Question: What 5th generation USAF tactical fighter built by Lockheed Martin and Boeing will remain in service alongside the new sixth generation fighter?

full_context: Document 1: Sixth-generation jet fighter: A sixth-generation jet fighter is a conceptualized class of fighter aircraft design more advanced than the fifth-generation jet fighters that are currently in service in the United States and in development in other countries. The United States Air Force (USAF) and United States Navy (USN) are anticipated to field their first sixth-generation fighters in the 2025–30 time frame. The USAF is pursuing development and acquisition of a sixth-generation fighter through the F-X program to complement existing platforms in service such as the Lockheed Martin F-22 Raptor. The USN is pursuing a similar program called the Next Generation Air Dominance, likewise intended to complement and/or replace its existing aircraft such as the Boeing F/A-18E/F Super Hornet.
Document 2: Northrop YF-23: The Northrop/McDonnell Douglas YF-23 was an American single-seat, twin-engine stealth fighter aircraft technology demonstrator designed for the United States Air Force (USAF). The design was a finalist in the USAF's Advanced Tactical Fighter (ATF) competition, battling the Lockheed YF-22 for a production contract. Two YF-23 prototypes were built, nicknamed "Black Widow II" and "Gray Ghost".
Document 3: Lockheed SR-71 Blackbird: The Lockheed SR-71 "Blackbird" is a long-range, Mach 3+ strategic reconnaissance aircraft that was operated by the United States Air Force. It was developed as a black project from the Lockheed A-12 reconnaissance aircraft in the 1960s by Lockheed and its Skunk Works division. American aerospace engineer Clarence "Kelly" Johnson was responsible for many of the design's innovative concepts. During aerial reconnaissance missions, the SR-71 operated at high speeds and altitudes to allow it to outrace threats. If a surface-to-air missile launch was detected, the standard evasive action was simply to accelerate and outfly the missile. The SR-71 was designed with a reduced radar cross-section.
Document 4: Lockheed Martin F-22 Raptor: The Lockheed Martin F-22 Raptor is a fifth-generation, single-seat, twin-engine, all-weather stealth tactical fighter aircraft developed for the United States Air Force (USAF). The result of the USAF's Advanced Tactical Fighter program, the aircraft was designed primarily as an air superiority fighter, but also has ground attack, electronic warfare, and signal intelligence capabilities. The prime contractor, Lockheed Martin, built most of the F-22's airframe and weapons systems and conducted final assembly, while Boeing provided the wings, aft fuselage, avionics integration, and training systems.
Document 5: Sukhoi/HAL FGFA: The Sukhoi/HAL Fifth Generation Fighter Aircraft (FGFA) or Perspective Multi-role Fighter (PMF) is a fifth-generation fighter being developed by India and Russia. It is a derivative project of the Russian Sukhoi Su-57 being developed for the Russian Air Force. The FGFA was the earlier designation for the Indian version, while the combined project is now called the Perspective Multi-Role Fighter (PMF).
Document 6: J-XX: J-XX J-X, and XXJ are names applied by Western intelligence agencies to describe programs by the People's Republic of China to develop one or more fifth-generation fighter aircraft. General He Weirong, Commander of the People's Liberation Air Force (PLAAF), stated that China had several such programs underway and that an undesignated fifth-generation fighter developed jointly by Chengdu Aerospace Corporation and Shenyang Aerospace Corporation would be in service by 2018.
Document 7: Grumman F-14 Tomcat: The Grumman F-14 Tomcat is an American supersonic, twin-engine, two-seat, variable-sweep wing fighter aircraft. The Tomcat was developed for the United States Navy's Naval Fighter Experimental (VFX) program after the collapse of the F-111B project. The F-14 was the first of the American teen-series fighters, which were designed incorporating air combat experience against MiG fighters during the Vietnam War.
Document 8: General Dynamics F-16 Fighting Falcon: The General Dynamics F-16 Fighting Falcon is a single-engine supersonic multirole fighter aircraft originally developed by General Dynamics (now Lockheed Martin) for the United States Air Force (USAF). Designed as an air superiority day fighter, it evolved into a successful all-weather multirole aircraft. Over 4,500 aircraft have been built since production was approved in 1976. Although no longer being purchased by the U.S. Air Force, improved versions are still being built for export customers. In 1993, General Dynamics sold its aircraft manufacturing business to the Lockheed Corporation, which in turn became part of Lockheed Martin after a 1995 merger with Martin Marietta.
