Taxiway excursion by taxiing traffic in a night operation.

Attributes
ACN	224100
Time
Date	199210
Day	Fri
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : pit
State Reference	PA
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Light Transport, High Wing, 2 Turboprop Eng
Flight Phase	ground other : taxi
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
ASRS Report	224100
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 240 flight time total : 20268 flight time type : 10000
ASRS Report	223922
Events
Anomaly	non adherence : far other anomaly other other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : detected after the fact
Consequence	other Other
Supplementary
Primary Problem	Airport
Air Traffic Incident	Pilot Deviation
Situations
Airport	other physical facility

Narrative:

While making a 90 degree turn from the ramp onto taxiway Y south, the right main wheel slipped off the pavement into the adjacent soft dirt. The wheel and brake assembly received minor damage. Passenger were deplaned without incident, and the aircraft extricated using air bags (by airport crews). Aircraft was being taxied by the captain at the time of the incident. Crew was performing taxi checklist, and initial thoughts were that we had a flat tire. Visual inspection confirmed above. Contributing factors were the width, design, and lighting on the taxiway: width: taxiway was built narrower than standard, with plans to widen them later (as per airport manager). Design: taxiway corner uses segmented instead of smooth curve. Lighting: because of plans to widen the taxiway, lighting was installed far from the present edge of the pavement, giving the illusion of a wider surface. This was, I believe, a primary factor. The yellow centerline stripe, though painted with reflective paint, is nearly invisible due to the low angle of aircraft taxi lights and the high cockpit viewing angle. During winter months, this situation will be even more hazardous.

Original NASA ASRS Text

Title: TAXIWAY EXCURSION BY TAXIING TFC IN A NIGHT OP.

Narrative: WHILE MAKING A 90 DEG TURN FROM THE RAMP ONTO TAXIWAY Y S, THE R MAIN WHEEL SLIPPED OFF THE PAVEMENT INTO THE ADJACENT SOFT DIRT. THE WHEEL AND BRAKE ASSEMBLY RECEIVED MINOR DAMAGE. PAX WERE DEPLANED WITHOUT INCIDENT, AND THE ACFT EXTRICATED USING AIR BAGS (BY ARPT CREWS). ACFT WAS BEING TAXIED BY THE CAPT AT THE TIME OF THE INCIDENT. CREW WAS PERFORMING TAXI CHKLIST, AND INITIAL THOUGHTS WERE THAT WE HAD A FLAT TIRE. VISUAL INSPECTION CONFIRMED ABOVE. CONTRIBUTING FACTORS WERE THE WIDTH, DESIGN, AND LIGHTING ON THE TAXIWAY: WIDTH: TAXIWAY WAS BUILT NARROWER THAN STANDARD, WITH PLANS TO WIDEN THEM LATER (AS PER ARPT MGR). DESIGN: TAXIWAY CORNER USES SEGMENTED INSTEAD OF SMOOTH CURVE. LIGHTING: BECAUSE OF PLANS TO WIDEN THE TAXIWAY, LIGHTING WAS INSTALLED FAR FROM THE PRESENT EDGE OF THE PAVEMENT, GIVING THE ILLUSION OF A WIDER SURFACE. THIS WAS, I BELIEVE, A PRIMARY FACTOR. THE YELLOW CTRLINE STRIPE, THOUGH PAINTED WITH REFLECTIVE PAINT, IS NEARLY INVISIBLE DUE TO THE LOW ANGLE OF ACFT TAXI LIGHTS AND THE HIGH COCKPIT VIEWING ANGLE. DURING WINTER MONTHS, THIS SITUATION WILL BE EVEN MORE HAZARDOUS.

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.