Citationjet (C525/C526) - CJ I / II / III / IV
Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Flight Instructor
Flight Crew Last 90 Days 17; Flight Crew Total 8000; Flight Crew Type 400
Situational Awareness; Communication Breakdown
ATC Issue All Types; Conflict Airborne Conflict; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Published Material / Policy
General None Reported / Taken
Human Factors
We had just started a descent out of nine thousand feet for descent into SMO. Going through seven thousand; ATC instructed us to start an immediate climb and turn left to avoid traffic. We had set 6 thousand in altitude alerter; and both of us recall that was the altitude assigned and read back. After complying with ATC instructions; ATC told us we were assigned seven thousand. We informed ATC we thought six thousand was assigned and that is what we recalled reading back. ATC did not dispute our readback; only that we were assigned seven thousand. All other communications with ATC were normal. Corrective actions from this experience are to be better disciplined about both pilots confirming altitude changes and reading them aloud. Also both pilots need to confirm what is set in the altitude selector. This will ensure that correct altitudes are put in the altitude selector and help avoid traffic conflicts.
I issued Aircraft X 060 and meant 070. I noticed Aircraft Y at 060 and thought that I will needed to issue traffic as they got closer; but mistakenly issued 060. I observed Aircraft X descending out of 068 and issued climb; turn; and traffic. It happened because I screwed up! Pay more attention; actively listen to readback; state altitude of traffic instead of 'restricted 1;000 FT below you'; maybe the pilot would have caught the mistake.
Corporate aircraft landing SMO with SCT described a conflict event when ATC mistakenly issued the wrong altitude assignment; ATC acknowledging the error.