ACMI Lease Explained: ACMI Leasing, Wet vs Dry Lease

ACMI leasing is a wet lease in which one operator provides the Aircraft, Crew, Maintenance and Insurance, while the customer pays the variable costs of flying, such as fuel, landing and handling charges, and sells the capacity. In a dry lease, by contrast, the customer gets only the aircraft and must crew, maintain, insure and operate it under its own air operator certificate.

What is ACMI leasing?

ACMI leasing is a wet lease: the lessor supplies the Aircraft, Crew, Maintenance and Insurance, and the lessee pays to use the aircraft on its own network.

The aircraft normally flies under the lessor's air operator certificate (AOC), with the lessor keeping operational control and responsibility for airworthiness. The lessee schedules the flights, sells the cargo space and carries the commercial risk. In cargo, ACMI is how many airlines, integrators and large forwarders add whole freighters to their networks for a season or for several years without buying aircraft, hiring pilots or building a maintenance organization.

The opposite end of the scale is the dry lease, where a lessor (often a financial leasing company) supplies only the aircraft. The lessee registers it on its own certificate, crews it, maintains it, insures it and carries all operating risk. Most airline fleets are built on dry leases; ACMI is the flexible layer on top.

Who pays for what in an ACMI lease?

The lessor pays for the aircraft, crew, maintenance and insurance; the lessee pays the costs that vary with each flight.

How do block hours and minimum guarantees work?

ACMI rates are usually quoted per block hour, measured from chocks off at departure to chocks on at arrival, so taxi time counts as well as time in the air. The contract then sets a minimum guarantee: a number of block hours per month (or per year) that the lessee pays for whether or not it flies them.

A hypothetical example shows why the guarantee matters. Say a contract guarantees 300 block hours a month. If the lessee flies 340 hours, it pays for 340. If a slow month means it flies only 250, it still pays for 300, so the fixed cost per hour actually flown rises. The guarantee is what lets the lessor commit an aircraft and crews to one customer, and it is the main commercial risk the lessee takes on. Contracts also commonly set the crew base, the maximum hours per month, and how unscheduled maintenance downtime is credited.

How do wet, damp and dry leases compare with CMI and charter?

The difference is who supplies each element, and above all whose certificate the aircraft flies under: the lessor's in a wet lease, CMI or charter, the lessee's in a dry lease.

"Damp lease" is mainly a passenger-airline term, where the lessee often adds its own cabin crew. In cargo, the more common split is between full ACMI and CMI, where an owner such as an integrator supplies its own freighter and pays a specialist to crew, maintain, insure and operate it.

Two other ways to buy capacity sit alongside these leases:

• Block space agreements guarantee a set amount of space on another carrier's flights, with the risk shared. They suit steady volumes that do not justify a whole aircraft.
• Partial charters sell part of a charter flight's capacity, which suits shippers with large but not aircraft-sized loads.

How is wet leasing regulated?

Regulators care about one question above all: who is responsible for operating the aircraft safely. Wet leases are therefore reviewed or approved by the aviation authority before flying starts.

• United States. Under 14 CFR 119.53, a US certificate holder must give the FAA a copy of a wet lease before operating under it. The FAA then decides which party has operational control, looking at crewmembers and training, airworthiness and maintenance, dispatch, servicing and scheduling, and amends both parties' operations specifications. The same section bars US certificate holders from wet leasing aircraft from a foreign air carrier. Separately, the truth-in-leasing rule in 14 CFR 91.23 requires leases of large US-registered civil aircraft to state who holds operational control.
• European Union. Article 13 of Regulation (EC) No 1008/2008 makes wet-lease agreements involving EU carriers subject to prior approval. Wet leasing in an aircraft registered outside the EU is allowed only in limited, time-bound cases, such as exceptional needs, seasonal capacity that cannot reasonably be met with EU-registered aircraft, or operational difficulties, and the safety standards must be equivalent to EU rules.
• Traffic rights. Because the lessee usually sells the flights, it needs the traffic rights and permits for the route, while the lessor's AOC and aircraft must be accepted by every country the flight enters. Cross-border wet leases can take weeks to clear, which is why lead time matters.

