B747-100 crew started the approach with touchdown RVR below landing minimums at anc.

Attributes
ACN	534619
Time
Date	200112
Day	Wed
Local Time Of Day	0001 To 0600
Place
Locale Reference	airport : anc.airport
State Reference	AK
Altitude	msl single value : 2000
Environment
Flight Conditions	IMC
Weather Elements	Fog
Light	Night
Aircraft 1
Controlling Facilities	tracon : a11.tracon
Operator	common carrier : air carrier
Make Model Name	B747-100
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : cfi pilot : atp pilot : flight engineer pilot : multi engine
Experience	flight time last 90 days : 120 flight time total : 11000 flight time type : 3500
ASRS Report	534619
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	inflight encounter : weather inflight encounter other non adherence : company policies non adherence : far non adherence : published procedure other anomaly other
Independent Detector	other flight crewa other flight crewb
Resolutory Action	none taken : anomaly accepted
Supplementary
Problem Areas	Weather Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

As is typical in winter, anc WX went below forecast. Nearing whitehorse, WX deteriorated to 1/4 mi visibility in ice and fog. A plan was developed, including a fuel at which we would divert to alternate which was 40000 pounds (we estimated arriving over anc with 60000 pounds). Once on downwind at anc, WX was varying rapidly with RVR ranging from 1600 ft to 2000 ft. The captain (new) advised the controller that we needed 1800 ft RVR to accept an approach clearance. On base leg, TRACON advised '...touchdown 1600 ft, mid 1800 ft, rollout 2000 ft...' and cleared us for approach. I queried the captain if this was legal (keeping in mind we were outside of FAF) and he said as long as one of the 3 RVR's was above minimums, it was legal. I landed with no problem, but now am unable to determine the truth.

Original NASA ASRS Text

Title: B747-100 CREW STARTED THE APCH WITH TOUCHDOWN RVR BELOW LNDG MINIMUMS AT ANC.

Narrative: AS IS TYPICAL IN WINTER, ANC WX WENT BELOW FORECAST. NEARING WHITEHORSE, WX DETERIORATED TO 1/4 MI VISIBILITY IN ICE AND FOG. A PLAN WAS DEVELOPED, INCLUDING A FUEL AT WHICH WE WOULD DIVERT TO ALTERNATE WHICH WAS 40000 LBS (WE ESTIMATED ARRIVING OVER ANC WITH 60000 LBS). ONCE ON DOWNWIND AT ANC, WX WAS VARYING RAPIDLY WITH RVR RANGING FROM 1600 FT TO 2000 FT. THE CAPT (NEW) ADVISED THE CTLR THAT WE NEEDED 1800 FT RVR TO ACCEPT AN APCH CLRNC. ON BASE LEG, TRACON ADVISED '...TOUCHDOWN 1600 FT, MID 1800 FT, ROLLOUT 2000 FT...' AND CLRED US FOR APCH. I QUERIED THE CAPT IF THIS WAS LEGAL (KEEPING IN MIND WE WERE OUTSIDE OF FAF) AND HE SAID AS LONG AS ONE OF THE 3 RVR'S WAS ABOVE MINIMUMS, IT WAS LEGAL. I LANDED WITH NO PROB, BUT NOW AM UNABLE TO DETERMINE THE TRUTH.

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.