Grounded by Error: Common Hangar Valuation Mistakes

Abstract

1. Introduction

The United States has 5,179 public-use landing facilities, of which 4,889 are airports, and 3,287 of them are included in the National Plan of Integrated Airport Systems, the federal inventory of airports eligible for grant funding (Federal Aviation Administration 2024). Nearly every one of those airports has hangars on it, and nearly every hangar at a publicly owned airport sits on leased land. The stock is large, the transactions are thin, and the valuation discipline that serves it remains, by the standard of other specialized property types, underdeveloped. The only published practitioner methodology devoted to the subject is a two-part series in The Appraisal Journal that is now nearly two decades old (Lindsey 2008a, 2008b).

The consequences of error are not academic. At the construction costs implied by current institutional development, roughly $300 to $340 per rentable square foot for business-aviation hangar campuses (Sky Harbour Group 2026a), a 40,000-square-foot facility represents an investment on the order of $12 million, and a 20 percent valuation error moves that figure by $2.4 million. On the public side, the Department of Transportation's Office of Inspector General found that Denver International Airport's sponsor sold former airport parcels for less than fair market value, at a loss to the airport of at least $71 million, on the strength of a single appraisal that had been fixed for 25 years (U.S. Department of Transportation Office of Inspector General 2011a). The same office found that the City of Venice, Florida, transferred airport properties to itself at prices well below assessed value (U.S. Department of Transportation Office of Inspector General 2011b), and that Los Angeles World Airports leased airport property to city departments at rents below the fair market rates its own board had adopted (U.S. Department of Transportation Office of Inspector General 2014). These are not hangar appraisals in the narrow sense, but they are the same failure: airport property valued without reference to what the airport market would actually pay.

The pattern on the private side is consistent. An appraiser with sound commercial credentials is handed a hangar assignment, reaches for industrial warehouse comparables and a standard template, and produces a report that looks professional, reads well, and is wrong. The error is one of specialization, not competence. The Uniform Standards of Professional Appraisal Practice anticipate exactly this situation: the Competency Rule requires an appraiser either to be competent to perform the assignment, to acquire the necessary competency, or to decline it (The Appraisal Foundation 2024). Aviation real estate operates under rules that conventional commercial method was never designed to address, and this paper is a catalogue of what those rules require.

2. Scope and Method

The ten errors below were selected on three criteria: each is observed repeatedly in hangar appraisals, review assignments, lender files, and property tax and insurance disputes; each produces a value distortion large enough to change a decision; and each has a corrective that can be stated as a procedure. For every error the paper gives the mechanism, the evidence that documents it, and the correction. Companion papers in this series treat the ground-lease problem (Carter 2026a, 2026b, 2026c), depreciation (Carter 2026d), environmental contamination (Carter 2026e), and the airport characteristics that drive hangar value (Carter 2026f) at greater length.

None of this requires an exotic method. The three approaches to value, the highest and best use analysis, and the reconciliation that USPAP requires are the same for a hangar as for any other improved property (The Appraisal Foundation 2024; Appraisal Institute 2026). What differs is the evidence each step demands, and the errors below are, without exception, failures of evidence rather than failures of method.

2.1 The rules the errors break

Each error below offends a specific provision rather than a general standard of care, and naming the provision is what converts a criticism into a finding.

Problem identification requires the appraiser to identify "the real property interest to be valued," "any known easements, restrictions, encumbrances, leases, reservations, covenants, contracts, declarations, special assessments, ordinances, or other items of a similar nature," and "whether the subject property is a fractional interest, physical segment, or partial holding" (Appraisal Standards Board 2024, Standards Rule 1-2(e)(ii), (iv), (v)). A hangar assignment breaks all three at once when the ground lease goes unread.

Two development rules are overlooked more often than any others in this property type. The appraiser must, "[w]hen developing an opinion of the value of a leased fee estate or a leasehold estate," analyze "the effect on value, if any, of the terms and conditions of the lease(s)" (Standards Rule 1-4(d)). And where "personal property, trade fixtures, or intangible assets are included in the appraisal, the appraiser must analyze the effect on value of such non-real property assets," which the Comment notes requires competency in personal property or business appraisal (Standards Rule 1-4(g)). A third is a direct prohibition on a shortcut that appears in hangar work: "[a]n appraiser must refrain from valuing the whole solely by adding together the individual values of the various estates or component parts" (Standards Rule 1-4(e)).

