The increasing airtraffic demands on aircraft capacity, sustainability and profitability, require the investigation of unconventional aircraft configurations with high aerodynamic efficiency, as the commonly applied fuselage-wing-tail configuration shows to reach an optimum in that respect which cannot be further improved using current technology. The application of the box wing system, following from the Best Wing System theory presented by Ludwig Prandtl in 1924, theoretically results in an aircraft configuration generating minimum induced drag, named Prandtl Plane. A balanced performance analysis and comparison is performed in this research, in terms of fuel burn, structural weight and cost benefits, to indicate the types of missions in which the Prandtl Plane could provide a superior alternative to conventional aircraft. For the purpose of this research, the Initiator has been used as the design and analysis environment. Methods applied specifically for the design and analysis of the Prandtl Plane configuration have been implemented in the tool, to compare the performance with respect to conventional aircraft, in the high subsonic transport category. Parametric studies have been performed on the wing design variables to assess the sensitivity of the Prandtl Plane performance. The aspect ratio of the total wing system showed to have the largest influence on the aerodynamic performance, where a large AR results in high aerodynamic efficiency, however at the same time this yields a high wing weight. Three comparison studies have been performed between a PrP and conventional aircraft, designed using the Initiator to perform a single aisle - medium range mission typically covered by an A320-200 (144 pax, range of 4,000 km), a twin aisle - long range mission typically flown by an A340-300 (270 pax, 10,500 km) and finally a high payload - low range mission (514 pax, 2,500 km) for which no conventional aircraft are specifically designed, but large aircraft such as the A380 are exploited. On each of these missions, the PrP design shows lower induced drag during cruise, as expected, and a lower fuselage weight due to distributed bending loads from the double-wing system. An a single aisle – medium range mission this results in 8% savings in fuel burn, on the long range mission in 10% savings in fuel burn and 9% on DOC. Due to a smaller wing span, the capacity of this type of Prandtl Plane can be increased further without exceeding the dimensional constraints on wing span, and could therefore be a competitor of the A380 which currently marks the maximum capabilities of aircraft in terms of maximum range and payload capacity, due to span restrictions imposed by gate dimensions on existing airports. Prandtl planes with a higher passenger capacity could be exploited on existing routes, while meeting identical airport restrictions.