UNITED STATES

Securities registered pursuant to Section 12(g) of the Act: None

This document is also available on our website at http://ir.delta.com/.

Unless otherwise indicated or the context otherwise requires, the terms "Delta," "we," "us," and "our" refer to Delta Air Lines, Inc. and its subsidiaries.

FORWARD-LOOKING STATEMENTS

Statements in this Form 10-K (or otherwise made by us or on our behalf) that are not historical facts, including statements about our estimates, expectations, beliefs, intentions, projections or strategies for the future, may be "forward-looking statements" as defined in the Private Securities Litigation Reform Act of 1995. Forward-looking statements involve risks and uncertainties that could cause actual results to differ materially from historical experience or our present expectations. Known material risk factors applicable to Delta are described in "Risk Factors Relating to Delta" and "Risk Factors Relating to the Airline Industry" in "Item 1A. Risk Factors" of this Form 10-K, other than risks that could apply to any issuer or offering. All forward-looking statements speak only as of the date made, and we undertake no obligation to publicly update or revise any forward-looking statements to reflect events or circumstances that may arise after the date of this report.

Part I

As a global airline based in the U.S.,United States, we connect customers across our expansive global network.network with a commitment to industry-leading customer service, safety and innovation. In 2019, prior to the onset of the COVID-19 pandemic,2023, we served approximately 200over 190 million customers and were the world’s largest airline by total revenues and the most profitable with five consecutive years of $5 billion or more in pre-tax income from 2015 through 2019. In 2020, we made significant adjustments to our network and operations as a result of the unprecedented and widespread impact of COVID-19 and the related travel restrictions and social distancing measures that significantly reduced demand for air travel.

We have fiveThe competitive advantages that support our trusted consumer brand includinginclude our people and culture, ouroperational reliability, global network, our operational reliability, our customer loyalty and our financial foundation. Through the pandemic, we believe that we have strengthened our advantages and our brand. In 2021,2023, we continued to havedifferentiate Delta from the world’s most valuable airline brand.industry by strengthening our competitive advantages.

People and Culture

Global Network

We and our alliance partners collectively serve over 130 countries and territories and over 800700 destinations around the world. In 2019, prior to the onset of the COVID-19 pandemic, we offered more than 5,000 daily departures and as many as 15,000 affiliated departures including the premier SkyTeam alliance, of which Delta is a founding member. At the end of 2021,2023, we offered more than 4,000 daily departures and approximately 5,500 affiliated departures as we began restoring our network.flights to more than 280 destinations on six continents.

Our global network is supported by a fleet of approximately 1,2001,273 aircraft as of December 31, 20212023 that are varied in size and capabilities, giving us flexibility to adjust aircraft to the network. PriorWe are continuing to the pandemic, we began refreshingrefresh our fleet by acquiring new and more fuel efficientfuel-efficient aircraft with increased premium seating and cargo capacity to replace older aircraft, and had begun to reduceretiring aircraft. Simultaneously, we continue on our fleet complexity with fewer fleet types. We accelerated thismulti-year journey of fleet simplification strategy by replacing retiring 227 aircraft in 2020, with plans to retire additionaldeliveries of next-generation aircraft. In 2023, we took delivery of 43 aircraft, by 2025, though we remain flexibleincluding new A321neos, A220-300s and may decide to fly certain aircraft beyond their planned retirement date, to the extent supported by demand.A330-900s. Our new aircraft delivered since 2019 are on average 25%28% more fuel efficient per seat mile than retiringaircraft retired since 2019. In January 2024, we entered into a purchase agreement with Airbus for 20 A350-1000 aircraft, with an option to purchase an additional 20 widebody aircraft. Deliveries of these aircraft are scheduled to begin in 2026.

Customer Loyalty

Our award-winning SkyMiles program, discussed in further detail below, is designed to attract lifetime members and to grow customer loyalty by offering incentives to increase travel with us. Our award-winning program offersour customers a wide variety of benefits including award travel and access to complimentary elite benefits and services when traveling with us and our partners. Aspartners, and personalizing our brand has strengthened,engagement with them. We aim to increase the value of our program for customers and to deepen customer engagement with Delta through a growing ecosystem of partnerships with premier brands, extending the value of our SkyMiles program has seen an acceleration in membership growth.currency beyond flight and introducing new technology initiatives. We believe there is opportunity to continue this trend asand expect the increased value we seekprovide customers to elevate our customer engagement through opportunities to earndeliver high-margin revenue and redeem mileage credits (“miles”) as well as co-brand card offerings coupled with a strong customer experience. The SkyMiles program has a large, growing and premium membership base. This membership base has historically resulted in higher premium revenues and more resilient cash flows for us. SkyMiles has been widely recognized as a top loyalty program by external reviewers such as U.S. News and World Report and The Points Guy.

Financial Foundation

In response to2023, we made significant progress restoring our financial foundation with strong profitability and $2 billion of free cash flow for the effectsyear. Our financial results are discussed in more detail in "Item 7. Management's Discussion and Analysis," which includes definitions and reconciliations of non-GAAP financial measures, including free cash flow, under the COVID-19 pandemic, we raised significant amounts of liquidity in 2020 through the issuance of debt securities or through bilateral and syndicated secured and/or unsecured credit facilities and through the entry into sale-leaseback transactions. Our capital raising efforts were aided by the strength of our balance sheet prior to the pandemic. "Supplemental Information" section.

Restoring the strength of our balance sheet and reducing debt is a key financial priority. During 2021,2023, we executed on our financial priority of stabilizingrepaid approximately $4.1 billion in debt and finance lease obligations and the business on the pathcompany remains committed to restoration and recovery. Since October 2020, we have made progress in restoring our balance sheet by reducing our debt by approximately $12 billion and voluntarily contributing $1.5 billion to our pension plans. We continue to be disciplined in managing non-fuel costs. We are efficiently rebuilding the airline, capturing fleet renewal benefits and driving operating leverage that we expect to produce a competitive cost structure. We expect that our unit revenue premium to the industry and competitive cost structure will support industry-leading margins and strong operating cash flow.regaining investment grade metrics.

Our tickets are soldpremium yield growth has significantly outpaced main cabin, with record paid load factors in premium cabin in 2023, as demand for premium products continues to grow. In 2023, we grew our mix of premium seats, including the continued expansion of Delta Premium Select. The sale of premium products is facilitated through various distribution channels, with 64%62% of tickets sold through direct channels in 2021.2023. These include digital channels, such as delta.com and the Fly Delta app, which surpassed one billion visits in 2023, delta.com and our reservations specialists where we deliver more direct, personalized interactions with our customers at reduced distribution costs.specialists. Indirect distribution channels include online travel agencies and traditional "brick and mortar" agencies. We make fare and product information widely available across those channels in an effort to ensure customers receive the best information and service options.options, further supporting the growth of premium products.

In recent years,Our SkyMiles program provides members with the ability to earn mileage credits ("miles") when traveling on Delta, Delta Connection and our partner airlines. Miles may also be earned by using certain services offered by program partners, such as credit card, retail, ridesharing, car rental and hotel companies. To facilitate transactions with participating companies, we have diversified revenue streams beyond the basic sale of an airline ticket in an effortsell miles to reduce the impact of cyclicalitynon-airline businesses and other reductions in air travel demand on our results. Our partnership with American Express provides us a co-brand revenue stream tied to broader consumer spending. Our continued focus on premium products and customer segmentation enhanced our revenue growth prior to the pandemic and reduced reliance on the most price sensitive customer segment, a differentiator that we believe has benefited us during the pandemic. We also maintain complementary portfolio businesses, such as our cargo business, which has grown significantly during the pandemic, and our Maintenance, Repair and Overhaul (“MRO”) operation, where we believe we remain well positioned for growth through contractual agreements with jet engine manufacturers.

Our objective is to make technology a strategic differentiator. We continue to invest in technological improvements that enhance the customer experience, support our operations and provide tools forempower our employees.people. These investments include innovations to customer facing applications and improvements to infrastructure and technology architecture to unify and improve access to data sources and continuing innovations to customer facing applications.sources. We believe this digital transformation enhances interactions with our customers and allows our people to deliver more personalized service, further enhancing the customer experience, and strengthening our brand.brand and driving revenue and efficiency.

