2 FOR A VFR LETDOWN TO S-50, AND ON AN IFR FLT PLAN IN ACTUAL NIGHT CONDITIONS (IFR), ENCOUNTERED MODERATE RIME ICING AT ABOUT 8000 FT. THE AIRSPD INDICATED 160 KTS, THE GPS INDICATED 94 KTS. THE DME INDICATED 95 KTS. I HAD A CRAB ANGLE OF 15 DEGS L TO MAINTAIN PRESENT HDG. LIGHT TO MODERATE TURB AND A MODERATE BUILDUP OF ICE ON AIRFRAME. UPSLOPE ICING WAS IN FORECAST. COLD FRONT LOCATED ON WINDWARD SIDE OF CASCADES WHERE I WAS. I ATTEMPTED TO ARREST 2000 FT A MINUTE DSCNT RATE AT 7000 FT FOR A SLOWER RATE TO 6000 FT. AS I WAS ATTEMPTING TO RAISE THE NOSE (ATTITUDE) ON THE ATTITUDE BAR OF ATTITUDE INDICATOR TO 0 DEGS WHICH I DID, I THINK THE MODERATE ICING BLOCKED THE PIPER PA32T HEATED PITOT (WHICH WAS ON AS I HAVE A LIGHT ON THE PANEL) INDICATING IT WAS ON. THE VSI, THE ALTIMETER AND THE AIRSPD MOMENTARILY DUMPED ABOUT 600 FT BACKWARDS, THEN FORWARD. THE AIRSPD I WAS NOT LOOKING AT IT, AS I WAS SORTING OUT WHICH INSTS WERE RIGHT. I HIT THE ALTERNATE AIR LEVER WHICH STABILIZED THE ALTIMETER AND THE VSI. THE CTLR CAME ON ASKING ME IF I HAD A PROB. I DID NOT ANSWER. (I 'BLEW' THROUGH ALT ABOUT 300 FT LOWER.) WHEN I HAD THE PLANE UNDER CTL, I CLBED BACK TO 6000 FT AND TOLD THE CTLR 'I HAD A LITTLE ICING PROB.' THE REST OF THE FLT WENT NORMAL AND I LOST THE ICE AT ABOUT 5000 FT, BROKE OUT OF THE CLOUDS AT 4000 FT, THEN ON TO S-50, 10 MI TO THE W. MORAL OF THE STORY: DON'T FLY ON THE UPSLOPE OF THE CASCADES WITH A COLD FRONT 'CAMPING OUT' THERE WITH A 'NO ICE PROTECTION' AIRPLANE. THIS WAS A DUMB MOVE -- I ASKED FOR IT.

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.

Pilot of an small aircraft sel momentarily lost control of the aircraft during descent in icing conditions due to the pitot static system icing up causing loss of basic flight instruments.