11 Mar 2026

Residual Value Models Under Stress: Rethinking Depreciation Assumptions

Residual value models are under more pressure today because the market no longer behaves in the neat, stable way older spreadsheets assumed. Aircraft values now move against a backdrop of supply chain delays, engine shortages, uneven demand recovery, and stronger-than-expected value floors for some ageing assets. That means the old idea of a smooth depreciation curve is becoming less reliable, especially when stress hits liquidity, demand, or redeployment options. Recent valuation commentary from Cirium and IBA shows just how much market conditions, engine values, and retirement economics can reshape value assumptions. That is why lessors and appraisers are moving towards more dynamic thinking. Instead of leaning on a single residual value line, the market is increasingly using blended approaches that combine market evidence, part-out logic, engine value, utilisation, and scenario testing. The direction is clear: valuation must respond to signals, not just history. In stressed conditions, the question is no longer whether the model looks tidy. It is whether the model still makes sense when the market turns sharply against it.

 

What is residual value in aircraft leasing?

Residual value in aircraft leasing is the expected value of an aircraft at a future point in time, usually at lease expiry, sale or the end of an investment period. It is one of the most important assumptions in aviation finance because it directly affects lease pricing, portfolio returns, financing decisions, and impairment risk. For lessors, residual value is not just a technical estimate sitting in a model. It is a commercial judgement about where the aircraft will stand in the market after years of use, maintenance, ageing, and changes in demand. That is why getting it wrong can distort both pricing discipline and balance-sheet confidence.

Its importance becomes clearer when you look at what it affects:

• Lease pricing: Residual value plays a major role in how lease rentals are structured, because it affects how much value the lessor expects to recover from the aircraft at the end of the lease term.
• Portfolio returns : It shapes overall investment performance by influencing how much capital can be recovered through sale, re-lease, or part-out once the original lease period ends.
• Financing assumptions : Lenders and financiers often assess residual value when deciding how much risk sits in an aircraft-backed transaction and how secure the long-term asset value really is.
• Impairment risk : If the projected residual value proves too high compared to real market conditions, the lessor may be forced to recognise impairment and adjust the asset’s carrying value.
• Exit strategy planning : Residual value helps determine whether the aircraft is better suited for sale, lease extension, freighter conversion, teardown, or another exit route at a later stage.

Residual value matters because so many downstream decisions depend on it. If the assumption is too optimistic, the lease may look stronger on paper than it really is. If it is too conservative, the lessor may misprice the opportunity. In stressed markets, that balance becomes even harder to judge, which is why residual value assumptions need regular challenge, not blind carry-forward.

 

Why do residual value models fail under market stress?

Residual value models fail under market stress because most of them are built on stability assumptions that stop holding up when demand drops sharply, liquidity dries up, or transaction evidence becomes thin. In calm markets, depreciation curves often look predictable enough. But once stress enters the system, values can diverge much faster than the model expects. A type that looked liquid six months earlier can suddenly face weak trading depth, uncertain lease demand, or a much lower saleable population. That is when a clean depreciation line starts to break. Thin trade markets and delayed transaction visibility make the problem worse because the model may still be using yesterday’s signals to price today’s risk.

That usually happens for a few practical reasons:

• Demand falls faster than assumptions: Most models assume a more gradual decline in demand, but in stressed markets buyer interest can weaken much faster than expected, causing values to drop sharply.
• Trade evidence becomes limited: When fewer aircraft are changing hands, there is less real market evidence available to support valuations, making pricing assumptions harder to defend.
• Transaction data arrives late: By the time transaction information becomes visible to the wider market, pricing conditions may already have shifted, leaving the model behind current reality.
• Liquidity varies by type and age: Some aircraft remain relatively liquid even in weak markets, while others become much harder to place, which makes broad depreciation assumptions less reliable.
• Stress exposes weak floor assumptions: Downside value floors that looked reasonable in stable conditions may turn out to be too optimistic once remarketing pressure, weak demand, or part-out uncertainty sets in.

