A PA44 CFI and student, on an IFR flight plan, encountered icing in clouds which caused the static p...

Attributes
ACN	598271
Time
Date	200311
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : nct.tracon
State Reference	CA
Altitude	msl bound lower : 8500 msl bound upper : 9000
Environment
Flight Conditions	Mixed
Weather Elements	Ice
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : nct.tracon
Operator	general aviation : instructional
Make Model Name	PA-44 Seminole Turbo Seminole
Operating Under FAR Part	Part 91
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	other
Function	instruction : instructor
Qualification	pilot : multi engine pilot : atp pilot : cfi
Experience	flight time last 90 days : 30 flight time total : 1582 flight time type : 1185
ASRS Report	598271
Person 2
Affiliation	other
Function	instruction : trainee
Events
Anomaly	aircraft equipment problem : critical altitude deviation : overshoot non adherence : far non adherence : clearance
Independent Detector	other controllera other flight crewa
Resolutory Action	flight crew : overcame equipment problem
Consequence	other
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

On a training flight, we were on an IFR flight plan from sac to ral. While flying our route, we were going through small amounts of clouds, but were VMC most of the time. We did pick up some trace ice (mixed ice). The altimeter and vsi started to jump around. The vsi jumped and stuck at a 2000 FPM descending, while the altimeter stayed at 8900 ft. Then, the vsi started coming back to zero, and the altimeter jumped to 8500 ft. We decided our static port was plugged with ice. The pitot heat was on and didn't stop it. As we were trying to open the alternate air, approach called and asked us our altitude. I told him we were indicating 8500 ft and our static port was frozen and correcting. He told us to remain at 8500 ft or above. I also asked him what altitude he showed for us and he said 8500 ft. As soon as I opened the alternate air, we were at 9000 ft. The pitot (airspeed indicator) worked ok the whole time. The pitot heat was on before entering the cloud. When the instruments were acting up, we were VMC. I think moisture was in the static lines and froze. It also happened on our flight home to sac, but just as they started jumping around, I opened the alternate air. On the ground check, pitot heat worked. I think we were at 9000 ft MSL the whole time.

Original NASA ASRS Text

Title: A PA44 CFI AND STUDENT, ON AN IFR FLT PLAN, ENCOUNTERED ICING IN CLOUDS WHICH CAUSED THE STATIC PORT TO FREEZE WHICH RESULTED IN AN ALT OVERSHOOT.

Narrative: ON A TRAINING FLT, WE WERE ON AN IFR FLT PLAN FROM SAC TO RAL. WHILE FLYING OUR RTE, WE WERE GOING THROUGH SMALL AMOUNTS OF CLOUDS, BUT WERE VMC MOST OF THE TIME. WE DID PICK UP SOME TRACE ICE (MIXED ICE). THE ALTIMETER AND VSI STARTED TO JUMP AROUND. THE VSI JUMPED AND STUCK AT A 2000 FPM DSNDING, WHILE THE ALTIMETER STAYED AT 8900 FT. THEN, THE VSI STARTED COMING BACK TO ZERO, AND THE ALTIMETER JUMPED TO 8500 FT. WE DECIDED OUR STATIC PORT WAS PLUGGED WITH ICE. THE PITOT HEAT WAS ON AND DIDN'T STOP IT. AS WE WERE TRYING TO OPEN THE ALTERNATE AIR, APCH CALLED AND ASKED US OUR ALT. I TOLD HIM WE WERE INDICATING 8500 FT AND OUR STATIC PORT WAS FROZEN AND CORRECTING. HE TOLD US TO REMAIN AT 8500 FT OR ABOVE. I ALSO ASKED HIM WHAT ALT HE SHOWED FOR US AND HE SAID 8500 FT. AS SOON AS I OPENED THE ALTERNATE AIR, WE WERE AT 9000 FT. THE PITOT (AIRSPD INDICATOR) WORKED OK THE WHOLE TIME. THE PITOT HEAT WAS ON BEFORE ENTERING THE CLOUD. WHEN THE INSTS WERE ACTING UP, WE WERE VMC. I THINK MOISTURE WAS IN THE STATIC LINES AND FROZE. IT ALSO HAPPENED ON OUR FLT HOME TO SAC, BUT JUST AS THEY STARTED JUMPING AROUND, I OPENED THE ALTERNATE AIR. ON THE GND CHK, PITOT HEAT WORKED. I THINK WE WERE AT 9000 FT MSL THE WHOLE TIME.

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.

A PA44 CFI and student, on an IFR flight plan, encountered icing in clouds which caused the static port to freeze which resulted in an altitude overshoot.