A stowaway or clandestine traveller is a person who secretly boards a vehicle , such as a ship , an aircraft , a train , cargo truck or bus .
111-474: Sometimes, the purpose is to get from one place to another without paying for transportation. In other cases, the goal is to enter another country without first obtaining a travel visa or other permission. Stowaways differ from people smuggling in that the stowaway needs to avoid detection by the truck driver, ship crew, and others responsible for the safe and secure operation of the transportation service. Thousands of stowaways have travelled by sea or land over
222-486: A Residence Permit after they have arrived in the country. In the United Kingdom, applications can be made to UK Visas and Immigration . In certain circumstances, it is impossible for the holder of the visa to do this, either because the country does not have a mechanism to prolong visas or, most likely, because the holder of the visa is using a short stay visa to live in a country. Some foreign visitors engage in what
333-494: A ski-jump on take-off is subjected to loads of 0.5g which also last for much longer than a landing impact. Helicopters may have a deck-lock harpoon to anchor them to the deck. Some aircraft have a requirement to use the landing-gear as a speed brake. Flexible mounting of the stowed main landing-gear bogies on the Tupolev Tu-22 R raised the aircraft flutter speed to 550 kn (1,020 km/h). The bogies oscillated within
444-414: A "boat" hull/floats and retractable wheels, which allow it to operate from land or water. Beaching gear is detachable wheeled landing gear that allows a non-amphibious floatplane or flying boat to be maneuvered on land. It is used for aircraft maintenance and storage and is either carried in the aircraft or kept at a slipway. Beaching gear may consist of individual detachable wheels or a cradle that supports
555-442: A 10 in (25 cm) thick flexible asphalt pavement . The 210,000 lb (95 t) Boeing 727 -200 with four tires on two legs main landing gears required a 20 in (51 cm) thick pavement. The thickness rose to 25 in (64 cm) for a McDonnell Douglas DC-10 -10 with 443,000 lb (201 t) supported on eight wheels on two legs. The heavier, 558,000 lb (253 t), DC-10-30/40 were able to operate from
666-468: A 90° angle during the rearwards-retraction sequence to allow the main wheel to rest "flat" above the lower end of the main gear strut, or flush within the wing or engine nacelles, when fully retracted. Examples are the Curtiss P-40 , Vought F4U Corsair , Grumman F6F Hellcat , Messerschmitt Me 210 and Junkers Ju 88 . The Aero Commander family of twin-engined business aircraft also shares this feature on
777-419: A consulate, embassy, or other diplomatic mission. Also known as visas on arrival (VOA), they are granted at a port of entry. This is distinct from visa-free entry, where no visa is required, as the visitor must still obtain the visa on arrival before proceeding to immigration control. An electronic visa (e-Visa or eVisa) is stored in a computer and is linked to the passport number so no label, sticker, or stamp
888-423: A country that limits the visa-free regime negatively by only listing nationals who require a visa, thus the number represents the number of UN member states reduced by the number of nationals who require a visa and "+" stands for all possible non-UN member state nationals that might also not require a visa. "N/A" indicates countries that have contradictory information on its official websites or information supplied by
999-466: A forward and aft position. The forward position was used for take-off to give a longer lever-arm for pitch control and greater nose-up attitude. The aft position was used to reduce landing bounce and reduce risk of tip-back during ground handling. The tandem or bicycle layout is used on the Hawker Siddeley Harrier, which has two main-wheels behind a single nose-wheel under the fuselage and
1110-505: A high altitude. According to experts, at 18,000 feet (5,500 m), hypoxia causes lightheadedness , weakness, vision impairment and tremors . By 22,000 feet (6,700 m) the oxygen level of the blood drops and the person will struggle to stay conscious. Above 33,000 feet (10,000 m) their lungs would need artificial pressure to operate normally. The temperature could drop as low as −63 °C (−81 °F) which causes severe hypothermia. Those stowaways who managed to not be crushed by
1221-573: A higher sink-rate requirement because the aircraft are flown onto the deck with no landing flare . Other features are related to catapult take-off requirements for specific aircraft. For example, the Blackburn Buccaneer was pulled down onto its tail-skid to set the required nose-up attitude. The naval McDonnell Douglas F-4 Phantom II in UK service needed an extending nosewheel leg to set the wing attitude at launch. The landing gear for an aircraft using
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#17330860921911332-470: A higher sink-rate requirement if a carrier-type, no-flare landing technique has to be adopted to reduce touchdown scatter. For example, the Saab 37 Viggen , with landing gear designed for a 5m/sec impact, could use a carrier-type landing and HUD to reduce its scatter from 300 m to 100m. The de Havilland Canada DHC-4 Caribou used long-stroke legs to land from a steep approach with no float. A flying boat has
1443-489: A light aircraft, an emergency extension system is always available. This may be a manually operated crank or pump, or a mechanical free-fall mechanism which disengages the uplocks and allows the landing gear to fall under gravity. Aircraft landing gear includes wheels equipped with solid shock absorbers on light planes, and air/oil oleo struts on larger aircraft. As aircraft weights have increased more wheels have been added and runway thickness has increased to keep within
1554-463: A list of excludable aliens, including stowaways. Several stowaways arrived in United States by boat during the first half of twentieth century; they were paying for 25 to 30 dollars to travel. The Convention on Facilitation of International Maritime Traffic , 1965, as amended, (The FAL Convention), define stowaway as "A person who is secreted on a ship, or in cargo which is subsequently loaded on
