Pilot of an atx ambiguity small transport twin turboprop made an ILS approach and landing below repo...

Attributes
ACN	394940
Time
Date	199802
Day	Fri
Local Time Of Day	0001 To 0600
Place
Locale Reference	airport : rap
State Reference	SD
Altitude	msl bound lower : 3160 msl bound upper : 4700
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : den military facility : elr
Operator	common carrier : air taxi
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 135
Flight Phase	descent : approach landing other
Route In Use	arrival other
Flight Plan	IFR
Person 1
Affiliation	company : air taxi
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : cfi pilot : commercial
Experience	flight time last 90 days : 110 flight time total : 3950 flight time type : 67
ASRS Report	394940
Person 2
Affiliation	government : military
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	non adherence : far other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : anomaly accepted
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

I filed a lifeguard flight from ien, sd, to spf, sd. We are based in rap, sd, and due to reported fog 100 ft and 1/4 mi visibility, we planned to land in spearfish, sd, with a possibility of landing in 49B, sd, if there was no fog at this airport. Spearfish is a 55 min drive by ambulance to rap and sturgis is a 35 min drive to rap. After leaving pine ridge, I climbed to 12000 ft. After leveling off, I could see rapid city city lights in front of me. After being handed off from ZDV to ellsworth approach, I was given descent clearance for the approach at rap (possibly due to the fact we always come back to rap). I asked the WX at rap and at ellsworth. Rap was 100 ft, 1/4 mi visibility versus ellsworth 100 ft 1/16 mi visibility. At this point I clicked up the lights at rap airport since tower was closed. I could see the runway and occasionally the lead-in lights. I then told ellsworth approach that I would try the ILS and if I missed then go to sturgis with possibility of ending up in spearfish. After crossing the middle marker, I could see part of the lead-in lights and some of the runway lights. At decision ht, I could see most, if not all, of the runway lights and landed with no problem or incident. The problem was the difference between reported WX and my observed WX. I observed much better WX than reported. It seemed more like a thick haze layer versus a fog layer, and looked by my judgement 3/4 mi visibility.

Original NASA ASRS Text

Title: PLT OF AN ATX AMB SMT TWIN TURBOPROP MADE AN ILS APCH AND LNDG BELOW RPTED LNDG MINIMUMS REQUIRED UNDER PART 135 OF THE FARS. THE RPTR STATED THAT HE COULD VISUALLY SEE BETTER THAN RPTED DURING APCH AND LNDG.

Narrative: I FILED A LIFEGUARD FLT FROM IEN, SD, TO SPF, SD. WE ARE BASED IN RAP, SD, AND DUE TO RPTED FOG 100 FT AND 1/4 MI VISIBILITY, WE PLANNED TO LAND IN SPEARFISH, SD, WITH A POSSIBILITY OF LNDG IN 49B, SD, IF THERE WAS NO FOG AT THIS ARPT. SPEARFISH IS A 55 MIN DRIVE BY AMBULANCE TO RAP AND STURGIS IS A 35 MIN DRIVE TO RAP. AFTER LEAVING PINE RIDGE, I CLBED TO 12000 FT. AFTER LEVELING OFF, I COULD SEE RAPID CITY CITY LIGHTS IN FRONT OF ME. AFTER BEING HANDED OFF FROM ZDV TO ELLSWORTH APCH, I WAS GIVEN DSCNT CLRNC FOR THE APCH AT RAP (POSSIBLY DUE TO THE FACT WE ALWAYS COME BACK TO RAP). I ASKED THE WX AT RAP AND AT ELLSWORTH. RAP WAS 100 FT, 1/4 MI VISIBILITY VERSUS ELLSWORTH 100 FT 1/16 MI VISIBILITY. AT THIS POINT I CLICKED UP THE LIGHTS AT RAP ARPT SINCE TWR WAS CLOSED. I COULD SEE THE RWY AND OCCASIONALLY THE LEAD-IN LIGHTS. I THEN TOLD ELLSWORTH APCH THAT I WOULD TRY THE ILS AND IF I MISSED THEN GO TO STURGIS WITH POSSIBILITY OF ENDING UP IN SPEARFISH. AFTER XING THE MIDDLE MARKER, I COULD SEE PART OF THE LEAD-IN LIGHTS AND SOME OF THE RWY LIGHTS. AT DECISION HT, I COULD SEE MOST, IF NOT ALL, OF THE RWY LIGHTS AND LANDED WITH NO PROB OR INCIDENT. THE PROB WAS THE DIFFERENCE BTWN RPTED WX AND MY OBSERVED WX. I OBSERVED MUCH BETTER WX THAN RPTED. IT SEEMED MORE LIKE A THICK HAZE LAYER VERSUS A FOG LAYER, AND LOOKED BY MY JUDGEMENT 3/4 MI VISIBILITY.

Data retrieved from NASA's ASRS site as of July 2007 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.

Pilot of an atx ambiguity small transport twin turboprop made an ILS approach and landing below reported landing minimums required under part 135 of the FARS. The reporter stated that he could visually see better than reported during approach and landing.