Narrative:

Clearance to descend to FL240 was given to air carrier X approximately 65 mi north of palmdale VOR by ZLA. We were at FL330 going direct to pmd to join the ziggy 3 arrival into ont. We acknowledged the clearance and started our descent. While we were descending through FL317, ZLA called a similar number stating, 'make an immediate left turn 30 degrees, climb and maintain FL330.' center told another aircraft Y to immediately descend to FL290. Our flight was air carrier X, but due to the urgency of this call and similar call sign, we complied with the instructions without hesitation. During the climb and turn, the first officer observed the conflicting traffic at our 12 O'clock position slightly below our altitude and closing fast. As we leveled at FL330, the traffic passed approximately 1500 ft beneath us. We asked ZLA about the traffic conflict and the controller stated it was his fault. The controller appeared to be overworked. He was working several different frequencys and talking to 3 different flts with similar call signs. Due to the late hour I feel fatigue was also a factor. After this incident, we were handed off to the next ZLA controller. He gave us a clearance to cross majek intersection at 14000 ft, then descend and maintain 13000 ft. This was approximately 3 mins after the traffic conflict. Due to a combination of anxiety and confusion from the first incident, I misunderstood the crossing restriction and descended to 13000 ft. We leveled at 13000 ft 10 mi from majek intersection and wetr contacted by ZLA, stating we were supposed to be at 14000 ft till majek intersection. We immediately climbed back to 14000 ft. We had set 13000 ft in the altitude alerter and were discussing the first incident which also contributed to our crossing restriction error.

Related reports:

Google
 

Original NASA ASRS Text

Title: ACR X DSCNT THROUGH OCCUPIED ALT. ACFT Y HAD LTSS. SYS ERROR. ACR X NON ADHERENCE TO ATC CLRNC XING RESTRICTION. PLTDEV.

Narrative: CLRNC TO DSND TO FL240 WAS GIVEN TO ACR X APPROX 65 MI N OF PALMDALE VOR BY ZLA. WE WERE AT FL330 GOING DIRECT TO PMD TO JOIN THE ZIGGY 3 ARR INTO ONT. WE ACKNOWLEDGED THE CLRNC AND STARTED OUR DSCNT. WHILE WE WERE DSNDING THROUGH FL317, ZLA CALLED A SIMILAR NUMBER STATING, 'MAKE AN IMMEDIATE L TURN 30 DEGS, CLB AND MAINTAIN FL330.' CTR TOLD ANOTHER ACFT Y TO IMMEDIATELY DSND TO FL290. OUR FLT WAS ACR X, BUT DUE TO THE URGENCY OF THIS CALL AND SIMILAR CALL SIGN, WE COMPLIED WITH THE INSTRUCTIONS WITHOUT HESITATION. DURING THE CLB AND TURN, THE FO OBSERVED THE CONFLICTING TFC AT OUR 12 O'CLOCK POS SLIGHTLY BELOW OUR ALT AND CLOSING FAST. AS WE LEVELED AT FL330, THE TFC PASSED APPROX 1500 FT BENEATH US. WE ASKED ZLA ABOUT THE TFC CONFLICT AND THE CTLR STATED IT WAS HIS FAULT. THE CTLR APPEARED TO BE OVERWORKED. HE WAS WORKING SEVERAL DIFFERENT FREQS AND TALKING TO 3 DIFFERENT FLTS WITH SIMILAR CALL SIGNS. DUE TO THE LATE HR I FEEL FATIGUE WAS ALSO A FACTOR. AFTER THIS INCIDENT, WE WERE HANDED OFF TO THE NEXT ZLA CTLR. HE GAVE US A CLRNC TO CROSS MAJEK INTXN AT 14000 FT, THEN DSND AND MAINTAIN 13000 FT. THIS WAS APPROX 3 MINS AFTER THE TFC CONFLICT. DUE TO A COMBINATION OF ANXIETY AND CONFUSION FROM THE FIRST INCIDENT, I MISUNDERSTOOD THE XING RESTRICTION AND DSNDED TO 13000 FT. WE LEVELED AT 13000 FT 10 MI FROM MAJEK INTXN AND WETR CONTACTED BY ZLA, STATING WE WERE SUPPOSED TO BE AT 14000 FT TILL MAJEK INTXN. WE IMMEDIATELY CLBED BACK TO 14000 FT. WE HAD SET 13000 FT IN THE ALT ALERTER AND WERE DISCUSSING THE FIRST INCIDENT WHICH ALSO CONTRIBUTED TO OUR XING RESTRICTION ERROR.

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.