Narrative:

We were at bwi; taxiing out to runway 28 for takeoff. The first 1000 ft of runway 28 was closed; so another carrier chose not to use runway 28; and was taxiing out to runway 33L. His taxi instructions included holding short of taxiway P on runway 4/22; to let us pass by. After we passed; the first officer switched to tower frequency; and the tower cleared us for takeoff. As we made the turn at taxiway U1 for the intersection takeoff; the first officer said; 'he's not stopping;' referring to the other carrier; who was just pulling out across runway 28. As I lined up with the centerline; the B757 was completely blocking the runway; crossing at the intersection with runway 4/22. I asked the tower; 'are we still cleared for takeoff with X right in front of us?' there was a pause; and then the tower said 'uh...yes;' just as the B757's tail cleared the runway. I said; 'great; nice job;' and we took off for an uneventful flight. The flight crew remained situationally aware; and prevented what could have been a major problem. I am unsure of the clearance given to the other carrier B757; whether he was told to hold short of the runway or cross it; since he was on ground frequency and we were on tower. But either way; the tower controller should not have cleared us for takeoff with him headed onto the runway. At the very least; the tower should have canceled our takeoff clearance until he got across the runway. He was moving at a typical taxi speed. It appeared that the tower controller was not aware of the position of the B757 until I asked him about our takeoff clearance.

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Original NASA ASRS Text

Title: B737-700 WAS CLEARED FOR TKOF WITH AN ACFT CROSSING THE TKOF RWY.

Narrative: WE WERE AT BWI; TAXIING OUT TO RWY 28 FOR TKOF. THE FIRST 1000 FT OF RWY 28 WAS CLOSED; SO ANOTHER CARRIER CHOSE NOT TO USE RWY 28; AND WAS TAXIING OUT TO RWY 33L. HIS TAXI INSTRUCTIONS INCLUDED HOLDING SHORT OF TXWY P ON RWY 4/22; TO LET US PASS BY. AFTER WE PASSED; THE FO SWITCHED TO TWR FREQ; AND THE TWR CLRED US FOR TKOF. AS WE MADE THE TURN AT TXWY U1 FOR THE INTXN TKOF; THE FO SAID; 'HE'S NOT STOPPING;' REFERRING TO THE OTHER CARRIER; WHO WAS JUST PULLING OUT ACROSS RWY 28. AS I LINED UP WITH THE CTRLINE; THE B757 WAS COMPLETELY BLOCKING THE RWY; XING AT THE INTXN WITH RWY 4/22. I ASKED THE TWR; 'ARE WE STILL CLRED FOR TKOF WITH X RIGHT IN FRONT OF US?' THERE WAS A PAUSE; AND THEN THE TWR SAID 'UH...YES;' JUST AS THE B757'S TAIL CLRED THE RWY. I SAID; 'GREAT; NICE JOB;' AND WE TOOK OFF FOR AN UNEVENTFUL FLT. THE FLT CREW REMAINED SITUATIONALLY AWARE; AND PREVENTED WHAT COULD HAVE BEEN A MAJOR PROB. I AM UNSURE OF THE CLRNC GIVEN TO THE OTHER CARRIER B757; WHETHER HE WAS TOLD TO HOLD SHORT OF THE RWY OR CROSS IT; SINCE HE WAS ON GND FREQ AND WE WERE ON TWR. BUT EITHER WAY; THE TWR CTLR SHOULD NOT HAVE CLRED US FOR TKOF WITH HIM HEADED ONTO THE RWY. AT THE VERY LEAST; THE TWR SHOULD HAVE CANCELED OUR TKOF CLRNC UNTIL HE GOT ACROSS THE RWY. HE WAS MOVING AT A TYPICAL TAXI SPD. IT APPEARED THAT THE TWR CTLR WAS NOT AWARE OF THE POS OF THE B757 UNTIL I ASKED HIM ABOUT OUR TKOF CLRNC.

Data retrieved from NASA's ASRS site as of May 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.