The evaluation of the maximum depth of corrosion patches is a major issue in the oil and aerospace industries. In this context, time‐of‐flight Lamb wave tomography is a potentially attractive technique. The accuracy of the reconstruction depends on the guided modes and frequencies employed. The higher the dispersion of a mode the more sensitive it is to thickness changes. However for practical implementation it is very important to take the excitability, the detectability and the leakage attenuation into account. In this paper the most suitable point of operation for time‐of‐flight tomography is identified.