Narrative:

During the descent into sheman, tx we were given numerous altitude and heading changes. More than one of these clrncs was conditional on leaving an altitude before proceeding on course. I was somewhat busy evaluating an area of WX we were about to enter on the radar when we were assigned an altitude of 5000'. For some reason I set the autoplt to level out at 4000'. The copilot acknowledged for the 5000' altitude, but apparently never checked to ensure that I had set the autoplt correctly. The autoplt leveled the aircraft off at 4000' and 1-2 mins later the controller advised that our assigned altitude was 5000'. I queried him (ATC) as to what he wanted us to do. The response was, 'no problem, maintain 4000',' so I assume no traffic conflict occurred. Even though we operate the aircraft with a 2-M crew, it is not required by the regulations. Because of this, we have had no formal training on crew coordination and most of the cockpit duties are shared by an informal set of rules. In this situation the copilot was the only person who was in a position to detect the erroneous altitude setting in the autoplt window, since I believed our assigned altitude to be 4000'. This situation could have been avoided if the copilot had been better disciplined on x-chking the PF's activities. It has been my experience that many times in GA 2 pilots are put on an aircraft based on the assumption that 2 pilots must be better than 1, but west/O some training on who is responsible for what duties there is the distinct possibility that the safety factor may be reduced by introducing this additional untrained crew member.

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Original NASA ASRS Text

Title: CPR LTT ALT DEVIATION OVERSHOT DURING DESCENT.

Narrative: DURING THE DSNT INTO SHEMAN, TX WE WERE GIVEN NUMEROUS ALT AND HDG CHANGES. MORE THAN ONE OF THESE CLRNCS WAS CONDITIONAL ON LEAVING AN ALT BEFORE PROCEEDING ON COURSE. I WAS SOMEWHAT BUSY EVALUATING AN AREA OF WX WE WERE ABOUT TO ENTER ON THE RADAR WHEN WE WERE ASSIGNED AN ALT OF 5000'. FOR SOME REASON I SET THE AUTOPLT TO LEVEL OUT AT 4000'. THE COPLT ACKNOWLEDGED FOR THE 5000' ALT, BUT APPARENTLY NEVER CHKED TO ENSURE THAT I HAD SET THE AUTOPLT CORRECTLY. THE AUTOPLT LEVELED THE ACFT OFF AT 4000' AND 1-2 MINS LATER THE CTLR ADVISED THAT OUR ASSIGNED ALT WAS 5000'. I QUERIED HIM (ATC) AS TO WHAT HE WANTED US TO DO. THE RESPONSE WAS, 'NO PROB, MAINTAIN 4000',' SO I ASSUME NO TFC CONFLICT OCCURRED. EVEN THOUGH WE OPERATE THE ACFT WITH A 2-M CREW, IT IS NOT REQUIRED BY THE REGS. BECAUSE OF THIS, WE HAVE HAD NO FORMAL TRNING ON CREW COORD AND MOST OF THE COCKPIT DUTIES ARE SHARED BY AN INFORMAL SET OF RULES. IN THIS SITUATION THE COPLT WAS THE ONLY PERSON WHO WAS IN A POS TO DETECT THE ERRONEOUS ALT SETTING IN THE AUTOPLT WINDOW, SINCE I BELIEVED OUR ASSIGNED ALT TO BE 4000'. THIS SITUATION COULD HAVE BEEN AVOIDED IF THE COPLT HAD BEEN BETTER DISCIPLINED ON X-CHKING THE PF'S ACTIVITIES. IT HAS BEEN MY EXPERIENCE THAT MANY TIMES IN GA 2 PLTS ARE PUT ON AN ACFT BASED ON THE ASSUMPTION THAT 2 PLTS MUST BE BETTER THAN 1, BUT W/O SOME TRNING ON WHO IS RESPONSIBLE FOR WHAT DUTIES THERE IS THE DISTINCT POSSIBILITY THAT THE SAFETY FACTOR MAY BE REDUCED BY INTRODUCING THIS ADDITIONAL UNTRAINED CREW MEMBER.

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.