Narrative:

We understood we were cleared to descend via the riivr [STAR] and also cleared for the runway 24R ILS approach. Therefore; we complied. After riivr; between 11;000 and 10;000; we were told to level at 10;000 and turn left to intercept the 25L ILS approach; which is what the controller said we had been originally cleared for. We complied. If memory serves me; this problem has occurred for quite some time. Often; controllers speak very rapidly while issuing clearances; which also include requests to make speed and altitude changes different from the SID or STAR. These requests while easy to make; often require immediate computer; aircraft configuration; and control changes in order to comply. They are usually followed by frequency changes; aircraft noise; radio congestion; and other distractions. I respectfully suggest that maybe since this event has occurred before; a simple fix we might consider would be for example; to confirm the name of the first fix for the runway extension as a backup.sometimes it can be easy to misunderstand a directive because of many factors; from rapid speaking on the part of the controllers; flight deck noise; radio congestion; etc. Since my first officer and I both were convinced we heard 24R; as evidenced by the FMC being loaded accordingly and the fact that we turned after riivr toward the first 24R fix; maybe it would be best; since this has happened before to others as well; to have the controllers and pilots confirm the very first fix initiating the runway extension as a backup.

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Original NASA ASRS Text

Title: B737-700 Flight Crew reports being cleared for the ILS 24R off the RIIVR 2 to LAX. Before intercepting the LOC for 24R; ATC cancels the clearance and tells the crew to turn left and intercept the LOC for the ILS 25L; and that the original clearance had been to 25L.

Narrative: We understood we were cleared to descend via the RIIVR [STAR] and also cleared for the Runway 24R ILS approach. Therefore; we complied. After RIIVR; between 11;000 and 10;000; we were told to level at 10;000 and turn left to intercept the 25L ILS approach; which is what the Controller said we had been originally cleared for. We complied. If memory serves me; this problem has occurred for quite some time. Often; Controllers speak very rapidly while issuing clearances; which also include requests to make speed and altitude changes different from the SID or STAR. These requests while easy to make; often require immediate computer; aircraft configuration; and control changes in order to comply. They are usually followed by frequency changes; aircraft noise; radio congestion; and other distractions. I respectfully suggest that maybe since this event has occurred before; a simple fix we might consider would be for example; to confirm the name of the first fix for the runway extension as a backup.Sometimes it can be easy to misunderstand a directive because of many factors; from rapid speaking on the part of the Controllers; flight deck noise; radio congestion; etc. Since my First Officer and I both were convinced we heard 24R; as evidenced by the FMC being loaded accordingly and the fact that we turned after RIIVR toward the first 24R fix; maybe it would be best; since this has happened before to others as well; to have the Controllers and Pilots confirm the very first fix initiating the runway extension as a backup.

Data retrieved from NASA's ASRS site 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.