Narrative:

I departed lgb airport with an IFR flight plan on file to my destination. The plan, using low airways, had been created using flight planning software, and the vors which define the route had been previously stored in a flight plan in my IFR approved GPS. In addition, the planned route had been highlighted on my low altitude en route charts. At lgb, clearance delivery provided a clearance that differed from the expected route. After radar vectors, the clearance navigated to eed (needles), then 'as filed.' the lgb clearance delivery controller, who was very busy with multiple IFR departures, gave the clearance very quickly. I copied the clearance and read it back after some difficulty and corrections in readback. I then updated the route of flight in the GPS and highlighted the new route of flight on my en route chart with a new color of highlight. The ATC clearance included V208 from trm to eed. However, I only marked (and programmed in the GPS) V208 from trm to tnp, and then flew V264 from tnp to pke and V135 from pke to eed as originally planned rather than V208 from tnp all the way to eed. When east of tnp, ATC informed me that I was 15 NM south of course, and we discussed the clearance. I then realized the error in understanding the expected route of flight. ATC then cleared me to my flight plan as I had expected it, and proceeded without further incident. ATC commented that my route of flight had worked out better, as it had a lower MEA and there was icing at higher altitudes required by the route over V208. There was no traffic conflict.

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Original NASA ASRS Text

Title: PLT OF A PIPER COMANCHE, PA30, FAILED TO FOLLOW FLT PLAN CLRNC DUE TO NOT HEARING THE RTE CHANGE GIVEN DURING CLRNC DELIVERY PRIOR TO TKOF.

Narrative: I DEPARTED LGB ARPT WITH AN IFR FLT PLAN ON FILE TO MY DEST. THE PLAN, USING LOW AIRWAYS, HAD BEEN CREATED USING FLT PLANNING SOFTWARE, AND THE VORS WHICH DEFINE THE RTE HAD BEEN PREVIOUSLY STORED IN A FLT PLAN IN MY IFR APPROVED GPS. IN ADDITION, THE PLANNED RTE HAD BEEN HIGHLIGHTED ON MY LOW ALT ENRTE CHARTS. AT LGB, CLRNC DELIVERY PROVIDED A CLRNC THAT DIFFERED FROM THE EXPECTED RTE. AFTER RADAR VECTORS, THE CLRNC NAVIGATED TO EED (NEEDLES), THEN 'AS FILED.' THE LGB CLRNC DELIVERY CTLR, WHO WAS VERY BUSY WITH MULTIPLE IFR DEPS, GAVE THE CLRNC VERY QUICKLY. I COPIED THE CLRNC AND READ IT BACK AFTER SOME DIFFICULTY AND CORRECTIONS IN READBACK. I THEN UPDATED THE RTE OF FLT IN THE GPS AND HIGHLIGHTED THE NEW RTE OF FLT ON MY ENRTE CHART WITH A NEW COLOR OF HIGHLIGHT. THE ATC CLRNC INCLUDED V208 FROM TRM TO EED. HOWEVER, I ONLY MARKED (AND PROGRAMMED IN THE GPS) V208 FROM TRM TO TNP, AND THEN FLEW V264 FROM TNP TO PKE AND V135 FROM PKE TO EED AS ORIGINALLY PLANNED RATHER THAN V208 FROM TNP ALL THE WAY TO EED. WHEN E OF TNP, ATC INFORMED ME THAT I WAS 15 NM S OF COURSE, AND WE DISCUSSED THE CLRNC. I THEN REALIZED THE ERROR IN UNDERSTANDING THE EXPECTED RTE OF FLT. ATC THEN CLRED ME TO MY FLT PLAN AS I HAD EXPECTED IT, AND PROCEEDED WITHOUT FURTHER INCIDENT. ATC COMMENTED THAT MY RTE OF FLT HAD WORKED OUT BETTER, AS IT HAD A LOWER MEA AND THERE WAS ICING AT HIGHER ALTS REQUIRED BY THE RTE OVER V208. THERE WAS NO TFC CONFLICT.

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.