Changelog

2026-02-23 — Initial publication.

What is DOT Form 41?

DOT Form 41 represents one of the most comprehensive financial and operational reporting systems for U.S. airlines. Under 49 CFR Part 241, Form 41 is a mandatory submission for U.S. passenger and cargo carriers meeting specific size thresholds. The form has existed in its modern iteration since the late 1970s, following deregulation of the U.S. airline industry in 1978, and traces its lineage to the Civil Aeronautics Board (CAB) era of federal aviation oversight. In 2024, Form 41 remains the primary source of verified, standardized financial data for airline analysis across academia, investment research, regulatory analysis, and airport finance work.

Form 41 is submitted to the U.S. Department of Transportation (DOT) via the Bureau of Transportation Statistics (BTS), which maintains all historical and current filings. The form captures balance sheet data, income statement performance, operating expenses, employment data, fuel costs, aircraft utilization, and segment-level traffic statistics. This makes Form 41 fundamentally different from airline 10-K filings: 10-K filings follow generally accepted accounting principles (GAAP) and are audited by external auditors, while Form 41 follows DOT's Uniform System of Accounts (14 CFR Part 241) and emphasizes operational consistency across carriers.

Who Must File Form 41?

Regulatory requirements for Form 41 are straightforward but important. The DOT requires Form 41 filing from any U.S. air carrier (certificated by the FAA) with annual operating revenues exceeding $20 million. This threshold captures most of the commercial airline industry: the so-called "large certificated carriers" include the three major legacy carriers (United, American, Delta), three major low-cost carriers (Southwest, Spirit, Frontier), several regional carriers (SkyWest, Republic, Endeavor), and specialized carriers (FedEx Feather), among others. Approximately 25–35 carriers file Form 41 in any given year, with the number fluctuating based on airline consolidations, failures, and market entry/exit.

Carriers below the $20 million threshold (typically regional and air taxi operators) are not required to file Form 41. However, regional carriers often file on behalf of their larger operating partners (e.g., SkyWest operating United Express flights). Foreign carriers operating U.S. international routes file a separate international Form 41 derivative, making the database heterogeneous in how international revenue and costs are apportioned.

Filing frequency varies by carrier size and complexity. Large certificated carriers typically file Form 41 monthly, with quarterly and annual consolidations. Some smaller carriers may file quarterly or semi-annually. All filings are due to BTS within specific deadlines (typically 30–45 days after month/quarter end), and BTS publishes the data for public access.

Form 41 Schedules: A Complete Breakdown

Form 41 is organized into distinct schedules, each focusing on a specific financial or operational domain. Understanding the structure is essential for effective analysis.

Income Statement and Operating Revenue Schedules

Schedule P-1 (Operating Revenue and Related Data) is the top-line financial statement. It shows total operating revenues broken down by revenue category: passenger revenue, cargo revenue, mail revenue, incidental revenue (baggage, excess baggage, seat assignments), and "other operating revenue" (codeshare, ancillary services). Schedule P-1 also includes revenue adjustments (passenger revenue refunds, interline settlements) and ends with net operating revenue. For airport finance professionals, Schedule P-1 is essential for understanding how airlines generate revenue and how revenue concentration in passenger operations affects their financial stability.

Schedule P-2 (Operating Expenses by Objective) complements P-1 by presenting total operating expenses. This schedule groups expenses into broad categories: salaries and wages, employee benefits (pensions, health insurance), fuel and oil, maintenance materials and repairs, depreciation and amortization, and other operating expenses. The P-2 schedule is organized by "objective" (what the cost was for) rather than "function" (which airline department incurred it), making it easier for analysts to track specific cost drivers without needing to reconcile departmental allocations.

Operating Expense Detail Schedules

Schedule P-5 (Fuel and Oil Costs) is a dedicated schedule for fuel expenses, broken down by type (jet fuel, aviation gasoline, diesel) and by operating segment (mainline vs. regional). Since fuel is typically 20–35% of airline operating costs and prices fluctuate significantly, Schedule P-5 is critical for understanding fuel hedging strategies, margin sensitivity to energy prices, and CASM decomposition.

Schedule P-6 (Maintenance and Overhaul Costs) details spending on aircraft maintenance, parts, labor, and third-party maintenance contracted to vendor shops. This schedule reveals carrier fleet age, maintenance philosophy (preventive vs. reactive), and aircraft utilization intensity. Older fleets or heavy maintenance programs (like Airbus 380 operations) show higher P-6 expenses.