Highest and best use must rest on analysis of "the relevant legal, physical, and economic factors," and the rule warns expressly against "making an unsupported assumption or premise about market area trends, effective age, and remaining life" (Standards Rule 1-3(a), (b)). Reporting requires "stating the reasons for excluding the sales comparison, cost, or income approach(es) if any have not been developed" (Standards Rule 2-2(a)(x)(2)), and stating the real property interest appraised (Standards Rule 2-2(a)(v)).

Underneath all of it is competency. The rule requires the appraiser, before accepting an assignment, to have "the knowledge and experience to complete the assignment competently" or to disclose the lack of it, take the steps necessary to acquire it, and describe those steps in the report. Most of what follows is a competency failure expressed as a methodological one.

3. The Ten Errors

3.1 Treating hangars as industrial warehouses

This is the original sin of hangar valuation, and it remains widespread. Appraisers without aviation experience default to the asset type they know best, industrial warehouses, and apply warehouse comparables, warehouse capitalization rates, and warehouse depreciation schedules to an asset that shares almost nothing with warehouse real estate beyond a large enclosed volume.

The differences are structural. A hangar floor carries the concentrated wheel loads of aircraft with maximum takeoff weights above 100,000 pounds: the Gulfstream G700 is certificated at 107,600 pounds and the Bombardier Global 7500 at 114,850 pounds (Gulfstream Aerospace 2026; Bombardier 2020). Clear-span requirements for aircraft maneuvering mean that column-supported industrial buildings are functionally incompatible with hangar use. Door systems large enough to pass a 103-foot wingspan have no warehouse equivalent (Gulfstream Aerospace 2026). Fire protection is governed by a dedicated standard, NFPA 409, whose 2022 and 2026 editions define hangar groups by door height and hazard classification and determine whether foam suppression is required at all (National Fire Protection Association 2026; National Air Transportation Association 2022, 2026). Aviation-grade electrical service, ground power, and compressed air serve operational needs that warehouses never address. Lindsey (2008a) observed that standard cost manuals may not capture hangar-specific components and recommended unit-in-place or quantity-survey costing for them.

The cost gap is documented. Sky Harbour's priced development pipeline implies roughly $300 to $340 per rentable square foot for business-aviation hangar campuses, and its chief executive has described a hard cost below $250 per square foot as the threshold that would expand the addressable market (Sky Harbour Group 2026a, 2026b). By contrast, Cushman and Wakefield's 2025 industrial construction cost guide reports averages of $77 per square foot for large ground-up projects, $85 for medium, and $139 for small across 46 markets in the Americas (Cushman and Wakefield 2025), and Rider Levett Bucknall's third-quarter 2025 report places warehouse hard costs between about $80 and $170 per square foot in Sun Belt metros and higher on the coasts (Rider Levett Bucknall 2025). An appraiser who applies warehouse cost benchmarks to a corporate hangar will understate replacement cost by half or more before considering the site work, taxiway access, and security infrastructure that warehouses do not require.

The income approach is equally distorted by warehouse assumptions. Hangar rents reflect aviation market variables, including fleet composition, based-aircraft counts, transient traffic, and fixed-base operator service quality, none of which are captured by industrial rent comparables (Carter 2026f). Capitalization rates for hangars must reflect aviation-specific risks, including regulatory dependency, ground lease structure, and aviation market cyclicality, which industrial capitalization rate surveys do not measure.

Correction. Never use industrial warehouse comparables as the primary basis for a hangar valuation; if warehouse sales are referenced at all, they serve only as a floor or ceiling check. Source comparable data from airport-specific transactions: airport authority lease files, county deed records for on-airport parcels, and aviation broker networks. Apply construction costs from aviation contractors and hangar-specific cost evidence. Develop capitalization rates from aviation-specific risk analysis, not from industrial surveys that exclude aviation assets from their samples. Where the appraiser lacks this evidence, the Competency Rule governs (The Appraisal Foundation 2024).