1665-533: A long-stay visa for those who intend to apply for a residence permit . For example, the EU does not require a visa of citizens of many countries for stays under 90 days, but its member states require a long-stay visa of such citizens for longer stays. Many countries have a mechanism to allow the holder of a visa to apply to extend a visa. In Denmark, a visa holder can apply to the Danish Immigration Service for
1776-621: A low altitude. Two cases are known of people who survived at an altitude of about 38,000 feet (12,000 m) – a man on an 8-hour flight, whose body core temperature fell to 79 °F (26 °C), and a 16-year-old boy who was unharmed by a 5.5 hour flight, despite losing consciousness. Almost all aircraft stowaways are male. Aside from risk to themselves, aircraft stowaways can also cause significant risk and stress to others when impacted equipment compromises safety, as well as significant cost of equipment repair, damage to aircraft on landing, and runway closures. In 1994, Flight PH844 discovered
1887-403: A lower fuselage with the shape of a boat hull giving it buoyancy. Wing-mounted floats or stubby wing-like sponsons are added for stability. Sponsons are attached to the lower sides of the fuselage. A floatplane has two or three streamlined floats. Amphibious floats have retractable wheels for land operation. An amphibious aircraft or amphibian usually has two distinct landing gears, namely
1998-524: A nosewheel) chassis. Landing is done on skids or similar simple devices (fixed or retractable). The SNCASE Baroudeur used this arrangement. Historical examples include the "dolly"-using Messerschmitt Me 163 Komet rocket fighter, the Messerschmitt Me 321 Gigant troop glider, and the first eight "trolley"-using prototypes of the Arado Ar 234 jet reconnaissance bomber. The main disadvantage to using
2109-476: A number of airports around the world can make it easier for people to stow away on planes. Stowaways in aircraft wheel wells face numerous health risks, many of which are fatal: being mangled when the undercarriage retracts, tinnitus , deafness , hypothermia , hypoxia , frostbite , acidosis and finally falling when the doors of the compartment reopen. The landing gear compartment is not equipped with heating, pressure or oxygen, which are vital for survival at
2220-436: A private visa service specialist who is specialized in the issuance of international travel documents. These agencies are authorized by the foreign authority, embassy, or consulate to represent international travellers who are unable or unwilling to travel to the embassy and apply in person. Private visa and passport services collect an additional fee for verifying customer applications, supporting documents, and submitting them to
2331-423: A ship with or without the assistance of port personnel. Once on board the ship, stowaways hide in empty containers, cargo holds, tanks, tunnels, behind false panels, stores, accommodation areas, engine rooms, void spaces, cranes and chain lockers. The presence of stowaways on board ships may bring serious consequences for ships and, by extension, to the shipping industry as a whole; the ship could be delayed in port;
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#17330860921912442-453: A similar arrangement, except that the fore and aft gears each have two twin-wheel units side by side. Quadricycle gear is similar to bicycle but with two sets of wheels displaced laterally in the fore and aft positions. Raymer classifies the B-52 gear as quadricycle. The experimental Fairchild XC-120 Packplane had quadricycle gear located in the engine nacelles to allow unrestricted access beneath
2553-509: A smaller wheel near the tip of each wing. On second generation Harriers, the wing is extended past the outrigger wheels to allow greater wing-mounted munition loads to be carried, or to permit wing-tip extensions to be bolted on for ferry flights. A tandem layout was evaluated by Martin using a specially-modified Martin B-26 Marauder (the XB-26H) to evaluate its use on Martin's first jet bomber,
2664-441: A specific duration include: Granted for those intending to settle permanently in the issuing country (obtain the status of a permanent resident with a prospect of possible naturalization in the future): These are granted to officials doing jobs for their governments, or otherwise representing their countries in the host country, such as the personnel of diplomatic missions. Normally visa applications are made at and collected from
2775-485: A stowaway when crossing national borders. Stowaways on sailing ships and on steamships made this way of illicit travel known throughout the world. Throughout the nineteenth and twentieth centuries poor, would-be emigrants and travelers seeking adventure for no cost helped to make it seem romantic. Noted stowaways to America by steamship have included Henry Armetta , Bruno Richard Hauptmann , Willem de Kooning , Jan Valtin , and Florentino Das . Poor perimeter security at
2886-702: A territory and thus are, in most countries, distinct from actual formal permission for an alien to enter and remain in the country. In each instance, a visa is subject to entry permission by an immigration official at the time of actual entry and can be revoked at any time. Visa evidence most commonly takes the form of a sticker endorsed in the applicant's passport or other travel document but may also exist electronically. Some countries no longer issue physical visa evidence, instead recording details only in immigration databases. Some countries, such as Turkey , require that their citizens, and sometimes foreign travelers, obtain an exit visa in order to be allowed to leave
2997-630: A test approved by a medical authority to enter Chilean territory. The issuing authority may also require applicants to attest that they have no criminal convictions, or that they do not participate in certain activities (like prostitution or drug trafficking). Some countries will deny visas if passports show evidence of citizenship of, or travel to, a country that is considered hostile by that country. For example, some Arabic-oriented countries will not issue visas to nationals of Israel and those whose passports bear evidence of visiting Israel. Many countries frequently demand strong evidence of intent to return to
