Narrative:

Upon approach to hib the WX visibility was hazy. Duluth approach, the controling ATC, was giving us vectors for the hib ILS runway 31. We broke out of the clouds but still the airport was to our left approximately 6 mi. Not in sight. It was at our 9 O'clock position. Our heading was 120 degree. I requested vectors for the visual approach. Duluth gave us a heading of 360 degree. We were descending to assigned altitude of 3500 ft. We turned to 360 degrees, tuned in the localizer to hib 31 to intercept to aid in guiding to the runway. During the turn to 360 degree we descended to 3100 ft when duluth reminded us to maintain 3500 ft. At that point we were VFR (airport still not in sight) and requested IFR cancellation with duluth. Our cancellation was received. We proceeded to the airport (hib) and landed. Chain of events. We were in the descent from our cruise altitude, deviating around rain showers via our radar screen during the descent, looking for the airport in the haze, getting vectors and turning. The copilot (the PF in this case) was inexperienced (less than 500 hours total time) and the PIC (PNF in this case) had just come off a 2 1/2 week vacation and was not as sharp on planning ahead as he should have been compared to where he was in proficiency just before his vacation. Being too busy with radio frequency changing the PIC allowed the aircraft to descend below assigned altitude. At the point of being reminded of the assigned altitude by ATC, we just cancelled IFR, intercepted the hib localizer proceeded inbound and landed with approximately 3 mi visibility in haze.

Related reports:

Google
 

Original NASA ASRS Text

Title: FLC OF CPR LTT ACFT OVERSHOT DSCNT ALT DURING VECTORS TO FINAL APCH.

Narrative: UPON APCH TO HIB THE WX VISIBILITY WAS HAZY. DULUTH APCH, THE CTLING ATC, WAS GIVING US VECTORS FOR THE HIB ILS RWY 31. WE BROKE OUT OF THE CLOUDS BUT STILL THE ARPT WAS TO OUR L APPROX 6 MI. NOT IN SIGHT. IT WAS AT OUR 9 O'CLOCK POS. OUR HDG WAS 120 DEG. I REQUESTED VECTORS FOR THE VISUAL APCH. DULUTH GAVE US A HDG OF 360 DEG. WE WERE DSNDING TO ASSIGNED ALT OF 3500 FT. WE TURNED TO 360 DEGS, TUNED IN THE LOC TO HIB 31 TO INTERCEPT TO AID IN GUIDING TO THE RWY. DURING THE TURN TO 360 DEG WE DSNDED TO 3100 FT WHEN DULUTH REMINDED US TO MAINTAIN 3500 FT. AT THAT POINT WE WERE VFR (ARPT STILL NOT IN SIGHT) AND REQUESTED IFR CANCELLATION WITH DULUTH. OUR CANCELLATION WAS RECEIVED. WE PROCEEDED TO THE ARPT (HIB) AND LANDED. CHAIN OF EVENTS. WE WERE IN THE DSCNT FROM OUR CRUISE ALT, DEVIATING AROUND RAIN SHOWERS VIA OUR RADAR SCREEN DURING THE DSCNT, LOOKING FOR THE ARPT IN THE HAZE, GETTING VECTORS AND TURNING. THE COPLT (THE PF IN THIS CASE) WAS INEXPERIENCED (LESS THAN 500 HRS TOTAL TIME) AND THE PIC (PNF IN THIS CASE) HAD JUST COME OFF A 2 1/2 WK VACATION AND WAS NOT AS SHARP ON PLANNING AHEAD AS HE SHOULD HAVE BEEN COMPARED TO WHERE HE WAS IN PROFICIENCY JUST BEFORE HIS VACATION. BEING TOO BUSY WITH RADIO FREQ CHANGING THE PIC ALLOWED THE ACFT TO DSND BELOW ASSIGNED ALT. AT THE POINT OF BEING REMINDED OF THE ASSIGNED ALT BY ATC, WE JUST CANCELLED IFR, INTERCEPTED THE HIB LOC PROCEEDED INBOUND AND LANDED WITH APPROX 3 MI VISIBILITY IN HAZE.

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.