Air carrier makes CAT ii approach. After landing dispatch says approach not authorized.

Attributes
ACN	202308
Time
Date	199202
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : gso
State Reference	NC
Altitude	msl bound lower : 2900 msl bound upper : 2900
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : gso artcc : zmp
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	descent : approach landing other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 80 flight time total : 6000 flight time type : 1200
ASRS Report	202308
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	non adherence : published procedure non adherence : far
Independent Detector	other other : unspecified
Resolutory Action	none taken : detected after the fact
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

After departing dca for gso the WX began to deteriorate. RVR was fluctuating between 1100 and 1600. There were no NOTAMS listed on the ATIS nor on the WX hard copy provided by operations at dca. When gso approach informed us the RVR was down to 1100 ft, the captain told them we needed 1200 ft for the runway 23 CAT ii ILS approach. We were issued holding instructions at the OM. Prior to entering the hold the RVR went to 1200 ft and we were 'cleared for the approach.' we performed a monitored approach with the captain watching 'outside' while I monitored 'inside.' when I called out 100 ft above mins the captain called the runway in sight took control of the aircraft and made a normal, uneventful landing. We were notified by the dispatcher the approach was 'not authorized.' callback conversation with reporter revealed the following information. Callback made to determine on what basis approach not authorized. Reporter states he does not know. Captain going to check but has not done so. A notice posted on crew room board reference not authorized, but seen after the fact. No NOTAM issued. Reporter asked through his chain of command but received no real answer. It appears to be the great mystery. Notice no longer on crew board.

Original NASA ASRS Text

Title: ACR MAKES CAT II APCH. AFTER LNDG DISPATCH SAYS APCH NOT AUTHORIZED.

Narrative: AFTER DEPARTING DCA FOR GSO THE WX BEGAN TO DETERIORATE. RVR WAS FLUCTUATING BTWN 1100 AND 1600. THERE WERE NO NOTAMS LISTED ON THE ATIS NOR ON THE WX HARD COPY PROVIDED BY OPS AT DCA. WHEN GSO APCH INFORMED US THE RVR WAS DOWN TO 1100 FT, THE CAPT TOLD THEM WE NEEDED 1200 FT FOR THE RWY 23 CAT II ILS APCH. WE WERE ISSUED HOLDING INSTRUCTIONS AT THE OM. PRIOR TO ENTERING THE HOLD THE RVR WENT TO 1200 FT AND WE WERE 'CLRED FOR THE APCH.' WE PERFORMED A MONITORED APCH WITH THE CAPT WATCHING 'OUTSIDE' WHILE I MONITORED 'INSIDE.' WHEN I CALLED OUT 100 FT ABOVE MINS THE CAPT CALLED THE RWY IN SIGHT TOOK CTL OF THE ACFT AND MADE A NORMAL, UNEVENTFUL LNDG. WE WERE NOTIFIED BY THE DISPATCHER THE APCH WAS 'NOT AUTHORIZED.' CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO. CALLBACK MADE TO DETERMINE ON WHAT BASIS APCH NOT AUTHORIZED. RPTR STATES HE DOES NOT KNOW. CAPT GOING TO CHK BUT HAS NOT DONE SO. A NOTICE POSTED ON CREW ROOM BOARD REF NOT AUTHORIZED, BUT SEEN AFTER THE FACT. NO NOTAM ISSUED. RPTR ASKED THROUGH HIS CHAIN OF COMMAND BUT RECEIVED NO REAL ANSWER. IT APPEARS TO BE THE GREAT MYSTERY. NOTICE NO LONGER ON CREW BOARD.

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.