3.2 Ignoring or mispricing the ground lease

Ground lease analysis is often the decisive element of a hangar valuation, and it is where the expensive errors occur. The majority of hangars at public-use airports sit on land owned by the airport sponsor under ground leases that create a fundamentally different bundle of rights than fee simple ownership. At expiration the improvements typically revert to the sponsor without compensation (Karaskiewicz 2024; Carter 2026b). A building that cost $10 million or more to construct becomes worthless to the leaseholder at term, and the economic effect is a clock on value that must be quantified rather than acknowledged.

Three sub-errors dominate. First, applying fee simple capitalization rates to leasehold interests. Practitioners have applied lease-term adjustments across a range from 25 to 300 basis points without a published empirical basis (Lindsey 2008a, 2008b), and the author's research indicates that the appropriate adjustment rises steeply, not linearly, as remaining term shortens (Carter 2026a). The arithmetic is unforgiving: capitalizing a leasehold income stream at 7.0 percent when 9.5 percent is warranted overstates value by about 36 percent. Second, failing to model the ground lease to full term. A discounted cash flow analysis that projects ten years of income for a hangar on a 25-year ground lease misses the terminal value problem entirely; the analysis must run to lease expiration and model the reversion explicitly, which is often zero. Third, ignoring rent reset and escalation provisions. Consumer price index adjustment is the usual escalation mechanism in general aviation airport leases, and periodic reappraisal resets and revenue-sharing formulas are also in use (Karaskiewicz 2024); an appraiser who projects flat ground rent materially understates the ground lease burden.

Source: Author's practice framework, drawn from the author's research on remaining lease term, capitalization rates, and lender behavior (Carter 2026a, 2026c).

Correction. Read the lease. Identify the expiration date, every renewal option and the conditions attached to it, the reversion clause, the escalation and reset provisions, and the assignment and leasehold mortgage provisions. Model the cash flow to expiration. Adjust the capitalization or discount rate for remaining term, and say in the report how the adjustment was derived.

3.3 Using stale or geographically inappropriate comparables

The aviation real estate market operates with a degree of opacity that surprises investors accustomed to conventional property. There is no subscription database of hangar sales comparable to those that serve office or industrial property, no quarterly market report from the major brokerages, and little institutional research. The Airport Cooperative Research Program's guidance on market value and market rent at small airports exists precisely because sponsors and their consultants could not otherwise find the evidence (National Academies of Sciences, Engineering, and Medicine 2020). The scarcity creates a temptation: appraisers reach for whatever comparable sales they can find, regardless of age or distance.

The result is valuations built on comparables that may be three to five years old, from airports with different market characteristics, during a different phase of the cycle, and involving different property types. A T-hangar sale at a rural general aviation airport in 2020 says little about the value of a corporate hangar complex at a major reliever airport in 2026. Business aviation demand is driven by corporate earnings, executive travel, and new aircraft deliveries, indicators that diverge from office, retail, or industrial market drivers (Carter 2026f). Table 2 sets out the indicators an appraiser should consult to place a comparable in its market context.

Source: Author's framework. Delivery and billing series are published annually by the General Aviation Manufacturers Association (2026).

Correction. Prefer fewer, better comparables. Verify each with a party to the transaction. Adjust for date using aviation-cycle evidence rather than a generic property index. Document the search, so a reviewer can see what was found and what was rejected.

3.4 Misunderstanding highest and best use at airports

Highest and best use analysis is the foundation of any credible appraisal, and it is routinely mishandled at airports because appraisers fail to account for the federal regulatory environment that constrains the universe of permissible uses. Every airport that has accepted federal grant funds is bound by the FAA's grant assurances, which require the sponsor to make the airport available for aeronautical use on reasonable terms and without unjust discrimination, to maintain a fee and rental structure that makes the airport as self-sustaining as possible, and to use airport revenue for the capital and operating costs of the airport (Federal Aviation Administration 2025). The FAA's compliance manual, reissued as Order 5190.6C in February 2026, sets out how those obligations apply to airport property and leases (Federal Aviation Administration 2026a), and the agency's 2016 hangar-use policy restricts what a hangar on a federally obligated airport may be used for (Federal Aviation Administration 2016). An appraiser who posits a highest and best use of retail development for a parcel on an obligated airport has made an error that invalidates the appraisal.

