Abstract: The invention relates to multi deck passenger aircraft, having passenger cabins and/or service facilities arranged on the upper and lower deck and inner load bearing cell structure provided within aircraft body. The present invention is also directed toward methods for manufacturing derivative multi deck aircrafts. Energy absorbing, floatable cargo containers (24) attached to fuselage belly. External fuel tanks (26) displaced on the top of fuselage. Center wing region of the fuselage is using for arranging rows of seats and service facilities. Addition seating configuration for narrow and wide bodied aircraft is provided. Multi deck seating configuration significantly reduces per passenger operating cost over existing technology. Less fuel per passenger is required since there is less airframe weight and wetted area per passenger. Due to the lower overall cost per passenger seat within the multi deck seating structure, the net profit and return on investment in the aircraft are also increased.