The crack opening behaviour of a fatigue crack in a centrally cracked panel was studied using a discretised version of the Dugdale and Barenblatt model. The effect of crack growth was also included. Results obtain ed for constant amplitude loading were in agreement with data reported in the open literature. The effect of application of single overload-underload combinations and of simple block loading programs on the crack opening behaviour were analysed. The results were compared with predictions based on an existing empirical model (CORPUS). In this way the criteria used in the CORPUS model to select significant load excursions in the applied load sequence were checked. Finally, both models were used to predict crack growth under a simplified landing gear load sequence. The predicted crack opening loads and the crack growth were in agreement with experimental data. Presented on the International Symposium on fatigue crack closure. May 1986, Charleston, USA.