A new experimental method was developed to visualise air flow patterns and spatial distribution of the mean air velocity irt large food planes. The continuous motion of an anemometer measuring air velocity at regular intervals made it possible to rapidly obtain measurements at several thousands of points. The processing of these measurements by Fourier＇s series and a low-pass filter eliminated the time-fluctuations due to air flow unsteadiness and only rite spatial variations of the mean air velocity were kept afterwards. This paper shows how this method was applied in the food industry to a typical meat chiller The graphical representation of the mean air velocity distribution br ought to light dysfunction inside the chiller The experimental fool presented here can help specialists to carry out diagnoses of the airflow in food plants.