Question: An American twin-engine attack helicopter that was developed for the United States Marine Corps as part of the H-1 upgrade program is also called what when based on the ICAO phonetic alphabet pronunciation of it's variant letter? 

full_context: Document 1: NATO phonetic alphabet: The International Radiotelephony Spelling Alphabet, commonly known as the ICAO phonetic alphabet, sometimes called the NATO phonetic alphabet or spelling alphabet and the ITU radiotelephonic or phonetic alphabet, is the most widely used radiotelephonic spelling alphabet. Although often called "phonetic alphabets", spelling alphabets are unrelated to phonetic transcription systems such as the International Phonetic Alphabet. Instead, the International Civil Aviation Organization (ICAO) alphabet assigned codewords acrophonically to the letters of the English alphabet, so that critical combinations of letters and numbers are most likely to be pronounced and understood by those who exchange voice messages by radio or telephone, regardless of language differences or the quality of the communication channel.
Document 2: H-1 upgrade program: The H-1 upgrade program is the United States Marine Corps's program to develop the AH-1Z Viper and UH-1Y Venom military helicopters to replace its aging fleets of AH-1W SuperCobras and UH-1N Twin Hueys. The contract was awarded in 1996 to Bell Helicopter, the original manufacturer of both aircraft, to design the new airframes as modernized attack and utility helicopters with considerable design commonality, to reduce operating costs.
Document 3: List of NATO country codes: This is the list of NATO country codes. Up to and including the seventh edition of STANAG 1059, these were two-letter codes (digrams). The eighth edition, promulgated February 19, 2004, and effective April 1, 2004, replaced all codes with new ones based on the ISO 3166-1 alpha-2 codes. Additional codes cover gaps in the ISO coverage, deal with the imaginary countries used for exercise purposes, and designate large geographical groupings and water bodies (ranging from oceans to rivers). It consists of two-letter codes for geographical entities, four-letter codes for subdivisions, and lists the ISO three-letter codes for reference. The digrams match the FIPS 10-4 codes with a few exceptions.
Document 4: Harbin Z-20: The Harbin Z-20 or Zhi-20 is a medium lift helicopter produced in the Northeast of China. Its first flight was on 23 December 2013. The helicopter has a maximum takeoff weight in the range of 10 tons, can drop troops at locations of up to 3,000 ft altitude, and could operate from the Chinese aircraft carrier Liaoning. It is thought to be comparable to the US made Sikorsky UH-60 Black Hawk helicopter, the civilian Sikorsky S-70C-2 variant of which has been used by the People's Liberation Army since 1984. Some sources suggest that the Z-20 is a copy of the Black Hawk and link the design to the Black Hawk that was abandoned by US special forces in Pakistan during the operation to kill Osama bin Laden on 1 May 2011. The sources say that Pakistan allowed Chinese officials to examine the Black Hawk wreckage. However, Aviation Week also points out that although some aspects of the design do appear similar, such as the tail wheel arrangement, there are also marked differences. For example, the Chinese Z-20 has a five blade rotor compared with the Black Hawks' four blades.
Document 5: Bell AH-1 SuperCobra: The Bell AH-1 SuperCobra is a twin-engine attack helicopter based on the United States Army's single-engine AH-1 Cobra. The twin Cobra family, itself part of the larger Huey family, includes the AH-1J SeaCobra, the AH-1T Improved SeaCobra, and the AH-1W SuperCobra. The AH-1W, the backbone of the United States Marine Corps's attack helicopter fleet for decades is being replaced by the next generation Bell AH-1Z Viper attack helicopter.
Document 6: Procedure word: Procedure words or prowords are words or phrases limited to radio telephone procedure used to facilitate communication by conveying information in a condensed standard verbal format. Prowords are voice versions of the much older prosigns for Morse code first developed in the 1860s for Morse telegraphy, and their meaning is identical. The U.S. military communications manual ACP-125 is the most formal and perhaps earliest modern (post-WW-II) definitions of procedure words), but its definitions have been replicated by many other organizations, including the United Nations Development Programme, , the U.S. Coast Guard, the Rhode Island Department of Emergency Management, Civil Air Patrol, Military Auxiliary Radio System, and others.
