Aviation Leasing Glossary

FAA Form 8130-3. Airworthiness Approval Tag issued by the FAA (or a FAA-approved repair station) to certify that a part or component has been approved for return to service. The 8130-3 is the US equivalent of the EASA Form 1 and is widely accepted in FAA-regulated markets. Dual-release parts carry both an 8130-3 and an EASA Form 1, making them usable in either regulatory environment.

Aircraft, Crew, Maintenance and Insurance. A lease structure where the lessor provides a fully operational aircraft including flight crew, maintenance programme and insurance. The lessee provides fuel and pays per block hour flown. The most common structure for short-term capacity needs. Also called wet lease.

Air Operator Certificate. The regulatory approval granted by a civil aviation authority (e.g. EASA, FAA, GCAA) that permits an airline to use aircraft for commercial air transport. Required to operate flights under your own brand. In a dry lease, the lessee must have its own AOC to operate the aircraft. In ACMI, the lessor operates under their AOC.

Aircraft on Ground. Status indicating an aircraft is unserviceable and cannot fly until a defect is repaired. One of the most common triggers for emergency ACMI sourcing — an AOG with booked flights results in immediate capacity need, sometimes within hours.

Auxiliary Power Unit. A small turbine engine that provides electrical power and air conditioning on the ground when main engines are shut down. APU hours and cycles are tracked separately and appear in aircraft technical logs. APU status can affect lease return conditions.

Aircraft Utilization Score. ACMIhub's proprietary metric measuring how efficiently a listed aircraft is being deployed — calculated from average monthly block hours relative to type benchmarks. A higher AUS indicates an in-demand, well-managed asset. A low AUS may indicate available capacity or maintenance downtime.

The time from the moment an aircraft moves from its parking position (blocks off) to when it arrives at its destination parking position (blocks on). This includes taxi time, flight time and any airborne holds. ACMI and wet lease rates are almost always quoted per block hour (e.g. €3,800/BH for a B737-800).

Bill of Costs Analysis. A detailed financial breakdown of all operational costs associated with a lease agreement, used to calculate the true all-in cost to the lessee versus the block hour rate.

A short-term lease (typically 1–12 months) used to fill a gap between fleet redelivery and new aircraft delivery, or during a transition period. Common during fleet type transitions or new route launches where owned aircraft are not yet available.

A major scheduled maintenance event requiring the aircraft to be taken out of service, typically for 1–6 weeks. C-checks involve a comprehensive inspection of structure, systems, and components. Lease agreements must clearly specify which party is responsible for C-check costs and scheduling.

Condition Monitoring Report. A structured document describing the current technical condition of an aircraft's major components, used to track degradation trends and inform maintenance planning during and after lease periods.

A standardised document recording the physical and technical condition of an aircraft at lease start (delivery) and end (redelivery). Essential for avoiding disputes over damage, maintenance deferred during the lease, and return condition discrepancies. ACMIhub supports digital Condition Reports with photo documentation.

A deposit-style fee charged when a rotable or repairable component is exchanged. The buyer pays the core charge on top of the exchange price as security that they will return a serviceable "core" unit (the old component) within an agreed timeframe. If the core is returned in acceptable condition, the charge is refunded. Core charges are standard in engine module and LRU exchanges.

When one airline leases an aircraft from another airline rather than from a dedicated lessor. Common during seasonal peaks when carriers in opposite hemispheres exchange capacity. Also called airline-to-airline (A2A) ACMI.

Cycles Since New. The total number of flight cycles (takeoff-to-landing sequences) accumulated by a part or component since it was manufactured, without reset. Distinct from CSO (Cycles Since Overhaul). CSN is particularly important for Life Limited Parts (LLPs) which have a hard cycle limit before mandatory retirement regardless of condition.

A lease structure where the lessor provides the aircraft and crew, but the lessee assumes responsibility for maintenance and insurance. A hybrid between ACMI and dry lease. Less common than pure ACMI, used where lessees have existing maintenance arrangements but need crew supplementation.

