Narrative:

The flight from ZZZ started as an IFR flight. Aircraft was unable to maintain an altitude for ATC's IFR plan; and IFR flight was cancelled by the pilot. VFR flight was commenced at 14500 ft MSL en route; the same route as the original IFR plan; but at VFR altitude. At the time of the cancellation; we were inside of the washington ADIZ. The controling agency did not inform us that this would cause any violation. Looking at VFR chart for the area; we noticed the top of this airspace to be 10000 ft MSL and both of us thought we were at a safe altitude. The flight continued. Looking at the VFR chart for this area; I feel that it is very confusing that the ceiling for this airspace is noted at 10000 ft and the important information regarding the 18000 ft minimum altitude is noted on the side bar of the chart. I have been flying for over 15 safe years and have never had any violations or problems of any sort. I consider myself a safe and informed pilot.supplemental information from acn 777311: we departed on an IFR flight plan. We could not climb to assigned altitude so we elected to continue on original VFR route at 14500 ft. We misinterpreted the VFR chart and the IFR chart; thinking the top of the airspace was 10000 ft. I would recommend that the 10000 ft upper limit should be removed from both VFR and IFR charts as this makes it hard to discern top of class B from washington ADIZ. The fact that the commercial low altitude en route chart divides the washington area adds to the confusion. I would also recommend a 'side bar' map of washington area be included on the same chart as you do with new york.

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Original NASA ASRS Text

Title: A FLT CREW VFR AT 14500 FT VIOLATED THE DCA FLT RESTRICTED ZONE (FRZ) AFTER CONFUSING THE 10000 FT CLASS B CHART NOTATIONS WITH THE 18000 FT FRZ CONSTRAINT.

Narrative: THE FLT FROM ZZZ STARTED AS AN IFR FLT. ACFT WAS UNABLE TO MAINTAIN AN ALTITUDE FOR ATC'S IFR PLAN; AND IFR FLT WAS CANCELLED BY THE PLT. VFR FLT WAS COMMENCED AT 14500 FT MSL ENRTE; THE SAME RTE AS THE ORIGINAL IFR PLAN; BUT AT VFR ALTITUDE. AT THE TIME OF THE CANCELLATION; WE WERE INSIDE OF THE WASHINGTON ADIZ. THE CTLING AGENCY DID NOT INFORM US THAT THIS WOULD CAUSE ANY VIOLATION. LOOKING AT VFR CHART FOR THE AREA; WE NOTICED THE TOP OF THIS AIRSPACE TO BE 10000 FT MSL AND BOTH OF US THOUGHT WE WERE AT A SAFE ALTITUDE. THE FLT CONTINUED. LOOKING AT THE VFR CHART FOR THIS AREA; I FEEL THAT IT IS VERY CONFUSING THAT THE CEILING FOR THIS AIRSPACE IS NOTED AT 10000 FT AND THE IMPORTANT INFO REGARDING THE 18000 FT MINIMUM ALTITUDE IS NOTED ON THE SIDE BAR OF THE CHART. I HAVE BEEN FLYING FOR OVER 15 SAFE YEARS AND HAVE NEVER HAD ANY VIOLATIONS OR PROBLEMS OF ANY SORT. I CONSIDER MYSELF A SAFE AND INFORMED PLT.SUPPLEMENTAL INFO FROM ACN 777311: WE DEPARTED ON AN IFR FLT PLAN. WE COULD NOT CLB TO ASSIGNED ALTITUDE SO WE ELECTED TO CONTINUE ON ORIGINAL VFR RTE AT 14500 FT. WE MISINTERPRETED THE VFR CHART AND THE IFR CHART; THINKING THE TOP OF THE AIRSPACE WAS 10000 FT. I WOULD RECOMMEND THAT THE 10000 FT UPPER LIMIT SHOULD BE REMOVED FROM BOTH VFR AND IFR CHARTS AS THIS MAKES IT HARD TO DISCERN TOP OF CLASS B FROM WASHINGTON ADIZ. THE FACT THAT THE COMMERCIAL LOW ALTITUDE ENRTE CHART DIVIDES THE WASHINGTON AREA ADDS TO THE CONFUSION. I WOULD ALSO RECOMMEND A 'SIDE BAR' MAP OF WASHINGTON AREA BE INCLUDED ON THE SAME CHART AS YOU DO WITH NEW YORK.

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.