Narrative:

Departed ZZZ on an IFR flight plan to ZZZ1. About 1 hour into the flight the WX at ZZZ1 had improved to VFR. At this time I cancelled IFR and went direct ZZZ1. I asked to stay on frequency for VFR advisories. Halfway between ZZZ and ZZZ1 vors around ZZZ2 VOR, I was told advisories were cancelled and to squawk VFR and try ZZZ approach. I contacted them and they to told me that I was outside their airspace and to try again in 10 miles. I decided to fly between ZZZ and ZZZ1 vors. This would have kept me just outside of the power plant at ZZZ2. When I finally saw the stacks we looked closer than 10 miles (about 8 miles). I immediately turned right to put more distance between us. A couple of miles later I was getting advisories from ZZZ approach. I had received an IFR WX briefing before the flight. The night before I mapped out all the power plant locations on my VFR sectional. After looking at the airway, it outside of the 10 NM ring. Contributing factors are non precise locations of plants (example xa mi northeast of X city). Would that be nautical or statute miles. Is that from the city, the airport, or VOR. Latitude and longitude information would provide for better avoidance. Changing the symbol of the plants on VFR sectionals would also help. The plants are denoted with the obstruction symbol with the words plant and cooling stacks. These words are around the symbol and are never in the same locations around the plant or symbol. Using the obstructing symbol (tower) in a group of 4 or 5 other towers in the area makes it hard to tell where exactly the plant is located. Lastly I could have been a little more vigilant. While staying on victor airway led me to believe that I would be clear of all restr areas I let my guard down a little bit. Lastly the stacks I looked to be 8 miles from may have been the ones 5 miles to the southwest of ZZZ3 or the plant by ZZZ2. I am not 100 percent sure.

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Original NASA ASRS Text

Title: A POSSIBLE INADVERTENT ENTRY INTO A TEMPORARY FLT RESTR AREA.

Narrative: DEPARTED ZZZ ON AN IFR FLT PLAN TO ZZZ1. ABOUT 1 HR INTO THE FLT THE WX AT ZZZ1 HAD IMPROVED TO VFR. AT THIS TIME I CANCELLED IFR AND WENT DIRECT ZZZ1. I ASKED TO STAY ON FREQ FOR VFR ADVISORIES. HALFWAY BETWEEN ZZZ AND ZZZ1 VORS AROUND ZZZ2 VOR, I WAS TOLD ADVISORIES WERE CANCELLED AND TO SQUAWK VFR AND TRY ZZZ APCH. I CONTACTED THEM AND THEY TO TOLD ME THAT I WAS OUTSIDE THEIR AIRSPACE AND TO TRY AGAIN IN 10 MILES. I DECIDED TO FLY BETWEEN ZZZ AND ZZZ1 VORS. THIS WOULD HAVE KEPT ME JUST OUTSIDE OF THE POWER PLANT AT ZZZ2. WHEN I FINALLY SAW THE STACKS WE LOOKED CLOSER THAN 10 MILES (ABOUT 8 MILES). I IMMEDIATELY TURNED RIGHT TO PUT MORE DISTANCE BETWEEN US. A COUPLE OF MILES LATER I WAS GETTING ADVISORIES FROM ZZZ APCH. I HAD RECEIVED AN IFR WX BRIEFING BEFORE THE FLT. THE NIGHT BEFORE I MAPPED OUT ALL THE PWR PLANT LOCATIONS ON MY VFR SECTIONAL. AFTER LOOKING AT THE AIRWAY, IT OUTSIDE OF THE 10 NM RING. CONTRIBUTING FACTORS ARE NON PRECISE LOCATIONS OF PLANTS (EXAMPLE XA MI NE OF X CITY). WOULD THAT BE NAUTICAL OR STATUTE MILES. IS THAT FROM THE CITY, THE ARPT, OR VOR. LATITUDE AND LONGITUDE INFO WOULD PROVIDE FOR BETTER AVOIDANCE. CHANGING THE SYMBOL OF THE PLANTS ON VFR SECTIONALS WOULD ALSO HELP. THE PLANTS ARE DENOTED WITH THE OBSTRUCTION SYMBOL WITH THE WORDS PLANT AND COOLING STACKS. THESE WORDS ARE AROUND THE SYMBOL AND ARE NEVER IN THE SAME LOCATIONS AROUND THE PLANT OR SYMBOL. USING THE OBSTRUCTING SYMBOL (TOWER) IN A GROUP OF 4 OR 5 OTHER TWRS IN THE AREA MAKES IT HARD TO TELL WHERE EXACTLY THE PLANT IS LOCATED. LASTLY I COULD HAVE BEEN A LITTLE MORE VIGILANT. WHILE STAYING ON VICTOR AIRWAY LED ME TO BELIEVE THAT I WOULD BE CLR OF ALL RESTR AREAS I LET MY GUARD DOWN A LITTLE BIT. LASTLY THE STACKS I LOOKED TO BE 8 MILES FROM MAY HAVE BEEN THE ONES 5 MILES TO THE SW OF ZZZ3 OR THE PLANT BY ZZZ2. I AM NOT 100 PERCENT SURE.

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.