Planetary gearboxes are used widely and sudden failure of gearbox may cause large economic losses. Although vibration diagnostics is widely applied to detect failures in gears, planetary stages still create a problem, because of multiple modulated signals causing its vibration the signal of the faulted gear is masked by other well operating gears. The technique is required that would overcome the above problem and provide detection of any potential failures of planetary/differential gears, including planet driver cracking, assembling errors, etc.The paper considers the advanced technique that is capable to solve the problem. The authors discuss spatial-time approach to gear interactions in a planetary gearbox that are described by the impulse mesh model. As the tool for the above approach the Spatial Time Domain Distribution (STDD) is proposed. The paper discusses potential application cases for the spatial mesh model as estimation of dynamic loads distribution between any components of the planetary gear. Based on the results of analytical works the authors make the conclusion about STDD capability to become the basis of vibration diagnostic techniques for technical condition monitoring of planetary gearboxes in engineering and transport machines.