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66-483: The Ayles Ice Shelf was one of six major ice shelves in Canada, all on the north coast of Ellesmere Island , Nunavut . The ice shelf broke off from the coast on August 13, 2005, forming a giant ice island 37 m (121 ft) thick and measuring around 14 by 5 km (8.7 by 3.1 mi) in size (approximately 55 km (21 sq mi) in area or 2.6 km (0.62 cu mi) in volume). The oldest ice in

132-438: A C-47 Skytrain , all of the equipment to outfit the 14 prefabricated buildings was transported to the newly discovered iceberg. Scientific operations restarted on 23 May 1961 and continued all the way into 11 May 1965. Resupply of ARLIS II during the first year was carried out by airdrops from large aircraft such as Lockheed Model 18 Lodestar and C-47 Skytrains, and also by the icebreaker USCGC Staten Island (WAGB-278) twice in

198-415: A "hotspot of global warming". It broke over a period of three weeks or less, with a factor in this fast break-up being the powerful effects of water; ponds of meltwater formed on the surface during the near 24 hours of daylight in the summertime, flowed down into cracks and, acting like a multitude of wedges, levered the shelf apart. Other likely factors in the break-up were the higher ocean temperatures and

264-522: A huge ice island in 2017. From 31 January 2002 to March 2002 the Larsen B sector partially collapsed and parts broke up, 3,250 km (1,250 sq mi) of ice 220 m (720 ft) thick, an area comparable to the US state of Rhode Island . In 2015, a study concluded that the remaining Larsen B ice-shelf would disintegrate by 2020, based on observations of faster flow and rapid thinning of glaciers in

330-615: A large crack in the Ward Hunt shelf had begun to form, and in 2003 it was announced that the ice sheet had split completely in two in 2002, releasing a huge pool of freshwater from the largest epishelf lake in the Northern Hemisphere, located in Disraeli Fjord. In April 2008, scientists discovered that the shelf fractured into dozens of deep, multi-faceted cracks. On August 13, 2005, The Ayles Ice Shelf , which

396-470: A photographic examination of its ridges, T-2 was discovered to be the same ice island spotted off Ellesmere Island in 1947. Later in July 1950, the U.S. Air Force found Fletcher's Ice Island , or T-3, a kidney-shaped island, 14.5 by 7.2 km (9 by 4.5 mi). This was later occupied for brief periods in the early and mid-1950s. In August 1951, T-1 was relocated, nestled along the coast of Ellesmere Island. It

462-607: A project in order to establish a weather station on one of the icebergs and conduct geophysical and oceanographic research. Joseph O. Fletcher , who was the Commanding Officer of a U.S. Air Force weather squadron stationed in the Arctic right after the World War II, was placed in charge of the entire project. In March 1952, Thule Air Base sent C-47 aircraft to T-3, and several research stations were installed on

528-558: A slow melt rate, in contrast to the undefended western portion. According to the American Geophysical Union in a 2021 study, the Thwaites Eastern Ice Shelf (TEIS) buttresses one-third of Thwaites glacier . Removal of the shelf has the potential to increase the contribution of Thwaites glacier to sea level rise by up to 25%. As of 2021 , the ice shelf appears to be losing its grip on

594-459: A submarine shoal that acts as a pinning point and the shear margin that separates the Thwaites Eastern Ice Shelf from the Thwaites glacier Tongue has extended, further weakening the ice shelf connection to the pinning point. A sequence of Sentinel-1 radar imagery shows that parallel wing and comb cracks have recently formed rifts at high angles to the main shear margin and are propagating into

660-521: Is about 1028 kg/m and that of glacial ice from about 850 kg/m to well below 920 kg/m , the limit for very cold ice without bubbles. The height of the shelf above the sea can be even larger, if there is much less dense firn and snow above the glacier ice. A large portion of the Antarctic coastline has ice shelves attached. Their aggregate area is over 1,550,000 square kilometers (600,000 square miles). It has been found that of all