Through the development of innovative new technologies, we can better serve customers and give our employees the best tools. For our customers, we are making investments in the digital platforms on the ground and in the airport and onboard our aircraft.air. We are evolvingcontinue to evolve the Fly Delta app into a digital travel concierge for our customers to offer convenient services on the day of travel and deliver thoughtful notifications to make their travel journeys more seamless. InOn the airport,ground, we are investing to create a smoother, less stressful and increasingly contactless travel experience. Onboard the aircraft, we continue to invest in in-flight entertainment and announced fast and free Wi-Fi for all customers through a free SkyMiles account on most domestic mainline flights, with free messagingplans for full availability on international and improved Wi-Fi connectivity. Asregional aircraft. We also introduced Delta Sync, which will enable the creation of December 31, 2021, approximately 95% of our mainline aircraft were equippedmore personalized experiences over the next several years and further elevate the consumer experience across the travel journey, including partnerships with seat-back screens.leading brands. For our employees, we are investing in applications that allow our people to have more meaningful interactions with our customers, as well as tools to make our employees safer and better able to do their jobs.customers.

Each of our joint venture or cooperation arrangements provides for joint commercial cooperation with the relevant partner within the geographic scope of the arrangement, including the sharing of revenues and/or profits and losses generated by the parties on the joint venture routes, as well as joint marketing and sales, coordinated pricing and revenue management, network and schedule planning and other coordinated activities with respect to the parties' operations on joint venture routes. Our implemented commercial joint venturesventures/cooperation agreements consist of the following:

We have air service agreements with domestic regional air carriers that feed traffic to our route systemnetwork by serving passengers primarily in small and medium-sized cities in the domestic market. These arrangements enable us to better match capacity with demand in these markets.

Our contractual agreements with regional carriers are primarily capacity purchase arrangements, under which we control the scheduling, pricing, reservations, ticketing and seat inventories for the regional carriers' flights operating under our "DL" designator code. We are entitled to all ticket, cargo, mail, in-flight and ancillary revenues associated with the flights under these capacity purchase arrangements. We pay those airlines an amount, as defined in the applicable agreement, which is based on a determination of their cost of operating those flights and other factors intended to approximate market rates for those services. These capacity purchase agreements are long-term agreements, usually with initial terms of at least ten years, which grant us the option to extend the initial term. Certain of these agreements provide us the right to terminate the entire agreement, or in some cases remove some of the aircraft from the scope of the agreement, for convenience at certain future dates.

SkyWest Airlines operates some flights for us under a revenue proration agreement. This proration agreement establishes a fixed dollar or percentage division of revenues for tickets sold to passengers traveling on connecting flight itineraries.

During 2021,In 2023, we built onoutlined our previouslyroadmap to a more sustainable future of travel that details our strategy for achieving net-zero greenhouse gas emissions from our airline operations by 2050. As part of this roadmap, we announced plan to invest $1.0 billion through the endshort-, medium- and long-term milestones which will help us measure and report progress towards our ultimate net-zero goal. In 2023, we made progress toward achievement of 2030 toward airline carbon neutrality (the “$1.0 billion airline carbon neutrality goal”) by announcing our intention to set new climate goals that are aligned with the applicable framework of the Science Based Targets initiative (“SBTi”):across three key areas:

The global aviation industry is viewed as a hard-to-abate"hard-to-abate" sector, meaning it is innately difficult to decarbonize. We expectAchieving our path toward achievementlong-term goals will require substantial expansion of these ambitious climate goalsthe SAF market, the adoption of new technologies, engagement from both internal and external stakeholders, as well as partnerships across industries to include the following levers, with the fleetincrease production of alternative fuels and fuel levers expected to play the most significant roles:help drive down costs.

Human Capital and Commitment to Diversity, Equity and Inclusion

We believe that the Delta people and culture are our strongest competitive advantage, and the high-quality service that theyour employees provide sets us apart from other airlines. As of December 31, 2021,2023, we had approximately 83,000103,000 full-time employee equivalents, of which approximately 81,000100,000 were based in the U.S. In 2021, as our business began to recover from the impact of the COVID-19 pandemic, we hired approximately 11,000 new full-time employees across our business, including pilots, flight attendants, and gate and reservation agents.

The health and safety of our employees is foundational to achieving these objectives. We have long led the airline industry in employeeDelta's Safety Management System is central to promoting a positive safety culture, proactively managing safety risk, and seekmaking investments to achieve world-class personal safety performance. We have prioritized the health and safety ofensure a safe experience for our employees by offering an extensive employee COVID-19 testing program, partnering with Georgia to host the state’s largest COVID-19 vaccination site while steadily increasing the vaccination rate among our employees, providing pay protection programs for employees diagnosed with, exposed to or at high risk from COVID-19 and offering free flu shots for all U.S. employees.customers.

We continued to our employees, with more than62,000 employees participating. We also investedinvest in our leadership’s equity educationlearning and understanding in 2023, with nearly 30%80% of officers participating in aour voluntary two-day racial equity workshop in 2021 and the remaining officers slated to participate by the end of 2022. 2023. In 2023, we also introduced a new diversity, equity and inclusion education program, building on foundational learnings through a multitude of different training offerings.

In addition, we are reviewing and revising systems, practices and policies in support of our commitment to diversity, equity and inclusion and with a focus on achieving equitable outcomes. Two key areas on which we are focused are (1) reinforcement of our diverse talent pipeline by, among other things, requiring hiring candidate slates and interview panels to reflect diversity, and creating newtaking a proactive approach to build internal and external career pathways to certain roles by removing college degree requirements and introducing a skills-first talent approach, and (2) closing diversity gaps in senior leadership positions by increasing the representation of women, Black and other ethnic minorityLatin/Hispanic groups in those roles, including doubling the number of Black officers and director-level employees by 2025 as compared to 2020.

We also believe that listening, engaging and connecting with employees furthers our human capital management objectives. We have historically done so primarily through our open-door policy, digital communication across all levels of the company, in-person events with senior management and company-wide and division-specific surveys to evaluate employee satisfaction. Since the onsetMembers of the pandemic, senior management has participatedparticipate in regular company-wide town hall discussions with our employees and our senior executive leadership team has regularly sharedshares memos with all employees regarding our ongoing commitment to our people and our culture. We have also continued to conduct periodic employee surveys to seek feedback on engagement levels in general, our well-beingwellbeing programs, diversity, equity and inclusion efforts and our culture of safety.

Collective Bargaining

Labor unions periodically engage in organizing efforts to represent various groups of our employees, including at our operating subsidiaries, that are not represented for collective bargaining purposes.

Our results of operations are significantly impacted by changes in the price and availability of aircraft fuel. We purchase most of our aircraft fuel under contracts that establish the price based on various market indices and therefore do not provide material protection against price increases or assure the availability of our fuel supplies. We also purchase aircraft fuel on the spot market, from off-shoreoffshore sources and under contracts that permit the refiners to set the price. We are currently able to obtain adequate supplies of aircraft fuel, including fuel produced by Monroe or procured through the exchange of gasoline, diesel and other refined petroleum products ("non-jet fuel products") the refinery produces, and crude oil for Monroe's operations.

The following table shows our aircraft fuel consumption and costs, which were materially reduced in 2020 and 2021 in large part due to our reduced operations in response to the COVID-19 pandemic.costs:

Our Monroe subsidiaries operate the Trainer refinery and related logistics assets located near Philadelphia, Pennsylvania. The facilities include pipelines and terminal assets that allow the refinery to supply jet fuel to our airline operations throughout the Northeastern U.S., including our New York hubs at LaGuardia and JFK. These companies are distinct from us, operating under their own management teams and with their own boards. We own Monroe as part of our strategy to mitigate the cost of the refining margin reflected in the price of jet fuel, as well as to maintain sufficiency of supply to our New York operations.

Fuel Hedging Program

Our derivative contracts to hedge the financial risk from changing fuel prices are primarily related to Monroe’s inventory. We may utilize different contract and commodity types in this program and frequently test their economic effectiveness against our financial targets. We closely monitor the hedge portfolio and rebalance the portfolio based on market conditions, which may result in locking in gains or losses on hedge contracts prior to their settlement dates.

