PA-60 601/601P Aerostar
Flight Crew Flight Engineer; Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor; Flight Crew Multiengine
Flight Crew Last 90 Days 60; Flight Crew Total 25000; Flight Crew Type 250
Aircraft Equipment Problem Less Severe
General None Reported / Taken
Aircraft; Weather
During descent and initial approach; airspeed became unreliable. Began to under-indicate by 15-20kts; based on pitch and power settings; then rapidly decayed to zero. Unreliable airspeed was reported to ATC. After further descent and 3-5 minutes time; airspeed returned to normal. This was also reported to ATC after controller query.Flight conditions were IMC with negative ice and negative turbulence; outside air temp estimated to be -15C. Pitot heat was 'on.'
Piper Aerostar pilot reported the airspeed indicator displayed low airspeed then decayed rapidly to zero during approach.