726-579: Is believed to be the largest shelf breakup of its kind in Canada in over 30 years. The event was registered on seismometers in northern Canada , and it was also verified via satellite imagery. The breakup occurred over less than an hour. The event was noticed by the Canadian Ice Service at the time that it occurred, but it took a further 16 months to fully reconstruct the breakup sequence from past satellite images captured by Moderate Resolution Imaging Spectroradiometer (MODIS), to determine

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792-528: Is concern that the ice islands may become a hazard for ships and oil platforms. While the formation of the Ayles Ice Island received widespread attention at the time due to the availability of satellite imagery and the ability of news media and scientists to visit the island, it was by no means unprecedented. On August 14, 1946, a U.S. Air Force patrol plane flying 480 km (300 mi) north of Point Barrow spotted an ice island, dubbed T-1, which

858-477: Is not known how long prior T-1, T-2, and T-3 had been formed, but it is believed they had calved from ice shelves on northern Ellesmere Island. There are an estimated 80 ice islands in Canada's High Arctic, most of them part of the pack ice that covers the region. Between August 1961 and April 1962, almost 600 km (230 sq mi) of ice broke away from the Ward Hunt Ice Shelf . This event

924-627: Is one of the biggest ice shelves in West Antarctica , though it is highly unstable and disintegrating rapidly. Since the 1980s, the Thwaites Glacier , nicknamed the "Doomsday glacier", has had a net loss of over 600 billion tons of ice, though pinning of the Thwaites Ice Shelf has served to slow the process. The Thwaites Ice Shelf has acted like a dam for the eastern portion of glacier, bracing it and allowing for

990-545: The British Arctic Expedition . A 1986 survey of Canadian ice shelves found that 48 km (19 sq mi), a volume of 3.3 km (0.79 cu mi), of ice calved from the Milne and Ayles ice shelves between 1959 and 1974. Canada lost 94% of its overall ice shelf area between 1906 and 2015. On August 13, 2005, the entire shelf broke clear from the coast of Ellesmere, forming a new ice island. It

1056-607: The Karpinsky Ice Cap to the south and the Rusanov Ice Cap to the north. In 2012 it ceased to exist. In the last several decades, glaciologists have observed consistent decreases in ice shelf extent through melt, calving , and complete disintegration of some shelves. Well studied examples include disruptions of the Thwaites Ice Shelf , Larsen Ice Shelf , Filchner–Ronne Ice Shelf (all three in

1122-661: The Markham Ice Shelf broke up in 2008. The remaining ice shelves have also lost a significant amount of their area over time, with the Milne Ice Shelf being the last to be affected, with it breaking off in August 2020. The Matusevich Ice Shelf was a 222 square kilometers (86 square miles) ice shelf located in Severnaya Zemlya being fed by some of the largest ice caps on October Revolution Island ,

1188-617: The Northeast Air Command established a station called "BRAVO" on the iceberg. The reoccupied T-3 continued to drift off the northern Canadian coastline, eventually arriving in Alaskan waters by July 1959, where air support responsibilities were transferred to Alaskan bases. In May 1960, the ice island drifted aground at near Wainwright, Alaska , terminating several geophysical research programs. The following year in October,

1254-540: The Thwaites Ice Shelf , Larsen Ice Shelf , Filchner–Ronne Ice Shelf (all three in the Antarctic) and the disruption of the Ellesmere Ice Shelf in the Arctic. An ice shelf is "a floating slab of ice originating from land of considerable thickness extending from the coast (usually of great horizontal extent with a very gently sloping surface), resulting from the flow of ice sheets , initially formed by

1320-494: The Antarctic) and the disruption of the Ellesmere Ice Shelf in the Arctic. The effects of climate change are visible in the changes to the cryosphere , such as reduction in sea ice and ice sheets , and disruption of ice shelves. Thwaites Ice Shelf (), is an Antarctic ice shelf in the Amundsen Sea . It was named by ACAN after Fredrik T. Thwaites, a glacial geologist and geomorphologist . The Thwaites Ice Shelf

