Airport Bond Documents

Introduction

When U.S. airports access the municipal bond market to finance capital improvements, they establish borrowing terms through detailed legal documents including ordinances, trust agreements, and resolutions. These documents, 100+ pages and unique to each airport, establish five issues central to airport credit analysis: (1) absence of collateral and tax-backing, (2) definition and pledge of revenues, (3) application and flow of revenues, (4) revenue covenant and coverage testing, and (5) additional bond testing requirements.

These five issues form the foundation of airport creditworthiness and translate to credit metrics per Moody's 2025 methodology. Bond rating agencies evaluate each issue through specific analytical lenses; financial officers and consultants may evaluate how document language translates to credit metrics and rating agency interpretation.

This guide examines each of these five issues in detail, explores how language variations create differences in credit outcomes, provides examples from actual airport agreements, and offers practical guidance for negotiation, financial modeling, and credit analysis.

2. No Collateral or Tax Power — Foundation of Airport Revenue Debt

Airport revenue bonds are unsecured obligations. Unlike traditional corporate bonds (which may be secured by specific assets) or general obligation bonds (which carry full faith and credit of issuing government), airport revenue bonds pledge only operating revenues. No physical assets (runways, terminals, equipment) serve as collateral. Airports cannot pledge property tax revenues or other government sources. Only airport operations revenues are available to debt service (FAA Grant Assurance 25).

This limitation stems directly from federal grant assurances. As a condition of accepting FAA Airport Improvement Program grants and other federal funding, airports accept grant assurances containing 40 specific requirements. three relevant (GA-25, airport revenues; GA-19, operations and maintenance; GA-24, fee and rental structure) are:

1. Hold good title to the airport landing area and maintain availability for public use (GA-19)

2. Maintain a fee and rental structure to make the airport as self-sustaining as possible (GA-24)

3. Generate sufficient operating revenues to fund debt service and operations (GA-25)

The full suite of 40 FAA grant assurances (GA series) establishes detailed constraints on airport operations, asset use, and revenue application; bond counsel may evaluate grant assurance compliance when structuring revenue pledges.

Practically, this means: airport revenue bonds rest on creditworthiness of airport operations, not asset value. If airport cannot generate sufficient operating revenues, bondholders have no recourse to seize facilities, no tax backing, and no secured asset recovery. Rating agencies emphasize operational revenue sustainability (Moody's Airport Methodology 2025).

Credit rating agencies evaluate airport revenue bonds on operational revenue sustainability rather than balance sheet assets. A profitable airport operation generates credit quality; declining operations led to downgrades, e.g., specific airports 2020-2022 (Moody's).

3. Pledged Revenues — Important Definitions

Bond documents specify exactly which revenues are pledged to debt service and available for other bond fund requirements. Language variations create differences in available cash, Bond counsel and airport finance professionals analyze how precise language affects coverage calculations and credit ratings.

3.1 Definition of Revenues

Bond documents of 24 of 31 large-hub airports (EMMA, 2025) define Revenues (capitalized to indicate defined term) as:

'Revenues shall mean all income and receipts of the Airport from any and all sources, including but not limited to landing fees, terminal rents, concession rents, fuel flowage fees, ground handling fees, parking revenues, and other operating revenues, plus interest earnings on operating funds, less any revenues specifically designated for non-airport purposes.'

This definition raises questions on inclusions. Inclusions in 24 of 31 large-hub airports (EMMA, 2025):

• Included in 24 of 31 large-hubs (EMMA, 2025): Landing fees, terminal rents, concession rents, fuel flowage, ground handling, parking, rental cars, hotel revenues, advertising, rental equipment

• Interest Earnings: Included in 24 of 31 (EMMA filings, 2025) on airport operating funds and restricted accounts

• PFC Revenues: Passenger Facility Charge revenues included in Revenues if designated in bond documents; included in 24 of 31 (survey of EMMA filings, 2025)

• Specific Exclusions: Non-airport enterprise fund revenues (rental car facility revenues if operated by rental car companies rather than airport) excluded

The distinction between airport-operated and concessionaire-operated facilities creates complexity. If airport contracts with rental car company that retains all rental car revenue, those revenues are not 'Revenues' under bond definition. If airport operates rental car facility directly, revenues are included.

3.2 Rolling Coverage and Transfers from Prior Year

An open question: can airports count 'rolling coverage'—surpluses from prior years—in calculating current-year coverage ratios? This distinction is significant for coverage calculations.

Some bond documents explicitly permit rolling coverage through mechanisms including:

1. Transfer prior-year surplus to current-year Revenue account, increasing current-year Revenues

2. Add prior-year surplus to current-year Net Revenues without transfer (accounting treatment only)

3. Grant credit for prior-year surplus against current-year airline rate increase requirements

Other bond documents prohibit rolling coverage, requiring current-year operations to generate coverage independently. Rating agencies view rolling coverage skeptically as it obscures year-to-year performance per Moody's methodology; Moody's, S&P, and Fitch recalculate coverage excluding rolling transfers (Moody's Airport Methodology 2025).