The airline industry is highly competitive, marked by significant competition with respect to routes, fares, schedules (both timing and frequency), operational reliability, services, products, customer service and loyalty programs. The industry has evolved through mergers, and new entry,entries, both domestically and internationally, and evolutionchanges in international alliances. Consolidation in the airline industry, the presence of subsidized government sponsoredgovernment-sponsored international carriers, changes in international alliances and the creation of immunized joint ventures have altered, and will continue to alter, the competitive landscape in the industry, resulting in the formation of airlines and alliances with significant financial resources, extensive global networks and competitive cost structures.

Domestic

Our domestic operations are subject to significant competition from traditional network carriers, including American Airlines and United Airlines, national point-to-point carriers, including Alaska Airlines, JetBlue Airways and Southwest Airlines, and other discount or ultra-low-cost carriers, including SpiritAllegiant Air, Avelo Airlines, Breeze Airways, Frontier Airlines and Allegiant Air, someSpirit Airlines. Some of which maythese carriers have lowerbusiness models primarily focused on maintaining low costs, than we do and providewith the intention of providing service at lowlower fares to destinations served by Delta. In particular, we face significant competition at our domestic hubs and key airports either directly at those airports or at the hubs of other airlines that are located in close proximity. We also face competition in smallersmall- to medium-sized markets from regional jet operations of other carriers.

International

Our international operations are subject to competition from both foreign and domestic carriers, including from point-to-point carriers on certain international routes. Through alliance and other marketing and codesharing agreements with foreign carriers, U.S. carriers have increased their ability to sell international transportation, such as services to and beyond traditional European, Asian and AsianLatin American gateway cities. Similarly, foreign carriers have obtained increased access to interior U.S. passenger traffic beyond traditional U.S. gateway cities through these relationships.

In particular, several joint ventures among U.S. and foreign carriers, including several of our joint ventures as well as those of our competitors, have received grants of antitrust immunity allowing the participating carriers to coordinate networks, schedules, pricing, sales and inventory. In addition, alliances formed by domestic and foreign carriers, including SkyTeam, the Star Alliance (among United Airlines, Lufthansa German Airlines, Air Canada and others) and the oneworld alliance (among American Airlines, British Airways, Qantas and others) have enhanced competition in international markets.

The DOT and the Federal Aviation Administration (the "FAA") exercise regulatory authority over air transportation in the U.S. The DOT has authority to issue certificates of public convenience and necessity required for airlines to provide air transportation. An air carrier that the DOT finds fit, willing and able to perform the proposed service is given authority to operate domestic and international air transportation (including the carriage of passengers and cargo), as applicable. Since the passage of the Airline Industry Deregulation Act in 1978, airlines have generally been free to launch or terminate service to U.S airports without restriction, except with respect to certain slot-controlled and schedule-facilitated airports, as well as certain constraints related to service to small communities governed by the "Essential Air Services" program. The Coronavirus Aid, Relief, and Economic Security Act of 2020 (the "CARES Act") created certain continuation of service obligations in connection with the receipt of payroll support program funds by passenger airlines. Specifically, the DOT has the authority until March 1, 2022 to require airlines that received such funds to maintain scheduled air service deemed necessary to any point served by the airline before March 1, 2020. The DOT has issued several orders mandating such service, the most recent of which was finalized on April 29, 2021, mandating service levels through September 30, 2021, subject to certain definitions and exceptions as described in the order.

The DOT has jurisdiction over certain economic and consumer protection matters, such as unfair or deceptive practices and methods of competition, advertising, denied boarding compensation, baggage liability and disabled passenger transportation. The DOT also has authority to review certain joint venture agreements between domestic and international carriers. The DOT engages in regulation of economic matters such as transactions involving allocation of "slots" or similar regulatory mechanisms which limit the rights of carriers to conduct operations at airports where such mechanisms are in place. The FAA has primary responsibility for matters relating to the safety of air carrier flight operations, including airline operating certificates, control of navigable air space, flight personnel, aircraft certification and maintenance and other matters affecting air safety.

Authority to operate international routes and international codesharing arrangements is regulated by the DOT and by the governments of the foreign countries involved. International certificate authorities are also subject to the approval of the U.S. President for conformance with national defense and foreign policy objectives.

The Transportation Security Administration ("TSA") and the U.S. Customs and Border Protection, each a division of the Department of Homeland Security, are responsible for certain civil aviation security matters, including passenger and baggage screening at U.S. airports and international passenger prescreening prior to entry into or departure from the U.S.

Airlines are also subject to various other federal, state, local and foreign laws and regulations. For example, the U.S. Department of Justice has jurisdiction over some airline competition matters. The U.S. Postal Service has authority over certain aspects of the transportation of mail. Labor relations in the airline industry, as discussed below, are generally governed by the Railway Labor Act with oversight by the NMB.National Mediation Board ("NMB"). Environmental matters are regulated by various federal, state, local and foreign governmental entities. Privacy of passenger and employee data is regulated by domestic and foreign laws and regulations.

Fares and Rates

Airlines set ticket prices in all domestic and most international city-pairs with minimal governmental regulation, and the industry is characterized by significant price competition. Certain international fares and rates are subject to the jurisdiction of the DOT and the governments of the foreign countries involved. Many of our tickets are sold by travel agents, and fares are subject to commissions, overrides and discounts paid to travel agents, brokers and wholesalers.

Route Authority

Our flight operations are authorized by certificates of public convenience and necessity and also by exemptions and limited-entry frequency awards issued by the DOT. The requisite approvals of other governments for international operations are controlled by bilateral agreements (and a multilateral agreement in the case of the U.S. and the European Union)Union ("EU")) with, or permits or approvals issued by, foreign countries. Because international air transportation is governed by bilateral or other agreements between the U.S. and the foreign country or countries involved, changes in U.S. or foreign government aviation policies could result in the alteration or termination of such agreements, diminish the value of our international route authorities or otherwise affect our international operations. Bilateral agreements between the U.S. and various foreign countries that we serve are subject to renegotiation from time to time. The U.S. government has negotiated "Open Skies" agreements with many countries, which allow unrestricted access between the U.S. and these foreign markets.

Certain of our international route authorities are subject to periodic renewal requirements. We request extension of these authorities when and as appropriate. While the DOT usually renews temporary authorities on routes where the authorized carrier is providing a reasonable level of service, there is no assurance this practice will continue in general or with respect to a specific renewal. Dormant route authorities may not be renewed in some cases, especially where another U.S. carrier indicates a willingness to provide service.

Airport Access

Operations at three major domestic airports and certain foreign airports that we serve are regulated by governmental entities through allocations of "slots" or similar regulatory mechanisms. Each slot represents the authorization to land at or take off from the particular airport during a specified time period.

In the U.S., the FAA currently regulates the allocation of slots, slot exemptions, operating authorizations or similar capacity allocation mechanisms at Reagan National in Washington, D.C. and LaGuardia and JFK in the New York City area. Our operations at these airports generally require the allocation of slots or analogous regulatory authorizations. Similarly, our operations at London's Heathrow airport, Tokyo's Haneda airport and other international airports are regulated by local slot coordinators pursuant to the International Air Transport Association's Worldwide Scheduling Guidelines and applicable local law. We currently have sufficient slots or analogous authorizations to operate our existing flights, and we have generally been able to obtain the rights to expand our operations and to change our schedules. There is no assurance, however, that we will be able to do so in the future because, among other reasons, such allocations are subject to changes in governmental policies.

Airline Labor Regulation

In the U.S., airlines and labor unions are governed by the Railway Labor Act. Under the Railway Labor Act, a labor union seeking to represent an unrepresented craft or class of employees is required to file with the NMB an application alleging a representation dispute, along with authorization cards signed by at least 50% of the employees in that craft or class. The NMB then investigates the dispute and, if it finds the labor union has obtained a sufficient number of authorization cards, conducts an election to determine whether to certify the labor union as the collective bargaining representative of that craft or class. A labor union will be certified as the representative of the employees in a craft or class if more than 50% of votes cast are for representation. A certified labor union would then commence negotiations toward a collective bargaining agreement with the employer.