A flight segment operated without revenue passengers or cargo — typically a repositioning flight to move an aircraft from one base to another. Dead legs represent pure cost with no revenue. Marketplace visibility on platforms like ACMIhub can turn dead legs into revenue opportunities by finding demand along the route.

The agreed technical and physical state in which an aircraft must be delivered to the lessee at lease commencement. Typically defined in detail in the lease agreement and documented in the Delivery Condition Report. Discrepancies between agreed and actual delivery condition are addressed before or shortly after delivery.

Direct Operating Costs. Variable costs that are directly tied to aircraft operation: fuel, crew costs, maintenance, navigation charges, landing fees and handling. As opposed to IOC (Indirect Operating Costs). In ACMI, the lessor absorbs crew and maintenance DOC; in dry lease, the lessee absorbs all DOC.

A lease of the aircraft alone — no crew, maintenance or insurance. The lessee takes full operational control and operates the aircraft under its own AOC. Typical lease duration ranges from 1 to 12 years. The lessee is responsible for all direct operating costs.

Authorised Release Certificate issued by an EASA Part-145 approved organisation to certify that an aircraft part has been manufactured, repaired, or maintained in accordance with applicable airworthiness requirements and is in a condition for safe operation. The EASA Form 1 is the standard airworthiness release document required for all parts used on EASA-regulated aircraft. Parts without a valid Form 1 (or FAA 8130-3) cannot legally be installed. Also referred to as a release certificate or trace document.

Entry Into Service. The date an aircraft first begins commercial operations. Important for assessing aircraft age and maintenance status in lease evaluations.

Extended-range Twin-engine Operations Performance Standards. Certification allowing twin-engine aircraft to fly routes more than 60 minutes from the nearest diversion airport. Ratings of 120, 180 or 240 minutes exist. Critical for transatlantic or long oceanic routes — if you need ETOPS capability, this must be a specific requirement in your search.

A parts transaction where a serviceable unit is supplied immediately from stock and the buyer returns a repairable or as-removed unit (the "core") within an agreed period. Exchanges are faster than sending a unit for repair because the buyer gets a ready-to-install part straight away. Used extensively for APUs, landing gear components, avionics LRUs and engine modules. The exchange price reflects the labour and material cost of overhauling the returned core. A Core Charge is typically applied as security for return of the core.

Flight Cycles. The total number of takeoff-and-landing pairs an aircraft has completed since manufacture. Combined with Flight Hours, determines maintenance interval requirements for most components. High-cycle aircraft are common on short-haul routes and may have higher near-term maintenance costs.

A non-revenue repositioning flight, typically from the lessor's base to the lessee's operating base at lease start. Ferry flight costs are usually at the lessee's expense and can be material if the aircraft is far from base. Always clarify ferry cost and who bears it before finalising terms.

Flight Hours. Total accumulated flying time of an aircraft, engine or component. A key metric for maintenance scheduling, LLP tracking and lease valuation. Listed alongside Flight Cycles on every aircraft's maintenance records.

A lease delivery/redelivery condition where major components have their full remaining life at the time of delivery. More valuable to the lessee than half-life condition. Premium leases may specify full-life delivery and redelivery at maintenance half-life.

Ground Power Unit. A portable electrical power source used to supply 400Hz AC power to an aircraft when its own APU is not running or is shut down for maintenance. GPUs are essential ground support equipment at most commercial airports and MRO facilities. They are available for sale, lease or rental and are one of the most commonly traded categories on the ACMIhub GSE marketplace.

Remaining time or cycles before a component's next scheduled maintenance event. Higher green time means lower near-term maintenance cost for whoever holds the aircraft. A key factor in pricing ACMI and dry lease deals — more green time generally commands a higher rate.

Ground Support Equipment. The range of specialised vehicles and equipment used to service aircraft on the ground between flights. Categories include tow tractors, pushback tractors, belt loaders, container loaders, Ground Power Units (GPUs), Air Start Units (ASUs), Air Conditioning Units (ACUs), passenger stairs, jet bridges, de-icing trucks, fuel hydrant dispensers, and maintenance platforms. Airlines and ground handlers source GSE through purchase, long-term lease or short-term rental — all three transaction types are supported on ACMIhub's GSE marketplace.

