Dry-lease

Aircraft leases are leases used by airlines and other aircraft operators. Airlines lease aircraft from other airlines or leasing companies for two main reasons: to operate aircraft without the financial burden of buying them, and to provide temporary increase in capacity. The industry has two main leasing types: wet-leasing, which is normally used for short-term leasing, and dry-leasing which is more normal for longer-term leases. The industry also uses combinations of wet and dry. For example, when the aircraft is wet-leased to establish new services, then as the airline's flight or cabin crews become trained, they can be switched to a dry lease.

50% of global lessor set are based in Ireland and in 2015 over $120b of new commercial aircraft was delivered worldwide.Operating leases of jet airliner accounted for less than 2% of the fleet in 1976, then 15% in the early 1990s, 25% in 2000 and 40% in 2017, with lessors involved in 62% of second hand mid-life aircraft transactions since 2000: 42% in Europe and 29% in North America.

A wet lease is a leasing arrangement whereby one airline (the lessor) provides an aircraft, complete crew, maintenance, and insurance (ACMI) to another airline or other type of business acting as a broker of air travel (the lessee), which pays by hours operated. The lessee provides fuel and covers airport fees, and any other duties, taxes, etc. The flight uses the flight number of the lessee. A wet lease generally lasts 1–24 months; a shorter duration would be considered an ad hoc charter. A wet lease is typically utilized during peak traffic seasons or annual heavy maintenance checks, or to initiate new routes. A wet-leased aircraft may be used to fly services into countries where the lessee is banned from operating.

They can also be considered a form of charter whereby the lessor provides minimum operating services, including ACMI, and the lessee provides the balance of services along with flight numbers. In all other forms of charter, the lessor provides the flight numbers. Variations of a wet lease include a code share arrangement and a block seat agreement.

...
Wikipedia