1386-786: The Arctic Research Laboratory established two temporary drift stations northeast of Barrow, primarily for scientific studies of telluric currents, geomagnetic variation, micropulsations, and aurora . ARLIS III was established on 10 February 1964 and was evacuated on 16 May 1964, while ARLIS IV operated between February and May 1965. The last attempt to resupply T-3 occurred during the Bering Sea Patrol of September to November 1967: participating ships were USCGC  Glacier , CCGS  John A. Macdonald , USCGC  Staten Island and USCGC  Northwind . The station remained active until 1 Oct 1974, and it

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1452-554: The Ellesmere Ice Shelf had been in place for at least 3,000 years. During the twentieth century, the Ellesmere Ice Shelf broke up into six separate shelves. From west to east, these were the Serson Ice Shelf , Petersen Ice Shelf , Milne Ice Shelf , Ayles Ice Shelf , Ward Hunt Ice Shelf , and Markham Ice Shelf . The smaller pieces continued to disintegrate. In April 2000, satellite images revealed that

1518-507: The Milne Ice Shelf, also ultimately experienced a major breakup at the end of July 2020, losing over 40% of its area. The Ellesmere Ice Shelf was the largest ice shelf in the Arctic, encompassing about 9,100 square kilometres (3,500 square miles) of the north coast of Ellesmere Island , Nunavut , Canada. The ice shelf was first documented by the British Arctic Expedition of 1875–76, in which Lieutenant Pelham Aldrich 's party went from Cape Sheridan to Cape Alert . The continuous mass of

1584-492: The North Pole, then back west along the coast. In 1950, the U.S. Air Force 58th Reconnaissance Squadron was ordered to find T-1, and any other ice islands in the Arctic. In July 1950, T-2 was found, a roughly rectangular ice island estimated to be 32 by 32 km (20 by 20 mi) by dimension. In 1947, a joint U.S.-Canadian expedition had noted and photographed a fresh water sea formation in the sea off Ellesmere Island. From

1650-583: The November 2006 sighting of several large icebergs from the coast of the South Island of New Zealand , the first time since 1931 that any icebergs had been observed from the New Zealand mainland. A large group of small icebergs (the largest some 1000 metres in length), were seen off the south-east coast of the island, with one of them drifting close enough to shore to be visible from the hills above

1716-696: The abandoned buildings, and re-established the station which previously served as a second drifting station and a fuel depot for the flights to the station ARLIS II. In December 1963, the station ARLIS II reached the most northern point of its journey and eventually drifted out through the Fram Strait with the East Greenland Current . During this period, re-supply operations were performed by Keflavik Naval Air Station in Iceland . After 47 months and 18 days of continuous operation, ARLIS II

1782-678: The accumulation of snow, and often filling embayments in the coastline of an ice sheet." In contrast, sea ice is formed on water, is much thinner (typically less than 3 m (9.8 ft)), and forms throughout the Arctic Ocean . It is also found in the Southern Ocean around the continent of Antarctica . The term captured ice shelf has been used for the ice over a subglacial lake , such as Lake Vostok . Ice shelves are thick plates of ice, formed continuously by glaciers, that float atop an ocean. The shelves act as "brakes" for

1848-400: The area. Larsen B was stable for at least 10,000 years, essentially the entire Holocene period since the last glacial period. By contrast, Larsen A was absent for a significant part of that period, reforming about 4,000 years ago. Despite its great age, the Larsen B was clearly in trouble at the time of the collapse. With warm currents eating away the underside of the shelf, it had become

1914-453: The central part of the ice shelf at rates as high as 2 km per year. Satellite data, ground-penetrating radar, and GPS measurements taken in 2021 indicate that collapse of the ice shelf may be initiated by intersection of rifts with hidden basal crevasse zones as soon as 2026. Two sections of Antarctica's Larsen Ice Shelf broke apart into hundreds of unusually small fragments (hundreds of meters wide or less) in 1995 and 2002, Larsen C calved

1980-714: The city of Dunedin . If these were indeed the remnants of this calving, then over the course of five and a half years they had travelled slowly north and also east around over half the globe, a journey of some 13,500 km. From January 12 and January 13, 2010, an area of sea ice larger than the state of Rhode Island , or one-seventh the size of Wales , broke away from the Ronne–Filchner Ice Shelf and shattered into many smaller pieces. The Moderate-Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua and Terra satellites captured this event in this series of photo-like images. In May 2021, Iceberg A-76 broke off