The converse error is equally damaging: assuming the only possible use is the current use. Airport land may support several aviation uses at different economic densities, from T-hangars and corporate hangars to fixed-base operations, maintenance facilities, and flight training. The analysis must evaluate which permissible aviation use maximizes the productivity of the site given the regulatory constraints, the physical characteristics, and demand.

A structural feature of the airport market belongs in the highest and best use analysis as well. Each airport has a single ground lessor, and a tenant who wishes to operate on the field has no alternative. That bilateral monopoly gives the sponsor bargaining power that no conventional landlord possesses, with direct consequences for renewal probability, ground rent projections, and terminal value assumptions (Carter 2026a).

Correction. Establish the airport's federal obligation status, read the applicable grant assurances and the sponsor's minimum standards and leasing policy, and confine the legally permissible test to uses those instruments allow. Then test the permissible uses for physical possibility, financial feasibility, and maximum productivity as USPAP requires (The Appraisal Foundation 2024).

3.5 Neglecting functional obsolescence from fleet evolution

Aircraft grow, and hangars do not. A hangar built to house one generation of aircraft may be functionally obsolete for the next, and the impairment is measurable in rent, occupancy, and value. The usual source is door height and width. A Cessna Citation CJ4, a light jet, stands 15 feet 5 inches tall with a 51-foot 9-inch wingspan (Textron Aviation 2026). A Gulfstream G700 stands 25 feet 5 inches with a 103-foot wingspan, and a Bombardier Global 7500 stands 27 feet with a 104-foot wingspan (Gulfstream Aerospace 2026; Bombardier 2026). A hangar with an 18-foot door opening cannot house the large-cabin aircraft that now dominate the value of new deliveries, and its addressable market is permanently confined to smaller, older types that command lower rents. Sky Harbour reports that the square footage of the United States business aircraft fleet with tail heights above 24 feet grew 120 percent between 2010 and 2025, against 73 percent for the fleet as a whole (Sky Harbour Group 2026a). The three large-cabin manufacturers delivered 352 of the 854 business jets shipped worldwide in 2025 but accounted for about $20 billion of the industry's $31.0 billion in airplane billings (General Aviation Manufacturers Association 2026).

Other sources of functional obsolescence include electrical service inadequate for turbine aircraft support, interior columns that prevent accommodation of current aircraft, manual door operation in markets that expect powered systems, and fire protection that does not meet the current edition of NFPA 409 for the hangar's group and use (National Fire Protection Association 2026). Table 3 classifies the common forms by curability.

Source: Author's classification, following the curable and incurable distinction in Appraisal Institute (2026) and the hangar-specific treatment in Carter (2026d).

Correction. Measure the door opening, the clear height, and the ramp depth, and state in the report which aircraft classes the facility can accommodate. Test the current tenants' likely replacement aircraft against those dimensions. Estimate the cost to cure for curable items from contractor evidence and treat incurable items through the income or sales comparison approach as a permanent restriction on the addressable market.

3.6 Applying uniform depreciation rather than component analysis

Standard practice often applies a single age-life depreciation rate to the entire building. For hangars this produces unreliable results because the major systems have very different economic lives and cost profiles. The Appraisal Institute distinguishes the overall age-life method from the breakdown, or component, method and treats the latter as the more precise tool where components deteriorate at different rates (Appraisal Institute 2026). A hangar is the paradigm case: a structural steel frame may serve for 50 to 75 years while an HVAC system sized for a clear-span building with frequent door openings may need replacement in 15 to 25 years (Carter 2026d). Applying a uniform 30-year schedule to both either overstates depreciation on the long-lived structure or understates it on the short-lived mechanical systems.