Under the Railway Labor Act, a collective bargaining agreement between an airline and a labor union does not expire, but instead becomes amendable as of a stated date. Either party may request that the NMB appoint a federal mediator to participate in the negotiations for a new or amended agreement. If no agreement is reached in mediation, the NMB may determine, at any time, that an impasse exists and offer binding arbitration. If either party rejects binding arbitration, a 30-day "cooling off" period begins. At the end of this 30-day period, the parties may engage in “self-help,”"self-help," unless the U.S. President appoints a Presidential Emergency Board ("PEB") to investigate and report on the dispute. The appointment of a PEB maintains the "status quo" for an additional 60 days. If the parties do not reach agreement during this period, the parties may then engage in self-help. Self-help includes, among other things, a strike by the union or the imposition of proposed changes to the collective bargaining agreement by the airline. The U.S. Congress and the President have the authority to prevent self-help by enacting legislation that, among other things, imposes a settlement on the parties.

Environmental Regulation

We are also subject to certain environmental laws and contractual obligations governing the management and release of regulated substances, which may require the investigation and remediation of affected sites. Soil and/or ground water impacts have been identified at certain of our current or former leaseholds at several domestic airports. To address these impacts, we have a program in place to investigate and, if appropriate, remediate these sites. Although the ultimate outcome of these matters cannot be predicted with certainty, we believe that the resolution of these matters will not have a material adverse effect on our Consolidated Financial Statements.

The airline industry may face additional regulation of aircraft emissions in the U.S. and abroad and become subject to further taxes, charges or additional requirements to obtain permits or purchase allowances or emission credits for GHG emissions in various jurisdictions. For example, in 20212023, the European Commission proposedEU adopted legislation that could expand the reachwill impose a SAF mandate on fuel supplied at EU airports. The mandate requires that, of the jet fuel supplied in the EU, ETS to include flights into and out of the EEA beginning in 2027 under certain circumstances, increase the stringency of the program, and establish a sustainable aviation fuel blending mandate for aviation fuel suppliers2% must be SAF beginning in 2025, among other requirements. Individual EU member states have been developing their own requirements, including for example, aand the percentage increases incrementally over time to 70% in 2050. This mandate is expected to increase the cost of SAF mandate in France that will be phased in beginning in 2022. In the United States, various exploratory discussions continue around approaches to address climate change, such as carbon pricing, without a clear legislative path forward.EU. Additional regulation could result in taxation, regulatory or permitting requirements from multiple jurisdictions for the same operations and significant costs for us and the airline industry. In addition to direct costs, such regulation could result in increased fuel costs passed through from fuel suppliers affected by any such regulations. Certain airports have also adopted, and others could in the future adopt, GHG emission or climate-related goals and requirements that could impact our operations or require us to make changes or investments in our infrastructure. We are monitoring and evaluating the potential impact of such developments.

Under the Energy Policy Act of 2005, as expanded by the Energy Independence and Security Act of 2007, the Renewable Fuel Standard ("RFS") was created, setting up specific targets of renewable fuel to be used in the U.S. economy by mandating the blending of renewable fuels into gasoline and on-road diesel ("Transportation Fuels"). Renewable Identification Numbers ("RINs") are assigned to renewable fuels produced by or imported into the U.S. that are blended into Transportation Fuels to demonstrate compliance with this obligation. A refinery may meet its obligation under RFS by blending the necessary volumes of renewable fuels with Transportation Fuels, by purchasing RINs in the open market or through a combination of blending and purchasing RINs. Because Monroe is able to blend only a small amount of renewable fuels, it must purchase the majority of its RINs requirement in the secondary market. Market prices for RINs have been volatile and marked by periods of sharp increases and decreases primarily in response to speculation about what the EPA and/or the U.S. Congress will do with respect to compliance obligations. In December 2021,June 2023, the EPA issued proposedfinalized RFS volume requirements for 2020, 20212023, 2024 and 2022,2025. These volume requirements are below projected production of Transportation Fuels, which are expected to be finalizedhas resulted in a decrease in the first halfprice of 2022. The EPA has not finalized the compliance deadlines to retire our obligations for 2020 and 2021, but we expect those deadlines to be within one year of the effective date of the new RFS volume requirements.RINs.

Civil Reserve Air Fleet Program

We participate in the Civil Reserve Air Fleet program (the "CRAF Program"), which permits the U.S. military to use the aircraft and crew resources of participating U.S. airlines during airlift emergencies, national emergencies or times of war. We have agreed to make available under the CRAF Program a portion of our international aircraft during the contract period endingthat ends on September 30, 2022.2024. The CRAF Program has only been activated three times since it was created in 1951, most recently in 2021 to support the military’s effort to evacuate people from Afghanistan following the withdrawal of U.S. troops from the country. Delta played a central role in transporting 10,000 Afghan refugees that were evacuated from Afghanistan and delivering needed supplies.

In addition to the other information set forth in this report, you should carefully consider the following material risk factors applicable to Delta. As described below, these risks could materially affect our business, financial condition or results of operations in the future.

An aircraft crash or other serious accident involving our aircraft or those of our airline partners could expose Deltaus to significant liability. Although we believe that our insurance coverage is appropriate, we may be forced to bear substantial losses from an accident in the event that the coverage was not sufficient.

In addition, any accident involving an aircraft that we operate or an aircraft that is operated by an airline that is one of our regional carriers or codeshare, alliance or joint venture partners could create a negative public perception about safety and reliability for aviation authorities and the public, which could harm our reputation, resulting in air travelers being reluctant to fly on our aircraft and therefore harm our business.

Breaches or lapses in the security of the technology systems we use and rely on andcould compromise the data stored within them as well as ever-evolving global privacy and security regulatory obligations,consequently expose us to liability, disruption to our operations and damage to our reputation, any or all of which could have a material adverse effect on our business.

As a regular part of our ordinary business operations, we collect and store sensitive data, including information necessary for our operations, personal information of our passengers and employees and information of our business partners. The secure operation of theour networks and systems, and those of our business partners and third-party service providers, on which this type of information is stored, processed and maintained is critical to our business operations and strategy.

We expect unauthorized parties to continue attempting to gain access to our systems or information, or those of our business partners and third-party service providers, including through fraud or other means of deception, or introduction of malicious code, such as viruses, worms, Trojan horsesmalware and ransomware. If successful, these actions could cause harm to our computer systems or compromise data stored on our computer networks or those of our business partners and third-party service providers. For example, we were notified in 2018 that a third-party vendor of chat services for Delta and other companies determined we had been involved in a cyber incident for a short period in 2017. We have incurredproviders, potentially causing us to incur remedial, legal and other costs, in connection with this incident but the costs were not material to our financial position or results of operations.which could be material. Hardware or software we or our business partners or third-party service providers develop, acquire or use in connection with our systems may contain defects that could unexpectedly compromise information security.

The methods used to obtain unauthorized access, disable or degrade service or sabotage systems are constantly evolving and may be difficult to anticipate or to detect for long periods of time. As a result of these types of risks and regular attacks on our systems, we regularly review and update procedures and processes to prevent and protect against unauthorized access to our systems and information and inadvertent misuse of data. In addition to continuously assessing risk and reviewing our procedures, processes and technologies, we continue to educate our peopleemployees about these risks and to monitor, review and update the process and control requirements we expect third parties and vendors to leverage and implement for the protection of information regarding our customers, employees or business partners that is in their care. However, the constantly changing nature of the threats means that we may not be able to prevent all information security breaches or misuse of data. In addition, as cybercriminals become more sophisticated, the cost of proactive defensive measures continues to increase.

We are also subject to evolving global privacy and security regulatory obligations and an increasing customer focus on privacy issues and data security in the United States and abroad, as well as to geopolitical risks associated with international data transfer. The compromise of our or our business partners’ or third-party service providers’ technology systems resulting in the loss, interruption, disclosure, misappropriation of, or access to, our information or that of our customers, employees or business partners could result in legal claims or proceedings, liability or regulatory penalties under laws protecting the privacy and security of personal information, disruption to our operations and damage to our reputation, any or all of which could adversely affect our business. The costs to remediate breaches and similar system compromises that do occur could be material. In addition, as cybercriminals become more sophisticated, the cost of proactive defensive measures continues to increase.

Disruptions of our information technology infrastructure could interfere with our operations, possibly having a material adverse effect on our business.

