In this contribution, we assess the vertical accuracy of the Advanced Land Observing Satellite (ALOS) World 3D 30m (AW3D30) digital elevation model (DEM) using the runway method (RWYM). The RWYM utilizes the longitudinal profiles of runways which are reliable and ubiquitous reference data. A reference dataset used in this project consists of 36 runways located at various points throughout the world. We found that AW3D30 has a remarkably low root mean square error (RMSE) of 1.78m (one sigma). However, while analysing the results, it has become apparent that it also contains a widespread elevation anomaly. We conclude that this anomaly is the result of uncompensated sensor noise and the data processing algorithm. Also, we note that the traditional accuracy assessment of a DEM does not allow for identification of these type of anomalies in a DEM.