28 Sep 2026

Wet Leasing and ACMI in 2026: Why Airlines Use Temporary Capacity and What It Means for Aircraft Owners

An airline can have strong passenger demand, attractive routes and available airport slots, yet still lack enough serviceable aircraft to operate the schedule it wants. New aircraft may be delayed, engines may be undergoing maintenance, or a seasonal traffic peak may require additional capacity for only a few months. In these situations, an aircraft wet lease can provide something a conventional fleet acquisition often cannot: additional flying capacity that can be introduced relatively quickly.

That flexibility explains why wet leasing and ACMI remain important tools in airline fleet planning. For airlines, the structure can protect schedules, revenue and network opportunities without immediately committing to permanent fleet growth. For aircraft owners and lessors, however, the economics extend beyond whether the aircraft is generating income. Utilisation, maintenance consumption, counterparty strength, technical records and the condition of the aircraft at transition can all affect the commercial outcome.

Understanding wet leasing therefore requires looking at both sides of the transaction: why an airline needs the capacity and what providing that capacity means for the aircraft and its owner.

 

What Is an Aircraft Wet Lease?

An aircraft wet lease is an arrangement in which an aircraft is supplied together with much of the operational capability required to fly it. Unlike a dry lease, where the airline taking the aircraft generally assumes responsibility for operating it, a wet lease provides a more complete operating solution.

The customer is therefore purchasing more than access to an aircraft. It is purchasing available flying capacity.

 

What Does ACMI Mean in Aircraft Leasing?

ACMI stands for Aircraft, Crew, Maintenance and Insurance. The provider supplies the aircraft, the crews required to operate it, maintenance responsibility and aircraft insurance. The customer airline then uses that capacity within its commercial network according to the commercial and operational responsibilities agreed between the parties.

The regulatory distinction is also important. Under EASA's air operations rules, a wet-leased aircraft used for commercial air transport is generally operated under the air operator certificate, or AOC, of the lessor. An AOC is the regulatory approval that allows an operator to conduct specified commercial air transport operations. Under a dry lease, the aircraft is generally operated under the lessee's AOC.

A damp lease sits between these structures. The exact allocation varies, but the provider may supply the aircraft and flight crew while the customer provides some or all cabin crew. The distinction matters because the allocation of people, costs and operational responsibilities changes the economics of the agreement.

 

Why Do Airlines Use Wet-Leased Aircraft?

The principal attraction of an aircraft wet lease is speed. Introducing an owned or dry-leased aircraft can require crew recruitment or training, maintenance integration, insurance arrangements, regulatory approvals and substantial fleet-entry preparation. ACMI allows an airline to obtain aircraft capacity with much of that operating infrastructure already in place.

This is particularly useful when the underlying requirement is temporary. Permanently expanding a fleet to cover a three-month demand peak may solve the immediate problem but create underutilised aircraft once traffic normalises.

 

How Do Seasonal Peaks and Fleet Disruptions Create ACMI Demand?

Seasonality is one of the clearest applications. Airlines may need significantly more capacity during summer, major holidays, religious travel periods or other traffic peaks. Wet leasing allows a carrier to add aircraft while the revenue opportunity exists without necessarily committing to the same capacity for several years.

Technical disruption can create the same requirement. Engine removals, heavy maintenance events or unexpected aircraft-on-ground situations can reduce the available fleet. Aircraft delivery delays can also leave an airline with a gap between the schedule it planned and the aircraft actually available to operate it.

Short-term aircraft leasing should therefore not automatically be considered inferior to permanent capacity. If the underlying problem is genuinely temporary, flexibility itself has commercial value.

The issue becomes more strategic when temporary shortages continue. Effective airline fleet management and aircraft acquisition require distinguishing between a temporary capacity gap and a structural fleet problem. Persistent reliance on ACMI can indicate that fleet size, delivery planning or long-term aircraft availability needs to be reconsidered.

 

What Is the Difference Between a Wet Lease and a Dry Lease Aircraft Structure?

The key difference is how operational responsibility is allocated.

Under a dry lease, the lessor supplies the aircraft but generally not the crews, maintenance organisation or insurance included within an ACMI arrangement. The lessee therefore has to integrate the aircraft into its own operating platform. This can involve crew qualification, technical management, maintenance planning, insurance and regulatory approvals.

Wet leasing reduces much of that integration burden because the operational capability remains with the provider.

