approval and certification, and operate our jets, assumed Vertiport networks available to us in our target markets, assumed safety protocols and redundancies, our internal processes and general market conditions. While we believe our assumptions and the data underlying our estimates are reasonable, these assumptions and estimates may not be correct, and the conditions supporting our assumptions or estimates may change at any time, thereby reducing the predictive accuracy of these underlying factors. As a result, our estimates of the annual total addressable market for our RAM passenger transport and goods transport services, as well as the expected growth rate for the total addressable market, may prove to be incorrect, which could negatively affect our operating revenue, costs, operations and potential profitability.
We may be unable to adequately control the costs associated with our pre-launch operations, and our costs will continue to be significant after we commence operations.
We will require significant capital to develop and grow our business, including designing, developing, testing, certifying and manufacturing our aircraft, building our manufacturing plant, securing leases and contractual arrangements for our Vertiports and other commercial activities, educating customers on the safety, efficiency and cost-effectiveness of our services and building our brand. Our research and development expenses were €38.1 million, €90.3 million and €144.6 million in 2019, 2020 and 2021, respectively, and we expect to continue to incur significant expenses, which will impact our profitability, including continuing research and development expenses, manufacturing, maintenance and procurement costs, marketing, customer and payment system expenses, and general and administrative expenses as we scale our operations. In addition, we expect to incur significant costs in connection with operating our services, such as our Lilium Network, including scaling out our operations by building and operating a fleet of jets (including, but not limited to pilot salaries, landing fees, jet maintenance and energy costs), training staff on the operation and maintenance of our aircraft, expanding our Vertiport network and promoting our services. Our ability to become profitable in the future will not only depend on our ability to successfully market our jets and services but also our ability to control our costs. If we are unable to cost efficiently design, certify, manufacture, market, operate, sell and service our jets and operations, our margins, profitability and prospects would be materially and adversely affected.
We may experience difficulties in managing our growth and commercializing our operations.
We expect to experience significant growth in the scope and nature of our manufacturing and service operations. Our ability to manage our operations and future growth will require us to continue to improve our operational, financial and management controls, compliance programs and reporting systems. We are currently in the process of strengthening our compliance programs, including our compliance programs related to internal controls, intellectual property management, privacy and cybersecurity. We may not be able to implement improvements in an efficient or timely manner and may discover deficiencies in existing controls, programs, responsible personnel, systems and procedures, which could have an adverse effect on our business, reputation and financial results.
We may be unable to sell our jets or launch our services on the timeline, or with the scope of services, that we are anticipating.
We need to resolve significant regulatory, operational, logistical and other challenges in order to launch our Lilium Network services or sell our aircraft under our Turnkey Enterprise or Private and Fractional Sales business models. We do not currently have infrastructure in place to operate our services, and such infrastructure may not become available at all or at the times or under conditions we anticipate. Our Lilium Jets have not yet received any EASA or FAA certification/approvals, and we are working through the details of the required airspace, operational authority and other relevant and necessary multinational, federal, national and local government approvals, which are essential to the sale of our jets and the operation of our services. In addition, the EASA and FAA certification and approval processes may be further impacted by any changes to applicable regulations in the future and may raise requirements, such as range reserve requirements, which may impact our ability to achieve our target specifications or require us to implement design changes in order to obtain such certification and approvals, and could lead to delays in our certification and commercialization timelines. Any delay in the financing, design, manufacture, and commercial launch of our Lilium Jets, any delay in the receipt of all necessary regulatory approvals and certifications, and any determination by a transportation or aviation authority that we cannot manufacture, sell our jets or provide or otherwise engage in the services as we contemplate could materially damage our brand, business, prospects, financial condition and operating results, and may require us to incur additional costs and create adverse publicity for our business. If we are not able to overcome these challenges, our business, prospects, operating results and financial condition will be negatively impacted and our ability to grow our business will be harmed.