Skyhawk 172/Cutlass 172
Flight Crew Commercial; Flight Crew Flight Instructor
Flight Crew Total 800
Distraction; Workload; Situational Awareness
ATC Issue All Types; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter CFTT / CFIT; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Issued Advisory / Alert; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Took Evasive Action
Procedure; Weather
IFR flight. Encountered smooth but severe downdrafts. Advised ATC that we could not maintain altitude and was dropping below MEA for the arrival. They helped/vectored us around the mountain to clear terrain. We went from 11;500 FT MSL to below 10;500 FT MSL with a 200-700 FPM descent while we had full power and Vx climb pitch and speed (65 KIAS) with clean configuration. ATC advised us to call to talk with them because we deviated from IFR routing.
An IFR C172 was unable to maintain 11;500 FT MSL due to mountain waves over Southern California mountains and after asking for ATC assistance to clear terrain were advised to call because of an IFR routing deviation.