Hydrodynamic instabilities generated due to interaction of air flow over liquid films are a phenomenon of substantial importance that is dealt in various natural and industrial processes. One of the major instances where this can be observed is our respiratory tract, where underlying a liquid layer (mucus) air flow. Such interaction can lead to instability and can results in formation of droplets and ligaments of different sizes and shape. An experimental investigation is carried out to understand the phenomenon and distribution of droplets and ligaments in a channel which is subjected to air flow over an underlying liquid layer. The analysis is carried out for different air flow rate ranging from 5 to 10 lpm considering a constant liquid feed rate of 1 ml/min. The effect of liquid viscosity is also studied by considering two liquids—water and glycerol—having different viscosities. Co-current flow of air and liquid is considered with focus on understanding the underlying physics behind the destabilization of the liquid film under different flow conditions. The extent of destabilization of the liquid film is observed to be dependent on the magnitude of the air flow rate. Viscosity is also observed to play an important role in determining the flow pattern and destabilization of liquid film. Formation of ligaments is observed to be more probable for lower air flow rates, while droplets are formed for higher air flow rates. Size of the droplets formed is observed to be in the sub-millimeter range.