3108-546: A tricycle undercarriage to prevent damage to the underside of the fuselage if over-rotation occurs on take-off leading to a tail strike . Aircraft with tail-strike protection include the B-29 Superfortress , Boeing 727 trijet and Concorde . Some aircraft with retractable conventional landing gear have a fixed tailwheel. Hoerner estimated the drag of the Bf 109 fixed tailwheel and compared it with that of other protrusions such as
3219-504: A visa in advance are usually advised to obtain them at a diplomatic mission of their destination country. Several countries allow nationals of countries that require a visa to obtain them online. The following table lists visa policies of all countries by the number of foreign nationalities that may enter that country for tourism without a visa or by obtaining a visa on arrival with normal passport. It also notes countries that issue electronic visas to certain nationalities. Symbol "+" indicates
3330-435: A visa is not needed under certain conditions, e.g., when the visit is for tourism and for a relatively short period. Such reciprocal agreements may stem from common membership in international organizations or a shared heritage: Other countries may unilaterally grant visa-free entry to nationals of certain countries to facilitate tourism, promote business, or even to cut expenses on maintaining consular posts abroad. Some of
3441-435: A visa run is necessary to activate new visas or change the immigration status of a person. An example would be leaving a country and then returning immediately to activate a newly issued work visa before a person can legally work. In general, an applicant may be refused a visa if they do not meet the requirements for admission or entry under that country's immigration laws. More specifically, a visa may be denied or refused when
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3552-483: Is 1 July (if the traveller entered on 30 March). This interpretation of visas is common in the Americas. With other countries, a person may not stay beyond the period of validity of their visa, which is usually set within the period of validity of their passport. The visa may also limit the total number of days the visitor may spend in the applicable territory within the period of validity. This interpretation of visa periods
3663-408: Is a central principle of the EU's common visa policy. The EU aims to achieve full visa reciprocity with non-EU countries whose citizens can travel to the EU without a visa. For example, when in 2009, Canada reintroduced visa requirements for Czech nationals, arguing it was necessary due to a surge in asylum applications, it raised concerns within the EU about the implications for the common visa policy,
3774-424: Is a conditional authorization granted by a polity to a foreigner that allows them to enter, remain within, or leave its territory. Visas typically include limits on the duration of the foreigner's stay, areas within the country they may enter, the dates they may enter, the number of permitted visits, or if the individual can work in the country in question. Visas are associated with the request for permission to enter
3885-412: Is also unique in that all four pairs of main wheels can be steered. This allows the landing gear to line up with the runway and thus makes crosswind landings easier (using a technique called crab landing ). Since tandem aircraft cannot rotate for takeoff, the forward gear must be long enough to give the wings the correct angle of attack during takeoff. During landing, the forward gear must not touch
3996-536: Is common in Europe. Once in the country, the validity period of a visa or authorized stay can often be extended for a fee at the discretion of immigration authorities. Overstaying a period of authorized stay given by the immigration officers is considered illegal immigration even if the visa validity period is not over (i.e., for multiple entry visas) and a form of being "out of status" and the offender may be fined , prosecuted, deported , or even blacklisted from entering
4107-455: Is considered more likely that people from these countries will seek to illegally immigrate. Visa restrictions may also be imposed when nationals of another country are perceived as likelier to be terrorists or criminals, or by autocratic regimes that perceive foreign influence to be a threat to their rule. According to Professor Eric Neumayer of the London School of Economics : The poorer,
4218-399: Is illegal in most jurisdictions to embark on aircraft, boats or trains as stowaways. Airports , sea ports and train stations are typically marked as "no trespassing " or " private property " zones to anyone but customers and employees. Seaports, train stations, and airports often attempt further security by designating restricted areas with signs saying "Authorized Personnel Only". Since
4329-442: Is known as a visa run : leaving a country—usually to a neighboring country—for a short period just before the permitted length of stay expires, then returning to the first country to get a new entry stamp in order to extend their stay ("reset the clock"). Despite the name, a visa run is usually done with a passport that can be used for entry without a visa. Visa runs are frowned upon by immigration authorities as they may signify that
4440-499: Is not a violation of a visa, despite the common misuse of the phrase, but a violation of status – hence the term "out of status". Even having a visa does not guarantee entry to the host country. The border crossing authorities make the final determination to allow entry, and may even cancel a visa at the border if the alien cannot demonstrate to their satisfaction that they will abide by the status their visa grants them. Some countries that do not require visas for short stays may require
4551-402: Is permitted into the country. For example, if a visa has been issued to begin on 1 January and to expire on 30 March, and the typical authorized period of stay in a country is 90 days, then the 90-day authorized stay starts on the day the passenger enters the country (entrance has to be between 1 January and 30 March). Thus, the latest day the traveller could conceivably stay in the issuing country