Why do cargo airlines, forwarders and e-commerce platforms use ACMI?

Because it turns freighter capacity into a variable cost that can be added or removed far faster than an aircraft can be bought, converted or certified.

The cargo ACMI market is built around a handful of specialist freighter operators and a broad customer base. Some data points, with their dates:

• Air Transport Services Group, a US freighter lessor and operator, said ACMI accounted for 61 percent of its 2022 revenue of about $2 billion, as reported by STAT Times in July 2023.
• In the same July 2023 article, an Asia-based cargo network executive said that with cargo demand lower than during the pandemic, operators were offering ACMI to win market share, and that leasing out aircraft reduces an operator's exposure to volatile fuel prices.
• In January 2025, the ACMI operator SmartLynx Airlines said delays in new aircraft deliveries, often by several years, had led airlines to increasingly turn to ACMI providers to bridge capacity gaps.

Each customer group uses ACMI for different reasons:

• Cargo airlines cover maintenance downtime, late aircraft deliveries and seasonal peaks, or test a new route before committing their own fleet.
• Integrators and express networks outsource whole fleets, keeping control of the schedule and the brand while the operator handles pilots, maintenance and certification.
• Forwarders run their own controlled lanes on busy trade routes, so they are not exposed to space shortages and rate spikes on scheduled flights.
• E-commerce platforms build dedicated networks for predictable, high-volume flows, especially around peak shopping seasons.

What are the pros and cons of ACMI?

Whether ACMI beats scheduled capacity depends on how full the aircraft will fly. When volumes are smaller or irregular, booking space on scheduled freighters and belly holds, or comparing air against ocean on cost and transit time as in our air freight vs sea freight guide, usually makes more sense.

What should you check before signing?

1. Minimum guaranteed block hours and what happens if you fly fewer.
2. Which costs are included, from crew hotels to de-icing.
3. Aircraft type, payload and volume on your actual routes, including any outsize loading capability and the pallet and container positions it offers (see our guide to unit load devices and main deck containers).
4. Replacement aircraft commitments if the aircraft goes unserviceable.
5. Traffic rights, permits and regulatory approvals for the routes you plan to fly.
6. Who holds operational control, and how that is documented for each authority involved.

If you only need one flight rather than a lease, see our comparison of air charter vs scheduled freighter capacity.

How do shippers benefit from ACMI without leasing an aircraft?

By booking through a provider that already operates ACMI capacity. You get access to dedicated freighter space, priority on peak dates and, on suitable aircraft, nose-door loading for long pieces, without committing to block hours yourself. That is how Jumbo Air Cargo works with world-class ACMI providers to give customers capacity for high-volume e-commerce and heavy and outsize cargo.

Frequently asked questions

What does ACMI stand for?

Aircraft, Crew, Maintenance and Insurance: the four things the lessor provides in a wet lease.

What is the difference between a wet lease and a dry lease?

In a wet lease (ACMI) the lessor supplies the aircraft with crew, maintenance and insurance and usually keeps operational control. In a dry lease the lessor supplies only the aircraft, and the lessee crews, maintains, insures and operates it under its own certificate.

What is the difference between ACMI and a charter?

In ACMI the lessee takes on the commercial risk and operating costs and sells the space. In a charter, the customer pays an all-in price for a specific flight.

What is CMI?

Crew, Maintenance and Insurance only. The customer supplies the aircraft and the CMI provider operates it.

Who has operational control in an ACMI lease?

The lessor normally keeps operational control and flies the aircraft under its own air operator certificate. In the US, the FAA decides which party has operational control when it reviews a wet lease.

Sources

1. IATA: Cargo
2. EUR-Lex: Regulation (EC) No 1008/2008 on the operation of air services in the Community (Article 13, leasing)
3. eCFR: 14 CFR 119.53, Wet leasing of aircraft and other arrangements for transportation by air
4. STAT Times: ACMI market continues to grow, come what may (July 2023)
5. SmartLynx Airlines: SmartLynx Airlines carried more than 10 million passengers in 2024 (January 2025)

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