Disruptions in our information technology capability could result from a technology error or failure impacting our internal systems, whether hosted internally at our data centers or externally at third-party locations, or large scalelarge-scale external interruption in technology infrastructure support on which we depend, such as power, telecommunications or the internet. The operation of our technology systems and the use of related data may also be vulnerable to a variety of other sources of interruption, including natural disasters, terrorist attacks, computer viruses, hackers and other security issues. A significant individual, sustained or repeated failure of our information technology infrastructure, including third-party networks we utilize and on which we depend, could impact our operations and our customer service, result in increased costs and damage our reputation. While we have in place initiatives to prevent disruptions and disaster recovery plans and continue to invest in improvements to these initiatives and plans, we have previously experienced infrastructure disruptions and thesedisruptions. These measures may not be adequate to prevent a future business disruption and any material adverse financial and reputational consequences to our business as recent outages of large cloud providers whom we rely on has shown.

Failure of the technology we use to perform effectively could have a material adverse effect on our business.

We are dependent on technology initiatives and capabilities to provide customer service and operational effectiveness in order to compete in the current business environment. For example, substantially all of our tickets are issued to our customers as electronic tickets, and a growing number of our customers check in using our website, airport kiosks and our FlyDelta mobile application. We have made and continue to make significant investments in customer facing technology such as delta.com, the FlyDelta mobile application, in-flight wireless internet, check-in kiosks, customer service applications, application of biometric technology, airport information displays and related initiatives, including security for these initiatives. We are also investing in significant upgrades to technology infrastructure and other supporting systems and transitioning to cloud-based technologies. The performance, reliability and security of the technology we use are critical to our ability to serve customers. If this technology does not perform effectively, including as a result of the implementation or integration of new or upgraded technologies or systems, our business and operations would be negatively affected, which could be material.

Our business and results of operations are dependent on the price of aircraft fuel. High fuel costs or cost increases, including in the cost of crude oil, could have a material adverse effect on our results of operations.

Our commercial relationships with airlines in other parts of the world and the investments that we have in certain of those carriers may not produce the results or returns we expect.

An important part of our strategy to expand our global network has been to develop and expand strategic relationships with a number of airlines through joint ventures and other forms of cooperation and support, including equity investments. We expect to continue exploring ways to deepen our alliance relationships with other carriers as part of our global business strategy. These relationships and investments involve significant challenges and risks, including that theyjoint ventures or cooperation agreements may be subject to ongoing review and renewal requirements and may not generate the expected financial results, or that we may not realize a satisfactory return on our investment. investments. For example, the DOT's approval of and antitrust immunity grant for our joint cooperation agreement with Aeroméxico is subject to a pending renewal application with the DOT, which was tentatively dismissed pursuant to an Order to Show Cause issued by the DOT on January 26, 2024. The existing immunity remains in effect pending final adjudication of the renewal application, the timing and outcome of which cannot be predicted at this time.

We are dependent on these other carriers for significant aspects of our network in the regions in which they operate.

A significant disruption in, or other problems with respect to, the operations or performance of third parties on which we rely, including third-party carriers, could have a material adverse effect on our business and results of operations.

We rely on the operations and performance of third parties in a number of areas that are important to our business, including third-party regional carriers, international alliance partners and ground operation providers at some airports. While we have agreements with certain of these third parties that define expected service performance, we do not have direct control over their operations. To the extent that the operations of a third partythird-party on which we rely is significantly disrupted including as a result of the pandemic, or if these third parties experience significant performance issues (including failing to satisfy any applicable performance standards) or fail to meet any applicable compliance requirements, our revenue may be reduced, our expenses may be increased and our reputation may be harmed, any or all of which could result in a material adverse effect on our business and results of operations.

Some regional carriers, including our wholly-ownedwholly owned subsidiary, Endeavor, have facedare facing a shortage of qualified pilots.pilots and experiencing operating constraints as a result. If this shortage becomes more widespread, third-party regional carriers may not be able to comply with their obligations to us, and Endeavor may not be able to perform as expected, which could reduce our expected capacity (available seat miles) and affect our revenue, resulting in a material adverse effect on our business and results of operations.

We may never realizeAgreements governing our debt, including our credit facilities and our SkyMiles financing agreements, include financial and other covenants. Certain of these covenants impose restrictions on our business, and failure to comply with any of the full valuecovenants in these agreements could result in events of our intangible assets or our long-lived assets, causing us to record impairments that may materially adversely affect our results of operations.default.

In accordanceOur debt agreements contain various affirmative, negative and financial covenants, including our credit facilities and our SkyMiles financing agreements, each of which contains a minimum liquidity covenant. Certain of our debt agreements and our SkyMiles financing agreements contain minimum coverage ratios. A decline in these coverage ratios, including due to factors that are beyond our control, could trigger an early amortization event or, if applicable, require us to post additional collateral. Our SkyMiles financing agreements also restrict our ability to, among other things, change the policies and procedures of the SkyMiles program in a manner that would reasonably be expected to materially impair repayment of our SkyMiles debt. Complying with applicable accounting standards, we are required to testcertain of the covenants in our goodwilldebt agreements, and other indefinite-lived intangible assets for impairment on an annual basis, or more frequently where there is an indication of impairment. In addition, we are required to test certain of our other assets for impairment where there is an indicationrestrictive covenants that an asset may be impaired. During the fiscal year ended December 31, 2020, we recorded significant impairmentcontained in any future debt agreements, could limit our ability to operate our business and related charges related to accelerationtake advantage of business opportunities that are in our fleet simplification strategy and the write-down of investments in certain airline partners, stemming from the impact of the COVID-19 pandemic.long-term interest.

We may be requiredWhile the covenants in our debt agreements are subject to recognize losses inimportant exceptions and qualifications, if we fail to comply with them and are unable to obtain a waiver or amendment, refinance the future dueindebtedness subject to these covenants or take other mitigating actions, an event of default would result. These arrangements also contain other events of default customary for such financings. If an event of default were to occur, the lenders or noteholders could, among other factors, extreme fuel price volatility, tight credit markets, government regulatory changes, declinethings, declare outstanding amounts due and payable and where applicable and subject to the terms of relevant collateral agreements, repossess collateral, including aircraft or other valuable assets. In addition, an event of default or acceleration of indebtedness under one agreement could result in an event of default under other of our financing agreements. The acceleration of significant indebtedness could require us to seek to renegotiate, repay or refinance the fair values of certain tangibleobligations under our financing arrangements, and there is no assurance that such renegotiation or intangible assets, such as aircraft, route authorities, and airport slots, unfavorable trends in forecasted results of operations and cash flows and an uncertain economic environment, as well as other uncertainties. Further impairment charges could have a material adverse effect on our results of operations.refinancing efforts would be successful.

Our business is labor intensive, utilizing large numbers of pilots, flight attendants, aircraft maintenance technicians, ground support personnel and other personnel. As of December 31, 2021,2023, 20% of our workforce, primarily pilots, was unionized. Relations between air carriers and labor unions in the United States are governed by the Railway Labor Act, which provides that a collective bargaining agreement between an airline and a labor union does not expire, but instead becomes amendable as of a stated date. The Railway Labor Act generally prohibits strikes or other types of self-help actions both before and after a collective bargaining agreement becomes amendable, unless and until the collective bargaining processes required by the Railway Labor Act have been exhausted. The collective bargaining agreement with our pilots became amendable on December 31, 2019 and we are in discussions with the representative of the pilots regarding terms of the agreement under the auspices of the NMB. Separately, the NLRA governs Monroe’s relations with the union representing their employees, which generally allows self help after a collective bargaining agreement expires.

If we or our subsidiaries are unable to reach agreement with any of our unionized work groups in future negotiations regarding the terms of their collective bargaining agreements or if additional segments of our workforce become unionized, we may be subject to work interruptions or stoppages, subject to the requirements of the Railway Labor Act or the NLRA, as the case may be. Strikes or labor disputes with our unionized employees may have a material adverse effect on our ability to conduct business. Likewise, if third-party regional carriers with which we have contract carrier agreements are unable to reach agreement with their unionized work groups in current or future negotiations regarding the terms of their collective bargaining agreements, those carriers may be subject to work interruptions or stoppages, subject to the requirements of the Railway Labor Act, which could have a material adverse effect on our operations.

