Skyhawk 172/Cutlass 172
Flight Crew Commercial; Flight Crew Flight Instructor; Flight Crew Instrument
Flight Crew Last 90 Days 30; Flight Crew Total 568; Flight Crew Type 80
Situational Awareness; Training / Qualification
Aircraft Equipment Problem Critical
Flight Crew Overcame Equipment Problem; Flight Crew Returned To Departure Airport
Aircraft
I was departing IFR from a non-towered field. After receiving my clearance via cell phone I initiated my takeoff. I notice the plane was wanting to takeoff at an indicated airspeed approximately 20 mph lower than normal. I committed to lifting off because I would not have enough runway to stop by this point and the plane was ready to fly. I recognized the airspeed was indicating improperly because the pitch and VSI was appropriate for a Vy climb; but the airspeed was way off. Pitching for a Vy airspeed would have put me into a building. I decided to remain visual and return to land. On final I split the difference between my indicated airspeed and GPS ground speed which was higher. I landed without incident and cancelled IFR via cell phone. I reported the condition to Maintenance and noted it in the log.Familiarity with known performance and power setting is what helped me ID this before entering IMC. The biggest thing is having options when taking off into IMC. Always consider the possibility of having to circle back to land and always leave the option available.
C-172 pilot describes an airspeed indication problem discovered too late to abort his takeoff on an IFR flight. A successful return was made before entering IFR conditions using pitch and power settings known to provide appropriate speeds.