This is exactly why old valuation rules tend to fail first when the market turns. The issue is not that the model has no logic. The issue is that the logic is often too linear for a market that can reset suddenly. Under stress, lessors need models that recognise value cliffs, not just value slopes.

 

How are aircraft lessors rethinking depreciation assumptions?

Aircraft lessors are rethinking depreciation assumptions by moving away from single-curve thinking and towards models that reflect how aircraft actually trade, part out, and redeploy under different market conditions. That means incorporating more than just age and historical book patterns. Today’s models increasingly account for engine value, green-time economics, production constraints, retirement behaviour, market liquidity, and type-specific demand outlooks. Cirium’s recent valuation updates, for example, point to higher base value floors partly because engine values and part-out proceeds have become more influential than older trends suggested.

That shift is showing up in a few clear ways:

• Shallower depreciation curves: Some ageing aircraft are holding value better than earlier models expected.
• More weight on engine and part-out value: Engine demand and teardown proceeds now play a bigger role in valuing older aircraft.
• Scenario-based valuation bands: Models increasingly use value ranges instead of a single forecast.
• Faster reassessment of assumptions: Demand and remarketing outlooks are reviewed more frequently.
• More frequent model updates: aluation inputs are refreshed regularly to reflect market changes.

The broader change is really about mindset. Lessors are no longer treating depreciation as a smooth accounting habit. They are treating it as a market judgement that needs to be refreshed when conditions change. That makes the model less comfortable, but also more useful.

 

What is a hybrid aircraft valuation model?

A hybrid aircraft valuation model is a valuation approach that combines more than one pricing logic instead of relying on a single metric. In practice, that often means blending market evidence, lease rate context, utilisation data, parts and engine values, and scenario testing into one valuation view. This matters because aircraft do not all derive value from the same source at every point in life. A younger in-production aircraft may be best understood through market and lease comparables, while an older type may need a much stronger parts-driven or engine-led floor assumption. A hybrid model tries to reflect that reality rather than forcing every asset through the same valuation template.

That usually means combining inputs such as:

• Market transaction evidence: Uses real aircraft sales and lease placements to anchor valuations in actual trading activity.
• Lease rate context: Lease-rate strength helps show how attractive the aircraft remains in service.
• Flight-hour or utilisation signals: Usage patterns indicate wear and remaining economic life.
• Engine and parts value: Engine demand and teardown value support lower-end pricing for older aircraft.
• Scenario-based stress cases: Tests how values may change under weaker demand or lower liquidity.

This is why hybrid models are gaining ground. They do not pretend one lens can explain every value outcome. Instead, they accept that aircraft value can come from different drivers at different life stages, especially when markets are under pressure.

 

Why does parts-based valuation matter for older aircraft?

Parts-based valuation matters for older aircraft because, as an asset ages, a larger share of its value may come from engines, modules, and recoverable material rather than from continued full-aircraft operation. In other words, the aircraft’s value floor is no longer driven only by what someone might pay to fly it. It may increasingly be shaped by what the market will pay to break it down. Cirium’s 2024 base value update highlighted that higher engine values are pushing up part-out value floors, especially for older-generation aircraft, and that some older aircraft are now “cashing out” at retirement at levels above historical expectations.

That matters for a few simple reasons:

• Engine values support the floor: Strong engine demand can prevent older aircraft values from falling too sharply.
• Higher part-out proceeds: Recoverable value from engines and components can exceed earlier assumptions.
• Retirement economics matters more: Decisions to operate, store, convert, or part out now strongly influence valuation.
• Aircraft may be worth more in parts: In some cases, teardown value exceeds full-aircraft resale value.
• Teardown logic shapes base values: Residual models now factor in parts and teardown economics in downside cases.

This does not mean every older aircraft should be valued mainly for teardown. It means the model must recognise when parts economics are setting the floor more credibly than full-aircraft trading evidence. For stressed assets, that can materially change the downside case.

 

How do demand shocks affect aircraft residual values?

