The first aircraft experiment with the wide-angle airborne laser ranging system has been conducted in May 1998 over a small network of 1 km2, equipped with 64 cube-corner retroreflectors. The ranging systemwas operated from a research aircraft (ARAT, Fokker 27) at an altitude of 1 km. Data have been collectedduring two 4-hour flights. The paper describes the data processing methods and presents the first resultsfrom this experiment. A precision of 2 cm has been achieved on the difference of vertical coordinatesfrom two sets of ~ 3000 distance measurements. Results are consistent with simulations and a posteriori covariance. A drastic data sorting for outliers, due to strong overlap of reflectedechoes, has been necessary. Hence, the actual number of measurements and the positioning precision becamerelatively small. Higher precision is expected in future experiments, once the instrument's link budgetwill be improved.