Narrative:

Passenger loaded, received taxi instructions. Taxi to runway 27R, clear to cross runway 35. This is a very, very unusual taxi instruction. Runway 27R full length is hardly used for takeoff. I personally, in 8 yrs of flying in and out of phl, have done so only once. The normal instructions that we receive: taxi to runway 27L, clear to cross runway 27R. This is what I believed that I had heard. I checked final for runway 27R and noticed a plane a few mi out so I picked up the taxi speed slightly. As we neared the hold line for runway 27R, the first officer called my name rather loudly, so I jumped on the brakes. At this point we had crossed the hold line for runway 27R but had not entered the runway. I then noticed a plane in position on runway 27R. Ground asked if we could do a 180 degree turn. We said yes, and did so immediately. The plane in position was then quickly cleared for takeoff. I then questioned the first officer where we should have gone and he told me. We then taxied to runway 27R without incident. I apologized to ground for the mix-up and he said it was no problem. The factors: I heard what I had expected to hear instead of what was actually said. More care must be taken to listen to taxi instructions. Never assume. Since I had always taken pride in being very safety conscious, this has served to heighten my situational awareness.

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Original NASA ASRS Text

Title: DH8 CAPT TAXIED TO THE CUSTOMARY TKOF RWY ON THE CUSTOMARY ROUTING. CTLR HAD CLRED HIM TO A DIFFERENT RWY VIA A DIFFERENT RTE. HE HAD A RWY INCURSION.

Narrative: PAX LOADED, RECEIVED TAXI INSTRUCTIONS. TAXI TO RWY 27R, CLR TO CROSS RWY 35. THIS IS A VERY, VERY UNUSUAL TAXI INSTRUCTION. RWY 27R FULL LENGTH IS HARDLY USED FOR TKOF. I PERSONALLY, IN 8 YRS OF FLYING IN AND OUT OF PHL, HAVE DONE SO ONLY ONCE. THE NORMAL INSTRUCTIONS THAT WE RECEIVE: TAXI TO RWY 27L, CLR TO CROSS RWY 27R. THIS IS WHAT I BELIEVED THAT I HAD HEARD. I CHKED FINAL FOR RWY 27R AND NOTICED A PLANE A FEW MI OUT SO I PICKED UP THE TAXI SPD SLIGHTLY. AS WE NEARED THE HOLD LINE FOR RWY 27R, THE FO CALLED MY NAME RATHER LOUDLY, SO I JUMPED ON THE BRAKES. AT THIS POINT WE HAD CROSSED THE HOLD LINE FOR RWY 27R BUT HAD NOT ENTERED THE RWY. I THEN NOTICED A PLANE IN POS ON RWY 27R. GND ASKED IF WE COULD DO A 180 DEG TURN. WE SAID YES, AND DID SO IMMEDIATELY. THE PLANE IN POS WAS THEN QUICKLY CLRED FOR TKOF. I THEN QUESTIONED THE FO WHERE WE SHOULD HAVE GONE AND HE TOLD ME. WE THEN TAXIED TO RWY 27R WITHOUT INCIDENT. I APOLOGIZED TO GND FOR THE MIX-UP AND HE SAID IT WAS NO PROB. THE FACTORS: I HEARD WHAT I HAD EXPECTED TO HEAR INSTEAD OF WHAT WAS ACTUALLY SAID. MORE CARE MUST BE TAKEN TO LISTEN TO TAXI INSTRUCTIONS. NEVER ASSUME. SINCE I HAD ALWAYS TAKEN PRIDE IN BEING VERY SAFETY CONSCIOUS, THIS HAS SERVED TO HEIGHTEN MY SITUATIONAL AWARENESS.

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.