Schedule P-7 (Depreciation and Amortization) captures non-cash expenses related to aircraft depreciation, leasehold improvements, and intangible assets. This schedule is essential for reconciling operating profit (GAAP) with operating cash flow, and for understanding how different depreciation methods (straight-line vs. accelerated) affect reported earnings.

Schedule P-10 (Employee Count and Cost) provides monthly headcount for various employee categories: flight crews (pilots, flight attendants), mechanics and ground personnel, management and administrative staff, and other groups. This schedule is essential for calculating labor cost per available seat mile (CASM labor) and for tracking hiring/attrition during economic cycles.

Balance Sheet Schedules

Schedule B-1 (Balance Sheet) shows assets, liabilities, and shareholders' equity as of the filing date. Assets include current assets (cash, accounts receivable), property and equipment (aircraft, ground infrastructure, leasehold improvements at airports), and intangible assets (goodwill, operating authorizations). Liabilities include current liabilities (accounts payable, current portion of debt), long-term debt (bonds, loans), and deferred revenue (advance ticket sales, loyalty program liabilities). Equity includes common stock, retained earnings, and accumulated other comprehensive income (AOCI).

Schedule B-43 (Stockholders' Equity) is a supplemental schedule showing changes in shareholders' equity during the period: beginning balance, net income (loss), dividends, share repurchases, other comprehensive income, and ending balance. This schedule is useful for tracking how airlines deploy capital (reinvestment vs. distribution to shareholders) and for understanding shareholder value creation/destruction during economic cycles.

Cash Flow and Capital Schedules

While Form 41 does not include a traditional cash flow statement, Schedule B-1 (balance sheet) and the income statement schedules (P-1, P-2) can be used to construct a simplified statement of cash flows. Operating cash flow is approximated as net income plus depreciation/amortization, minus changes in working capital (accounts receivable, payables). Capital expenditures are inferred from changes in net property and equipment.

How to Access Form 41 Data on BTS TranStats

Accessing Form 41 data is straightforward and free. The Bureau of Transportation Statistics publishes all Form 41 filings on its public website at www.transtats.bts.gov. Here is a step-by-step guide to download data.

Step 1: Navigate to TranStats Home Page

Go to https://www.transtats.bts.gov/. You will see the main TranStats portal with navigation options on the left side. Under "Resources," look for the "Data Finder" section. Click on "Aviation" to access the aviation data library.

Step 2: Select Form 41 Database

Once in the Aviation Data Library, scroll to find "Form 41 Financial Data." You will see options for:

• DB10 (Form 41 Financial Data) — This is the primary database containing all financial schedules (P-1, P-2, P-5, P-6, P-7, P-10, B-1, B-43) by carrier, year, and month/quarter.
• Schedule-specific databases — Some versions of TranStats allow direct queries to specific schedules (e.g., Schedule P-1 only, Schedule B-1 only).

For comprehensive analysis, use DB10. Click on the DB10 link or "Query Form 41 Financial Data."

Step 3: Use the Query Builder

TranStats provides a query builder interface that allows you to filter by:

• Year/Quarter or Year/Month — Select the time period of interest. Full-year 2024 data is available; 2025 data is being added as carriers file.
• Carrier — Select specific airlines (e.g., American, United, Delta, Southwest) or all carriers in a single query.
• Schedule — Choose which financial schedules to download (P-1, P-2, P-5, etc.).
• Data format — Choose CSV, Excel, or XML format for download.

Example: To analyze United Airlines' operating expenses for Q4 2024, select "United Airlines," "Q4 2024," "Schedule P-2," and download as CSV.

Step 4: Download Data

Click "Download" or "Get Data." TranStats will generate a .zip file containing the requested data. Most downloads are available immediately; large queries may take a few seconds. Unzip the file to access CSV or Excel files ready for analysis in spreadsheet or statistical software.

Alternative: Direct BTS Submission Data

If TranStats query tools are unavailable or slow, you can access raw Form 41 data directly at:

https://esubmit.rita.dot.gov/ (BTS e-Submit Portal)

This portal allows you to query and download Form 41 submissions in real-time as carriers file them. However, the interface is less user-friendly than TranStats, and it is primarily used by industry professionals and researchers.

