SEGMENTS The Companys businesses are organized and managed in three reporting segments: Power &amp; Control, Airframe and Non-aviation. The Power &amp; Control segment includes operations that primarily develop, produce and market systems and components that predominately provide power to or control power of the aircraft utilizing electronic, fluid, power and mechanical motion control technologies. Major product offerings include mechanical/electro-mechanical actuators and controls, ignition systems and engine technology, specialized pumps and valves, power conditioning devices, specialized AC/DC electric motors and generators, batteries and chargers, databus and power controls, advanced sensor products, switches and relay panels, high performance hoists, winches and lifting devices, and cargo loading, handling and delivery systems. Primary customers of this segment are engine and power system and subsystem suppliers, airlines, third party maintenance suppliers, military buying agencies and repair depots. Products are sold in the original equipment and aftermarket market channels. The Airframe segment includes operations that primarily develop, produce and market systems and components that are used in non-power airframe applications utilizing airframe and cabin structure technologies. Major product offerings include engineered latching and locking devices, engineered rods, engineered connectors and elastomer sealing solutions, cockpit security components and systems, specialized and advanced cockpit displays, aircraft audio systems, specialized lavatory components, seat belts and safety restraints, engineered and customized interior surfaces and related components, thermal protection and insulation, lighting and control technology and parachutes. Primary customers of this segment are airframe manufacturers and cabin system suppliers and subsystem suppliers, airlines, third party maintenance suppliers, military buying agencies and repair depots. Products are sold in the original equipment and aftermarket market channels. The Non-aviation segment includes operations that primarily develop, produce and market products for non-aviation markets. Major product offerings include headsets for high-noise, medium-noise, and dismounted applications, seat belts and safety restraints for ground transportation applications, mechanical/electro-mechanical actuators and controls for space applications, hydraulic/electromechanical actuators and fuel valves for land based gas turbines, and refueling systems for heavy equipment used in mining, construction and other industries and turbine controls for the energy and oil and gas markets. Primary customers of this segment are off-road vehicle suppliers and subsystem suppliers, child restraint system suppliers, satellite and space system suppliers, manufacturers of heavy equipment used in mining, construction and other industries and turbine original equipment manufacturers, gas pipeline builders and electric utilities. The Esterline businesses were acquired during the second quarter of fiscal 2019 and preliminarily assessed as a separate segment of the Company. During the third quarter of fiscal 2019, the Esterline businesses were integrated into TransDigm's existing Power &amp; Control, Airframe, and Non-Aviation segments. Previously reported operating results for the Esterline businesses were reclassified to conform to the presentation for the fiscal year ended September 30, 2020. The re-segmentation did not impact prior period results. The primary measurement used by management to review and assess the operating performance of each segment is EBITDA As Defined. The Company defines EBITDA As Defined as earnings before interest, taxes, depreciation and amortization plus certain non-operating items recorded as corporate expenses including refinancing costs, acquisition-related costs, transaction-related costs, foreign currency gains and losses, and non-cash compensation charges incurred in connection with the Companys stock incentive plans. Acquisition-related costs represent accounting adjustments to inventory associated with acquisitions of businesses and product lines that were charged to cost of sales when the inventory was sold; costs incurred to integrate acquired businesses and product lines into the Companys operations, facility relocation costs and other acquisition-related costs; transaction related costs comprising deal fees; legal, financial and tax diligence expenses and valuation costs that are required to be expensed as incurred and other acquisition accounting adjustments. EBITDA As Defined is not a measurement of financial performance under U.S. GAAP. Although the Company uses EBITDA As Defined to assess the performance of its business and for various other purposes, the use of this non-GAAP financial measure as an analytical tool has limitations, and it should not be considered in isolation or as a substitute for analysis of the Companys results of operations as reported in accordance with U.S. GAAP. The Companys segments are reported on the same basis used internally for evaluating performance and for allocating resources. The accounting policies for each segment are the same as those described in the summary of significant accounting policies in the Companys consolidated financial statements. Intersegment sales and transfers are recorded at values based on market prices, which creates intercompany profit on intersegment sales or transfers that is eliminated in consolidation. Intersegment sales were immaterial for the periods presented below. Certain corporate-level expenses are allocated to the operating segments. The following table presents net sales by reportable segment (in millions): Fiscal Years Ended September 30, 2020 2019 2018 Net sales to external customers Power &amp; Control Commercial OEM $ 623 $ 686 $ 499 Commercial Aftermarket 673 769 665 Defense 1,399 1,281 975 Total Power &amp; Control 2,695 2,736 2,139 Airframe Commercial OEM 783 836 509 Commercial Aftermarket 689 865 701 Defense 781 628 321 Total Airframe 2,253 2,329 1,531 Total Non-aviation 155 158 141 $ 5,103 $ 5,223 $ 3,811 The following table reconciles EBITDA As Defined by segment to consolidated income from continuing operations before income taxes (in millions): Fiscal Years Ended September 30, 2020 2019 2018 EBITDA As Defined Power &amp; Control $ 1,345 $ 1,395 $ 1,115 Airframe 955 1,063 759 Non-aviation 54 51 44 Total segment EBITDA As Defined 2,354 2,509 1,918 Unallocated corporate expenses 76 90 41 Total Company EBITDA As Defined 2,278 2,419 1,877 Depreciation and amortization 283 225 129 Interest expense - net 1,029 859 663 Acquisition-related costs 31 169 29 Stock compensation expense 93 93 58 Refinancing costs 28 3 6 COVID-19 pandemic &amp; 737 MAX restructuring costs 54   Other, net 20 7 6 Income from continuing operations before income taxes $ 740 $ 1,063 $ 986 The following table presents capital expenditures and depreciation and amortization by segment (in millions): Fiscal Years Ended September 30, 2020 2019 2018 Capital expenditures Power &amp; Control $ 89 $ 50 $ 39 Airframe 10 48 32 Non-aviation 4 3 2 Corporate 2 1  $ 105 $ 102 $ 73 Depreciation and amortization Power &amp; Control $ 117 $ 99 $ 67 Airframe 157 119 56 Non-aviation 7 6 5 Corporate 2 2 1 $ 283 $ 226 $ 129 The following table presents total assets by segment (in millions): September 30, 2020 September 30, 2019 Total assets Power &amp; Control $ 7,005 $ 7,037 Airframe 6,575 6,672 Non-aviation 251 262 Corporate 4,564 1,322 Assets of discontinued operations (Note 23)  962 $ 18,395 $ 16,255 The Companys sales principally originate from the United States, and the Companys long-lived assets are principally located in the United States.