Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 27; Flight Crew Total 4950; Flight Crew Type 370
Distraction; Physiological - Other; Situational Awareness; Workload
Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Issued Advisory / Alert; Flight Crew Took Evasive Action; Flight Crew Became Reoriented
Human Factors; Procedure; Weather; Environment - Non Weather Related
[I was receiving] vectors to ILS Runway 32 at RAP. Thunderstorms and rain; marginal VFR on IFR flight plan. Ellsworth; descend to 5;300 FT; heading 350 degrees; turbulence and rain downdraft. [I] disconnected autopilot. Arrested descent at 4;800 FT; busting altitude restriction of 5;300 FT. Ellsworth Approach called on low altitude; but already disconnected autopilot and corrected. [I] broke out of rain; airport in sight. Visual approach [was] given; 500 FT low. [I] should have corrected sooner.
The pilot of small jet reported that while on vectors for RAP Runway 32; thunderstorms; rain; and down drafts caused him to descend to 4;800 FT; which prompted ATC to issue a low altitude alert as he attempted to correct.