Narrative:

Landed runway 24R behind aircraft Y. Aircraft Y was holding short runway 24L at taxiway aa. Air carrier Z was cleared to cross runway 24L as we exited runway 24R at taxiway aa. I inquired if we could keep it rolling. Lax tower gave clearance, 'aircraft X cleared to cross runway 24L' I acknowledged the clearance. Once I terminated the transmission, it was obvious the controller had been talking while I was talking. I heard something like '...short.' immediately tower came back and told us to hold short of runway 24L. I acknowledged this new clearance and a B737 (Z) was told to go around. We had crossed the hold short line, but did not cross the line delineating the runway. A subsequent clearance to cross was issued and we proceeded to the gate uneventfully. Captain contacted the tower via phone. The controller said that they acknowledged that we were given a clearance to cross, but subsequently rescinded it. They said they saw we were not stopping and issued the hold short again, while ordering B737 to go around. We said we believed that I was reading back the original clearance as they were issuing the first 'hold short' clearance, thereby blocking the transmission. They said that since the B737 went around, there was no incursion and separation was not a problem.

Related reports:

Google
 

Original NASA ASRS Text

Title: RWY INCURSION AND A NEAR GND CONFLICT WHEN AN MD80 ON ROLLOUT RWY 24R, TXWY AA TURN OFF, AND A B737 LNDG RWY 24L CREATES A POTENTIAL TFC CONFLICT, AS LAX TWR CTLR CHANGES HIS MIND NECESSITATING A GAR.

Narrative: LANDED RWY 24R BEHIND ACFT Y. ACFT Y WAS HOLDING SHORT RWY 24L AT TXWY AA. ACR Z WAS CLRED TO CROSS RWY 24L AS WE EXITED RWY 24R AT TXWY AA. I INQUIRED IF WE COULD KEEP IT ROLLING. LAX TWR GAVE CLRNC, 'ACFT X CLRED TO CROSS RWY 24L' I ACKNOWLEDGED THE CLRNC. ONCE I TERMINATED THE XMISSION, IT WAS OBVIOUS THE CTLR HAD BEEN TALKING WHILE I WAS TALKING. I HEARD SOMETHING LIKE '...SHORT.' IMMEDIATELY TWR CAME BACK AND TOLD US TO HOLD SHORT OF RWY 24L. I ACKNOWLEDGED THIS NEW CLRNC AND A B737 (Z) WAS TOLD TO GO AROUND. WE HAD CROSSED THE HOLD SHORT LINE, BUT DID NOT CROSS THE LINE DELINEATING THE RWY. A SUBSEQUENT CLRNC TO CROSS WAS ISSUED AND WE PROCEEDED TO THE GATE UNEVENTFULLY. CAPT CONTACTED THE TWR VIA PHONE. THE CTLR SAID THAT THEY ACKNOWLEDGED THAT WE WERE GIVEN A CLRNC TO CROSS, BUT SUBSEQUENTLY RESCINDED IT. THEY SAID THEY SAW WE WERE NOT STOPPING AND ISSUED THE HOLD SHORT AGAIN, WHILE ORDERING B737 TO GO AROUND. WE SAID WE BELIEVED THAT I WAS READING BACK THE ORIGINAL CLRNC AS THEY WERE ISSUING THE FIRST 'HOLD SHORT' CLRNC, THEREBY BLOCKING THE XMISSION. THEY SAID THAT SINCE THE B737 WENT AROUND, THERE WAS NO INCURSION AND SEPARATION WAS NOT A PROB.

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.