Abstract: In order to quantitatively analyze the effects of risk factors on each other a concept of risk coupling for flight operation was introduced. On the basis, based of available civil aviation safety statistics, degrees of risk coupling were calculated for a number of types of coupling by using the N-K model and the coupling model. Risk coupling conditions were systematically analyzed for flights on the ground and those flying. The study shows that mechanical maintenance factor has a moderate degree of coupling with the weather factors, so their coexistence should be avoided, that the air traffic control factors have only a little effect on the flights flying, that when there is a risk to the crew, special attention should be paid to both the weather and the mechanical failure, that for flights on the ground, coexistence of three or more risk factors should be avoided, and that there is a high coincidence degree between the results obtained by using the two models.

Key words: flight safety, operations risk coupling, N-K model, coupling model, G₁model