2046-661: The climatic conditions during the event, and for the event to garner public attention. The event, which has been linked to global warming , is similar to the 2002 breakup of the Larsen B Ice Shelf in Antarctica . Within days of the breakup, the former shelf had drifted over 50 km (31 mi) from Ellesmere Island before freezing into the sea ice for the winter. It was estimated in May 2007 to be between 42 and 45 m (138 and 148 ft) thick, on average. The freed segment of

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2112-466: The decline of the ice of the peninsula. In October 1998, the iceberg A-38 broke off the Filchner–Ronne ice shelf. It had an extent of roughly 150 by 50 km and was thus larger than Delaware . It later broke up again into three parts. A similar-sized calving in May 2000 created an iceberg 167 by 32 km in extent, dubbed A-43 – the disintegration of this is thought to have been responsible for

2178-582: The direction of the Department of Defense . Before the era of satellites, the research station on T-3 had been a valuable site for measurements of the atmosphere in the Arctic . Produced by the northern coast of Ellesmere Island , the iceberg T-3 was a very large tabular iceberg . This 7 by 3 mile kidney-shaped iceberg was discovered near the North Pole by researchers studying the Arctic haze during

2244-509: The floating ice is above the ocean surface, depending on how much pressurized air is contained in the bubbles within the glacial ice, stemming from compressed snow. The formula for the denominators above is 1 / [ ( ρ seawater − ρ glacial ice ) / ρ seawater ] {\textstyle 1/[(\rho _{\text{seawater}}-\rho _{\text{glacial ice}})/\rho _{\text{seawater}}]} , density of cold seawater

2310-652: The glaciers. These shelves serve another important purpose—"they moderate the amount of melting that occurs on the glaciers' surfaces. Once their ice shelves are removed, the glaciers increase in speed due to meltwater percolation and/or a reduction of braking forces, and they may begin to dump more ice into the ocean than they gather as snow in their catchments. Glacier ice speed increases are already observed in Peninsula areas where ice shelves disintegrated in prior years." The density contrast between glacial ice and liquid water means that at least ⁠ 1 / 9 ⁠ of

2376-401: The grounded ice. That flow continually moves ice from the grounding line to the seaward front of the shelf. Typically, a shelf front will extend forward for years or decades between major calving events (calving is the sudden release and breaking away of a mass of ice from a glacier , iceberg , ice front , ice shelf, or crevasse ). Snow accumulation on the upper surface and melting from

2442-483: The ice shelf is believed to be over 3,000 years old. The ice shelf was at ( 82°52′N 80°30′W  /  82.867°N 80.500°W  / 82.867; -80.500 ), approximately 800 km (500 mi) south of the North Pole . The Ayles Ice Shelf, like the nearby Mount Ayles , was named for the Arctic explorer, Adam Ayles , who served under George Nares as the Petty Officer of HMS Alert in

2508-774: The ice shelf, known as Ayles Ice Island , drifted southwesterly for two years, and in January 2007 accelerated into the open Arctic Ocean , causing concern for oil rig operators in the Beaufort Sea north of Prudhoe Bay, Alaska . In August 2007, however, the island became wedged into the Sverdrup Inlet of the Queen Elizabeth Islands . Although scientists initially thought it was likely to remain there for some time, possibly permanently, it soon afterwards broke into two parts and resumed movement. There

2574-477: The ice shelf. The Ellesmere ice shelf was reduced by 90% in the twentieth century, leaving the separate Alfred Ernest , Ayles , Milne , Ward Hunt , and Markham ice shelves. A 1986 survey of Canadian ice shelves found that 48 km (3.3 cubic kilometres) of ice calved from the Milne and Ayles ice shelves between 1959 and 1974. The Ayles Ice Shelf calved entirely on August 13, 2005. The Ward Hunt Ice Shelf,