Document 9: HAL AMCA: The HAL Advanced Medium Combat Aircraft (AMCA) is an Indian programme of a fifth-generation fighter aircraft. It is being developed by an aerospace industry team which consists of the Aeronautical Development Agency (ADA) as the design firm with manufacturing carried out by Hindustan Aeronautics Limited (HAL) as the primary contractor and main assembly firm. It is a single-seat, twin-engine, stealth supermaneuverable all weather multirole fighter aircraft. Unofficial design work on the AMCA started in 2008 with official work started in 2011 and completed in 2014. In 2008, the Indian Navy joined the programme seeking a naval variant optimized for operation from aircraft carriers. The first flight is scheduled to occur in 2019.
Document 10: Advanced Tactical Fighter: The Advanced Tactical Fighter (ATF) was a demonstration and validation program undertaken by the United States Air Force to develop a next-generation air superiority fighter to counter emerging worldwide threats, including Soviet Sukhoi Su-27 and Mikoyan MiG-29 fighters under development in the 1980s. Lockheed and Northrop were selected in 1986 to develop the YF-22 and the YF-23 technology demonstrator aircraft. These aircraft were evaluated in 1991 and the Lockheed YF-22 was selected and later developed into the F-22 Raptor.
Document 11: Mikoyan MiG-29: The Mikoyan MiG-29 (Russian: Микоян МиГ-29 ; NATO reporting name: Fulcrum) is a twin-engine jet fighter aircraft designed in the Soviet Union. Developed by the Mikoyan design bureau as an air superiority fighter during the 1970s, the MiG-29, along with the larger Sukhoi Su-27, was developed to counter new American fighters such as the McDonnell Douglas F-15 Eagle, and the General Dynamics F-16 Fighting Falcon. The MiG-29 entered service with the Soviet Air Force in 1982.
Document 12: Skunk Works: Skunk Works is an official pseudonym for Lockheed Martin's Advanced Development Programs (ADP), formerly called Lockheed Advanced Development Projects. It is responsible for a number of famous aircraft designs, including the U-2, the Lockheed SR-71 Blackbird, the Lockheed F-117 Nighthawk, Lockheed Martin F-22 Raptor, and the Lockheed Martin F-35 Lightning II, which will be used in the air forces of several countries. Its name was taken from the moonshine factory in the comic strip "Li'l Abner". The designation "skunk works" or "skunkworks" is widely used in business, engineering, and technical fields to describe a group within an organization given a high degree of autonomy and unhampered by bureaucracy, with the task of working on advanced or secret projects.
Document 13: Sukhoi Su-57: The Sukhoi Su-57 (Russian: Сухой Су-57 ) is the designation intended for a stealth, single-seat, twin-engine jet multirole fighter aircraft designed for air superiority and attack operations. The aircraft is the product of the PAK FA (Russian: ПАК ФА , Russian: Перспективный авиационный комплекс фронтовой авиации , "Perspektivny Aviatsionny Kompleks Frontovoy Aviatsii", literally "Prospective Airborne Complex of Frontline Aviation"), a fifth-generation fighter programme of the Russian Air Force. Sukhoi's internal name for the aircraft is T-50. The Su-57 will be the first aircraft in Russian military service to use stealth technology. The fighter is planned to have supercruise, stealth, supermaneuverability and advanced avionics to overcome the prior generation fighter aircraft as well as ground and maritime defences.
Document 14: Lockheed YF-22: The Lockheed/Boeing/General Dynamics YF-22 was an American single-seat, twin-engine fighter aircraft technology demonstrator designed for the United States Air Force (USAF). The design was a finalist in the USAF's Advanced Tactical Fighter competition, and two prototypes were built for the demonstration/validation phase of the competition. The YF-22 won the contest against the Northrop YF-23, and entered production as the Lockheed Martin F-22 Raptor. The YF-22 has similar aerodynamic layout and configuration as the F-22, but with differences in the position and design of the cockpit, tail fins and wings, and in internal structural layout.
Document 15: Next-Generation Bomber: The Next-Generation Bomber (NGB; unofficially called 2018 Bomber) was a program to develop a new medium bomber for the United States Air Force. The NGB was initially projected to enter service around 2018 as a stealthy, subsonic, medium-range, medium payload bomber to supplement and possibly—to a limited degree—replace the U.S. Air Force's aging bomber fleet (B-52 Stratofortress and B-1 Lancer). The NGB program was superseded by the Long Range Strike Bomber (LRS-B) heavy bomber program.
ground_truth: Lockheed Martin F-22 Raptor