Narrative:

I was operating a cessna 180 floatplane in VMC on a VFR flight; in the vicinity of 0w0 in downtown seattle; washington; when I inadvertently entered one of the hot sports stadium tfrs. This action was necessitated and justified under far 91.3; as explained below. My flight originated from a private water operations site close to the class D airspace at rnt. Prior to takeoff; I checked all relevant NOTAMS and received the ATIS for rnt. I also received takeoff clearance and permission to operate within the rnt class D so as to transit north and west to be clear of the sea class B and bfi class D airspaces. After clearing the rnt area; I was close to the university of washington and headed southwest; under the sea class B. I was monitoring the CTAF of 122.9 in the vicinity of 0w0 on lake union. As I got closer to 0w0; I was aware of the possible presence of active commercial seaplane activity on lake union. Therefore; using the 0w0 CTAF; I announced my call sign; position; altitude; and stated my intent to transition slightly north of 0w0; from east to west; through the ship canal. This is a common transition route used by local pilots and it is familiar to seaplane pilots who fly in this area. After I made the radio call on the 0w0 CTAF; I determined that there were three other floatplanes also operating within the vicinity of lake union waterport. One floatplane was on a southerly heading approaching to land on the north end of the lake from eastlake; position reported northeast of me. The second floatplane was transitioning west to east through the ship canal; position reported east of me. The third floatplane was on a northerly takeoff roll on lake union; position reported south-east of me.at this point; I re-announced my position stating I was heading westbound to lake union; and was approaching the I-5 bridge; which is raised 300 feet over the ship canal. Then as I approached I-5; I continued scanning the skies; but I was unable to make a visual contact with any of the other 3 float planes.while crossing I-5; I obtained visual contact with the second floatplane which was still on climb out after taking off from 0w0. It was heading north and climbing over gasworks park. Suddenly; that aircraft turned toward my position and continued to climb in altitude. I know that this plane had to climb to clear the I-5 bridge and it was heading right toward me. I again announced my position over the CTAF; stating I was westbound over I-5; the climbing seaplane announced its intentions to turn east towards university; which placed him in a collision course with me. He did not say that he had me in sight. At that point; as pilot in command; I determined the safest course of action would be to turn out of the path of the climbing plane. I made a second visual scan but I could not get visual contact on the first seaplane (which had been westbound towards me through the ship canal) or the third seaplane (which was last reported as southbound coming from green lake). By making this slight southbound turn; later realized that I may have inadvertently and briefly entered the radius of the stadium tfr; which I believe was active for a game. My altitude at the time was 1;000 and I was approximately 1.5 NM away from the stadium. I believe that this brief and minor transit into an area where a tfr was operationally necessary for the safe operation of my flight under far 91.3. As I took these actions; I was maintaining separation from the one aircraft I had in sight while also accounting for the last know positions and headings of the other two aircraft which were not in sight. By making these maneuvers to avoid the oncoming traffic; I was able to complete my flight and the return flight to my home station without any incident. I was not contacted by ATC regarding a possible tfr violation at any point during my flight operations. I have not been contacted since that date by the FAA. The area surrounding 0w0is notoriously congested and often aircraft transit through the ship canal like a bottleneck between the sea class B and the rnt and bfi class D airspaces. Furthermore; when the stadium tfrs are hot; they prohibit uncontrolled flight over the majority of lake union; thus forcing seaplanes to perform take-offs; landings; and transitions; in a small; congested area at the very north end of the lake.I believe the best way to correct the situation would be to eliminate the stadium tfrs coverage in the vicinity of 0w0 so as to free up more airspace at lake union during stadium tfrs operations. Another less economically viable option would be to make the entire lake union area unavailable for operations during stadium tfrs to prevent congestion over a waterway. A third operation would be to commission a ATC tower for 0w0 making the area a class D which would provide flight following and allow air traffic to legally pass through the tfr when it is hot.

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Original NASA ASRS Text

Title: C180 floatplane pilot reported encroaching on a sports TFR during evasive action in response to an NMAC.