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4662-468: Is placed in the passport before travel. The application is done over the internet, and the receipt acts as a visa, which can be printed or stored on a mobile device. Visas can also be single-entry , which means the visa is cancelled as soon as the holder enters the country; double-entry ; or multiple-entry , which permits double or multiple entries into the country with the same visa. Countries may also issue re-entry permits that allow temporarily leaving
4773-465: Is required to reduce the impact with the surface of the water. A vee bottom parts the water and chines deflect the spray to prevent it damaging vulnerable parts of the aircraft. Additional spray control may be needed using spray strips or inverted gutters. A step is added to the hull, just behind the center of gravity, to stop water clinging to the afterbody so the aircraft can accelerate to flying speed. The step allows air, known as ventilation air, to break
4884-518: Is the undercarriage of an aircraft or spacecraft that is used for taxiing , takeoff or landing . For aircraft, it is generally needed for all three of these. It was also formerly called alighting gear by some manufacturers, such as the Glenn L. Martin Company . For aircraft, Stinton makes the terminology distinction undercarriage (British) = landing gear (US) . For aircraft, the landing gear supports
4995-678: The Beriev A-40 Hydro flaps were used on the Martin Marlin and Martin SeaMaster . Hydroflaps, submerged at the rear of the afterbody, act as a speed brake or differentially as a rudder. A fixed fin, known as a skeg , has been used for directional stability. A skeg, was added to the second step on the Kawanishi H8K flying boat hull. High speed impacts in rough water between the hull and wave flanks may be reduced using hydro-skis which hold
5106-558: The Han Dynasty in China , documents were required at checkpoints to verify travelers' identities. In medieval Europe , rulers issued "safe conduct" letters that protected travelers. In 1414, during the reign of King Henry V of England , passports became more formalized, allowing foreigners and citizens to travel safely within England. The 19th century saw an increase in international travel due to
5217-728: The Industrial Revolution , which led to the widespread adoption of passports, particularly for managing the movement of migrant workers. In Western Europe in the late 19th century and early 20th century, passports and visas were not generally necessary for moving from one country to another. The relatively high speed and large movements of people travelling by train would have caused bottlenecks if regular passport controls had been used. Passports and visas became usually necessary as travel documents only after World War I . After World War I , passports became essential for international travel. The League of Nations convened conferences in
5328-549: The Martin Marlin , the Martin M-270, was tested with a new hull with a greater length/beam ratio of 15 obtained by adding 6 feet to both the nose and tail. Rough-sea capability can be improved with lower take-off and landing speeds because impacts with waves are reduced. The Shin Meiwa US-1A is a STOL amphibian with blown flaps and all control surfaces. The ability to land and take-off at relatively low speeds of about 45 knots and
5439-677: The Martin XB-48 . This configuration proved so manoeuvrable that it was also selected for the B-47 Stratojet . It was also used on the U-2, Myasishchev M-4 , Yakovlev Yak-25 , Yak-28 and Sud Aviation Vautour . A variation of the multi tandem layout is also used on the B-52 Stratofortress which has four main wheel bogies (two forward and two aft) underneath the fuselage and a small outrigger wheel supporting each wing-tip. The B-52's landing gear
5550-542: The September 11 attacks , it has become more difficult to be a stowaway on board transportation arriving to or departing from the United States. Airport security has dramatically increased, and among the new security measures is trained professionals watching over the fences from which stowaways usually gain entrance to an airport's runway. Travel visa A visa ( lat. 'something seen', pl. visas from Latin charta visa 'papers that have been seen')
5661-470: The maximum takeoff weight (MTOW) and 1.5 to 1.75% of the aircraft cost, but 20% of the airframe direct maintenance cost. A suitably-designed wheel can support 30 t (66,000 lb), tolerate a ground speed of 300 km/h and roll a distance of 500,000 km (310,000 mi) ; it has a 20,000 hours time between overhaul and a 60,000 hours or 20 year life time. Wheeled undercarriages normally come in two types: The taildragger arrangement
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#17330860921915772-469: The polizón denomination. The US legislation set up a stowaway concept in 1850. Previously, entry into the territory was free and the stowaway word might be older. In 1891, the new US legislation required the boat to pay the return travel for people not admitted in US, even if stowaways were still admitted. 474 stowaways arrived in US in fiscal year 1910, and 528 next year. In 1917, a new legislation defined
5883-445: The 1920s to standardise passports, setting the foundation for modern versions. The International Civil Aviation Organization (ICAO) took over regulation in 1947, leading to machine-readable passports and, eventually, biometric passports in the late 20th century, offering enhanced security and speed in processing travelers. Some visas can be granted on arrival or by prior application at the country's embassy or consulate , or through
5994-774: The Government to IATA . Some countries that allow visa on arrival do so only at a limited number of entry points. Some countries such as the European Union member states have a qualitatively different visa regime between each other as it also includes freedom of movement. The following table is current as of 3 October 2019 . Source: Possession of a valid visa is a condition for entry into many countries, and exemption schemes exist. In some cases visa-free entry may be granted to holders of diplomatic passports even as visas are required by normal passport holders ( see: Passport ). Some countries have reciprocal agreements such that
6105-403: The United Kingdom. Stowaways sometimes hide themselves in vehicles such as cargo trucks to get between cities. Although this is also done by migrants who have paid the driver, it is also done by individuals hiding from the driver. In some places, drivers are legally responsible for making sure that stowaways do not board their vehicles, and can be fined or jailed if they do not detect and remove
