Flight Crew Multiengine
Flight Crew Last 90 Days 100; Flight Crew Total 4400; Flight Crew Type 325
Situational Awareness
Aircraft Equipment Problem Critical; Inflight Event / Encounter Weather / Turbulence
Aircraft Equipment Problem Dissipated; Flight Crew Became Reoriented
Aircraft; Weather; Human Factors
While descending from 17;000 FT in IMC we passed through a snow storm and lost the air speed indicator. While in the descent the airspeed fell to 120 KTS and continued decreasing to 60 KTS and I became concerned with an imminent stall and lost altitude awareness. When the airspeed went to zero I looked at the GPS airspeed which was nearly 200 KTS ground speed and realized we had a faulty airspeed indication and slowed our descent. I had checked the pitot heat operation before take off and my Mechanic checked it post landing. Both times pitot heat was operational. After descending below the clouds the airspeed indicator became operational again.
A PA34 lost the airspeed indicator in descent probably due to pitot icing. The indicator returned to normal after leaving icing conditions.