How Analysts Use Form 41 Data

Form 41 data is the foundation for multiple types of airline financial analysis used in airport finance, investment research, and regulatory work.

CASM Decomposition

Cost per Available Seat Mile (CASM) is perhaps the most critical metric in airline financial analysis. CASM is calculated as:

CASM = Total Operating Expenses ÷ Available Seat Miles (ASMs)

Form 41 provides total operating expenses in Schedule P-2. Analysts then decompose CASM into component parts using the individual expense schedules:

• Fuel CASM = Fuel costs (Schedule P-5) ÷ ASMs
• Labor CASM = Salaries + benefits (Schedule P-1) ÷ ASMs
• Maintenance CASM = Maintenance costs (Schedule P-6) ÷ ASMs
• Depreciation CASM = Depreciation (Schedule P-7) ÷ ASMs
• CASM ex-fuel = (Total operating expenses – fuel) ÷ ASMs

This decomposition reveals which airlines have structural cost advantages. For example, Southwest's lower CASM is driven by higher aircraft utilization (more ASMs per aircraft), lower labor costs per ASM (due to wages and staffing efficiency), and simpler operations (no international routes, no hub-and-spoke complexity).

Unit Revenue Analysis (TRASM and RASM)

Unit Revenue Analysis complements CASM analysis by examining revenue efficiency. Key metrics include:

• Total Revenue Available Seat Mile (TRASM) = Total operating revenue (Schedule P-1) ÷ ASMs
• Revenue per Available Seat Mile (RASM) = Passenger revenue only ÷ ASMs
• Yield = Total passenger revenue ÷ Revenue passengers
• Load factor = Revenue passengers ÷ Capacity (seats available)

Trends in TRASM reveal pricing power and demand. During economic downturns, TRASM typically falls as load factors decline and yield (price per passenger) drops. Premium carriers (United, American, Delta) typically achieve higher TRASM due to premium cabin revenue and ancillary services; low-cost carriers (Southwest, Spirit, Frontier) achieve lower TRASM but offset with lower CASM.

Profitability Benchmarking

Form 41 data enables direct comparison of operating margins and profitability across carriers:

Operating Margin = (Operating Revenue – Operating Expenses) ÷ Operating Revenue

Over a full year, profitable carriers typically achieve 5–15% operating margins; thin margins (0–5%) indicate competitive pressure or cost control issues; negative margins indicate losses. By comparing year-over-year operating margins alongside CASM and TRASM trends, analysts can diagnose whether a carrier's profitability is driven by cost discipline or revenue strength.

Debt Service Coverage and Financial Health

Form 41 balance sheet data (Schedule B-1) allows calculation of debt metrics essential for evaluating airline financial health, especially for airport finance professionals monitoring airline stability:

• Debt-to-EBITDA = Total debt ÷ (Operating income + depreciation)
• Interest coverage = Operating income ÷ Interest expense
• Net debt = Total debt – cash and equivalents

High debt levels relative to EBITDA (above 4–5x) indicate financial stress and risk of covenant violations or credit rating downgrades. This information is essential for airports assessing whether an airline partner can sustain capacity commitments or may exit a route.

Limitations and Caveats of Form 41 Data

While Form 41 is a comprehensive source, analysts must understand its limitations.

Allocations and Cross-Subsidies

Form 41 presents financial data at the carrier level (e.g., "United Airlines, Inc."), not at the business unit level. This means that international and domestic operations are commingled, and joint costs (headquarters rent, IT infrastructure, executive salaries) are allocated across business units using carrier-determined methodologies. Two carriers may allocate identical costs differently, making cross-carrier comparisons imprecise on component metrics.

Timing Differences

Form 41 filings have a lag of 30–45 days after month-end, and quarterly/annual consolidations may be delayed further due to audit requirements. Analysts seeking real-time insights into airline financial performance often rely on earnings press releases and earnings call transcripts (from quarterly investor calls), which are released faster but with less detailed financial statements.

Depreciation Methodologies

Airlines choose depreciation schedules for aircraft and equipment, leading to different reported earnings under GAAP. Form 41 requires standardized depreciation guidance, but the underlying asset lives and residual values still vary by carrier. This can distort net income and equity comparisons across carriers.

