Migrating birds fly in a regular V-shaped formation. This leads to reduction of the flight power for each wing, caused by the upwash field generated by other wings in the formation. The subject of the paper is this type of formation for the flight of unmanned aerial vehicles (UAVs). For modelling, each wing aircraft is considered as a point mass. The forces produced by the vortices of the adjacent leading aircraft are represented by nonlinear but linearly parametrized functions of relative position coordinates. A feedback linearizing nonlinear adaptive control law for position trajectory control is derived. In the closed-loop system, prescribed separation trajectories are asymptotically tracked while the leading aircraft performs maneuvers. As an example, the formation control of two UAVs is considered and simulation results are presented.