6216-472: The United States (if valid for at least three months on date of arrival). The ultimate example of such reliance is the microstate of Andorra , which imposes no visa requirements of its own because it has no international airport and is inaccessible by land without passing through the territory of either France or Spain and is thus "protected" by the Schengen visa system. Landing gear Landing gear
6327-459: The United States does not give visitors a new period of stay when they come back from visiting Canada, Mexico, or the Caribbean ; instead they are re-admitted to the United States for the remaining days granted on their initial entry. Some other countries, e.g. Thailand, allow visitors who arrive by land from neighboring countries a shorter length of stay than those who arrive by air. In some cases,
6438-556: The World, Volume 1 or 1637 Journals of the House of Lords, Volume 11 . The word was also used (later) for people. This gave names such as stow-aways , when the correct current name in modern English language is stowaway . Depending on the circumstances, people were stowed away in order to hide themselves, or to be transported as slaves. The concept of people hiding is not so recent; it was yet forbidden (and so known) in 1748 by king of Spain, under
6549-416: The aircraft can be landed in a satisfactory manner in a range of failure scenarios. The Boeing 747 was given four separate and independent hydraulic systems (when previous airliners had two) and four main landing gear posts (when previous airliners had two). Safe landing would be possible if two main gear legs were torn off provided they were on opposite sides of the fuselage. In the case of power failure in
6660-470: The airstream, it is called a semi-retractable gear. Most retractable gear is hydraulically operated, though some is electrically operated or even manually operated on very light aircraft. The landing gear is stowed in a compartment called a wheel well. Pilots confirming that their landing gear is down and locked refer to "three greens" or "three in the green.", a reference to the electrical indicator lights (or painted panels of mechanical indicator units) from
6771-466: The applicant can print before entering and produce on entry to the visited polity. Some countries do not require visitors to apply for a visa in advance for short visits. Visa applications in advance of arrival give countries a chance to consider the applicant's circumstances, such as financial security, reason for travel, and details of previous visits to the country. Visitors may also be required to undergo and pass security or health checks upon arrival at
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#17330860921916882-527: The applicant. This may include proof that the applicant is able to support him or herself in the host country (lodging, food), proof that the person hosting the applicant in his or her home really exists and has sufficient room for hosting the applicant, proof that the applicant has obtained health and evacuation insurance, etc. Some countries ask for proof of health status, especially for long-term visas; some countries deny such visas to persons with certain illnesses, such as HIV/AIDS . The exact conditions depend on
6993-525: The applicant: Even if a traveller does not need a visa, the aforementioned criteria can also be used by border control officials to refuse the traveller's entry into the country in question. The main reasons states impose visa restrictions on foreign nationals are to curb illegal immigration, security concerns, and reciprocity for visa restrictions imposed on their own nationals. Typically, nations impose visa restrictions on citizens of poorer countries, along with politically unstable and undemocratic ones, as it
7104-403: The appropriate authority. If there is no embassy or consulate in one's home country, then one would have to travel to a third country (or apply by post) and try to get a visa issued there. Alternatively, in such cases visas may be pre-arranged for collection on arrival at the border. The need or absence of need of a visa generally depends on the citizenship of the applicant, the intended duration of
7215-442: The body of a deceased male stowaway was jamming the starboard carriageway. After 3.5 hours of maneuvers attempting to dislodge the body, the flight made an emergency landing using only the nosewheel and port undercarriage. The air force of another country was required to assist move the damaged plane from the runway. In 1965, Brian Robson attempted to mail himself in a crate on a flight from Melbourne, Australia to London. The flight
7326-495: The considerations for a country to grant visa-free entry to another country include (but are not limited to): To have a smaller worldwide diplomatic staff, some countries rely on other country's (or countries') judgments when issuing visas. For example, Mexico allows citizens of all countries to enter without Mexican visas if they possess a valid American visa that has already been used. Costa Rica accepts valid visas of Schengen /EU countries, Canada , Japan , South Korea , and
7437-421: The country again. Entering a country without a valid visa or visa exemption may result in detention and removal (deportation or exclusion) from the country. Undertaking activities that are not authorized by the status of entry (for example, working while possessing a non-worker tourist status) can result in the individual being deemed liable for deportation—commonly referred to as an illegal alien . Such violation
7548-450: The country and category of visa. Notable examples of countries requiring HIV tests of long-term residents are Russia and Uzbekistan. In Uzbekistan, however, the HIV test requirement is sometimes not strictly enforced. Other countries require a medical test that includes an HIV test, even for a short-term tourism visa. For example, Cuban citizens and international exchange students require such
7659-409: The country of issue to a destination outside that country. Validity of transit visas are usually limited by short terms such as several hours to ten days depending on the size of the country or the circumstances of a particular transit itinerary. For short visits to the visited country. Many countries differentiate between different reasons for these visits, such as: Visas valid for long term stays of