2640-481: The ice shelves on Earth, nearly all of them are in Antarctica. In steady state, about half of Antarctica's ice shelf mass is lost to basal melt and half is lost to calving , but the relative importance of each process varies significantly between ice shelves. In recent decades, Antarctica's ice shelves have been out of balance, as they have lost more mass to basal melt and calving than has been replenished by

2706-437: The iceberg after it had been missing for six months. Dave Turner, an experienced NOAA pilot who was one of the last persons to observe T-3, reported that the ice floe was found about 150 miles from the North Pole . T-3 was easily spotted, as its surface was distinctly decorated by remaining structures of a C-47 aircraft wrecked years before. At the time of discovery, the iceberg was about one-third of its original thickness. It

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2772-488: The iceberg was actually "discovered". Concerned about Soviet postwar activities in the Arctic, the U.S. Air Force initiated B-29 reconnaissance flights over the Arctic region beginning in 1946, and, by 1951, the reconnaissance trips to the North Pole were being performed daily. During the reconnaissance flights, several large icebergs were discovered, and the following year of 1952, the Alaska Air Command started

2838-575: The iceberg's flat surface. The stations were abandoned in May 1954, when the weather observations were deemed redundant, but were reoccupied from April to September 1955. In April 1957, the station "ALPHA" was installed on the iceberg, which was the first long-term scientific base in the Arctic operated by a Western country. However, at the time of its establishment, the Soviets had already operated six drifting iceberg stations of this kind. In April 1958, several large cracks were observed around ALPHA, and

2904-448: The influx of new ice and snow. The Ross Ice Shelf is the largest ice shelf of Antarctica (as of 2013 , an area of roughly 500,809 square kilometres (193,363 sq mi) and about 800 kilometres (500 mi) across: about the size of France). It is several hundred metres thick. The nearly vertical ice front to the open sea is more than 600 kilometres (370 mi) long, and between 15 and 50 metres (50 and 160 ft) high above

2970-557: The largest remaining section of thick (>10 meters (33 feet)) landfast sea ice along the northern coastline of Ellesmere Island, lost 600 square kilometers (230 square miles) of ice in a massive calving in 1961–1962. It further decreased by 27% in thickness (13 meters (43 feet)) between 1967 and 1999. In the summer of 2002, the Ward Ice Shelf experienced another major breakup, and other instances of note happened in 2008 and 2010 as well. The last remnant to remain mostly intact,

3036-506: The lower surface are also important to the mass balance of an ice shelf. Ice may also accrete onto the underside of the shelf. The effects of climate change are visible in the changes to the cryosphere , such as reduction in sea ice and ice sheets , and disruption of ice shelves. In the last several decades, glaciologists have observed consistent decreases in ice shelf extent through melt, calving , and complete disintegration of some shelves. Well studied examples include disruptions of

3102-424: The northwest corner of the shelf. At 4320 km , it is larger than Majorca , several times larger than Iceberg A-74 which calved in the same year, or approximately 14% the size of Belgium . The ice of the Filchner–Ronne ice shelf can be as thick as 600 m; the water below is about 1400 m deep at the deepest point. The international Filchner–Ronne Ice Shelf Programme (FRISP) was initiated in 1973 to study

3168-561: The range limit of these aircraft, the station was evacuated in March 1961. A more permanent drifting ice station was desired for the second Arctic Research Laboratory Ice Station (ARLIS II), but with T-3 grounded, a tentative site on an ice floe was selected. However, during its deployment in May 1961 the ice ground began breaking up on a large scale, and the Navy found another 3.5 by 1.5 mile iceberg north of Point Barrow . In next 22 days, using

3234-405: The spring and summer. Although the thickness of the iceberg was 125 feet and it weighed over seven billion tons, it rose only ten feet above the surrounding ice packs and was virtually indistinguishable from the pack ice at any distance. The temporary drift station consisting of insulated huts was first assembled by the U.S. Military. By the end of May, 1957, a 1500-meter-long runway and most of

