Narrative:

I was working for about 10 mins on the local west position combined with local east. Also working both 135.1 and 118.5 tower frequencys. There was a stuck microphone on 118.5. Runway 27L (departure runway) was closed. We were landing runway 27R and runway 26 departing runway 27R and runway 35. Ground controller asked for a runway crossing with a B737 at the departure pad of runway 26. After reviewing the asde/amass; stars and a visual scan of the runway; I issued the crossing. The B737 saw the landing CRJ2 and did not cross. He questioned ground controller about the crossing. I notified the supervisor of the incident. Contributing factors: asde/amass has a split screen with the aircraft landing runway 26. You see the aircraft approach at the bottom right then disappear and reappear at the top right. There is a slight lag where you don't see any aircraft. Plus; we have a short tower. When you look at the runway 26 final; you are looking out at center city philadelphia and not at the horizon. This makes it difficult to see the aircraft 2 mi away touching down.

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Original NASA ASRS Text

Title: PHL LCL CTLR FAILED TO OBSERVE ACFT ABOUT TO LAND AND APPROVED RWY XING. TAXIING TFC OBSERVED LNDG ACFT AND DID NOT CROSS.

Narrative: I WAS WORKING FOR ABOUT 10 MINS ON THE LCL W POS COMBINED WITH LCL E. ALSO WORKING BOTH 135.1 AND 118.5 TWR FREQS. THERE WAS A STUCK MIKE ON 118.5. RWY 27L (DEP RWY) WAS CLOSED. WE WERE LNDG RWY 27R AND RWY 26 DEPARTING RWY 27R AND RWY 35. GND CTLR ASKED FOR A RWY XING WITH A B737 AT THE DEP PAD OF RWY 26. AFTER REVIEWING THE ASDE/AMASS; STARS AND A VISUAL SCAN OF THE RWY; I ISSUED THE XING. THE B737 SAW THE LNDG CRJ2 AND DID NOT CROSS. HE QUESTIONED GND CTLR ABOUT THE XING. I NOTIFIED THE SUPVR OF THE INCIDENT. CONTRIBUTING FACTORS: ASDE/AMASS HAS A SPLIT SCREEN WITH THE ACFT LNDG RWY 26. YOU SEE THE ACFT APCH AT THE BOTTOM R THEN DISAPPEAR AND REAPPEAR AT THE TOP R. THERE IS A SLIGHT LAG WHERE YOU DON'T SEE ANY ACFT. PLUS; WE HAVE A SHORT TWR. WHEN YOU LOOK AT THE RWY 26 FINAL; YOU ARE LOOKING OUT AT CENTER CITY PHILADELPHIA AND NOT AT THE HORIZON. THIS MAKES IT DIFFICULT TO SEE THE ACFT 2 MI AWAY TOUCHING DOWN.

Data retrieved from NASA's ASRS site as of January 2009 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.