Narrative:

While executing a STAR, approach control cleared us to descend to 7000'. I instructed the copilot to contact the FBO on unicom to forward an ETA and request a cabin attendant for our passenger. WX at our destination had been deteriorating with fog. We had previously discussed our landing minimum visibility requirements and an alternate airport. While the copilot was off frequency, approach control advised us that our destination visibility was at 1600 RVR, which was below our required minimum of 1800 RVR, and asked our intention. When the copilot completed his call to the FBO, I said to him, 'it's down to 1600.' I then turned to ask our passenger to come forward to advise him of the situation and determine if he wanted to wait for the visibility to improve or proceed immediately to our alternate. While briefing our passenger, the copilot understood my comment to mean that we were to descend to 1600' and dialed 1600 into the altitude preselect. After my discussion with our passenger, I noticed we were out of 6000' and still descending. I immediately began a climb back to 7000'. The controller caught the error and instructed us to climb back to 7000'. We then proceeded to our alternate and landed. After shutdown, the copilot and I discussed the incident and concluded: the crew workload was high due to rapidly changing WX conditions in a busy terminal area despite the automated cockpit. Comments can carry more than one meaning and should be worded carefully. Briefing passengers is a distraction and should not be done by the PF. We are an experienced, well-trained crew that has been flying together for 10 yrs. This should not have happened.

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Original NASA ASRS Text

Title: BREAKDOWN IN COCKPIT COORD LEADS TO ALT DEVIATION FOR CPR FLC.

Narrative: WHILE EXECUTING A STAR, APCH CTL CLRED US TO DSND TO 7000'. I INSTRUCTED THE COPLT TO CONTACT THE FBO ON UNICOM TO FORWARD AN ETA AND REQUEST A CAB FOR OUR PAX. WX AT OUR DEST HAD BEEN DETERIORATING WITH FOG. WE HAD PREVIOUSLY DISCUSSED OUR LNDG MINIMUM VISIBILITY REQUIREMENTS AND AN ALTERNATE ARPT. WHILE THE COPLT WAS OFF FREQ, APCH CTL ADVISED US THAT OUR DEST VISIBILITY WAS AT 1600 RVR, WHICH WAS BELOW OUR REQUIRED MINIMUM OF 1800 RVR, AND ASKED OUR INTENTION. WHEN THE COPLT COMPLETED HIS CALL TO THE FBO, I SAID TO HIM, 'IT'S DOWN TO 1600.' I THEN TURNED TO ASK OUR PAX TO COME FORWARD TO ADVISE HIM OF THE SITUATION AND DETERMINE IF HE WANTED TO WAIT FOR THE VISIBILITY TO IMPROVE OR PROCEED IMMEDIATELY TO OUR ALTERNATE. WHILE BRIEFING OUR PAX, THE COPLT UNDERSTOOD MY COMMENT TO MEAN THAT WE WERE TO DSND TO 1600' AND DIALED 1600 INTO THE ALT PRESELECT. AFTER MY DISCUSSION WITH OUR PAX, I NOTICED WE WERE OUT OF 6000' AND STILL DSNDING. I IMMEDIATELY BEGAN A CLB BACK TO 7000'. THE CTLR CAUGHT THE ERROR AND INSTRUCTED US TO CLB BACK TO 7000'. WE THEN PROCEEDED TO OUR ALTERNATE AND LANDED. AFTER SHUTDOWN, THE COPLT AND I DISCUSSED THE INCIDENT AND CONCLUDED: THE CREW WORKLOAD WAS HIGH DUE TO RAPIDLY CHANGING WX CONDITIONS IN A BUSY TERMINAL AREA DESPITE THE AUTOMATED COCKPIT. COMMENTS CAN CARRY MORE THAN ONE MEANING AND SHOULD BE WORDED CAREFULLY. BRIEFING PAXS IS A DISTR AND SHOULD NOT BE DONE BY THE PF. WE ARE AN EXPERIENCED, WELL-TRAINED CREW THAT HAS BEEN FLYING TOGETHER FOR 10 YRS. THIS SHOULD NOT HAVE HAPPENED.

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.