A C182 pilot reported problems with his pitot-static system that resulted in erroneous airspeed and ...

Attributes
ACN	884586
Time
Date	201004
Local Time Of Day	1801-2400
Place
Locale Reference	ZZZ.TRACON
State Reference	US
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Make Model Name	Skylane 182/RG Turbo Skylane/RG
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Route In Use	Direct
Flight Plan	IFR
Component
Aircraft Component	Pitot-Static System
Person 1
Function	Pilot Flying Single Pilot
Qualification	Flight Crew Instrument Flight Crew Private
Experience	Flight Crew Last 90 Days 21 Flight Crew Total 290 Flight Crew Type 285
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance

Narrative:

I was at 9000 ft; in and out of the clouds. I was asked by ATC to come left 10 degrees and descend to 7000 ft for traffic. This was later amended to 8000 ft. I reduced power and configured for descent. My airspeed indicator approached red line (vne) but the vsi indicated 0 FPM descent. Altitude remained unchanged at 9000 ft I reduced power further; ultimately to 13 inches mp. Still at red line; 0 FPM descent and 9000 ft on altimeter. I crosschecked with the GPS and groundspeed was 120 KTS while the airspeed indicated 180 KTS. I realized something was wrong with the pitot-static system and activated the alternate static. The asi immediately read 100 KTS; the vsi 750 FPM descent and the altimeter 7500 ft; which was 500 ft below my assigned altitude. I immediately climbed back to 8000 ft. After rechecking the aircraft systems; I requested a descent to VFR conditions and was cleared to 7000 ft. I was handed off to approach and preceded to my destination under visual conditions. The aircraft was taken for repairs the next day and the pitot-static system cleaned and tested.

Original NASA ASRS Text

Title: A C182 Pilot reported problems with his pitot-static system that resulted in erroneous airspeed and altimeter readings; which led to an altitude deviation. When he selected alternate static; all instruments returned to normal indications.

Narrative: I was at 9000 FT; in and out of the clouds. I was asked by ATC to come left 10 degrees and descend to 7000 FT for traffic. This was later amended to 8000 FT. I reduced power and configured for descent. My airspeed indicator approached red line (VNE) but the VSI indicated 0 FPM descent. Altitude remained unchanged at 9000 FT I reduced power further; ultimately to 13 inches MP. Still at red line; 0 FPM descent and 9000 FT on altimeter. I crosschecked with the GPS and groundspeed was 120 KTS while the airspeed indicated 180 KTS. I realized something was wrong with the pitot-static system and activated the alternate static. The ASI immediately read 100 KTS; the VSI 750 FPM descent and the altimeter 7500 FT; which was 500 FT below my assigned altitude. I immediately climbed back to 8000 FT. After rechecking the aircraft systems; I requested a descent to VFR conditions and was cleared to 7000 FT. I was handed off to Approach and preceded to my destination under visual conditions. The aircraft was taken for repairs the next day and the pitot-static system cleaned and tested.

Data retrieved from NASA's ASRS site as of April 2012 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 C182 pilot reported problems with his pitot-static system that resulted in erroneous airspeed and altimeter readings; which led to an altitude deviation. When he selected alternate static; all instruments returned to normal indications.