Narrative:

Our taxi clearance was 'outer, D, short of B for runway 4L.' we departed the ramp at right/G and turned right onto the outer taxiway. Approaching G, we decided we must be on the inner, because taxiway H on our left, appears to be the outer taxiway due to poor taxiway markings. Also, our nonstandard aircraft has no nose taxi light installed, requiring the left wing light to be utilized as an inadequate substitute. In this area you are looking at a 'sea' of blue lights consisting of 3 parallel txwys, a runway, and the ramp area. From the first officer's perspective, the inner taxiway appeared to be the edge of the ramp area. As we initiated our left turn onto taxiway G (to return to our assigned taxiway) we immediately observed the white runway edge lights (of runway 4L) and reversed our turn back onto the outer taxiway. At the present time, this is being investigated as a 'possible' runway incursion. The only explanation that has occurred to us, is that someone looking at our left turnoff light on this dark night, believing it to be our nose taxi light, would have the illusion that our aircraft was located about 1/2 of a wing length closer to the runway than it was in reality. Supplemental information from acn 233768: from my right, the inner taxiway looks like the edge of the ramp, so I agreed with him. This aircraft is nonstandard because of no taxi light. At this area you're looking at a runway, 3 curving parallel txwys and the ramp. Lack of signs and the use of reflectors instead of centerline lights on txwys were all factors. At this point we were actually on the outer, but convinced we were on the inner. We now turned left onto taxiway G to transition to the outer. We believe we made the turn without our wing crossing the hold line for runway 4L.

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Original NASA ASRS Text

Title: ACR FLC ALLEGEDLY INVOLVED IN RWY INCURSION IN NIGHT OP. RPTR'S CITE ARPT PROB TXWY.

Narrative: OUR TAXI CLRNC WAS 'OUTER, D, SHORT OF B FOR RWY 4L.' WE DEPARTED THE RAMP AT R/G AND TURNED R ONTO THE OUTER TXWY. APCHING G, WE DECIDED WE MUST BE ON THE INNER, BECAUSE TXWY H ON OUR L, APPEARS TO BE THE OUTER TXWY DUE TO POOR TXWY MARKINGS. ALSO, OUR NONSTANDARD ACFT HAS NO NOSE TAXI LIGHT INSTALLED, REQUIRING THE L WING LIGHT TO BE UTILIZED AS AN INADEQUATE SUBSTITUTE. IN THIS AREA YOU ARE LOOKING AT A 'SEA' OF BLUE LIGHTS CONSISTING OF 3 PARALLEL TXWYS, A RWY, AND THE RAMP AREA. FROM THE FO'S PERSPECTIVE, THE INNER TXWY APPEARED TO BE THE EDGE OF THE RAMP AREA. AS WE INITIATED OUR L TURN ONTO TXWY G (TO RETURN TO OUR ASSIGNED TXWY) WE IMMEDIATELY OBSERVED THE WHITE RWY EDGE LIGHTS (OF RWY 4L) AND REVERSED OUR TURN BACK ONTO THE OUTER TXWY. AT THE PRESENT TIME, THIS IS BEING INVESTIGATED AS A 'POSSIBLE' RWY INCURSION. THE ONLY EXPLANATION THAT HAS OCCURRED TO US, IS THAT SOMEONE LOOKING AT OUR L TURNOFF LIGHT ON THIS DARK NIGHT, BELIEVING IT TO BE OUR NOSE TAXI LIGHT, WOULD HAVE THE ILLUSION THAT OUR ACFT WAS LOCATED ABOUT 1/2 OF A WING LENGTH CLOSER TO THE RWY THAN IT WAS IN REALITY. SUPPLEMENTAL INFO FROM ACN 233768: FROM MY R, THE INNER TXWY LOOKS LIKE THE EDGE OF THE RAMP, SO I AGREED WITH HIM. THIS ACFT IS NONSTANDARD BECAUSE OF NO TAXI LIGHT. AT THIS AREA YOU'RE LOOKING AT A RWY, 3 CURVING PARALLEL TXWYS AND THE RAMP. LACK OF SIGNS AND THE USE OF REFLECTORS INSTEAD OF CTRLINE LIGHTS ON TXWYS WERE ALL FACTORS. AT THIS POINT WE WERE ACTUALLY ON THE OUTER, BUT CONVINCED WE WERE ON THE INNER. WE NOW TURNED L ONTO TXWY G TO TRANSITION TO THE OUTER. WE BELIEVE WE MADE THE TURN WITHOUT OUR WING XING THE HOLD LINE FOR RWY 4L.

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.