Wet Lease — Wet Lease / ACMI Lease

The Core Question: Who Controls the Aircraft?

Aircraft leasing arrangements in commercial aviation split along one central line: which party — the lessor providing the aircraft or the lessee operating it — holds actual operational control. That single distinction is what separates a dry lease from the family of wet lease arrangements, and it determines everything else about the deal: whose Air Operator's Certificate the flight operates under, who crews it, and who's liable for what.

Dry Lease

In a dry lease (also called an operating lease), the lessor supplies only the aircraft itself — bare metal, no crew, no maintenance, no insurance. The lessee places the aircraft on its own Air Operator's Certificate, supplies its own flight and cabin crew, funds and manages all maintenance, and arranges its own insurance. This is the arrangement most airlines use for the bulk of their long-term fleet — leasing rather than owning aircraft outright, typically for terms of six to twelve years or more, while retaining full operational control and integrating the aircraft fully into their own operation as if they owned it.

Wet Lease and ACMI

A wet lease reverses that: the lessor provides the aircraft, Aircraft, Crew, Maintenance and Insurance — the full package, commonly abbreviated ACMI — while the lessee essentially just directs the schedule the aircraft flies. Operational control stays with the lessor under this arrangement, since it's the lessor's crew, certificate and maintenance organisation actually running the flight. Wet leases are typically short-term — anywhere from a single flight up to around 18 months — and airlines reach for them to cover seasonal capacity peaks, unexpected fleet gaps during heavy maintenance, new route testing before committing to owned or dry-leased capacity, or sudden demand spikes that don't justify a long-term fleet decision.

Damp Lease — the Middle Ground

A damp lease sits between the two: the lessor still provides the aircraft, flight crew, maintenance and insurance, but the lessee supplies its own cabin crew — giving the lessee more control over the actual passenger-facing service and branding experience than a full wet lease allows, while still outsourcing the harder-to-source flight-deck crew and technical operation.

Why the Distinction Matters Commercially

Because operational control — and therefore regulatory responsibility and liability — tracks who's actually running the flight, the choice between dry, wet, damp or full ACMI leasing isn't just a financing decision; it determines which airline's safety record, certificate and insurance actually stands behind a given flight, something regulators, codeshare partners and increasingly passengers themselves pay close attention to.