Foreign Currency and International Operations

Airlines with significant international operations (United, American, Delta, Delta) report foreign currency gains and losses that can swing earnings. Form 41 consolidates all currencies into U.S. dollars, but the underlying foreign exchange volatility is a material business risk not fully captured in historical financial statements.

Form 41 vs. 10-K: Different Perspectives on Airline Finance

Airlines file both Form 41 with the DOT and 10-K annual reports with the SEC. While both are audited and comprehensive, they follow different accounting frameworks and serve different purposes.

Dimension	Form 41 (DOT)	10-K (SEC)
Accounting Standard	Uniform System of Accounts (14 CFR Part 241)	GAAP (Generally Accepted Accounting Principles)
Filing Frequency	Monthly (large carriers), quarterly, annual	Annual (quarterly 10-Q)
Primary Users	Researchers, airport finance, regulatory analysis	Investors, creditors, analysts
Cost Presentation	By objective (by expense type); operational detail	By function or object; consolidated
Segment Reporting	Mainline vs. regional; domestic vs. intl	Geographic and by business unit
Traffic Data	Detailed (passengers, ASMs, RPMs, seats)	Summary in MD&A section

For airport finance professionals, Form 41 is preferred because it provides monthly operational and financial data in a standardized format, making trend analysis and carrier comparison more reliable. 10-K reports are valuable for understanding management strategy and forward guidance, but the delay in filing and GAAP flexibility make them less suitable for ongoing financial monitoring.

Historical Context: Form 41 Since the CAB Era

Form 41 is not a new requirement. Its lineage traces to the Civil Aeronautics Board (CAB) era (1938–1978), when the CAB regulated airline rates and schedules and required detailed financial reporting to support regulatory decisions. After deregulation in 1978, Congress maintained Form 41 reporting requirements as a mechanism for monitoring airline financial health and supporting safety/security oversight.

The current Form 41 structure was formalized in the 1980s and has remained largely unchanged, reflecting the DOT's goal of maintaining long-term consistency in airline financial data. This consistency is invaluable for academic research, long-term trend analysis, and regulatory benchmarking.

Over the past 40+ years, Form 41 data has documented airline industry evolution: the rise of low-cost carriers (Southwest, JetBlue, Spirit, Frontier) and their impact on incumbent carriers; the impact of major events (9/11, the 2008 financial crisis, COVID-19 pandemic) on airline profitability; and shifts in fleet composition (from large wide-body aircraft to regional jets and back again). This historical depth makes Form 41 essential for understanding airline dynamics.

Practical Applications for Airport Finance Professionals

Airport operators and financial professionals use Form 41 data for several critical functions:

Airline Partner Financial Monitoring: By tracking an airline's CASM, operating margin, and debt ratios over time, airports can assess whether a key airline partner is financially healthy or at risk of reducing service, capacity, or route network. Early warning signs include declining TRASM, rising CASM-ex-fuel (indicating cost pressure), or deteriorating debt metrics.

Rate and Charge Benchmarking: Form 41 data reveals how much of airline costs are attributable to airport charges (landing fees, terminal rents, gate rents, ground handling). By comparing airport cost burdens across airports served by the same airline, benchmark analyses can identify whether a particular airport's charges are competitive or above market.

Capacity Planning: Trends in carrier-wide ASMs, aircraft type, and profitability inform whether an airline is likely to expand, maintain, or contract service at a given airport. An airline with rising CASM and declining margins may pull capacity from competitive secondary airports to concentrate resources at primary hubs.

Revenue Forecasting: Airport terminal rental income, concession fees, and cargo facilities revenue often scale with airline profitability and passenger growth. Understanding carrier-level TRASM and revenue per passenger helps forecast airport revenue growth.

Accessing Historical Form 41 Data

BTS maintains archives of Form 41 data back to the 1990s, with some schedules available from the 1980s. To access historical data:

1. Visit https://www.transtats.bts.gov/ and use the Data Finder to access "Form 41 Financial Data — Historical"
2. Select the year/quarter range of interest
3. Download data in bulk or by carrier
4. For data older than 1995, contact BTS directly or consult archived documents at the BTS library

Researchers analyzing long-term airline trends (20+ years) often combine Form 41 data with supplemental sources: SEC 10-K filings (which started in 1995), airline investor relations earnings reports, and academic databases like MIT's Airline Data Project.