Narrative: I was operating a Cessna 180 floatplane in VMC on a VFR flight; in the vicinity of 0W0 in downtown Seattle; Washington; when I inadvertently entered one of the hot sports stadium TFRs. This action was necessitated and justified under FAR 91.3; as explained below. My flight originated from a private water operations site close to the Class D airspace at RNT. Prior to takeoff; I checked all relevant NOTAMS and received the ATIS for RNT. I also received takeoff clearance and permission to operate within the RNT Class D so as to transit north and west to be clear of the SEA Class B and BFI Class D airspaces. After clearing the RNT area; I was close to the University of Washington and headed southwest; under the SEA Class B. I was monitoring the CTAF of 122.9 in the vicinity of 0W0 on Lake Union. As I got closer to 0W0; I was aware of the possible presence of active commercial seaplane activity on Lake Union. Therefore; using the 0W0 CTAF; I announced my call sign; position; altitude; and stated my intent to transition slightly north of 0W0; from east to west; through the ship canal. This is a common transition route used by local pilots and it is familiar to seaplane pilots who fly in this area. After I made the radio call on the 0W0 CTAF; I determined that there were three other floatplanes also operating within the vicinity of Lake Union Waterport. One floatplane was on a southerly heading approaching to land on the north end of the lake from Eastlake; position reported northeast of me. The second floatplane was transitioning west to east through the ship canal; position reported east of me. The third floatplane was on a northerly takeoff roll on Lake Union; position reported south-east of me.At this point; I re-announced my position stating I was heading westbound to Lake Union; and was approaching the I-5 Bridge; which is raised 300 feet over the ship canal. Then as I approached I-5; I continued scanning the skies; but I was unable to make a visual contact with any of the other 3 float planes.While crossing I-5; I obtained visual contact with the second floatplane which was still on climb out after taking off from 0W0. It was heading north and climbing over Gasworks Park. Suddenly; that aircraft turned toward my position and continued to climb in altitude. I know that this plane had to climb to clear the I-5 bridge and it was heading right toward me. I again announced my position over the CTAF; stating I was westbound over I-5; the climbing seaplane announced its intentions to turn east towards University; which placed him in a collision course with me. He did not say that he had me in sight. At that point; as pilot in command; I determined the safest course of action would be to turn out of the path of the climbing plane. I made a second visual scan but I could not get visual contact on the first seaplane (which had been westbound towards me through the ship canal) or the third seaplane (which was last reported as southbound coming from Green Lake). By making this slight southbound turn; later realized that I may have inadvertently and briefly entered the radius of the stadium TFR; which I believe was active for a Game. My altitude at the time was 1;000 and I was approximately 1.5 NM away from the stadium. I believe that this brief and minor transit into an area where a TFR was operationally necessary for the safe operation of my flight under FAR 91.3. As I took these actions; I was maintaining separation from the one aircraft I had in sight while also accounting for the last know positions and headings of the other two aircraft which were not in sight. By making these maneuvers to avoid the oncoming traffic; I was able to complete my flight and the return flight to my home station without any incident. I was not contacted by ATC regarding a possible TFR violation at any point during my flight operations. I have not been contacted since that date by the FAA. The area surrounding 0W0is notoriously congested and often aircraft transit through the ship canal like a bottleneck between the SEA Class B and the RNT and BFI Class D airspaces. Furthermore; when the Stadium TFRs are hot; they prohibit uncontrolled flight over the majority of Lake Union; thus forcing seaplanes to perform take-offs; landings; and transitions; in a small; congested area at the very north end of the lake.I believe the best way to correct the situation would be to eliminate the stadium TFRs coverage in the vicinity of 0W0 so as to free up more airspace at Lake Union during stadium TFRs operations. Another less economically viable option would be to make the entire Lake Union area unavailable for operations during stadium TFRs to prevent congestion over a waterway. A third operation would be to commission a ATC tower for 0W0 making the area a Class D which would provide flight following and allow air traffic to legally pass through the TFR when it is hot.

Data retrieved from NASA's ASRS site 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.