Commuter is given RVR below minimums when inside the OM.

Attributes
ACN	302134
Time
Date	199504
Day	Wed
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : iad
State Reference	VA
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : iad
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 135
Flight Phase	descent : approach
Route In Use	approach : straight in arrival other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time total : 6800
ASRS Report	302134
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	other anomaly other
Independent Detector	other flight crewa
Resolutory Action	other
Consequence	Other
Supplementary
Primary Problem	Airport
Air Traffic Incident	other

Narrative:

At a point inside the OM for the ILS runway 19L approach, the controller told us the RVR is 1600 ft, 1800 ft, 1200 ft. That is below the minimums for that runway. Tower visibility was 7 plus mi. In-flight visibility was at least 20 mi. I had the whole runway in sight throughout the approach. The temperature and dewpoint were at 50 degrees/50 degrees and the surface visibility was dropping quickly. But at the time we shot the approach visibility was good. Another airplane landed after we did. I think the RVR machines are in a valley which causes them to pick up ground fog more quickly.

Original NASA ASRS Text

Title: COMMUTER IS GIVEN RVR BELOW MINIMUMS WHEN INSIDE THE OM.

Narrative: AT A POINT INSIDE THE OM FOR THE ILS RWY 19L APCH, THE CTLR TOLD US THE RVR IS 1600 FT, 1800 FT, 1200 FT. THAT IS BELOW THE MINIMUMS FOR THAT RWY. TWR VISIBILITY WAS 7 PLUS MI. INFLT VISIBILITY WAS AT LEAST 20 MI. I HAD THE WHOLE RWY IN SIGHT THROUGHOUT THE APCH. THE TEMP AND DEWPOINT WERE AT 50 DEGS/50 DEGS AND THE SURFACE VISIBILITY WAS DROPPING QUICKLY. BUT AT THE TIME WE SHOT THE APCH VISIBILITY WAS GOOD. ANOTHER AIRPLANE LANDED AFTER WE DID. I THINK THE RVR MACHINES ARE IN A VALLEY WHICH CAUSES THEM TO PICK UP GND FOG MORE QUICKLY.

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.