Source: Carter (2026d), which derives component economic life estimates from engineering assessments, manufacturer specifications, contractor interviews, and the author's practice.

Correction. Use the component method. Estimate the replacement cost, effective age, and economic life of each major system independently, depreciate each, and sum. Where the door system alone represents a large share of the improvement cost, its condition and remaining life deserve a specific inspection finding rather than an allocation.

3.7 Ignoring the aviation demand cycle

Hangar values are driven by aviation demand, yet many appraisals treat aviation as a static market factor rather than a cycle that moves occupancy, rents, and values. The cycle is documented in the manufacturers' own data. Worldwide business jet shipments fell from 1,317 in 2008 to 874 in 2009 and 767 in 2010, and did not stop falling until 2012, when 672 were delivered, a decline of 49 percent from the 2008 peak (General Aviation Manufacturers Association 2016). By 2025, shipments had recovered to 854 and billings to a record $35.7 billion (General Aviation Manufacturers Association 2026). A hangar market underwritten at the 2008 peak and the one underwritten in 2012 were different markets, and an appraisal that did not say which one it was describing was incomplete.

The critical error is failing to assess where the aviation market stands in its cycle on the effective date. An appraiser who applies a stabilized vacancy assumption during a trough, or peak occupancy when the cycle is turning, produces a value that cannot be sustained. Market analysis must incorporate aviation-specific demand evidence: based-aircraft counts, registrations and deregistrations, order backlogs, used aircraft pricing, fuel volumes, and the hangar waiting list at the subject airport, which is direct evidence that demand exceeds supply at the posted rent (Carter 2026g).

Correction. Include an aviation market section in every hangar report that places the effective date in the cycle using the indicators in Table 2, and reconcile the vacancy, rent growth, and capitalization rate assumptions to that placement.

3.8 Underestimating environmental liability

Aviation operations generate environmental exposure that is qualitatively different from general commercial property. Per- and polyfluoroalkyl substances, or PFAS, from the aqueous film-forming foam historically required for aircraft rescue and firefighting are an emerging liability in aviation real estate that most hangar valuations do not account for (Carter 2026e). The regulatory record is now substantial. In April 2024 the Environmental Protection Agency issued the first national drinking water standard for six PFAS compounds, with maximum contaminant levels of 4.0 parts per trillion for PFOA and PFOS (Environmental Protection Agency 2024a), and designated PFOA and PFOS as hazardous substances under the federal Superfund statute effective July 8, 2024, which exposes owners and operators of contaminated sites to strict, joint, and several liability for response costs (Environmental Protection Agency 2024b). In 2025 the agency announced that it would retain the two hazardous substance designations and the PFOA and PFOS drinking water limits, while proposing to rescind the limits for four other compounds and to extend the compliance deadline for the remaining two to 2031; those proposals were published in May 2026 and remained pending as of September 2026 (Environmental Protection Agency 2025a, 2025b, 2026). The Department of Defense reports spending $2.6 billion on PFAS response between fiscal 2017 and 2023 and estimates more than $9.3 billion in further investigation and cleanup costs, much of it tied to airfield firefighting (U.S. Government Accountability Office 2025). The FAA has accepted fluorine-free foam at certificated airports since January 2023 but, as of its August 2026 guidance, permits rather than requires the transition (Federal Aviation Administration 2023, 2026b).

The valuation literature on contamination provides the framework. Mundy (1992) established that stigma, the market's discount for uncertainty beyond the cost of cleanup, is a distinct and measurable component of value loss. Jackson's studies of industrial property found that contaminated properties sold before or during remediation at roughly 28 to 30 percent below otherwise comparable unimpaired properties, and that the discount was no longer statistically significant after remediation was complete (Jackson 2001a, 2001b, 2002). PFAS differs from the petroleum and solvent contamination those studies examined in two respects that bear on stigma: cleanup technology is less mature, and the regulatory limits remain in motion, which creates the prospect of reopened obligations after an initial cleanup.

Additional considerations include legacy fuel contamination, deicing runoff, lead from decades of leaded aviation gasoline, and asbestos in older structures. The environmental allocation clauses of the ground lease directly affect both leasehold value and reversion value: where the tenant bears cleanup at expiration, the burden can be large relative to the remaining leasehold.

