Like any vehicle or system, the market value immediately after purchase decreases significantly because the aircraft becomes a second-hand machine and therefore if you sell it after a month from purchase, you will certainly have a capital loss (as they say: as soon as I turn the keys it is already worth half).
However, aircraft have a fairly flat depreciation curve (obviously it depends on the model) and therefore, after the initial period in which it depreciates significantly, the value, assuming that all maintenance is carried out, parts replaced and overhauls carried out, decreases much less than the value of the aircraft in the balance sheet.
Aircraft have a tax depreciation that in Europe ranges from 10% to 15%, which means that between 8 and 10 years of use the asset will be considered fully depreciated, despite having a residual value that is certainly not zero.
For this reason, selling an aircraft at the end of its depreciation will generate a capital gain, or additional revenue.
There are methods to account for an aircraft even with a lower annual cost to keep the fair value (commercial value) aligned with the book value (balance sheet value) and therefore have fewer costs and generate more throughput during use, however prudentially we believe it is better not to apply these methods to small aircraft in a training fleet and keep any capital gain as extra revenue that I know is set aside there until I sell it.
A change in the aircraft market, an accident or the replacement of some expensive spare part could eliminate this gap so it is always better to make prudential considerations.