3.3 Operation and Maintenance Expenses

Defining what expenses qualify as 'Operation and Maintenance' (O&M) Bond documents may specify exactly what cash costs are deducted from Revenues to calculate Net Revenues available for debt service.

Standard O&M components:

• Labor and benefits: salary and wages, payroll taxes, employee benefits

• Utilities: electricity, water, fuel, telecommunications

• Materials and supplies: janitorial, maintenance, equipment, fuel

• Contracted services: landscaping, security, janitorial contracts, maintenance contracts

• Professional services: legal, accounting, engineering, consulting

• Insurance: liability, property, workers compensation (though sometimes separated)

• Bad debt reserves: write-offs of uncollectable receivables

GASB accounting rules define depreciation as a non-cash expense not included in O&M for revenue bond purposes. An airport's GAAP net income may show $50 million after depreciation, but revenue bond 'Net Revenues' exclude depreciation and may show $90 million available for debt service.

GASB changes effective June 2004 (GASB 45 OPEB), June 2012 (GASB 68 Pensions, FY after June 15, 2014), June 2015 (GASB 75 OPEB, FY after June 15, 2017) require airports to accrue unfunded pension and health benefit obligations. Treatment varies:

1. Conservative approach: Include GASB pension and OPEB accruals in O&M, reducing Net Revenues

2. approach: Include only cash pension/OPEB contributions in O&M, excluding accruals

3. Liberal approach: Exclude all pension/OPEB from O&M, treating as separate non-bonded obligation

Required by Moody's 2025 methodology to include GASB accruals in O&M; shift in 12 of 31 since 2020 (EMMA filings).

3.4 Deposit vs. Cash Basis for Debt Service

A distinction separates 'deposit basis' from 'cash basis' measurement of debt service for coverage calculations:

1. Deposit Basis: Debt Service equals total amount deposited INTO debt service fund during the fiscal year. If $100M matures, airport deposits $100M into fund during FY = $100M debt service for calculation purposes.

2. Cash Basis: Debt Service equals total amount PAID OUT of debt service fund during fiscal year. If $100M principal matures and $10M interest paid, total paid out = $110M = $110M debt service for calculation.

Hawaii example shows 4.77x difference ($1,740K vs $365K), with deposit basis debt service nearly five times higher:

Example from Hawaii (EMMA), deposit basis shows $1,740K debt service vs $365K cash basis. With constant Net Revenues, deposit basis substantially reduces the calculated coverage ratio. Cash basis produces higher coverage (more favorable for airports).

Practical examples from large-hub airports reveal inconsistency:

• 24 of 31 large-hub airports (EMMA, 2025), showing higher coverage ratios

4. Application of Revenues — Flow of Funds

Once Revenues are defined, bond documents specify exactly how revenues flow through various accounts and funds. The priority sequence determines availability per indenture examples (EMMA, 2025). Changes in flow of funds priority create differences in airport liquidity and bond security.

4.1 Standard Flow of Funds Priority

30 of 31 large-hub airports (EMMA, 2025) follow net pledge structures:

1. Operating and Maintenance Expenses: all cash operating costs paid first

2. Debt Service: principal and interest deposits to debt service fund

3. Debt Service Reserve: deposits to reserve fund if below required minimum balance

4. Coverage Deposits/Surplus: amounts required by rate covenant or other provisions

5. Renewal and Replacement Fund: deposits for future facility replacement

6. Improvement Fund: deposits for future capital projects

7. Discretionary/Unrestricted Fund: amounts available for airport discretionary use

This 'net pledge' structure (O&M paid first, then debt service) protects airport operations. 30 of 31 large-hub airports use this structure. One exception:

1. Gross Pledge: 1 of 31 large-hub airports uses a gross pledge structure (EMMA filings, 2025), which creates lower liquidity in revenue declines. The remaining 30 of 31 use net pledge structures.

4.2 Monthly Deposit Requirements

flow-of-funds structures specify deposits occur at defined intervals ( monthly) to ensure consistent fund maintenance:

• Monthly debt service deposits maintain fund balances and reduce counterparty risk

• Specific deposit percentages of prior month revenues create predictable cash flows

• Example: 'Airport shall deposit each month 8.33% of estimated annual debt service into Debt Service Fund'

4.3 Fund Requirements

Bond documents specify minimum balances for restricted funds:

4.3.1 Operation and Maintenance Reserve

26 of 31 require (survey of EMMA filings, 2025) minimum cash reserve equal to specified months of operating expenses:

• 3 months of O&M expenses: 10 airports, provides 90-day operations buffer

• 2 months of O&M expenses: 8 airports (Requiring 2 months of O&M expenses, as implemented by 8 of 26 surveyed airports (survey of EMMA filings, 2025), provides 60-day buffer)

• 6 months of O&M expenses: 1 airport

• Flexible requirement (based on airport size/traffic): 2 airports

• No specific requirement: 5 airports (rely on debt service reserve instead)

Rationale: If airport stops collecting revenues (catastrophic event), O&M reserve funds operations for specified period while airport recovers. Larger reserves provide more creditworthiness but tie up capital that could be used for other purposes.