Correction. Treat a Phase I environmental site assessment as a standard element of hangar due diligence and read the lease's environmental provisions before concluding value. Where contamination is known, separate the cost to cure from the stigma effect, support each from evidence, and disclose the extraordinary assumptions on which the conclusion rests.

3.9 Failing to reconcile across the approaches to value

USPAP requires the appraiser to collect, verify, and analyze the information necessary for credible results, to develop the sales comparison, cost, and income approaches when necessary for credible results, and to reconcile both the quality of the data within each approach and the applicability of the approaches to the conclusion; the exclusion of any approach must be explained in the report (The Appraisal Foundation 2024, Standards Rules 1-4, 1-6, and 2-2). In hangar valuation, appraisers routinely over-rely on whichever approach has the readiest data and skip the reconciliation.

Each approach carries a specific weakness for hangars. The cost approach is essential because sales are scarce, yet it does not reflect the economic benefit of a favorable ground lease or a strong rental market and cannot capture below-market or above-market contract rent. The income approach is the cornerstone of investment-grade hangar valuation, but its reliability depends entirely on the appraiser's command of aviation rental rates and aviation-specific capitalization rate analysis. The sales comparison approach provides direct market evidence, but in thin markets the available comparables may be too old, too distant, or too dissimilar to be reliable (National Academies of Sciences, Engineering, and Medicine 2020).

Reconciliation is where aviation expertise matters most. Suppose, to illustrate, that the cost approach indicates $8.8 million, the income approach $7.2 million, and a thin sales comparison $9.5 million. The appraiser must evaluate the reliability of each for the property type and the assignment conditions and weight accordingly. For investment property the income approach usually carries the weight; for new construction in a thin market the cost approach may be the more reliable; and sales comparison should serve as a check rather than a primary indicator where fewer than a handful of truly comparable transactions exist.

Correction. Develop every approach for which credible evidence can be assembled, explain the exclusion of any that cannot, and write a reconciliation that states the weight given to each and why.

3.10 Misapplying insurance replacement cost concepts

Insurance replacement cost and market value are different concepts, yet confusion between them is a frequent source of hangar valuation error, particularly in claims adjustment and coverage review. Replacement cost new is the cost to construct a functional equivalent of the subject using current materials, design, and construction practice; market value is the most probable price in a competitive and open market under the conditions of the definition the assignment adopts (Appraisal Institute 2026). The two diverge for hangars as a matter of course. A hangar with a replacement cost new of $12 million may have a market value of $8 million if the ground lease has fifteen years to run, the local aviation market is soft, or the building is functionally obsolete; a well-located hangar in a supply-constrained market may command a value that approaches or exceeds its depreciated replacement cost.

The insurance-specific error is underinsurance. Policyholders and their agents estimate coverage from original construction cost without accounting for construction cost inflation, which has roughly doubled nonresidential building costs over the past two decades (Turner Construction Company 2013, 2026), for aviation-specific material and labor premiums, for current code requirements under NFPA 409, or for the specialized systems that generic cost estimators understate. When a loss occurs, the gap between actual replacement cost and insured value falls on the owner.

Correction. State in every hangar report which value is being estimated and for what use. For insurance purposes, build replacement cost from current aviation construction evidence, price the door system and fire protection specifically, include code-upgrade and demolition costs, and revisit the estimate as construction cost indices move.

4. What the Adjudicated Record Shows

The errors in Section 3 are not hypothetical. Each has been made in a proceeding where someone with authority said so, and the decisions are more instructive than any checklist because they show what the mistake cost.

