Narrative:

I chose to make the short flight to ZZZ to gas up at the lower cost. On the way back I cruised at 5;500 ft in a north easterly direction from ZZZ to ZZZ1. As a renter in the last three years I have always approached ZZZ1 at 5;500 ft from the southwest; but flew this route infrequently. There was therefore no past experience to alert me to a potential altitude violation of the class B airspace on this approach route at this altitude. ZZZ2 changed their class B airspace in march of this year (2013) to a different configuration and lowered the outer shelves. Although my new airplane does not have an onboard GPS; I use foreflight for situational awareness. My route of flight and referral to my position gave me no reason to suspect that I was violating the floor of the class B shelves. I was quite surprised to hear the tower ask me to call a number after landing. In my discussion with the FAA on the phone I was fairly convinced that I transitioned to the northwest of the shelf; although the person I spoke to said that I was a good 3 to 5 miles inside of it per the radar track. At home I pulled out an old tac chart; and opened foreflight on the ipad that has the latest charts in order to compare the two. The old 6;000 ft shelf has been lowered to 5;000 ft and the configuration was changed as well which explains why I violated the airspace. Since I used the ipad with foreflight for situation awareness during the flight; I was curious as to why I did not notice that I was too high for the shelf I thought I was flying under. I then found the problem. In foreflight; when you zoom in with the finger gesture on the VFR sectional; it switches to the tac chart which has more detail than the sectional chart. Since I prefer to fly using the tac chart when near class B airspace; I always as a matter of habit zoom in to the tac level. At the sectional level; the class B shelf with a floor of 5;000 ft is clearly marked and easily visible when the route of flight takes up the entire screen (the shelf altitudes on the chart are quite near the path of flight at this zoom level). When you zoom in to the tac with the route of flight taking up the whole screen however; the shelf altitudes for this particular shelf moves off the screen. If you scroll to the right the altitudes become visible. A pilot should of course scroll to the right to verify the shelf altitudes before flying there. At the time I spoke to the FAA person on the phone; I thought he was referring to the 4;000 ft shelf as the one I violated and I could not understand why he thought I was so deep into it. I now realize that he was referring to the next; 5;000 ft floor shelf on the path of flight at the time of our conversation; not the 4;000 ft floor shelf; and I could not see the next shelf floor at the tac zoom level for the path of flight; and my previous experience prior to the airspace modification had 5;500 ft as a safe altitude; I must have considered it unnecessary to zoom to the right to verify the floor of the airspace. How to prevent this from occurring? The shelf with the 5;000 ft floor is a very long one. The FAA prints the shelf altitudes on the left side and the right side of the shelf on the sectional chart to make it easier for the pilot to find the target altitudes for this long shelf. On the tac chart however; they only print it once in the center. On examining the tac chart on my ipad; if they printed the shelf altitudes on the left and the right on the tac chart like they did on the sectional; it would have shown up in my path of flight zoom level. This is not an excuse; but it would have improved pilot awareness by a significant degree; and it certainly would have caught my eye.

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Original NASA ASRS Text

Title: The pilot of a C182 attempted to remain clear of Class B airspace by the use of his iPad for navigation guidance. He was advised that he had entered Class B airspace by several miles. Later when he compared his iPad chart depiction to a paper chart; he realized that when he zoomed in on his iPad; the altitude was not visible.

Narrative: I chose to make the short flight to ZZZ to gas up at the lower cost. On the way back I cruised at 5;500 FT in a north easterly direction from ZZZ to ZZZ1. As a renter in the last three years I have always approached ZZZ1 at 5;500 FT from the southwest; but flew this route infrequently. There was therefore no past experience to alert me to a potential altitude violation of the Class B airspace on this approach route at this altitude. ZZZ2 changed their Class B airspace in March of this year (2013) to a different configuration and lowered the outer shelves. Although my new airplane does not have an onboard GPS; I use Foreflight for situational awareness. My route of flight and referral to my position gave me no reason to suspect that I was violating the floor of the Class B shelves. I was quite surprised to hear the Tower ask me to call a number after landing. In my discussion with the FAA on the phone I was fairly convinced that I transitioned to the northwest of the shelf; although the person I spoke to said that I was a good 3 to 5 miles inside of it per the radar track. At home I pulled out an old TAC chart; and opened Foreflight on the iPad that has the latest charts in order to compare the two. The old 6;000 FT shelf has been lowered to 5;000 FT and the configuration was changed as well which explains why I violated the airspace. Since I used the iPad with Foreflight for situation awareness during the flight; I was curious as to why I did not notice that I was too high for the shelf I thought I was flying under. I then found the problem. In Foreflight; when you zoom in with the finger gesture on the VFR Sectional; it switches to the TAC chart which has more detail than the Sectional chart. Since I prefer to fly using the TAC chart when near Class B airspace; I always as a matter of habit zoom in to the TAC level. At the Sectional level; the Class B shelf with a floor of 5;000 FT is clearly marked and easily visible when the route of flight takes up the entire screen (the shelf altitudes on the chart are quite near the path of flight at this zoom level). When you zoom in to the TAC with the route of flight taking up the whole screen however; the shelf altitudes for this particular shelf moves off the screen. If you scroll to the right the altitudes become visible. A pilot should of course scroll to the right to verify the shelf altitudes before flying there. At the time I spoke to the FAA person on the phone; I thought he was referring to the 4;000 FT shelf as the one I violated and I could not understand why he thought I was so deep into it. I now realize that he was referring to the next; 5;000 FT floor shelf on the path of flight at the time of our conversation; not the 4;000 FT floor shelf; and I could not see the next shelf floor at the TAC zoom level for the path of flight; and my previous experience prior to the airspace modification had 5;500 FT as a safe altitude; I must have considered it unnecessary to zoom to the right to verify the floor of the airspace. How to prevent this from occurring? The shelf with the 5;000 FT floor is a very long one. The FAA prints the shelf altitudes on the left side and the right side of the shelf on the sectional chart to make it easier for the pilot to find the target altitudes for this long shelf. On the TAC chart however; they only print it once in the center. On examining the TAC chart on my iPad; if they printed the shelf altitudes on the left and the right on the TAC chart like they did on the Sectional; it would have shown up in my path of flight zoom level. This is not an excuse; but it would have improved pilot awareness by a significant degree; and it certainly would have caught my eye.

Data retrieved from NASA's ASRS site as of July 2013 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.