7770-407: The country without invalidating the visa. Even a business visa will normally not allow the holder to work in the host country without an additional work permit . Once issued, a visa will typically have to be used within a certain period of time. In some countries, the validity of a visa is not the same as the authorized period of stay. The visa validity then indicates the time period when the entry
7881-463: The country. Until 2004, foreign students in Russia were issued only an entry visa on being accepted to University there, and had to obtain an exit visa to return home. This policy has since been changed, and foreign students are now issued multiple entry (and exit) visas. Historically, immigration officials were empowered to permit or reject entry of visitors on arrival at the frontiers. If permitted entry,
7992-422: The craft when it is not flying, allowing it to take off, land, and taxi without damage. Wheeled landing gear is the most common, with skis or floats needed to operate from snow/ice/water and skids for vertical operation on land. Retractable undercarriages fold away during flight, which reduces drag , allowing for faster airspeeds . Landing gear must be strong enough to support the aircraft and its design affects
8103-410: The entire aircraft. In the former case, the beaching gear is manually attached or detached with the aircraft in the water; in the latter case, the aircraft is maneuvered onto the cradle. Helicopters are able to land on water using floats or a hull and floats. For take-off a step and planing bottom are required to lift from the floating position to planing on the surface. For landing a cleaving action
8214-419: The foreigner wishes to reside permanently and might also work in that country – purposes that are prohibited and that usually require an immigrant visa or a work visa. Immigration officers may deny re-entry to visitors suspected of engaging in prohibited activities, especially when they have done repeated visa runs and have no evidence of spending reasonable time in their home countries or countries where they have
8325-418: The fuselage for attaching a large freight container. Helicopters use skids, pontoons or wheels depending on their size and role. To decrease drag in flight, undercarriages retract into the wings and/or fuselage with wheels flush with the surrounding surface, or concealed behind flush-mounted doors; this is called retractable gear. If the wheels do not retract completely but protrude partially exposed to
8436-424: The fuselage lower sides as retractable main gear units on modern designs—were first seen during World War II, on the experimental German Arado Ar 232 cargo aircraft, which used a row of eleven "twinned" fixed wheel sets directly under the fuselage centerline to handle heavier loads while on the ground. Many of today's large cargo aircraft use this arrangement for their retractable main gear setups, usually mounted on
8547-438: The fuselage. The 640 t (1,410,000 lb) Antonov An-225 , the largest cargo aircraft, had 4 wheels on the twin-strut nose gear units like the smaller Antonov An-124 , and 28 main gear wheels. The 97 t (214,000 lb) A321neo has a twin-wheel main gear inflated to 15.7 bar (228 psi), while the 280 t (620,000 lb) A350 -900 has a four-wheel main gear inflated to 17.1 bar (248 psi). STOL aircraft have
8658-506: The home country, if the visa is for a temporary stay, due to potential unwanted illegal immigration . Proof of ties to the visa applicant's country of residence is often demanded to demonstrate a sufficient incentive to return. This can include things such as documented evidence of employment, bank statements, property ownership, and family ties. Each country typically has a multitude of categories of visas with various names. The most common types and names of visas include: For passing through
8769-585: The hull out of the water at higher speeds. Hydro skis replace the need for a boat hull and only require a plain fuselage which planes at the rear. Alternatively skis with wheels can be used for land-based aircraft which start and end their flight from a beach or floating barge. Hydro-skis with wheels were demonstrated as an all-purpose landing gear conversion of the Fairchild C-123 , known as the Panto-base Stroukoff YC-134 . A seaplane designed from
8880-462: The hydrodynamic features of the hull, long length/beam ratio and inverted spray gutter for example, allow operation in wave heights of 15 feet. The inverted gutters channel spray to the rear of the propeller discs. Low speed maneuvring is necessary between slipways and buoys and take-off and landing areas. Water rudders are used on seaplanes ranging in size from the Republic RC-3 Seabee to
8991-418: The importance of reciprocity in maintaining good relations and ensuring equal treatment for citizens of member states. Government authorities usually impose administrative entry restrictions on foreign citizens in three ways - countries whose nationals may enter without a visa, countries whose nationals may obtain a visa on arrival, and countries whose nationals require a visa in advance. Nationals who require
9102-402: The landing gear usually consists of skis or a combination of wheels and skis. Some aircraft use wheels for takeoff and jettison them when airborne for improved streamlining without the complexity, weight and space requirements of a retraction mechanism. The wheels are sometimes mounted onto axles that are part of a separate "dolly" (for main wheels only) or "trolley" (for a three-wheel set with
9213-405: The landing gear usually only supports the vehicle on landing and during subsequent surface movement, and is not used for takeoff. Given their varied designs and applications, there exist dozens of specialized landing gear manufacturers. The three largest are Safran Landing Systems , Collins Aerospace (part of Raytheon Technologies ) and Héroux-Devtek . The landing gear represents 2.5 to 5% of
