A vortex-lattice numerical scheme that uses a novel decambering technique to predict post-stall aerodynamic characteristics is used to study the aerodynamics of tandem Cessna 172 aircrafts flflying in echelon formation. Results like CL -α from the current method are compared with experiment. Additional results like section Cl distributions over wing spans, CM - α and CLW αtw (i.e. CL of the leading aircraft for diαerent angles of attack of the trailing aircraft) and analysis for (-)ve y-oαset, which are available only from the current numerical method are reported that supplement the experimental results. Detailed post-stall numerical analysis and the eαect of chord-wise, span-wise and vertical oαsets on the aerodynamics of the formation are also reported.