Narrative:

We received a taxi clearance to runway xx left; following pushback and followed a B737 to the runway. Upon switching from ground control to tower frequency and visually observing the B737 that proceeded us rotating on the runway; we received what we both understood to be a 'callsign taxi into position and hold' clearance from tower for runway xxl and the first officer readback 'callsign; position and hold runway xxl' to ATC which had moderate to heavy communications traffic at the time. Both of us then visually checked and verified both the traffic proceeding us as well as the traffic on approximately 5mi final for a safe operating distance between the two. I the captain then called 'below the line' and proceeded past the hold line and onto runway xxl at a normal pace; after finishing the below line flows and checklist tower stated 'callsign continue across xxl and hold short of xxl at C8' (calmly with no urgency what so ever). We verified our original position and hold clearance with ATC at which time we were informed that the clearance we thought we heard and read back was for traffic on runway xy. We did a 180 on C8 held short of xxl and re ran checklist and then saw aircraft landing over the numbers. At no time did there seem to be any urgency or conflict with another aircraft. There also seemed to be time for the controller to have verified our readback was wrong even though there was moderate to heavy communications on the radio at the time. The visual picture seemed like normal spacing between the aircraft preceding us as well as the one we had in sight and verified to one another on final.

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Original NASA ASRS Text

Title: Flight crew believed they hear a clearance for 'position and hold' from the tower and read back that clearance before taxiing into position. Tower then asked the crew to continue across Runway XXL; make a 180 and hold short. The crew had accepted a clearance for another aircraft.

Narrative: We Received a taxi clearance to Runway XX L; following pushback and followed a B737 to the runway. Upon switching from ground control to tower frequency and visually observing the B737 that proceeded us rotating on the runway; we received what we both understood to be a 'Callsign taxi into position and hold' clearance from tower for Runway XXL and the First Officer readback 'Callsign; Position and hold Runway XXL' to ATC which had moderate to heavy communications traffic at the time. Both of us then visually checked and verified both the traffic proceeding us as well as the traffic on approximately 5mi final for a safe operating distance between the two. I the Captain then called 'below the line' and proceeded past the hold line and onto Runway XXL at a normal pace; after finishing the below line flows and checklist tower stated 'Callsign Continue across XXL and hold short of XXL at C8' (calmly with no urgency what so ever). We verified our original position and hold clearance with ATC at which time we were informed that the clearance we thought we heard and read back was for traffic on Runway XY. We did a 180 on C8 held short of XXL and re ran checklist and then saw aircraft landing over the numbers. At no time did there seem to be any urgency or conflict with another aircraft. There also seemed to be time for the controller to have verified our readback was wrong even though there was moderate to heavy communications on the radio at the time. The visual picture seemed like normal spacing between the aircraft preceding us as well as the one we had in sight and verified to one another on final.

Data retrieved from NASA's ASRS site as of April 2012 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.