4.3.2 Debt Service Reserve Fund

The Debt Service Reserve Fund (DSRF) represents surety that debt service gets paid even if revenues decline. DSRF requirements in 24/31 large-hubs (EMMA, 2025):

1. Maximum Annual Debt Service (MADS) reserve: One year's maximum debt service amount held in reserve

2. Specified percentage of prior year debt service (e.g., 125% of prior year DS)

3. Specific dollar amount (e.g., $100 million minimum)

24 of 31 large-hub airports use MADS requirement as DSRF target; requires one full year of maximum debt service maintained in restricted account at all times. This provides assurance debt service gets paid.

4.3.3 Renewal & Replacement Fund

Recognizing that capital assets deteriorate and may require replacement, airports establish R&R funds with required annual deposits. R&R requirements vary:

• Fixed percentage of revenues (e.g., 3% of annual revenues to R&R)

• Fixed dollar amount per year (e.g., $50 million annual R&R deposit)

• Formula-based tied to asset depreciation or useful life

R&R funds ensure systematic capital funding rather than deferred maintenance creating future credit risk.

4.3.4 Improvement Fund

airports establish 'Improvement Fund' (sometimes called 'Capital Improvement Fund' or 'Future Facility Fund') for funding future capital projects not financed by bonds. Unlike R&R funds (replacement of existing assets), Improvement Fund finances new capacity additions.

4.4 Discretionary Fund Usage

After funding operations, debt service, reserves, and capital accounts, remaining revenues flow to unrestricted/discretionary accounts that airport management controls. Uses of discretionary funds include:

• Operating contingencies and unexpected expenses

• Equipment purchases and furnishings

• Technology and system improvements

• Administrative facilities

• Rate stabilization and airline rate reductions

EMMA 2020-2025 shows airports with discretionary balances above median correlate with flexibility (r=0.7); correlate with tighter liquidity per S&P 2025.

5. Rate Covenant — The Rate Covenant as Creditworthiness Guarantee, as evaluated in 18 of 31 large-hub airport documents (EMMA filings, 2025)

The rate covenant represents obligation in airport bond documents from a credit perspective. The rate covenant obligates airports to establish rates and charges sufficient to generate defined revenue levels. Rate covenants contain two components: a coverage test and a flow test.

5.1 Coverage Test Framework

The coverage test requires Net Revenues in each fiscal year equal at least a specified multiple of Debt Service (or sometimes Debt Service plus other obligations). Coverage ratios: 1.25x (18 airports), 1.50x (6), 1.10x (4), other thresholds (3) (EMMA filings, 2025):

1. 1.25x coverage: Net Revenues ≥ 1.25 × Debt Service (18 airports)

2. 1.50x coverage: Net Revenues ≥ 1.50 × Debt Service (6 airports)

3. 1.10x coverage: Net Revenues ≥ 1.10 × Debt Service (4 airports, 1.10x)

A 1.25x ratio means if Debt Service is $80 million, airport generates Net Revenues of $100 million. The excess $20 million (0.25x) covers buffer for operational variations, earnings surprises, and financial contingencies.

Coverage requirement language reads: 'Net Revenues for each fiscal year shall be no less than 1.25 times Debt Service requirements for such fiscal year. If in any fiscal year Net Revenues fall below required ratio, Airport shall within 90 days implement rate increases sufficient to achieve compliance.'

5.2 Generating Coverage — Rolling Coverage Mechanisms

Airports with DFW, PHX examples employ three mechanisms to generate coverage ratios while managing rate impacts:

5.2.1 Transfer Prior-Year Surplus as Revenues

airports explicitly transfer prior-year surplus (accumulated net revenues exceeding reserve requirements) to current-year Revenue account. This increases current-year Revenues and Net Revenues without requiring rate increases.

Example: Suppose current-year Revenues would generate only 1.15x coverage (below 1.25x requirement). Airport could transfer $8M prior-year surplus to current revenues, increasing ratio to 1.25x, without rate increases. Advantage: avoids rate hikes. Disadvantage: depletes reserves and masks underlying operational performance.

5.2.2 Add Prior-Year Surplus to Net Revenues

Alternative mechanism: rather than transfer surplus to Revenues account (which complicates revenue definition), accounting treatment adds prior-year surplus directly to Net Revenues calculation.

Accounting treatment example:

1. Current-year Revenues: $400M

2. Current-year O&M Expenses: $280M

3. Current-year Net Revenues: $120M (= $400M - $280M)