Typically, this rests on the fact that, for tax purposes, some jurisdictions assign ownership and the attendant depreciation allowances to the entity that has legal title to an asset, while others (like the U.S.) assign it to the entity that has the most indicia of tax ownership (legal title being only one of several factors taken into account).
In these cases, with sufficiently long leases (often 99 years), an asset can end up with two effective owners, one in each jurisdiction; this is often referred to as a double-dip lease[4] Often the original owner of an asset is not subject to taxation in any jurisdiction, and therefore not able to claim depreciation.
The transaction often involves a city selling an asset (such as a sewerage system or power plant) to an investor (who can claim depreciation), and long-term leasing it right back (often referred to as a sale leaseback).
These airlines had no need for the depreciation deductions generated by their aircraft and were significantly more interested in reducing their operating expenses.
This resulted in the city having pre-funded all of its lease obligations as well as its option to repurchase the asset from the bank for less than the amount received in the initial sale of the asset, in which case the city would be left with additional cash after having pre-funded all of its lease obligations.