Our results of operations are impacted by severe weather, natural disastersa number of factors including seasonality and seasonality. Severechanging economic and other conditions beyond our control. Demand for air travel is typically higher in the June and September quarters, particularly in our international markets, because there is more vacation travel during these periods than during the remainder of the year. The seasonal shifting of demand causes our financial results to vary on a quarterly basis. Changes in the value of our equity investments in other airlines and airline service companies can also be significant and cause fluctuations in our results. Other factors that may affect our results include severe weather conditions and natural disasters (or other environmental events) can, which could significantly disrupt service and create air traffic control problems. These events decrease revenue and can also increase costs. In addition, increases in the frequency, severity or duration of thunderstorms, hurricanes, typhoons, floods or other severe weather events, including from changes in the global climate and rising global temperatures, could result in increases in delays and cancellations, turbulence-related injuries and fuel consumption to avoid such weather, any of which could result in loss of revenue and higher costs. In addition, demand for air travel is typically higher in the June and September quarters, particularly in our international markets, because there is more vacation travel during these periods than during the remainder of the year. The seasonal shifting of demand causes our financial results to vary on a seasonal basis. Because of fluctuations in our results from weather, natural disastersseasonality and seasonality,other factors, results of operations for a historical period are not necessarily indicative of results of operations for a future period and results of operations for an interim period are not necessarily indicative of results of operations for an entire year.

An environmental or other incident associated with the operation of the Monroe refinery could have a material adverse effect on our consolidated financial results if insurance is unable to cover a significant liability. In addition, such an incident could damage our reputation.

Monroe's refining operations are subject to various hazards unique to refinery operations, including explosions, fires, toxic emissions and natural catastrophes. Monroe could incur substantial losses, including cleanup costs, fines and other sanctions and third-party claims, and its operations could be interrupted, as a result of such an incident. Monroe's insurance coverage does not cover all potential losses, costs or liabilities, and Monroe could suffer losses for uninsurable or uninsured risks or in amounts greater than its insurance coverage. In addition, Monroe's ability to obtain and maintain adequate insurance may be affected by conditions in the insurance market over which it has no control. If Monroe were to incur a significant liability for which it is not fully insured or for which insurance companies do not or are unable to provide coverage, this could have a material adverse effect on our consolidated financial results of operations or consolidated financial position. In addition, because of our ownership of Monroe, the occurrence of an environmental or other incident could result in damage to our reputation, which could have a material adverse effect on our financial results.

The operation of the refinery by Monroe is subject to significant environmental regulation. Failure to comply with environmental regulations or the enactment of additional regulation applicable to Monroe could have a material adverse effect on our consolidated financial results.

Monroe’s operations are subject to extensive environmental, health and safety laws and regulations, including those relating to the discharge of materials into the environment, waste management, pollution prevention measures and greenhouse gas emissions, which are subject to change over time. Monroe could incur fines and other sanctions, cleanup costs and third-party claims as a result of violations of or liabilities under environmental, health and safety requirements, which if significant, could have a material adverse effect on our consolidated financial results. In addition, the enactment of new, more stringent environmental laws and regulations, including any laws or regulations relating to greenhouse gas emissions, could significantly increase the level of expenditures required for Monroe or restrict its operations.

In particular, in administering the RFS, created by the U.S. Congress under the Energy Independence and Security Act of 2007, the EPA has adoptedcreated a program to ensure compliance with RFS that mandates for the blending of renewable fuels into Transportation Fuels. RINs are assigned to renewable fuels produced or imported into the U.S. that are blended into Transportation Fuels to demonstrate compliance with this obligation. A refinery may meet its obligation under RFS by blending the necessary volumes of renewable fuels with Transportation Fuels, by purchasing RINs in the open market, or throughby a combination of blending and purchasing RINs.

Existing laws or regulations could change, and the minimum volumes of renewable fuels that must be blended with refined petroleum products may increase. Increases in the volume of renewable fuels that must be blended into Monroe’s products could limit the refinery’s production if sufficient numbers of RINs are not available for purchase, or if relief from this requirement is not obtained, which could have a material adverse effect on our consolidated financial results.

If we lose senior management and other key employees and they are not replaced by individuals with comparable skills, or we otherwise fail to maintain our company culture, our business and results of operations could be materially adversely affected.

Terrorist attacks, geopolitical conflict or security events may adversely affect our business, financial condition and results of operations.

Terrorist attacks, geopolitical conflict or security events, or the fear or threat of any of these events, could have a significant adverse effect on our business. Despite significant security measures at airports and airlines, the airline industry remains a high profile target for terrorist groups. We rely on government provided threat intelligence and utilize private sources to constantly monitor for threats from terrorist groups and individuals, including from violent extremists both internationally and domestically, with respect to direct threats against our operations and in ways not directly related to the airline industry. In addition, the impact on our operations of avoiding areas of the world, including airspace, in which there are geopolitical conflicts and the targeting of commercial aircraft by parties to those conflicts can be significant. Security events, primarily from external sources but also from potential insider threats, also pose a significant risk to our passenger and cargo operations. These events could include random acts of violence and could occur in public areas that we cannot control.

Terrorist attacks, geopolitical conflict or security events, or the fear or threat of any of these events, even if not made directly on or involving the airline industry, could have a significant negative impact on us by discouraging passengers from flying, leading to decreased ticket sales and increased refunds. In addition, potential costs from these types of events include increased security costs, impacts from avoiding flight paths over areas in which conflict is occurring or could occur, such as flight redirections or cancellations, reputational harm and other costs. If any or all of these types of events occur, they could have a material adverse effect on our business, financial condition and results of operations.

The global airline industry is highly competitive and, if we cannot successfully compete in the marketplace, our business, financial condition and results of operations will be materially adversely affected.

The airline industry is highly competitive, marked by significant competition with respect to routes, fares, schedules (both timing and frequency), operational reliability, services, products, customer service and loyalty programs. Consolidation in the airline industry, changes in international alliances, the creation of immunized joint ventures and the rise of subsidized government-sponsored international carriers have altered and will continue to alter the competitive landscape in the industry, resulting in the formation of airlines and alliances with increased financial resources, more extensive global networks and competitive cost structures.

Our domestic operations are subject to significant competition from traditional network carriers, including American Airlines and United Airlines, national point-to-point carriers, including Alaska Airlines, JetBlue Airways and Southwest Airlines, and other discount or ultra-low-cost carriers, including SpiritAllegiant Air, Avelo Airlines, Breeze Airways, Frontier Airlines and Allegiant Air, someSpirit Airlines. Some of which maythese carriers have lowerbusiness models primarily focused on maintaining low costs, than we do and providewith the intention of providing service at lowlower fares to destinations served by Delta. In particular, we face significant competition at our domestic hubs and key airports either directly at those airports or at the hubs of other airlines that are located in close proximity. We also face competition in smallersmall- to medium-sized markets from regional jet operations of other carriers. Our ability to compete in the domestic market effectively depends, in part, on our ability to maintain a competitive cost structure. If we cannot maintain our costs at a competitive level, then our business, financial condition and results of operations could be materially adversely affected.

Our international operations are subject to competition from both foreign and domestic carriers, including from point-to-point carriers on certain international routes. Through alliance and other marketing and codesharing agreements with foreign carriers, U.S. carriers have increased their ability to sell international transportation, such as services to and beyond traditional European, Asian and AsianLatin American gateway cities. Similarly, foreign carriers have obtained increased access to interior U.S. passenger traffic beyond traditional U.S. gateway cities through these relationships.

In particular, several joint ventures among U.S. and foreign carriers, including several of our joint ventures as well as those of our competitors, have received grants of antitrust immunity allowing the participating carriers to coordinate networks, schedules, pricing, sales and inventory. In addition, alliances formed by domestic and foreign carriers, including SkyTeam, the Star Alliance (among United Airlines, Lufthansa German Airlines, Air Canada and others) and the oneworld alliance (among American Airlines, British Airways, Qantas and others) have enhanced competition in international markets.

The airline industry also faces competition from surface transportation and technological alternatives such as virtual meetings, teleconferencing or videoconferencing, and the intensity of thisvideoconferencing. Increased competition has likely increased, at least in the near term, as a result of the COVID-19 pandemic. Increased competitionfrom these sectors in both the domestic and international markets may have a material adverse effect on our business, financial condition and results of operations.

Extended interruptions or disruptions in service at major airports in which we operate or significant problems associated with a type of aircraft or engine we operate could have a material adverse effect on our financial condition and results of operations.