4.1 Valuing a restricted airport interest as if the restriction did not exist

The strongest illustration is a federal takings case. Claimants at Dallas Love Field were awarded $133.5 million for a six-gate terminal and its leaseholds. Every claimant expert valued the property on the assumption that the federal statute restricting service from the airport would be repealed, one assuming immediate repeal and another assuming repeal after eight years. The Federal Circuit found that "none of plaintiffs' experts assessed the use or value of plaintiffs' leaseholds with the [restriction] in effect," and that the claimants could not show their ability to use the property for commercial service under the regime actually in force "had any value." The market evidence ran the other way: an airline serving the gates failed within eight months, no carrier would lease them, and the owners lost roughly $13 million over seven years. The award was reversed and compensation reduced to zero (Love Terminal Partners, L.P. v. United States, 889 F.3d 1331 (Fed. Cir. 2018), cert. denied, 139 S. Ct. 2744 (2019)).

The rejected premise is the same premise a hangar appraiser adopts when analyzing highest and best use without the federal aeronautical-use obligations described in Section 3.4. An assumption that a restriction will lift is an extraordinary assumption requiring a reasonable basis, not a background condition.

4.2 Assuming who owns the hangar

Three decisions, reaching three different results on similar facts, establish that ownership of a hangar on leased airport land is a document question rather than a general rule.

In Colorado, a tenant holding a ground lease at a county airport built a 39,900 square foot hangar facility for about $2.4 million, with title vesting in the lessor only at lease expiry in 2036. The court held that a lessee with exclusive use, the right to encumber and retention of all income holds ownership sufficient for taxation regardless of formal title (Rare Air Ltd. v. Property Tax Administrator, 2019 COA 134). In California, a hangar tenant at a municipal airport argued he owned the hangar outright and therefore held no possessory interest; the court held the ground lease created a taxable possessory interest and the hangar was a taxable improvement on exempt land (Seibold v. County of Los Angeles, 240 Cal. App. 4th 674 (2015)). In Texas, T-hangar owners at a municipal airport argued they held no taxable interest; the court held the hangars taxable because the improvements had been conveyed by separate bills of sale, observing that "[r]egardless of what portion of fee simple in the hangars was conveyed in the leases, the remainder was conveyed in the bills of sale" (DeGuerin v. Washington County Appraisal District, No. 01-11-00355-CV (Tex. App. Houston 1st Dist. 2012)).

Against those, the opposite outcome on a neighbouring question: hangars, offices and support structures at another Texas airport were held exempt because "the City is the owner of the improvements as of the date it accepted them" (Travis Central Appraisal District v. Signature Flight Support Corp., 140 S.W.3d 833 (Tex. App. Austin 2004)).

Read together, these four decisions say that the ground lease alone does not answer the ownership question. A bill of sale, an acceptance provision or a vesting clause elsewhere in the file can decide it, and an appraiser who reads only the lease has read only part of the instrument set.

4.3 Rate methodology, and what a defensible one looks like

Two administrative determinations describe the standard from the sponsor's side. A complaint challenging hangar rental rates at a large county airport was dismissed where the sponsor's methodology rested on a cost-recovery study examining land valuation and operating expenses, which the agency found "not overtly unreasonable and appears to follow common industry practices," with rates "reasonably related to land valuation, square footage, and cost recovery" for the general aviation cost center (Southern California Pilots Association v. County of Orange, FAA Docket No. 16-23-17, Director's Determination, Sept. 20, 2024).

A second determination declined to require a comparability analysis and restated that sponsors retain latitude to set fair market rental values and rate methodologies "provided that rates are reasonable, applied uniformly, and consistent with local economic conditions" (Feliciano and Yellow Hangar LLC v. Puerto Rico Ports Authority, FAA Docket No. 16-24-08, Director's Determination, Sept. 17, 2025).

The practical reading for an appraiser is that a rate supported by a documented cost-recovery study, applied uniformly, is defensible even where a tenant considers it high, and that a rate unsupported by any study is exposed from both directions. A sponsor charging below market for non-aeronautical use faces the revenue-use rules rather than the tenant.

4.4 Lease term is not a recovery period

A complainant argued that the hangar construction assurance entitled him to a lease long enough to depreciate a $200,000 investment. The agency repeated its guidance that "most tenant ground leases of 30 to 35 years are sufficient to retire a tenant's initial financing and provide a reasonable return for the tenant's development of major facilities," then held that this is a best-practice recommendation left to sponsor discretion rather than a mandate, and dismissed (Bresciani v. Puerto Rico Ports Authority, FAA Docket No. 16-23-15, Director's Determination, Aug. 19, 2025).