Document 7: Bell UH-1Y Venom: The Bell UH-1Y Venom (also called Super Huey) is a twin-engine, medium-sized utility helicopter, built by Bell Helicopter under the H-1 upgrade program of the United States Marine Corps. One of the latest members of the numerous Huey family, the UH-1Y is also called "Yankee", based on the NATO phonetic alphabet pronunciation of its variant letter.
Document 8: Bell AH-1Z Viper: The Bell AH-1Z Viper is an American twin-engine attack helicopter, based on the AH-1W SuperCobra, that was developed for the United States Marine Corps as part of the H-1 upgrade program. The AH-1Z features a four-blade, bearingless, composite main rotor system, uprated transmission, and a new target sighting system. The AH-1Z, one of the latest members of the prolific Huey family, is also called "Zulu Cobra", based on the military phonetic alphabet pronunciation of its variant letter.
Document 9: Sikorsky S-67 Blackhawk: The Sikorsky S-67 Blackhawk was a private-venture, prototype attack helicopter built in 1970 with Sikorsky Aircraft research and development (R&D) funds. A tandem, two-seat aircraft designed around the dynamic drive and rotor systems of the Sikorsky S-61, it was designed to serve as an attack helicopter or to transport up to eight troops into combat.
Document 10: Mil Mi-17: The Mil Mi-17 (NATO reporting name: Hip) is a Russian helicopter in production at two factories in Kazan and Ulan-Ude. It is known as the Mi-8M series in Russian service. It is a medium twin-turbine transport helicopter. There are also armed gunship versions.
Document 11: ISO 3166-1 alpha-3: ISO 3166-1 alpha-3 codes are three-letter country codes defined in ISO 3166-1, part of the ISO 3166 standard published by the International Organization for Standardization (ISO), to represent countries, dependent territories, and special areas of geographical interest. They allow a better visual association between the codes and the country names than the two-letter alpha-2 codes (the third set of codes is numeric and hence offers no visual association). They were first included as part of the ISO 3166 standard in its first edition in 1974.
Document 12: Bell UH-1 Iroquois: The Bell UH-1 Iroquois (nicknamed "Huey") is a utility military helicopter powered by a single turboshaft engine, with two-blade main and tail rotors. The first member of the prolific Huey family, it was developed by Bell Helicopter to meet a United States Army's 1952 requirement for a medical evacuation and utility helicopter, and first flew in 1956. The UH-1 was the first turbine-powered helicopter to enter production in 1960 for the United States military, and more than 16,000 have been built since.
Document 13: Americanist phonetic notation: Americanist phonetic notation, also known as the North American Phonetic Alphabet or NAPA, is a system of phonetic notation originally developed by European and American anthropologists and language scientists (students of Neogrammarians) for the phonetic and phonemic transcription of indigenous languages of the Americas and for languages of Europe. It is still commonly used by linguists working on, among others, Slavic, Uralic, Semitic languages and for the languages of the Caucasus and of India (however, Uralists commonly use a variant known as the Uralic Phonetic Alphabet). The term "Americanist phonetic alphabet" is misleading because it has always been widely used outside the Americas. For example, a version of it is the standard for the transcription of Arabic in articles published in the "Zeitschrift der Deutschen Morgenländischen Gesellschaft", the journal of the German Oriental Society.
Document 14: ICAO airport code: The ICAO ( , ) airport code or location indicator is a four-letter code designating aerodromes around the world. These codes are defined by the International Civil Aviation Organization, and published in ICAO Document 7910: "Location Indicators" are used by air traffic control and airline operations such as flight planning.
Document 15: E: E (named "e" , plural "ees") is the fifth letter and the second vowel in the modern English alphabet and the ISO basic Latin alphabet. It is the most commonly used letter in many languages, including Czech, Danish, Dutch, English, French, German, Hungarian, Latin, Latvian, Norwegian, Spanish, and Swedish.
ground_truth: Zulu Cobra