Pilots should be wary when operating close to the boundaries of Class B airspace, the FAA said recently in a Safety Alert for Operators. Flight crew who are on a visual approach may sometimes stray outside the boundaries of the designated airspace, the FAA said. In addition, the published approaches may sometimes take an airplane temporarily outside the airspace. At the same time, GA pilots may be operating close outside the boundaries without talking to ATC, as they depend more and more on inflight navigation aids such as GPS moving maps.
Source: avwebFAA Warns To Watch Class B Boundaries