 

When Does a Dry Lease Make More Commercial Sense?

A dry lease may be more appropriate when an airline expects to need the aircraft for several years and already has the infrastructure required to operate it efficiently. Once the aircraft has been integrated into the fleet, the long-term economics can be more attractive than continuously purchasing temporary capacity.

The comparison should not be reduced to headline lease rates. A dry-lease rental covers the aircraft but does not represent the airline's full cost of operating it. Crew, maintenance, insurance, training and operational infrastructure still need to be provided.

An ACMI rate may appear higher because substantially more is included. The relevant comparison is therefore between the total cost and commercial value of producing the required capacity under each structure.

 

How Are Wet-Lease and ACMI Contracts Structured?

ACMI contracts vary, but pricing is commonly linked to aircraft utilisation. A customer may pay according to the hours operated while also guaranteeing a minimum level of flying over the contract period.

That guarantee matters because the provider has allocated aircraft, crews and maintenance resources to the customer. If the customer subsequently reduces its schedule, many of those costs remain.

 

What Are Block Hours and Minimum Guaranteed Utilisation?

A block hour generally measures the period from when an aircraft begins moving for departure until it comes to a stop after arrival. ACMI agreements may specify a minimum number of block hours that the customer must pay for during a month or another agreed operating period.

This is commonly described as minimum guaranteed utilisation. It provides the provider with greater revenue certainty and reduces the risk of dedicating an aircraft and crew to a customer that ultimately operates considerably less flying than expected.

Other contractual provisions can materially change the economics:

• Cost allocation: Fuel, navigation charges, airport costs, positioning flights, crew accommodation and other expenses should be allocated clearly between the parties.
• Operational performance: Delay, cancellation, dispatch reliability and replacement-aircraft provisions determine who bears the financial consequences when the service is disrupted.
• Contract duration:A short seasonal arrangement creates different pricing and transition considerations from a multi-year ACMI programme.
• Availability obligations: The agreement may specify whether substitute capacity must be provided if the contracted aircraft becomes unavailable.

Two ACMI offers with similar hourly rates can therefore produce very different economic outcomes once minimum utilisation, cost allocation and performance obligations are considered.

 

What Does Wet Leasing Mean for Aircraft Owners and Lessors?

The ACMI provider operating an aircraft is not necessarily its ultimate owner. A specialist operator may itself use aircraft held under long-term dry leases from third-party lessors.

This creates another layer of exposure for the aircraft owner. The contractual lessee may be paying rent, while the aircraft itself is being used to provide flying capacity for several different customer airlines.

 

Why Do Utilisation and Maintenance Exposure Matter?

Aircraft utilisation describes how intensively the asset is operated, normally through flight hours and flight cycles. A flight cycle broadly represents one take-off and one landing.

Higher utilisation can increase the revenue-generating productivity of an aircraft, but it also consumes maintenance life more rapidly. Engines, landing gear and other maintenance-sensitive components move closer to scheduled maintenance events as hours and cycles accumulate.

High utilisation is therefore not automatically positive or negative for an owner. The commercial question is whether lease income, maintenance protections and return conditions adequately compensate for the technical value being consumed.

Effective aircraft advisory therefore extends beyond confirming whether lease payments are current. Maintenance status, asset value, market demand and the adequacy of maintenance protections can all influence the owner's true economic exposure.

 

Why Do Counterparty and Transition Risks Matter?

Counterparty risk is the possibility that another party to an agreement cannot or does not meet its contractual obligations.

For an aircraft owner, this can mean unpaid rent, deferred maintenance, disputes over aircraft condition or difficulties recovering the asset. For an airline purchasing ACMI capacity, the exposure works in the opposite direction. If the provider cannot supply the contracted aircraft and crew, the customer may lose capacity already built into its published schedule.

 

What Happens When the Aircraft Is Redelivered?

Redelivery conditions specify the technical and documentary standard in which an aircraft must be returned at the end of a lease. They can cover maintenance status, engine life, component condition, cabin configuration and technical records.

This connects directly to transition risk. An aircraft moving between operators may require inspections, maintenance work, cabin modifications, records review or regulatory preparation before returning to revenue service.

The records are particularly important. An aircraft can be physically serviceable but commercially difficult to transition if its maintenance documentation is incomplete or requires extensive reconciliation. Aircraft transitions can therefore require coordinated assessment of engine status, technical records, physical condition and continued airworthiness, areas that can be supported through aviation consultancy.

