 In September 2012, Avolon published an analysis of commercial aircraft economic lives and retirement patterns.The purpose was to test whether the current assumptions made by airlines, aviation investors and aircraft financiers, on the economic life of commercial jets - that aircraft should be depreciated over a useful life of approximately 25 years - remains valid.The reason this analysis is so relevant today is that approximately 8,000 aircraft are due to be retired over the next 10 years.