G2 with ZLA was issued descent to FL330 and experienced TCAS RA; FAA recorded pilot deviation because of apparent loss of separation.

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Attributes
ACN	731526
Time
Date	200703
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : psp.airport
State Reference	CA
Altitude	msl bound lower : 32000 msl bound upper : 33000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zla.artcc
Operator	common carrier : charter
Make Model Name	Gulfstream II
Operating Under FAR Part	Part 91
Flight Phase	descent : intermediate altitude
Route In Use	arrival : on vectors
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zla.artcc
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise : level
Person 1
Affiliation	company : charter
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 210 flight time total : 30000 flight time type : 4000
ASRS Report	731526
Person 2
Affiliation	company : charter
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : atp
Experience	flight time last 90 days : 50 flight time total : 11300 flight time type : 4500
ASRS Report	731622
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : airborne critical non adherence : clearance
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : took evasive action
Miss Distance	vertical : 600
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Operational Deviation

Narrative:

ATC cleared aircraft X to descend to FL330. Further instruction was given to turn left 20 degrees to avoid traffic. Just prior to leveling off at FL330 we received a TCAS RA; 'adjust altitude to avoid conflict; adjust altitude to avoid conflict.' at that time I saw a solid red target on my TCAS indicator and the ivsi command a descend. I immediately took evasive action and followed the command of the ivsi; I continued to descend; at approximately FL326 I received a TCAS report; 'clear of conflict.' just about that time we received a call from ATC; 'aircraft X you were cleared to FL330.' ATC was busy with other traffic at that time so we could not give him the reason we had to descend below FL330. I told the first officer to roger him I will talk to him on the ground. We then received a frequency change to socal approach who gave us a telephone number to call los angeles when we get on the ground which I did; and I explained to the supervisor why I deviated the assigned altitude as explained above.

Original NASA ASRS Text

Title: G2 WITH ZLA WAS ISSUED DESCENT TO FL330 AND EXPERIENCED TCAS RA; FAA RECORDED PLTDEV BECAUSE OF APPARENT LOSS OF SEPARATION.

Narrative: ATC CLRED ACFT X TO DSND TO FL330. FURTHER INSTRUCTION WAS GIVEN TO TURN L 20 DEGS TO AVOID TFC. JUST PRIOR TO LEVELING OFF AT FL330 WE RECEIVED A TCAS RA; 'ADJUST ALT TO AVOID CONFLICT; ADJUST ALT TO AVOID CONFLICT.' AT THAT TIME I SAW A SOLID RED TARGET ON MY TCAS INDICATOR AND THE IVSI COMMAND A DSND. I IMMEDIATELY TOOK EVASIVE ACTION AND FOLLOWED THE COMMAND OF THE IVSI; I CONTINUED TO DSND; AT APPROX FL326 I RECEIVED A TCAS RPT; 'CLR OF CONFLICT.' JUST ABOUT THAT TIME WE RECEIVED A CALL FROM ATC; 'ACFT X YOU WERE CLRED TO FL330.' ATC WAS BUSY WITH OTHER TFC AT THAT TIME SO WE COULD NOT GIVE HIM THE REASON WE HAD TO DSND BELOW FL330. I TOLD THE FO TO ROGER HIM I WILL TALK TO HIM ON THE GND. WE THEN RECEIVED A FREQ CHANGE TO SOCAL APCH WHO GAVE US A TELEPHONE NUMBER TO CALL LOS ANGELES WHEN WE GET ON THE GND WHICH I DID; AND I EXPLAINED TO THE SUPVR WHY I DEVIATED THE ASSIGNED ALT AS EXPLAINED ABOVE.

Data retrieved from NASA's ASRS site as of January 2009 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.