An pilot approaching slc diverted because of low visibility and encountered turbulence on the approa...

Narrative:

On the descent to salt lake city; ut (slc) the visibility reported on ATIS changed from three miles to 1/2 mile. The visibility reported at a nearby airport was substantially better and I decided to divert to that airport. The slc approach controller provided me with vectors to a base leg to the ILS. I was in IMC conditions during the descent; no substantial returns on the on board weather radar. At approximately 8;000 ft I entered an area of heavy turbulence with strong up and down drafts and was unable to hold the altitude of 8;000 ft and follow the vectors provided by ATC. I had difficulty reading the instruments and got disoriented. The autopilot had disconnected due to the turbulence. The controller advised me that I had descended below his vectoring altitude and asked me to climb immediately. I asked for vectors out of the area of weather. The controller then asked about my intentions. I asked for and was provided vectors for the ILS at the nearby airport. During this vector I again entered an area of turbulence and up and down drafts; but was able to more or less follow the localizer and glideslope; I broke out of the clouds at approximately 3;000 ft AGL and landed. During the approach I heard an airliner on approach to slc report a 45 KTS tailwind until short final when the wind changed to a headwind; there obviously were some strong windshear conditions in the area south of slc. After landing I was asked to call slc approach who advised me that I had descended below the vectoring altitude and apparently there were one or two aircraft on approach to slc which were vectored around or away from my airplane. I was not aware that I had been in the vicinity of any other aircraft during this episode. The approach controller was somewhat helpful albeit a bit impatient after I was back in control of the airplane. I do not know if he could see on his radar that he was giving me vectors into an area of bad weather. The precipitation in the area was not very heavy and there was no lightning; so I assume that he had no way of knowing that he was directing me into an area of very turbulent air.

Original NASA ASRS Text

Title: An pilot approaching SLC diverted because of low visibility and encountered turbulence on the approach which disoriented him causing an altitude deviation as he descended uncontrollably below the minimum vectoring altitude.

Narrative: On the descent to Salt Lake City; UT (SLC) the visibility reported on ATIS changed from three miles to 1/2 mile. The visibility reported at a nearby airport was substantially better and I decided to divert to that airport. The SLC Approach Controller provided me with vectors to a base leg to the ILS. I was in IMC conditions during the descent; no substantial returns on the on board weather radar. At approximately 8;000 FT I entered an area of heavy turbulence with strong up and down drafts and was unable to hold the altitude of 8;000 FT and follow the vectors provided by ATC. I had difficulty reading the instruments and got disoriented. The autopilot had disconnected due to the turbulence. The Controller advised me that I had descended below his vectoring altitude and asked me to climb immediately. I asked for vectors out of the area of weather. The Controller then asked about my intentions. I asked for and was provided vectors for the ILS at the nearby airport. During this vector I again entered an area of turbulence and up and down drafts; but was able to more or less follow the localizer and glideslope; I broke out of the clouds at approximately 3;000 FT AGL and landed. During the approach I heard an airliner on approach to SLC report a 45 KTS tailwind until short final when the wind changed to a headwind; there obviously were some strong windshear conditions in the area south of SLC. After landing I was asked to call SLC Approach who advised me that I had descended below the vectoring altitude and apparently there were one or two aircraft on approach to SLC which were vectored around or away from my airplane. I was not aware that I had been in the vicinity of any other aircraft during this episode. The Approach Controller was somewhat helpful albeit a bit impatient after I was back in control of the airplane. I do not know if he could see on his radar that he was giving me vectors into an area of bad weather. The precipitation in the area was not very heavy and there was no lightning; so I assume that he had no way of knowing that he was directing me into an area of very turbulent air.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	943163
Time
Date	201104
Local Time Of Day	1801-2400
Place
Locale Reference	S56.TRACON
State Reference	UT
Environment
Flight Conditions	IMC
Light	Dusk
Aircraft 1
Make Model Name	Small Aircraft Low Wing 1 Eng Retractable Gear
Operating Under FAR Part	Part 91
Flight Phase	Initial Approach
Route In Use	Vectors
Flight Plan	IFR
Person 1
Function	Pilot Flying Single Pilot
Qualification	Flight Crew Commercial Flight Crew Glider Flight Crew Instrument Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 25 Flight Crew Total 3385 Flight Crew Type 800
Events
Anomaly	Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance Inflight Event / Encounter CFTT / CFIT Inflight Event / Encounter Weather / Turbulence

An pilot approaching slc diverted because of low visibility and encountered turbulence on the approach which disoriented him causing an altitude deviation as he descended uncontrollably below the minimum vectoring altitude.