In earlier work, the safety benefit that results from the availability of the taxi route in an on-board airport electronic map system such as an electronic flight bag has been demonstrated. This benefit can be attributed to the explicit depiction of the route and the conformance monitor that serves as an additional safety net by providing alerts to the pilot in case of deviations from the route or a clearance violation. In this paper, it is illustrated that even without the availability of a route, there is a potential for an increase in safety beyond that which is already obtained from the depiction of an ownship-referenced map. The basis for the concept is that, even without an explicitly defined taxi route, it is still possible to detect certain types of navigation errors. The concept utilizes the current position and heading of the aircraft, a topologic description of the airport and a set of rules that define attributes to the topology. This paper discusses the concept, design and implementation. Based on available incident data, it was determined that for a majority of the incidents that were caused by a navigation error, the pilots would have been timely provided with an additional cue on the map that emphasizes the taxiways and/or runway that should not be entered from the current taxiway.