Taxiway excursion on snow covered surface not plowed.

Attributes
ACN	236264
Time
Date	199303
Day	Mon
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : bgm
State Reference	NY
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	Marginal
Light	Night
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	ground other : taxi landing other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
ASRS Report	236264
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 9000 flight time type : 7000
ASRS Report	235991
Events
Anomaly	non adherence : clearance non adherence : far other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : became reoriented
Consequence	Other
Supplementary
Primary Problem	Weather
Air Traffic Incident	Pilot Deviation

Narrative:

Approach was to runway 34 at bgm. Reported WX 0 obscured, latest RVR 2400 ft, braking action fair to poor. Stopped aircraft on the runway and was told to report clear of runway due to poor tower visibility. Visibility was poor due to blowing snow. We saw what we thought were the taxi lights to exit the runway at taxiway O. Due to the snow cover on the ground, an optical illusion was created and these lights were actually the lights to the parallel taxiway a. We ended up traversing across the unprepared ground between the runway and the taxiway a. All the ground looked the same because of the snow cover. I learned that extra care must be taken under reduced visibility conditions to ensure that what you are looking at is real and not an illusion created by inclement WX conditions. The snow and light combination created an illusion enabling us to mistake an unprepared surface for a taxiway. We ended up back on taxiway a and had a normal taxi to the gate. There was no damage to the aircraft or the airport facilities.

Original NASA ASRS Text

Title: TXWY EXCURSION ON SNOW COVERED SURFACE NOT PLOWED.

Narrative: APCH WAS TO RWY 34 AT BGM. RPTED WX 0 OBSCURED, LATEST RVR 2400 FT, BRAKING ACTION FAIR TO POOR. STOPPED ACFT ON THE RWY AND WAS TOLD TO RPT CLR OF RWY DUE TO POOR TWR VISIBILITY. VISIBILITY WAS POOR DUE TO BLOWING SNOW. WE SAW WHAT WE THOUGHT WERE THE TAXI LIGHTS TO EXIT THE RWY AT TXWY O. DUE TO THE SNOW COVER ON THE GND, AN OPTICAL ILLUSION WAS CREATED AND THESE LIGHTS WERE ACTUALLY THE LIGHTS TO THE PARALLEL TXWY A. WE ENDED UP TRAVERSING ACROSS THE UNPREPARED GND BTWN THE RWY AND THE TXWY A. ALL THE GND LOOKED THE SAME BECAUSE OF THE SNOW COVER. I LEARNED THAT EXTRA CARE MUST BE TAKEN UNDER REDUCED VISIBILITY CONDITIONS TO ENSURE THAT WHAT YOU ARE LOOKING AT IS REAL AND NOT AN ILLUSION CREATED BY INCLEMENT WX CONDITIONS. THE SNOW AND LIGHT COMBINATION CREATED AN ILLUSION ENABLING US TO MISTAKE AN UNPREPARED SURFACE FOR A TXWY. WE ENDED UP BACK ON TXWY A AND HAD A NORMAL TAXI TO THE GATE. THERE WAS NO DAMAGE TO THE ACFT OR THE ARPT FACILITIES.

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.