Narrative:

While on an IFR clearance in cruise flight; I was halfway to my destination and I loaded my vertical profile in the flight plan function of the FMS. As I neared the 'TOD' (top of descent); I started my descent to stay ahead of the airplane. After descending just over 1000 ft I realized that I had forgotten to ask for a lower altitude from center. At this point I called ATC and asked to cancel IFR. The controller said something like; 'welcome back; contact center on 1XX.6 and let them know of your intentions.' so not only did I begin a descent without a clearance; but I must have missed a radio call also. I contacted the new controller; and told him 'center...aircraft X...cancel IFR.' he acknowledged and told me to squawk VFR. Part of the cause for the above incident was the WX was so clear; very VFR. I had been in VFR conditions since I broke out on top of a marine layer at 2500 ft on my climb out just after takeoff. I had been cleared direct to ZZZ; and had been in VFR conditions for over an hour without coming near any clouds. For some reason; I didn't remember being on an IFR clearance; and I just started my descent using the autoplt at the 'recommended' time according to the GPS. Another cause might have been being tired from a long VFR flight the previous day; and not getting enough sleep. To prevent the situation from recurring I must remember that whenever I load the 'vertical profile/descent' into the flight plan function of the FMS that I must ask for the clearance before beginning the descent. I was trying to stay ahead of the airplane; by planning ahead; and preloading the descent. But I still need to verify that I ask permission for a lower altitude when the 'TOD' is getting close. It is also important to get the proper amount of rest before flying; so that 'stupid' mistakes like this are less likely to happen.

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Original NASA ASRS Text

Title: AN IFR COLUMBIA 400 PILOT BEGAN A DSCNT WITHOUT ATC CLRNC WHILE DISTRACTED ON A VMC DAY AND MINDLESSLY FOLLOWING THE ACFT'S FMC.

Narrative: WHILE ON AN IFR CLRNC IN CRUISE FLT; I WAS HALFWAY TO MY DEST AND I LOADED MY VERT PROFILE IN THE FLT PLAN FUNCTION OF THE FMS. AS I NEARED THE 'TOD' (TOP OF DSCNT); I STARTED MY DSCNT TO STAY AHEAD OF THE AIRPLANE. AFTER DSNDING JUST OVER 1000 FT I REALIZED THAT I HAD FORGOTTEN TO ASK FOR A LOWER ALT FROM CTR. AT THIS POINT I CALLED ATC AND ASKED TO CANCEL IFR. THE CTLR SAID SOMETHING LIKE; 'WELCOME BACK; CONTACT CTR ON 1XX.6 AND LET THEM KNOW OF YOUR INTENTIONS.' SO NOT ONLY DID I BEGIN A DSCNT WITHOUT A CLRNC; BUT I MUST HAVE MISSED A RADIO CALL ALSO. I CONTACTED THE NEW CTLR; AND TOLD HIM 'CTR...ACFT X...CANCEL IFR.' HE ACKNOWLEDGED AND TOLD ME TO SQUAWK VFR. PART OF THE CAUSE FOR THE ABOVE INCIDENT WAS THE WX WAS SO CLR; VERY VFR. I HAD BEEN IN VFR CONDITIONS SINCE I BROKE OUT ON TOP OF A MARINE LAYER AT 2500 FT ON MY CLBOUT JUST AFTER TKOF. I HAD BEEN CLRED DIRECT TO ZZZ; AND HAD BEEN IN VFR CONDITIONS FOR OVER AN HR WITHOUT COMING NEAR ANY CLOUDS. FOR SOME REASON; I DIDN'T REMEMBER BEING ON AN IFR CLRNC; AND I JUST STARTED MY DSCNT USING THE AUTOPLT AT THE 'RECOMMENDED' TIME ACCORDING TO THE GPS. ANOTHER CAUSE MIGHT HAVE BEEN BEING TIRED FROM A LONG VFR FLT THE PREVIOUS DAY; AND NOT GETTING ENOUGH SLEEP. TO PREVENT THE SITUATION FROM RECURRING I MUST REMEMBER THAT WHENEVER I LOAD THE 'VERT PROFILE/DSCNT' INTO THE FLT PLAN FUNCTION OF THE FMS THAT I MUST ASK FOR THE CLRNC BEFORE BEGINNING THE DSCNT. I WAS TRYING TO STAY AHEAD OF THE AIRPLANE; BY PLANNING AHEAD; AND PRELOADING THE DSCNT. BUT I STILL NEED TO VERIFY THAT I ASK PERMISSION FOR A LOWER ALT WHEN THE 'TOD' IS GETTING CLOSE. IT IS ALSO IMPORTANT TO GET THE PROPER AMOUNT OF REST BEFORE FLYING; SO THAT 'STUPID' MISTAKES LIKE THIS ARE LESS LIKELY TO HAPPEN.

Data retrieved from NASA's ASRS site as of May 2009 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.