Long-Lived & Infrastructure Assets

How to Underwrite an Aircraft Lease

Underwrite an aircraft lease by combining the lessee's credit with the aircraft's collateral value and remarketing liquidity. The key metrics are loan-to-value against independent appraisals (both current market and base value), the lease term remaining versus loan maturity, and maintenance condition measured by maintenance reserves or return conditions relative to time since last heavy check.

What makes aircraft lease underwriting different

An aircraft is a mobile, globally traded asset whose value depends on type, vintage, engine variant and maintenance status. Popular narrowbody types with large operator bases are easier to re-lease than niche or out-of-production types, so the airframe choice drives recovery more than almost anything else. Revenue comes from lease rentals paid by an airline, and the cash flow is only as strong as that airline's credit. Maintenance condition is a value driver in its own right: an aircraft just out of a heavy check and engine shop visit is worth materially more than the same tail approaching one, and maintenance reserves exist to close that gap.

Lenders underwrite a two-way exposure: the lessee pays during the lease, and the aircraft repays the loan if the lessee defaults. They focus on LTV against appraised base value, the jurisdiction's repossession regime and how quickly the aircraft could be re-leased. Equity investors and lessors underwrite the full life of the asset: lease rate factor, residual value at lease end, the cost of transition between lessees and the eventual part-out value of engines. Equity returns depend heavily on residual assumptions that lenders typically haircut.

Key metrics

Loan-to-value (appraised base value)

Appraised base value reflects long-run value in a balanced market and anchors the collateral cushion through cycles.

Secured aircraft debt is often sized somewhere around 60% to 80% of appraised value, lower for older or less liquid types.

Lease rate factor

Monthly rent as a percentage of aircraft value shows whether the lease compensates for depreciation and credit risk.

Remaining lease term vs loan maturity

A loan that outlasts the lease carries re-leasing risk on the lender rather than the lessor.

Lenders commonly prefer loans that amortize to a modest balloon within the contracted lease term.

Maintenance reserve coverage

Reserves collected per flight hour or cycle should match the accrued cost of the next heavy check and engine shop visit.

Residual value at lease expiry

Equity returns and any balloon repayment depend on what the aircraft is worth when the lease ends.

Lessee credit and fleet role

An aircraft core to the airline's network is less likely to be rejected in a restructuring.

How to underwrite it, step by step

Confirm aircraft type, vintage, engine variant and operator base to judge remarketing liquidity.
Obtain at least one independent appraisal showing current market value, base value and future base values.
Review maintenance records, back-to-birth traceability, time and cycles since last heavy check and engine shop visit.
Analyze lessee financials, liquidity, fleet plan and the aircraft's role in the network.
Review the lease for rent, maintenance reserves, return conditions, security deposit and events of default.
Assess the repossession and deregistration regime in the lessee's jurisdiction, including Cape Town Convention applicability.
Model downside cases with lessee default, transition cost, downtime and re-lease at a lower rate.
Structure LTV, amortization and balloon so the loan is covered by value at each point in the term.

Due diligence checklist

Aircraft lease agreement and any amendments
Independent appraisal reports (current market and base value)
Maintenance records and back-to-birth traceability
Engine shop visit and LLP status reports
Certificate of airworthiness and registration
Lessee audited financial statements
Maintenance reserve and security deposit account statements
Insurance certificates naming lender as additional insured
Cape Town Convention registrations and IDERA
Bill of sale and title chain
Return condition schedule

Key risks and mitigants

Lessee default or rejection of the lease in insolvency

Underwrite the lessee and the aircraft's fleet importance, and set LTV so value covers the loan after transition costs.

Residual value decline on aging or out-of-favor types

Use base value appraisals, haircut future values and amortize faster for older or niche aircraft.

Repossession difficulty in weak legal jurisdictions

Favor Cape Town jurisdictions with recorded IDERA and price for jurisdictional risk elsewhere.

Maintenance deficiency at return

Require maintenance reserves or strong return conditions backed by a security deposit or letter of credit.

Engine value concentration

Track engine LLP life and shop visit timing separately, since engines can represent a large share of value on older aircraft.

Typical financing and deal structure

Aircraft are financed through secured term loans to a lessor SPV, export credit agency guaranteed loans for new deliveries, enhanced equipment trust certificates for airlines, sale-leasebacks and asset-backed securitizations of lease portfolios. Debt is usually secured by a mortgage over the aircraft, assignment of the lease and insurances, and a pledge of SPV shares. Amortization is commonly matched to lease rentals with a balloon sized to projected value. Covenants and protections include LTV maintenance tests, maintenance reserve controls, lessee change restrictions and cash traps. Mezzanine or junior tranches appear in portfolio deals. Equity is supplied by lessors who earn the spread between lease rent and debt service plus residual value.

Red flags

Missing or incomplete back-to-birth records for life-limited parts.
Balloon at maturity exceeds a conservative projected base value.
Lessee is in a jurisdiction where repossession has historically been slow or obstructed.
Aircraft type is out of production with a shrinking operator base and no clear re-lease market.
Lease has no maintenance reserves and weak return conditions on an aircraft near a heavy check.

Frequently asked questions

What is the difference between current market value and base value?

Current market value is the appraiser's view of what the aircraft would trade for today under prevailing conditions. Base value is the appraiser's view of its underlying economic value in a balanced market with a willing buyer and seller. Lenders often size against base value for long-term stability but watch current market value for near-term recovery risk.

How are maintenance reserves used in aircraft leasing?

The lessee pays monthly amounts tied to flight hours or cycles into reserves for heavy airframe checks, engine shop visits, landing gear and APU. When qualifying work is done, the lessor reimburses from those reserves. Reserves protect the lessor and lender from receiving an aircraft that needs expensive work, which would reduce its value at repossession or lease end.

What is the Cape Town Convention and why does it matter?

It is an international treaty that standardizes creditor rights in aircraft and engines, including registration of interests and timelines for repossession after default. Where a country has adopted it with favorable declarations, lenders have more confidence they can recover the aircraft promptly. Many lenders price or limit exposure to non-Cape Town or weak-enforcement jurisdictions.

Why do older aircraft get lower LTV?

Older aircraft have fewer remaining years of useful life, a thinner re-lease market and values that depend more on engines and part-out potential. Their values fall faster in downturns. Lenders compensate with lower advance rates, shorter tenor and faster amortization so the loan stays covered.

Underwrite a aircraft lease deal in minutes

Drop a deck or data room. Underridge returns a verdict, investment memo, term sheet and a live model, with every headline figure traced to a page, a formula or a labeled assumption. Ten underwrites free.

Try Underridge free

Educational content, not investment, credit, legal or tax advice. Benchmarks are common practitioner rules of thumb and vary by lender, market and cycle.