9324-423: The last several centuries. A much smaller number of people have attempted to stowaway on aircraft. Many stowaways have died during the attempt, especially in cases of train surfing and wheel-well stowaway flights . The word takes its origin with the expression stow away . This stow away expression is old and was used for things (such as food), such usage is seen for instance in the 1689 book A New Voyage Round
9435-556: The less democratic, and the more exposed to armed political conflict the target country is, the more likely that visa restrictions are in place against its passport holders. The same is true for countries whose nationals have been major perpetrators of terrorist acts in the past. Some countries apply the principle of reciprocity in their visa policy. Visa reciprocity is a principle in international relations where two countries agree to give each other's citizens similar treatment when it comes to visa requirements. For example visa reciprocity
9546-417: The lower corners of the central fuselage structure. The prototype Convair XB-36 had most of its weight on two main wheels, which needed runways at least 22 in (56 cm) thick. Production aircraft used two four-wheel bogies, allowing the aircraft to use any airfield suitable for a B-29. A relatively light Lockheed JetStar business jet, with four wheels supporting 44,000 lb (20 t), needed
9657-496: The main gear struts lengthened as they were extended to give sufficient ground clearance for their large four-bladed propellers. One exception to the need for this complexity in many WW II fighter aircraft was Japan's famous Zero fighter, whose main gear stayed at a perpendicular angle to the centerline of the aircraft when extended, as seen from the side. The main wheels on the Vought F7U Cutlass could move 20 inches between
9768-483: The main gears, which retract aft into the ends of the engine nacelles . The rearward-retracting nosewheel strut on the Heinkel He 219 and the forward-retracting nose gear strut on the later Cessna Skymaster similarly rotated 90 degrees as they retracted. On most World War II single-engined fighter aircraft (and even one German heavy bomber design ) with sideways retracting main gear, the main gear that retracted into
9879-590: The nacelle under the control of dampers and springs as an anti-flutter device. Some experimental aircraft have used gear from existing aircraft to reduce program costs. The Martin-Marietta X-24 lifting body used the nose/main gear from the North American T-39 / Northrop T-38 and the Grumman X-29 from the Northrop F-5 / General Dynamics F-16 . When an airplane needs to land on surfaces covered by snow,
9990-444: The nosewheel/tailwheel and the two main gears. Blinking green lights or red lights indicate the gear is in transit and neither up and locked or down and locked. When the gear is fully stowed up with the up-locks secure, the lights often extinguish to follow the dark cockpit philosophy; some airplanes have gear up indicator lights. Redundant systems are used to operate the landing gear and redundant main gear legs may also be provided so
10101-459: The number of tourists requiring a visa before travelling was at its lowest level ever. The history of passports dates back several centuries, originating from early travel documents used to ensure safe passage across regions. One of the earliest known references to a passport-like document comes from 445 BC in Persia , where officials were provided letters by the king for safe travel. Similarly, during
10212-457: The official would issue a visa, when required, which would be a stamp in a passport. Today, travellers wishing to enter another country must often apply in advance for what is also called a visa, sometimes in person at a consular office , by post, or over the Internet. The modern visa may be a sticker or a stamp in the passport, an electronic record of the authorization, or a separate document which
10323-703: The outset with hydro-skis was the Convair F2Y Sea Dart prototype fighter. The skis incorporated small wheels, with a third wheel on the fuselage, for ground handling. In the 1950s hydro-skis were envisaged as a ditching aid for large piston-engined aircraft. Water-tank tests done using models of the Lockheed Constellation , Douglas DC-4 and Lockheed Neptune concluded that chances of survival and rescue would be greatly enhanced by preventing critical damage associated with ditching. The landing gear on fixed-wing aircraft that land on aircraft carriers have
10434-545: The pilot's canopy. A third arrangement (known as tandem or bicycle) has the main and nose gear located fore and aft of the center of gravity (CG) under the fuselage with outriggers on the wings. This is used when there is no convenient location on either side of the fuselage to attach the main undercarriage or to store it when retracted. Examples include the Lockheed U-2 spy plane and the Harrier jump jet . The Boeing B-52 uses
10545-477: The port of entry. Some polities which restrict emigration require individuals to possess an exit visa to leave the polity. These exit visas may be required for citizens, foreigners, or both, depending on the policies of the polity concerned. Unlike ordinary visas, exit visas are often seen as an illegitimate intrusion on individuals' right to freedom of movement . The imposition of an exit visa requirement may be seen to violate customary international law , as
10656-448: The repatriation of stowaways can be a very complex and costly procedure involving masters, shipowners, port authorities and agents, and the life of stowaways could be endangered as they may spend several days hidden, with the risk of suffocation and without any food or water. Some undocumented migrants travel around Europe in trucks and trains without being detected. A number of them try to get to other European countries, such as France and
10767-505: The retracting undercarriage or killed by the deadly conditions would most likely be unconscious when the compartment door re-opens during the approach and fall several thousand feet to their deaths. David Learmount, an aviation expert of Flight International , told BBC about a lot of ignorance in this area. He suggested that no one would be willing to risk such a journey having full understanding of this kind of ordeal. Stowaways who survived usually travelled relatively short distances or at
