B737-700 flight crew reports being cleared for the ILS 24R off the riivr 2 to lax. Before intercepti...

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.

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.

Attributes
ACN	1211710
Time
Date	201410
Place
Locale Reference	SCT.TRACON
State Reference	CA
Environment
Flight Conditions	Mixed
Aircraft 1
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Flight Phase	Descent
Route In Use	STAR RIIVR
Flight Plan	IFR
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 150
Person 2
Function	Pilot Not Flying First Officer
Experience	Flight Crew Last 90 Days 152
Events
Anomaly	Deviation - Procedural Clearance Deviation - Track / Heading All Types

B737-700 flight crew reports being cleared for the ILS 24R off the riivr 2 to lax. Before intercepting the localizer for 24R; ATC cancels the clearance and tells the crew to turn left and intercept the localizer for the ILS 25L; and that the original clearance had been to 25L.