For the owner, transition time has a direct financial consequence. Every additional week required to prepare the aircraft for its next operator can mean another week without lease revenue.

 

What Does 2026 Wet-Lease Activity Tell Us About the Aircraft Leasing Market?

Recent activity illustrates why ACMI remains relevant on both sides of the capacity equation. SpiceJet's wet-lease capacity expansion provides one example of temporary aircraft being used to support additional flying, while attention to airBaltic's wet-lease business shows how ACMI can also form part of a provider's commercial model.

These examples should not be interpreted as evidence that airlines broadly prefer wet leasing to conventional aircraft leasing. Higher ACMI activity can reflect aircraft scarcity, delivery delays, maintenance disruption, seasonal peaks or temporary mismatches between where aircraft are available and where capacity is needed.

The more useful market signal is therefore not the number of wet-lease transactions in isolation. It is what those transactions indicate about underlying aircraft availability, fleet disruption and the value airlines place on flexibility.

 

When Does Wet Leasing Create the Most Commercial Value?

Wet leasing creates the most commercial value when the cost of not having an aircraft is greater than the premium required to obtain temporary capacity.

An airline may rationally pay more for ACMI if the alternative is cancelling profitable flights, leaving valuable airport slots unused or missing a strong seasonal revenue opportunity. The appropriate comparison is therefore not simply an ACMI rate against a dry-lease rental. It is the cost of ACMI against the revenue and strategic value that could be lost without the aircraft.

 

When Does Temporary Capacity Become a Long-Term Fleet Problem?

The calculation changes when a temporary requirement becomes permanent. If an airline expects to require the same capacity for several years, continuously purchasing ACMI may become less efficient than acquiring or dry leasing aircraft and integrating them into its own operating platform.

Aircraft owners face a related trade-off. High utilisation can support attractive revenue, but that return needs to be assessed against maintenance consumption, counterparty exposure, records quality and the eventual cost of transitioning the aircraft.

The strategic question is therefore not whether wet leasing is inherently expensive or efficient. It is whether ACMI is being used to solve the type of problem it is best suited to solving: a capacity requirement where speed and flexibility have greater commercial value than permanent fleet integration.

 

Conclusion: Wet Leasing Solves a Capacity Problem, but the Risk Does Not Disappear

An aircraft wet lease can solve one of commercial aviation's most expensive problems: having passenger demand without enough available aircraft to serve it.

ACMI provides speed because the aircraft arrives with much of its operating capability already in place. That makes it particularly useful during seasonal peaks, maintenance disruption, aircraft delivery delays and other temporary shortages.

The flexibility does not eliminate risk. It redistributes it. Airlines gain faster access to capacity but accept the economics of temporary flying. ACMI providers assume operational and utilisation obligations, while aircraft owners remain exposed to maintenance consumption, counterparty strength, technical condition and transition risk.

The commercial value of wet leasing therefore depends on more than aircraft availability. It depends on whether the capacity problem is genuinely temporary, whether responsibilities are allocated clearly and whether the aircraft can move through the arrangement without compromising its longer-term technical and economic value.

 

FAQs

What does ACMI mean in aviation?

ACMI stands for Aircraft, Crew, Maintenance and Insurance. The provider supplies these elements so another airline can obtain operational capacity without independently building the full operating structure around the aircraft.

 

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

Under a wet lease, the provider normally supplies the aircraft together with crew, maintenance and insurance. Under a dry lease, the lessee assumes significantly more responsibility for operating and integrating the aircraft.

 

Why do airlines use aircraft wet leases?

Airlines use wet leases to cover seasonal demand, replace unavailable aircraft, bridge delivery delays and add capacity quickly. They can also provide flexibility when an airline does not want to commit immediately to permanent fleet expansion.

 

Is ACMI aircraft leasing more expensive than a dry lease?

The headline ACMI rate may be higher because the airline is purchasing more than an aircraft. Crew, maintenance, insurance and operating capability are included, so the appropriate comparison should consider the total cost of producing equivalent capacity under each structure.

 

What are the main risks for an aircraft owner in ACMI operations?

Important exposures include aircraft utilisation, maintenance consumption, technical-record quality, counterparty strength and aircraft condition at transition. Owners therefore need to assess preservation of the asset's technical and economic value alongside the income generated during the operating period.