The article deals with a problem of fatigue load calculations when designing the aircraft wing. Much of fatigue damage is done to the wing by occasional air gusts in turbulent atmosphere. Therefore, the author considers the pattern of continuous atmospheric turbulence that gives an idea of low-altitude gusts. It is at low altitudes that nonstandard flights are performed for which it is wrong to use the statistical data on fatigue damage available from the previously operated airplanes of the same class. The method is offered to determine the equivalent bending moments along the wing span in discrete flight modes and within the entire routine flight. The above method takes into account the profile parameters of routine flights, the dynamic vibrations of the wing and fatigue characteristics of the structural material. To prove the reliability of the method the calculation results have been compared to those of medium-range aircraft testing flights.