10878-736: The right to leave any country is provided for in the Universal Declaration of Human Rights . Uniquely, the Norwegian special territory of Svalbard is an entirely visa-free zone under the terms of the Svalbard Treaty . Some countries—such as those in the Schengen Area —have agreements with other countries allowing each other's citizens to travel between them without visas. In 2015, the World Tourism Organization announced that
10989-420: The right to reside and work. To combat visa runs, some countries have limits on how long visitors can spend in the country without a visa, as well as how much time they have to stay out before "resetting the clock". For example, Schengen countries impose a maximum of 90 days in any 180-day period. Some countries do not "reset the clock" when a visitor comes back after visiting a neighboring country. For example,
11100-513: The runway loading limit . The Zeppelin-Staaken R.VI , a large German World War I long-range bomber of 1916, used eighteen wheels for its undercarriage, split between two wheels on its nose gear struts, and sixteen wheels on its main gear units—split into four side-by-side quartets each, two quartets of wheels per side—under each tandem engine nacelle, to support its loaded weight of almost 12 t (26,000 lb). Multiple "tandem wheels" on an aircraft—particularly for cargo aircraft , mounted to
11211-524: The same thickness pavements with a third main leg for ten wheels, like the first Boeing 747 -100, weighing 700,000 lb (320 t) on four legs and 16 wheels. The similar-weight Lockheed C-5 , with 24 wheels, needs an 18 in (46 cm) pavement. The twin-wheel unit on the fuselage centerline of the McDonnell Douglas DC-10 -30/40 was retained on the MD-11 airliner and the same configuration
11322-405: The ship, without the consent of the shipowner or the master or any other responsible person and who is detected on board the ship after it has departed from a port, or in the cargo while unloading it in the port of arrival, and is reported as a stowaway by the master to the appropriate authorities". Unnoticed by the captain , crew, port officials and customs authorities, stowaways may gain access to
11433-401: The stay, and the activities that the applicant may wish to undertake in the country he or she visits; these may delineate different formal categories of visas, with different issue conditions. The issuing authority, usually a branch of the country's foreign ministry or department (e.g. U.S. State Department ), and typically consular affairs officers, may request appropriate documentation from
11544-508: The takeoff dolly/trolley and landing skid(s) system on German World War II aircraft—intended for a sizable number of late-war German jet and rocket-powered military aircraft designs—was that aircraft would likely be scattered all over a military airfield after they had landed from a mission, and would be unable to taxi on their own to an appropriately hidden "dispersal" location, which could easily leave them vulnerable to being shot up by attacking Allied fighters. A related contemporary example are
11655-676: The water suction on the afterbody. Two steps were used on the Kawanishi H8K . A step increases the drag in flight. The drag contribution from the step can be reduced with a fairing. A faired step was introduced on the Short Sunderland III. One goal of seaplane designers was the development of an open ocean seaplane capable of routine operation from very rough water. This led to changes in seaplane hull configuration. High length/beam ratio hulls and extended afterbodies improved rough water capabilities. A hull much longer than its width also reduced drag in flight. An experimental development of
11766-482: The weight, balance and performance. It often comprises three wheels, or wheel-sets, giving a tripod effect. Some unusual landing gear have been evaluated experimentally. These include: no landing gear (to save weight), made possible by operating from a catapult cradle and flexible landing deck: air cushion (to enable operation over a wide range of ground obstacles and water/snow/ice); tracked (to reduce runway loading). For launch vehicles and spacecraft landers ,
11877-491: The wings was raked forward in the "down" position for better ground handling, with a retracted position that placed the main wheels at some distance aft of their position when downairframe—this led to a complex angular geometry for setting up the "pintle" angles at the top ends of the struts for the retraction mechanism's axis of rotation. with some aircraft, like the P-47 Thunderbolt and Grumman Bearcat , even mandating that
11988-424: The wingtip support wheels ("pogos") on the Lockheed U-2 reconnaissance aircraft, which fall away after take-off and drop to earth; the aircraft then relies on titanium skids on the wingtips for landing. Some main landing gear struts on World War II aircraft, in order to allow a single-leg main gear to more efficiently store the wheel within either the wing or an engine nacelle, rotated the single gear strut through
12099-445: Was common during the early propeller era, as it allows more room for propeller clearance. Most modern aircraft have tricycle undercarriages. Taildraggers are considered harder to land and take off (because the arrangement is usually unstable , that is, a small deviation from straight-line travel will tend to increase rather than correct itself), and usually require special pilot training. A small tail wheel or skid/bumper may be added to
12210-525: Was diverted to Los Angeles, where he was discovered after four days in the crate. In one reported case, in 2003, a young man mailed himself in a large box and had it shipped on UPS planes from New York City to Texas. He survived because the box travelled in a pressurized hold of an aircraft. From 1947 until September 2012, there were 96 known stowaway attempts worldwide in wheel wells of 85 separate flights, which resulted in 73 deaths with only 23 survivors. Stowaways may risk being fined or imprisoned, since it
12321-467: Was used on the initial 275 t (606,000 lb) Airbus A340 -200/300, which evolved in a complete four-wheel undercarriage bogie for the heavier 380 t (840,000 lb) Airbus A340-500/-600. The up to 775,000 lb (352 t) Boeing 777 has twelve main wheels on two three-axles bogies, like the later Airbus A350 . The 575 t (1,268,000 lb) Airbus A380 has a four-wheel bogie under each wing with two sets of six-wheel bogies under
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