Demand shocks affect aircraft residual values by changing the speed, depth, and confidence of the secondary market. When demand drops sharply, fewer buyers are active, redeployment takes longer, and values can fall faster than a model built on normal conditions would expect. The impact is not uniform across the fleet. More liquid narrowbodies may hold value better, while older, less liquid, or operationally challenged types can see much sharper valuation pressure. Stress also affects lease rates, downtime assumptions, conversion optionality, and retirement timing, all of which feed back into residual value logic. IBA’s and Cirium’s market updates both show how value resilience can vary significantly by type, age, and market position.

That impact usually shows up through:

• Lower buyer appetite: Demand shocks reduce the number of active buyers, putting pressure on aircraft prices.
• Longer remarketing periods: Aircraft take longer to place or sell, increasing downtime risk.
• Wider bid-ask gaps: Buyers and sellers move further apart, making transactions harder to close.
• Sharper pressure on older types: Older or less liquid aircraft typically face stronger value declines.
• Higher exit-value uncertainty: Future resale or redeployment outcomes become harder to predict.

This is why stress testing matters. A residual value model that only works in normal demand conditions is not doing enough. The real test is whether it still holds together when demand falls hard and market confidence disappears.

 

What challenges weaken residual value model accuracy?

Residual value model accuracy weakens when the underlying inputs are too thin, too delayed, or too dependent on assumptions that cannot be verified easily. In aviation, that problem shows up often because not every aircraft type trades frequently, not every transaction is transparent, and not every parts market is easy to price cleanly. That creates blind spots. A model may look detailed, but if it sits on stale trades, opaque teardown economics, or slow market feeds, the output can become misleading very quickly. In stressed markets, those weaknesses show up even faster because the market moves before the model catches up.

The biggest challenges usually include:

• Thin trading markets: Limited aircraft transactions reduce reliable pricing evidence.
• Opaque parts pricing: Teardown and component values are not always transparent.
• Lagging transaction data: Market data often becomes visible after conditions have changed.
• Weak comparables: Differences in age, configuration, and maintenance make direct comparisons harder.
• Slow model refresh cycles: Infrequent updates can leave valuation models behind current market signals.

This is why valuation needs to be signal-driven rather than spreadsheet-driven. Accuracy improves when the model is updated with live market judgement, refreshed assumptions, and stress-tested downside logic. Without that, even a detailed model can become comfort rather than analysis.

 

Conclusion: When should lessors stress-test residual value assumptions?

Lessors should stress-test residual value assumptions before the market forces them to. Waiting for distress to prove the model wrong is the expensive way to learn. In a market shaped by supply constraints, stronger engine floors, uneven liquidity, and fast-changing demand signals, residual value needs to be tested against more than one future. A 30% demand shock, a slower remarketing cycle, a weaker teardown market, or a sudden drop in lease appetite can all expose where the model is too optimistic.

The point of stress testing is not to produce dramatic numbers. It is to see whether the assumptions still hold when the market stops behaving politely. If valuation is going to support real decisions on leasing, financing, impairment, and exit strategy, it has to be dynamic enough to absorb bad news early. So when did you last stress-test your residual value model against a 30% demand shock?

 

FAQs

Q.What is the difference between market value and residual value in aircraft leasing?

A.Market value is the aircraft’s estimated value today, while residual value is its expected value at a future point such as lease expiry or sale.

Q.Why are older depreciation curves less reliable now?

A.Because current aircraft markets are being influenced by engine shortages, supply chain constraints, parts demand, and uneven trading depth, which make simple linear curves less dependable.

Q.What makes a hybrid valuation model useful?

A.A hybrid model is useful because it combines market evidence, parts logic, lease context, and stress scenarios instead of relying on one valuation lens only.

Q.Why do parts and engine values matter more for ageing aircraft?

A.Because as aircraft get older, more of their value may sit in recoverable engines, modules, and teardown economics rather than continued full-aircraft operation.

Q.How often should a lessor review residual value assumptions?

A.Residual value assumptions should be reviewed regularly and more aggressively when market conditions, liquidity, lease demand, or engine economics shift materially.