The error the determination corrects is the assumption that a tenant is entitled to a term matched to its capital recovery. It is not, and the valuation consequence of a term shorter than the recovery period is developed at length elsewhere (Carter 2026a, 2026c).

4.5 Appraisals rejected for what they did not explain

A municipal tax dispute over a large airport property produced criticism of both sides. The court found that one expert justified a fivefold per-acre differential between two areas of the airport while pointing "to no difference in topographical features" between them, and that the opposing expert relied on undisclosed hypothetical conditions and offered "no information as to what residential acreage is worth" (City of Burlington v. City of South Burlington, Vt. Super. Ct., Chittenden Unit, Mar. 3, 2016).

Neither failure was a failure of conclusion. Both were failures of support, which is the form most rejections take. An adjustment without a stated basis and an assumption without disclosure are the two findings that recur across this record.

5. A Corrective Framework

Table 5 collects the ten errors, the standard or authority each offends, and the evidence that cures it. The table is intended for use by review appraisers and by the lenders, sponsors, and counsel who commission hangar appraisals and need a short list of questions to ask of a report.

Source: Author's synthesis of The Appraisal Foundation (2024), Appraisal Institute (2026), Federal Aviation Administration (2016, 2025, 2026a), National Fire Protection Association (2026), and the sources cited in Section 3.

6. Limitations

The ten errors in Section 3 are drawn from practice, from the authorities cited against each, and from the adjudicated record in Section 4. They are not a sample. No study has measured how often any of them occurs, and nothing here establishes a frequency, a ranking by cost, or a base rate against which an individual appraisal can be judged.

The decisions in Section 4 come from five states and two federal fora, and several turn on statutes that differ materially across jurisdictions. The ownership cases in Section 4.2 show this plainly: the same facts produce different answers in Colorado, California and Texas, and the point of citing them together is that variation rather than a rule. None should be read as stating a national position.

One item in the record could not be verified at the primary-document level. A Director's Determination reported to have found a large county sponsor in violation of the fee and rental structure and airport revenue assurances for charging below market for non-aeronautical hangar use is described in a party's filing in the docket. The determination itself could not be retrieved, and the characterization is the complainant's rather than the agency's. It is therefore excluded from Section 4 rather than reported there.

The standards quoted in Section 2 are from the 2024 edition, which remains in force. The text was verified against the Appraisal Standards Board's record of changes, which confirms that none of the rules relied on here was amended for that edition.

Finally, this paper describes appraisal practice in the United States at federally obligated public-use airports. Errors at privately owned airports, at airports without federal obligations, and outside the United States may differ, and the regulatory sections do not transfer.

7. Conclusion

The ten errors documented here share a root cause: the application of general commercial real estate method to a specialized asset class that requires purpose-built evidence. The aviation market's opacity, thin transaction volume, regulatory complexity, and leasehold structure create valuation problems that generic practice was not designed to address, and the errors are failures of evidence rather than of method.

The consequences are substantial and recurring. Sponsors leave public revenue uncollected through mispriced leases, as the Inspector General's audits record. Investors acquire hangars without understanding the reversion embedded in a finite term. Lenders extend credit against collateral they have not valued as a leasehold. Insurers and their policyholders discover the gap between coverage and replacement cost after the loss. In each case the error was avoidable with aviation-specific analysis.

Three developments would reduce the error rate. The appraisal profession needs aviation-specific guidance that extends the single published framework (Lindsey 2008a, 2008b) into the leasehold, environmental, and fleet questions that now dominate the asset class. The market needs better data infrastructure: empirical capitalization rate research, cross-market transaction records, and validated depreciation studies for aviation improvements. And the parties who commission hangar appraisals need to ask the questions in Table 5 before they accept a report. None of this requires a new method. It requires the right evidence, gathered by someone who knows where to look.

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This paper is research and general information for professionals evaluating aviation real estate. It is not appraisal, legal, or tax advice, and it does not create an engagement.