Narrative:

We were descending on the rydrr 1 RNAV arrival into lax when we were assigned an arrival clearance that included a crossing restriction of 8;000 feet at fix clify. As pilot monitoring; I misheard the instructions and read back to ATC that we were to cross fix kevvi at 8;000 feet.the instructions as we misheard them were confirmed between myself and the captain; and the inputs into the FMS were executed. We then hurried down to cross kevvi at 8;000 feet; which we were able to accomplish. We were not corrected for the incorrect read-back to ATC of our instructions. The events eventually led to vectors assigned by ATC in order to steer the airplane away from traffic.this was a miscommunication between ATC and the pilots. We had flown from the north into lax earlier the same day; and had received instructions to 'descend via' with alterations to the published routing of the assigned arrival. We were not surprised by the alteration from the published altitude of the misinterpreted crossing restriction; and so we descended according to our read-back assignment. Suggestions: first; two fixes in the same route; that phonetically sound as similar as clify and kevvi could be avoided in order to minimize miscommunications. Second; as pilots; we ought to brief the fact that phonetically similar fixes are a threat; in order to heighten our awareness of potential miscommunications.

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Original NASA ASRS Text

Title: CRJ-200 flight crew reported incorrect clearance read back for crossing a fix on STAR; which had similar sounding fixes names.

Narrative: We were descending on the RYDRR 1 RNAV arrival into LAX when we were assigned an arrival clearance that included a crossing restriction of 8;000 feet at fix CLIFY. As pilot monitoring; I misheard the instructions and read back to ATC that we were to cross fix KEVVI at 8;000 feet.The instructions as we misheard them were confirmed between myself and the Captain; and the inputs into the FMS were executed. We then hurried down to cross KEVVI at 8;000 feet; which we were able to accomplish. We were not corrected for the incorrect read-back to ATC of our instructions. The events eventually led to vectors assigned by ATC in order to steer the airplane away from traffic.This was a miscommunication between ATC and the pilots. We had flown from the north into LAX earlier the same day; and had received instructions to 'descend via' with alterations to the published routing of the assigned arrival. We were not surprised by the alteration from the published altitude of the misinterpreted crossing restriction; and so we descended according to our read-back assignment. Suggestions: First; two fixes in the same route; that phonetically sound as similar as CLIFY and KEVVI could be avoided in order to minimize miscommunications. Second; as pilots; we ought to brief the fact that phonetically similar fixes are a threat; in order to heighten our awareness of potential miscommunications.

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.