The airline industry is heavily dependent on business models that concentrate operations in major airports in the United States and throughout the world. An extended interruption or disruption at an airport or facility where we have significant operations, whether resulting from a discrete event, such as a hurricane,air traffic control delays, failure of computer systems or the manifestationtechnology infrastructure, weather events or natural disasters, or performance issues from third-party service providers, if sustained for an extended period of a chronic physical risk, such as rising sea levels,time, could have a material adverse effect on our business, financial condition and results of operations.

Similarly, the airline industry is heavily dependent on a limited number of aircraft and engine manufacturers whose products are subject to extensive regulatory requirements. Any significant problems associated with an aircraft or engine type that we operate, including new aircraft or engine types, such as design defects, mechanical problems, contractual performance by the manufacturers or adverse perception by the public leading to customer avoidance, or adverse actions by the FAA resulting in limitations on use or grounding could have a negative impact on our operations if we are not able to substitute or replace the affected aircraft or engine type andtype. Any of the foregoing could in any event, have a material adverse effect on our financial condition and results of operations.

The airline industry is subject to extensive government regulation, which is costly and could materially adversely affect our business.

Airlines are subject to extensive regulatory and legal compliance requirements that result in significant costs and may have material adverse effects on our business. For instance, the FAA from time to time issues directives and other regulations relating to the maintenance and operation of aircraft that necessitate significant expenditures and could carry operational implications. We expect to continue incurring significant expenses to comply with the FAA’s regulations. In addition, a directive or other regulation that has a significant operational impact on us could have a material adverse impact on our financial results.

Other laws, regulations, taxes and airport rates and charges have also been imposed from time to time that significantly increase the cost of airline operations, reduce revenues or otherwise impact our business. The industry is heavily taxed. Additional taxes and fees, if implemented, could negatively impact our results of operations.

Airport slot access is subject to government regulation and changes in slot regulations or allocations could impose a significant cost on the airlines operating in airports subject to such regulations or allocations or otherwise adversely affect an airline’s business. Certain of our hubs are among the most congested airports in the United States and have been, and could in the future be, the subject of regulatory action that might limit the number of flights and/or increase costs of operations at certain times or throughout the day. Air traffic control inefficiencies can also enhance these pressures.

In addition, the failure of the federal government to upgradeinefficiencies in the U.S. air traffic control system, which is regulated by the FAA, has resultedcan result in delays and disruptions of air traffic, especially during peak travel periods in certain congested markets. The failureFailure to implement measures to improve the air traffic control system could lead to increased delays and inefficiencies in flight operations as demand for U.S. air travel increases, having a material adverse effect on our operations. Failure to update the air traffic control system in a timely manner, and the substantial funding requirements of an updated system that may be imposed on air carriers, may have an adverse impact on our financial condition and results of operations.

As an international carrier, we are subject to a wide variety of U.S. and foreign laws that affect trade, including tariff and trade policies, export and import requirements, taxes, monetary policies and other restrictions and charges. In particular, the imposition of significant tariffs with respect to aircraft that we are not able to mitigate could substantially increase our costs, which in turn could have a material adverse effect on our financial results.

In addition, some of our operations are in high-risk legal compliance environments. Failure to comply with trade sanctions and restrictions, the Foreign Corrupt Practices Act (the "FCPA") and similar anti-bribery laws in non-U.S. jurisdictions, as well as other applicable laws or regulations could result in litigation, assessment of damages, imposition of penalties or other consequences, any or all of which could harm our reputation and have an adverse effect on our financial results. In certain circumstances, we also may be subject to consequences of the failure of our airline partners to comply with laws and regulations, including U.S. laws to which they may be subject such as the FCPA.

We and other U.S. carriers are subject to U.S. and foreign laws regarding privacy and security of passenger and employee data that are not consistent in all countries in which we operate and which are continuously evolving, requiring ongoing monitoring and updates to our privacy and information security programs. Although we dedicate significant resources to manage compliance with global privacy and information security obligations, this challenging regulatory environment may pose material risks to our business, including increased operational burdens and costs, regulatory enforcement, and legal claims or proceedings.

The airline industry is subject to many forms of environmental regulation, including but not limited to regulation of hazardous substances, increased regulation to reduce emissions and other risks associated with climate change. The cost of compliance with more stringent environmental regulations, failure to comply with existing or future regulations or failure to otherwise manage the risks of climate change effectively could have a material adverse effect on our business.

Many aspects of our operations are subject to evolving and increasingly stringent federal, state, local and international laws governing the protection of the environment.environmental protection. Compliance with existing and future environmental laws and regulations could require capital investment and increase operational costs, and violations can lead to significant fines and penalties and reputational harm.

Future regulatory action concerning climate change, aircraft emissions and noise emissions could have a significant effect on the airline industry. In order to address aircraft carbon dioxide emissions, the International Civil Aviation Organization (ICAO), a United Nations specialized agency, formally adopted a global, market-based emission offset program known as CORSIA. This program establishes a goal for the aviation industry to achieve carbon-neutral growth in international aviation beginning in 2021 through the use of carbon offsets and/or lower carbon aviation fuel. TheICAO set the baseline for establishing airlines’ offset obligations under CORSIA was originallyfor 2021 to 2023 based on 2019 travel, and in 2022 set as an averagea new, more stringent CORSIA baseline of 85% of 2019, and 2020 emissions. However, given the COVID-19 pandemic and resulting unprecedented reduction in international travel, ICAO removed 2020which will apply from the baseline calculation for the first phases of CORSIA, from 2021 to 2027. ICAO has yet to decide how to apply the baseline beyond 2027. Some countries and other stakeholders, however, have advocated for reestablishing 2020 in the baseline and for using 2020 for the future baseline calculation, which, if adopted, would significantly increase the airline industry’s projected obligations under the program and the cost of compliance. Certain2024 through 2035. Because certain CORSIA program details remain to be developed and could potentially be affected by political developments in participating countries or the results of the pilot phaseinitial phases of the program, and thus the impact of CORSIA cannot be predicted at this time. However, CORSIA is expected to increase operating costs for airlines that operate internationally.

In addition to CORSIA, we may face a patchwork of regulation of aircraft emissions in the U.S. and abroad and could become subject to further taxes, charges or additional requirements to obtain permits or purchase allowances or emission credits for greenhouse gas emissions in various jurisdictions. For example, in 20212023, the European Commission proposedEU adopted updated legislation that would expandon the reachEU Emissions Trading System (“ETS”). The new legislation continues in effect the so-called “stop-the-clock” provision whereby EU ETS does not apply to flights to or from locations outside the EEA, Switzerland or the UK until 2027. However, the legislation provides for a review of the effectiveness of CORSIA in 2026 that could, if CORSIA is not deemed sufficiently effective, lead to the application of EU ETS to includeall flights intodeparting the EU and out ofEEA. Also in 2023, the European Economic Area beginning in 2027 under certain circumstances, increase the stringency of the program, and establish a sustainable aviation fuel blending mandate for aviation fuel suppliers, among other requirements. Individual EU member states have been developing their own requirements, including for example,adopted legislation that will impose a SAF mandate on fuel supplied at EU airports. The mandate initially requires that, of the jet fuel supplied in France that willthe EU, 2% must be phasedSAF beginning in at2025, and the beginningpercentage increases incrementally over time to 70% in 2050. This mandate is expected to increase the cost of 2022. InSAF in the United States various exploratory discussions continue around approaches to address climate change, such as carbon pricing, without a clear legislative path forward.EU. Additional regulation could result in taxation, regulatory or permitting requirements from multiple jurisdictions for the same operations and significant costs for the airline industry, including Delta. In addition to direct costs, such regulation could result in increased fuel costs passed through from fuel suppliers affected by any such regulations. While the specific nature of future actions is hard to predict, new laws or regulations related to environmental matters adopted in the U.S. or other countries could impose significant additional costs on or otherwise adversely affect our operations. Certain airports have also adopted, and others could in the future adopt, greenhouse gas emission or climate-related goals and requirements that could impact our operations or require us to make changes or investments in our infrastructure.

In addition to risks from potential changes to environmental regulation and policy, the transition to lower-carbon technologies, such as SAF, or changes in consumer preferences resulting from a negative perception of the environmental impact of air travel could materially adversely affect our business and financial results. For example, lower-carbon technologies such as SAF and direct air capture technologies are currently not available at scale and may take decades to develop, and the cost to transition to them could be prohibitively expensive without appropriate government policies and incentives in place. As more businesses have publicly announced environmental sustainability goals, the cost of carbon offsets has also increased significantly and will likely continue to do so.

