Narrative:

I had requested the shoreline route from lindbergh tower while flying at 500 feet MSL southbound over the ocean. I was cleared into san class B airspace and subsequently handed off to north island tower. North island asked my intentions; I responded with the shoreline route and a 180 back up the bay; and was given a 1200 foot altitude for a live-fire exercise. I climbed to 1200 feet and turned east towards coronado island. North island tower said I was clear of the area and could descend back to 500 feet and to let him know when I was making the 180 turn up the bay. At 500 feet and in the turn I informed the tower. The tower instructed me to then climb to 1500 feet and he would hand me off to lindbergh tower. He also asked if I was going to fly up taxiway D. I had never heard this request before as the other times I had flown the shoreline route I was instructed to fly up the bay and out the channel to the ocean. I responded in the affirmative and referenced a taxiway chart for north island. At 1500 feet I turned down the taxiway and inquired whether I was doing the correct procedure. I was told I was supposed to be talking to lindbergh tower and I was in their airspace. According to the san diego VFR chart I was not; as the class B starts at 2800 feet. I was told to immediately turn west and a 737 below was told to stop their climb at 1000 feet; then they were told to continue their climb. I was told to contact lindbergh tower and that I should be at 500 feet now. I responded that I was under the impression he was going to hand me off to lindbergh and I normally do not change altitude in controlled airspace without being told. Plus; I didn't want to descend back into the live-fire area. I then started an immediate descent from 1500 to 500 feet; turned northbound along the point loma coast; and contacted lindbergh tower. I started to make a 360 degree turn to the left to avoid class B airspace when I contacted lindbergh tower. Lindbergh tower told me I was already in their airspace; which I realized at that point that I was; and to then continue northbound and report at crystal pier. After that I was out of their airspace and continued on.as I said; I had flown the shoreline route and up the bay a few times before and was always given pretty much the same instructions. 'Fly up the bay; follow the channel outbound.' the taxiway D instruction was a curveball that I should have asked to clarify. It sounded to me like I was expected to fly down the taxiway (at 1500 feet) but in retrospect I think I was just supposed to reference it when I passed it. I also should have asked to clarify when I was supposed to go back to lindbergh tower. In the past I was headed back up the coast and a lot farther away when I was to talk to lindbergh; not over north island since I was still in north island airspace.luckily; it was a clear VFR day without a lot of traffic. I was well-rested and in good health. I feel it was a breakdown in communication on my part since I should have inquired quickly about the instructions I ended up not understanding. Then I was behind the situational awareness curve when I realized I was already inside the san class B airspace.

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Original NASA ASRS Text

Title: Small fixed wing pilot flying VFR west of SAN at 1500 feet; entered SAN airspace without clearance on an incorrect track; conflicting with a B737.

Narrative: I had requested the Shoreline Route from Lindbergh Tower while flying at 500 feet MSL Southbound over the ocean. I was cleared into SAN Class B airspace and subsequently handed off to North Island Tower. North Island asked my intentions; I responded with the Shoreline Route and a 180 back up the bay; and was given a 1200 foot altitude for a live-fire exercise. I climbed to 1200 feet and turned East towards Coronado Island. North Island Tower said I was clear of the area and could descend back to 500 feet and to let him know when I was making the 180 turn up the bay. At 500 feet and in the turn I informed the tower. The tower instructed me to then climb to 1500 feet and he would hand me off to Lindbergh Tower. He also asked if I was going to fly up Taxiway D. I had never heard this request before as the other times I had flown the Shoreline Route I was instructed to fly up the bay and out the channel to the ocean. I responded in the affirmative and referenced a taxiway chart for North Island. At 1500 feet I turned down the taxiway and inquired whether I was doing the correct procedure. I was told I was supposed to be talking to Lindbergh Tower and I was in their airspace. According to the San Diego VFR Chart I was not; as the Class B starts at 2800 feet. I was told to immediately turn West and a 737 below was told to stop their climb at 1000 feet; then they were told to continue their climb. I was told to contact Lindbergh Tower and that I should be at 500 feet now. I responded that I was under the impression he was going to hand me off to Lindbergh and I normally do not change altitude in controlled airspace without being told. Plus; I didn't want to descend back into the live-fire area. I then started an immediate descent from 1500 to 500 feet; turned Northbound along the Point Loma coast; and contacted Lindbergh Tower. I started to make a 360 degree turn to the left to avoid Class B airspace when I contacted Lindbergh Tower. Lindbergh Tower told me I was already in their airspace; which I realized at that point that I was; and to then continue Northbound and report at Crystal Pier. After that I was out of their airspace and continued on.As I said; I had flown the Shoreline Route and up the bay a few times before and was always given pretty much the same instructions. 'Fly up the bay; follow the channel outbound.' The Taxiway D instruction was a curveball that I should have asked to clarify. It sounded to me like I was expected to fly down the taxiway (at 1500 feet) but in retrospect I think I was just supposed to reference it when I passed it. I also should have asked to clarify when I was supposed to go back to Lindbergh Tower. In the past I was headed back up the coast and a lot farther away when I was to talk to Lindbergh; not over North Island since I was still in North Island airspace.Luckily; it was a clear VFR day without a lot of traffic. I was well-rested and in good health. I feel it was a breakdown in communication on my part since I should have inquired quickly about the instructions I ended up not understanding. Then I was behind the situational awareness curve when I realized I was already inside the SAN Class B airspace.

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.