Narrative:

I was being vectored for an NDB 13 approach at foe. Center was reporting 2500 ft ceiling, 10 mi. ATIS was out of service. I was in VFR conditions. Ceiling was approximately 5000 ft visibility greater than 6 mi. Center advised that conditions had improved at foe and I could go direct for a visual. However, I was not cleared for a visual. I turned direct to foe and, thinking 'visual,' started a descent. When I called airport in sight I was approaching 2500 ft. The controller cleared me for a visual and informed me that I should have not left assigned altitude. In transitioning from an instrument approach to a visual approach, I got the cart before the horse. It is a reminder that when switching from one mind set to another, we must be careful not to act on what we are anticipating, but pay careful attention to instructions and proper procedures.

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Original NASA ASRS Text

Title: A C 414 PLT, ON AN IFR FLT PLAN WITH MCI, CHANGED HIS HDG AND ALT ON HIS OWN WHEN HE THOUGHT HE HAD BEEN CLRED FOR THE VISUAL AT FOE.

Narrative: I WAS BEING VECTORED FOR AN NDB 13 APCH AT FOE. CTR WAS RPTING 2500 FT CEILING, 10 MI. ATIS WAS OUT OF SVC. I WAS IN VFR CONDITIONS. CEILING WAS APPROX 5000 FT VISIBILITY GREATER THAN 6 MI. CTR ADVISED THAT CONDITIONS HAD IMPROVED AT FOE AND I COULD GO DIRECT FOR A VISUAL. HOWEVER, I WAS NOT CLRED FOR A VISUAL. I TURNED DIRECT TO FOE AND, THINKING 'VISUAL,' STARTED A DSCNT. WHEN I CALLED ARPT IN SIGHT I WAS APCHING 2500 FT. THE CTLR CLRED ME FOR A VISUAL AND INFORMED ME THAT I SHOULD HAVE NOT LEFT ASSIGNED ALT. IN TRANSITIONING FROM AN INST APCH TO A VISUAL APCH, I GOT THE CART BEFORE THE HORSE. IT IS A REMINDER THAT WHEN SWITCHING FROM ONE MIND SET TO ANOTHER, WE MUST BE CAREFUL NOT TO ACT ON WHAT WE ARE ANTICIPATING, BUT PAY CAREFUL ATTENTION TO INSTRUCTIONS AND PROPER PROCS.

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.