A conventional lease return condition where an aircraft's key components (engines, landing gear, C-check) are at the midpoint of their maintenance interval. "Half-life condition" is frequently used as a delivery/redelivery baseline in lease contracts. It simplifies valuation by avoiding the need to precisely track residual value of each component.

A major scheduled maintenance event (C-check or D-check) requiring significant downtime (weeks to months). Heavy checks are the largest single maintenance cost event in a lease. Lease agreements typically specify who bears this cost and whether the lessor or lessee must accomplish it.

International Air Transport Association. The global trade association for airlines, representing approximately 290 airlines. IATA codes (two-character) are used to identify airlines and airports globally (e.g. BA = British Airways, LHR = London Heathrow).

International Civil Aviation Organization. The United Nations agency responsible for setting global aviation safety, security and environmental standards. ICAO four-character codes identify airports (e.g. EGLL = London Heathrow, OMDB = Dubai). Used extensively in aircraft leasing documentation.

Indirect Operating Costs. Fixed overhead costs not directly tied to individual flights: leasing costs, depreciation, ground handling contracts, office overhead. Contrasted with DOC (Direct Operating Costs).

IATA Operational Safety Audit. A standardised audit programme evaluating an airline's operational management and control systems. IOSA registration is widely used in the ACMI market as a proxy for operational safety standards. Many sophisticated lessors require lessees to be IOSA registered.

Know Your Business. The corporate equivalent of KYC (Know Your Customer). A verification process to confirm a company's legal identity, beneficial ownership, regulatory status and authorisation to operate. ACMIhub requires KYB verification for all operators before they can post listings or engage in Deal Rooms.

Life Limited Part. An aircraft or engine component with a fixed maximum number of cycles or hours before mandatory replacement — regardless of condition. Examples include fan discs, turbine discs and landing gear components. LLP status significantly affects aircraft value and lease return conditions. Always verify remaining LLP life when evaluating an ACMI or dry lease.

Letter of Intent. A preliminary document outlining the key commercial terms of a lease before the formal contract is negotiated. May be binding on certain terms (exclusivity, deposit) or fully non-binding depending on how it is drafted. Usually the first formal step after agreeing a price in principle.

Manufacturer Serial Number. The unique serial number assigned to an airframe during production by the manufacturer (Boeing, Airbus, etc.). Used to track the complete history of a specific aircraft. All lease documentation should reference the MSN, not just the registration, as registration can change between operators.

Maintenance, Repair and Overhaul. The industry segment that provides aircraft maintenance services. MRO availability affects lease feasibility in certain regions — if there is no approved MRO for a given aircraft type near the lessee's base, operational costs rise significantly.

Non-Disclosure Agreement. A confidentiality agreement signed before sensitive commercial or technical information is shared between parties. In aircraft leasing, NDAs are typically signed before sharing detailed engine records, financial terms or proprietary operational data. ACMIhub's Deal Room supports digital NDA signing.

Power by the Hour. A maintenance payment structure where the lessee pays a fixed rate per flight hour or cycle to the lessor or MRO to cover engine and component maintenance. Common in ACMI arrangements — the block hour rate includes a PBH component which covers future maintenance events.

Pilot in Command. The captain with final authority over the aircraft. In ACMI, the PIC is provided by the lessor and operates under the lessor's AOC. A key distinction from dry lease where the lessee provides the PIC.

Quick Engine Change. A pre-assembled engine module package that includes all the accessories and equipment required to quickly install a replacement engine on a specific aircraft type. QECs dramatically reduce engine change time at the line maintenance level. Airlines often keep QEC kits in stock or source them from parts traders on short notice — a common AOG mitigation strategy. The QEC configuration is specific to both the engine type and the aircraft it will be installed on.