Because of the global nature of our business, unfavorable economic or political conditions in the markets in which we operate or volatility in currency exchange rates could have a material adverse effect on our business, financial condition and results of operations.

As a result of the discretionary nature of air travel, the airline industry has been cyclical and particularly sensitive to changes in economic conditions. Because we operate globally, our business is subject to economic and political conditions throughout the world. During periods of unfavorable or volatile economic conditions in the economy in the U.S. or abroad, including as a result of the COVID-19 pandemic and the worldwide response to it, demand for air travel can be significantly impacted as business and leisure travelers choose not to travel, seek alternative forms of transportation for short trips or conduct business using technological alternatives. If unfavorable economic conditions occur, particularly for an extended period, our business, financial condition and results of operations may be adversely affected. In addition, significant or volatile changes in exchange rates between the U.S. dollar and other currencies, and the imposition of exchange controls or other currency restrictions, may have a material adverse effect on our liquidity, financial conditions and results of operations.

Our international operations are an important part of our route network. Political disruptions and instability around the world can negatively impact the demand and network availability for air travel. Additionally, any deterioration in global trade relations, such as increased tariffs or other trade barriers, could result in a decrease in the demand for international air travel.

None.

Our operating aircraft fleet, purchase commitments and options at December 31, 20212023 are summarized in the following table. We have been experiencing a recovery in demand from the COVID-19 pandemic, which has led to an increase in our capacity and utilization of our aircraft compared to the year ended December 31, 2020. Accordingly, as of December 31, 2021, all aircraft in our operating fleet are reflected in the table below compared to approximately 10% that were temporarily parked as of December 31, 2020. See Note 15 of the Notes to the Consolidated Financial Statements for additional information on the restructuring charges recorded in 2020 related to our fleet retirement plans.

The following table summarizes the aircraft operated by regional carriers on our behalf at December 31, 2021.2023. In 2023, we retired all remaining CRJ-200 aircraft from service.

Aircraft Purchase Commitments

As part of a multi-year effort, we have been investing in new aircraft to provide an improved customer experience, greater fuel efficiency and thusthat results in reduced carbon emissions, better operating economics and more premium products. Our contractual purchase commitments for additional aircraft atas of December 31, 20212023 are detailed in the following table:

Airline Operations

We lease most of the land and buildings that we occupy. Our largest aircraft maintenance base, various equipment maintenance, cargo, flight kitchen and training facilities and most of our principal offices are located at or near the Atlanta airport on land leased from the City of Atlanta. We lease ticket counters, gate areas, operating facilities and other terminal space in most of the airports that we serve. At most airports, we have entered into use agreements which provide for the non-exclusive use of runways, taxiways and other improvements and facilities; landing fees under these agreements normally are based on the number of landings and weight of aircraft. These leases and use agreements generally run for periods of less than one year to 30 years or more, and often contain provisions for periodic adjustments of lease rates, landing fees and other charges applicable under that type of agreement. We also lease aircraft maintenance, equipment maintenance and air cargo facilities at several airports. Our facility leases generally require us to pay the cost of providing, operating and maintaining such facilities, including, in some cases, amounts necessary to pay debt service on special facility bonds issued to finance their construction. We also lease computer facilities, marketing offices, reservations offices and other off-airport facilities in certain locations for varying terms.

We own our Atlanta reservations center, other real property in Atlanta and reservations centers in Minot, North Dakota and Chisholm, Minnesota.

Refinery Operations

Our Monroe subsidiaries own and operate the Trainer refinery and related assets in Pennsylvania. The facilities include pipelines and terminal assets that allow the refinery to supply jet fuel to our airline operations throughout the Northeastern U.S., including our New York hubs at LaGuardia and JFK.

In July 2015, a number of purported class action antitrust lawsuits were filed alleging that Delta, American, United and Southwest had conspired to restrain capacity. The lawsuits were filed in the wake of media reports that the U.S. Department of Justice had served civil investigative demands upon these carriers seeking documents and information relating to this subject. The lawsuits have been consolidated into a single Multi-District Litigation proceeding in the U.S. District Court for the District of Columbia. In August 2023, the Court denied the defendants' motions for summary judgment that had been pending for over two years. In Fall 2023, we moved to certify the decision for an interlocutory appeal or for reconsideration, and briefing related to that motion is now complete. We believe the claims in these cases are without merit and are vigorously defendeddefending these lawsuits. Our summary judgment motion has been fully briefed and pending since May 2021.

Not applicable.

Part II

Our common stock is listed on the New York Stock Exchange ("NYSE") under the trading symbol DAL.

As of January 31, 2022,2024, there were approximately 2,3002,100 holders of record of our common stock.

We made cashAfter suspending dividends in March 2020, our Board of Directors re-instated a quarterly dividend program in 2023 with $0.10 per share dividend payments in both the September and December quarters. The Board expects to be able to continue to pay cash dividends for the foreseeable future, subject to applicable limitations under Delaware law and compliance with covenants in certain of $980 million during the year ended December 31, 2019 and $260 million in the March 2020 quarter prior to the COVID-19 pandemic. In March 2020, we suspended dividends due to the impact of the COVID-19 pandemic. The CARES Act and payroll support program extensions restrict the payment of dividends through September 2022.our credit facilities. Dividend payments beyond that time will beare dependent upon our results of operations, financial condition, cash requirements, future prospects and other factors deemed relevant by the Board of Directors.

The following graph compares the cumulative total returns during the period from December 31, 20162018 to December 31, 20212023 of our common stock to the Standard & Poor's 500 Stock Index and the NYSE ARCA Airline Index. The comparison assumes $100 was invested on December 31, 20162018 in each of our common stock and the indices and assumes that all dividends were reinvested.

The following table presents information with respect to purchases of common stock we made during the December 20212023 quarter. The table reflects shares withheld from employees to satisfy certain tax obligations due in connection with grants of stock under the Delta Air Lines, Inc. Performance Compensation Plan (the "Plan"). The Plan provides for the withholding of shares to satisfy tax obligations but it does not specify a maximum number of shares that can be withheld for this purpose. The shares of common stock withheld to satisfy tax withholding obligations may be deemed to be "issuer purchases" of shares that are required to be disclosed pursuant to this Item.

Our CASMtotal operating cost per available seat mile ("CASM") decreased 35% to 14.40 cents4% compared to 2020,2022 to 19.31 cents, primarily due to a 45%17% increase in capacity, as well as lower fuel expense and lower expenses related to refinery sales to third parties. Non-fuel unit costs ("CASM-Ex", a non-GAAP financial measure), which excludes fuel, expenses related to refinery sales to third parties, and other items, increased 2.3% to 13.17 cents.

Also, during 2023 we had cash outflows of approximately $4.1 billion related to 12.12 cents.repayments of our debt and finance leases, including approximately $2.0 billion for early repayments and the remainder from scheduled maturities. Our cash, cash equivalents, short-term investments and aggregate principal amount committed and available to be drawn under our revolving credit facilities ("liquidity") at December 31, 2023 was $6.8 billion.

Operating Revenue

See "Refinery Segment" below for additional details on the refinery's operations, including third-party refinery sales recorded in other revenue, during each period.

Domestic

Domestic passenger unit revenue ("PRASM") for 2023 increased 2% compared to 2022 due to a 12% increase in revenue on a 10% increase in capacity and a slight increase in load factor.

Domestic revenue in 2023 was above 2022 levels as we experienced strong revenue results across the year ended December 31, 2021 increased 27%domestic network, with capacity up 45%coastal hub markets such as New York and Boston improving significantly compared to the prior year, ended December 31, 2020 asdomestic business travel revenue improving and a result10% increase in domestic capacity compared to 2022. We believe spending patterns for services are returning to historical levels compared to spending on goods. We also experienced higher growth in premium product revenue (including Delta One, First Class, Delta Premium Select and Delta Comfort+) compared to main cabin with the delivery of the low levels ofnew aircraft that include more premium seat capacity and demand during 2020 due to the COVID-19 pandemic and the ongoing recovery throughout 2021.