Narrative:

I departed mry, VFR about 20 mins after sunset, on a flight returning to pao. My intended route of flight was back via the coast, a flight I had made many times. Before departure, I set the altitude alert to 4500 ft MSL, appropriate for a VFR flight in the intended direction and one providing excellent terrain clearance. Departing mry on the standard VFR departure (heading 340 degrees), mry departure cleared me to resume my own navigation passing through 2000 ft. I could see that significant stratus had moved on-shore along the intended route of flight and so decided to alter the return flight to go inland via gilroy and then transition to pao via the sjc class C airspace. As the climb continued, the altitude alert chimed and I leveled off at 4500 ft MSL and proceeded. I verified from the chart that the cruise altitude provided good terrain clearance -- the highest terrain was just less than 2000 ft MSL. I started to get the ATIS for pao in preparation for a handoff to bay approach. Sometime later (perhaps 10 mins), the controller asked me my heading and I responded with '016 degrees.' the controller responded and then advised me to xfer to bay approach. As I contacted bay approach, I realized that I should have been at an odd altitude plus 500 ft, appropriate for the direction of flight. I corrected by altering my heading to 300 degrees, a heading that put me on course for pao. This situation could have been avoided by using the change in flight plan to trigger a full assessment of all parameters of the flight including the cruise altitude. The combination of night flying and the change of plan caused a resource crunch leading to the error.

Related reports:

Google
 

Original NASA ASRS Text

Title: PLT OF A BEECH BE-A36 WAS ON THE WRONG ALT FOR A VFR HDG. HE ADJUSTED HIS HDG AFTER DEP CTLR ASKED HIS HDG.

Narrative: I DEPARTED MRY, VFR ABOUT 20 MINS AFTER SUNSET, ON A FLT RETURNING TO PAO. MY INTENDED RTE OF FLT WAS BACK VIA THE COAST, A FLT I HAD MADE MANY TIMES. BEFORE DEP, I SET THE ALT ALERT TO 4500 FT MSL, APPROPRIATE FOR A VFR FLT IN THE INTENDED DIRECTION AND ONE PROVIDING EXCELLENT TERRAIN CLRNC. DEPARTING MRY ON THE STANDARD VFR DEP (HDG 340 DEGS), MRY DEP CLRED ME TO RESUME MY OWN NAV PASSING THROUGH 2000 FT. I COULD SEE THAT SIGNIFICANT STRATUS HAD MOVED ON-SHORE ALONG THE INTENDED RTE OF FLT AND SO DECIDED TO ALTER THE RETURN FLT TO GO INLAND VIA GILROY AND THEN TRANSITION TO PAO VIA THE SJC CLASS C AIRSPACE. AS THE CLB CONTINUED, THE ALT ALERT CHIMED AND I LEVELED OFF AT 4500 FT MSL AND PROCEEDED. I VERIFIED FROM THE CHART THAT THE CRUISE ALT PROVIDED GOOD TERRAIN CLRNC -- THE HIGHEST TERRAIN WAS JUST LESS THAN 2000 FT MSL. I STARTED TO GET THE ATIS FOR PAO IN PREPARATION FOR A HDOF TO BAY APCH. SOMETIME LATER (PERHAPS 10 MINS), THE CTLR ASKED ME MY HDG AND I RESPONDED WITH '016 DEGS.' THE CTLR RESPONDED AND THEN ADVISED ME TO XFER TO BAY APCH. AS I CONTACTED BAY APCH, I REALIZED THAT I SHOULD HAVE BEEN AT AN ODD ALT PLUS 500 FT, APPROPRIATE FOR THE DIRECTION OF FLT. I CORRECTED BY ALTERING MY HDG TO 300 DEGS, A HDG THAT PUT ME ON COURSE FOR PAO. THIS SIT COULD HAVE BEEN AVOIDED BY USING THE CHANGE IN FLT PLAN TO TRIGGER A FULL ASSESSMENT OF ALL PARAMETERS OF THE FLT INCLUDING THE CRUISE ALT. THE COMBINATION OF NIGHT FLYING AND THE CHANGE OF PLAN CAUSED A RESOURCE CRUNCH LEADING TO THE ERROR.

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.