ACMIhub's feature enabling lessees to request an indicative price from a lessor with minimal input — just dates, base airport and optional notes. Designed to replace the traditional multi-email RFP process. A Quick Quote response is non-binding but serves as a fast qualification of commercial interest. Acceptance converts the Quick Quote into a structured Deal Room.

The agreed technical and physical state in which an aircraft must be returned to the lessor at lease end. Misalignment between agreed and actual redelivery conditions is the most common source of disputes in aircraft leasing. May involve redelivery maintenance (e.g. C-check, engine shop visit) at the lessee's expense. Always negotiate redelivery conditions explicitly and document delivery condition clearly at lease start.

Request for Proposal. A formal document issued by a lessee specifying its aircraft requirements and inviting capacity proposals from multiple lessors. ACMIhub supports RFP broadcast to all matching operators simultaneously, enabling parallel rather than sequential negotiation — dramatically reducing the time to first competitive offer.

An aircraft component that can be repaired, overhauled and returned to service an indefinite number of times and is tracked individually by serial number. Rotables are distinct from expendables (single-use) and are valuable enough to warrant individual tracking. Common rotables include avionics line replaceable units (LRUs), actuators, valves, pumps and wheels. Rotables move through a pool or exchange cycle: removed from aircraft → sent to approved MRO → repaired/overhauled → returned to stock for the next installation. Airlines and MROs maintain rotable pools or rely on global trading platforms to source rotables on short notice.

Service Bulletin. A document issued by an aircraft or engine manufacturer recommending or mandating a modification, inspection or repair. Service Bulletin compliance may be a condition of lease delivery. Review open SBs carefully when evaluating an aircraft.

When a lessee re-leases an aircraft it has on lease to a third party. Almost always requires the lessor's written consent. Sub-leasing without permission is a breach of the lease contract. Common in the broker market where an operator may sub-lease from a lessor to another airline.

ACMIhub's reputation metric calculated from verified reviews across six dimensions: reliability, aircraft condition, communication, terms compliance, payment behaviour and overall satisfaction. Scores are public on every company profile and accumulate across all completed deals. A high Trust Score enables companies to win business with counterparties they have never worked with before.

Time Since New. The total number of flight hours accumulated by a component since it was manufactured, without reset at overhaul. Often distinguished from TSO (Time Since Overhaul). TSN is used to assess accumulated wear and estimate remaining useful life. Particularly relevant for engine hot-section components, LLPs, and landing gear.

Time Since Overhaul. The number of flight hours accumulated by a component since its last overhaul or major repair. Combined with TSN, TSO defines where a part sits in its maintenance cycle. A part with low TSO but high TSN has been recently overhauled but is an older unit. Parts suppliers routinely quote both TSN and TSO on listings — these figures directly determine the green time remaining and therefore the value of the component.

The regulatory authorisation for a pilot to fly a specific aircraft type (e.g. B737, A320, B777). Type ratings are aircraft-family specific and require specific training. In ACMI, matching the crew's type rating to the leased aircraft is mandatory. If the lessee's crew needs to operate the aircraft (dry lease), their type ratings must be valid.

Used Serviceable Material. A part or component that has been removed from an aircraft in a serviceable condition and is accompanied by full traceability documentation to original manufacture (full trace). USM parts must have unbroken paperwork showing the complete service history back to a new-part source — this is mandatory for them to be legally installed on a certified aircraft. USM is distinct from scrap (not airworthy) and from overhauled parts (which have been returned to full manufacturer specifications). USM is widely traded in the parts marketplace and can provide significant cost savings over new or overhauled equivalents, provided the documentation is complete.

The number of block hours or cycles an aircraft flies per day, month or year. Higher utilization generates more revenue per aircraft. Idle aircraft represent significant carrying cost. Marketplace visibility through platforms like ACMIhub helps operators identify demand for underutilised assets, improving utilization in traditionally slow months.

A synonym for ACMI. The lessor provides everything needed to operate: Aircraft, Crew, Maintenance and Insurance. The lessee provides fuel and handles commercial operations (selling seats or cargo space). The lessee operates the flights under its own brand but the aircraft operates under the lessor's AOC.