3300-425: The station was abandoned again, but the site was left intact for possible future use. As U.S. Navy was still eager to continue Arctic based operations, the Arctic Research Laboratory planned to install a new station to replace the former station CHARLIE. However, this intention was balked at the costs required to charter a C-47 for the installation. Instead, following September an icebreaker USS Burton Island (AGB-1)

3366-554: The station was forced to relocate 2 km away from its original location. In August 1958, after the US Submarine USS ; Skate  (SSN-578) made a visit to the station ALPHA, the surrounding ice ground began cracking and ridging again, so the station was finally abandoned in November 1958. However, the U.S. Department of Defense still had interest in continuing research in the Arctic. In April 1959, another scientific station named "CHARLIE" (also named as ALPHA II)

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3432-423: The station's 26 Jamesway huts had been completed, allowing the commencement of scientific operations. Beginning in 1952 scientists including Albert P. Crary arrived and performed numerous scientific investigations including hydrographic measurements, seismic soundings, and meteorological observations. In general, 25- to 30-person military crews and scientists staffed the camp at any one time. The resupply

3498-457: The summer. Between 1962 and 1964, as the iceberg drifted farther north, away from Barrow and across the Arctic Ocean , resupply from Alaska became difficult. While station ARLIS II was drifting away from Barrow, the iceberg T-3 was rediscovered in February 1962 over 100 miles north of where it had been previously observed. The Arctic Research Laboratory reoccupied the iceberg, refurbished

3564-554: The water surface. Ninety percent of the floating ice, however, is below the water surface. All Canadian ice shelves are attached to Ellesmere Island and lie north of 82°N. Ice shelves that are still in existence are the Alfred Ernest Ice Shelf , Ward Hunt Ice Shelf , Milne Ice Shelf and Smith Ice Shelf . The M'Clintock Ice Shelf broke up from 1963 to 1966; the Ayles Ice Shelf broke up in 2005; and

3630-468: Was 24 by 29 km (15 by 18 mi). It was estimated to be from 62 to 488 m (204 to 1,600 ft) thick, with sides that rose from 9.1 to 61.0 m (30 to 200 ft) above the sea surface - much larger than the Ayles Ice Island. Over the following three years, it travelled around 2,400 km (1,500 mi) along the Beaufort Eddy, a slow-moving ocean current that flows eastward across

3696-619: Was abandoned in 1954 but reinhabited on two subsequent occasions. The station was inhabited mainly by scientists along with a few military crewmen and was resupplied during its existence primarily by military planes operating from Utqiagvik, Alaska . The iceberg was later occupied by the Naval Arctic Research Laboratory , and served as a base of operations for the Navy's arctic research projects such as sea bottom and ocean swell studies, seismographic activities, meteorological studies and other classified projects under

3762-420: Was an iceberg discovered by U.S. Air Force Colonel Joseph O. Fletcher . Between 1952 and 1978 it was used as a staffed scientific drift station that included huts, a power plant , and a runway for wheeled aircraft . The iceberg was a thick tabular sheet of glacial ice that drifted throughout the central Arctic Ocean in a clockwise direction. First inhabited in 1952 as an arctic weather report station , it

3828-652: Was attributed to tidal and seismic events. Ice shelf Ice shelves are found in Antarctica and the Arctic ( Greenland , Northern Canada , and the Russian Arctic ), and can range in thickness from about 100–1,000 m (330–3,280 ft). The world's largest ice shelves are the Ross Ice Shelf and the Filchner-Ronne Ice Shelf in Antarctica. The movement of ice shelves is principally driven by gravity -induced pressure from

3894-503: Was employed to transport the equipment, and the Arctic Research Laboratory Ice Station I (known as ARLIS I) was constructed in under 40 hours. Although ARLIS I was designed to support eight scientists and four technical personnel, the station never achieved its full potential. As the iceberg drifted westward, small aircraft ( Cessna 180 ) were employed to resupply the station. However, upon approaching

3960-418: Was established by the Alaska Air Command with assistance from the Navy's Arctic Research Laboratory. Scientific research activity was conducted from June 1959 to January 1960. When the ice floe cracked and shortened the runway sufficiently to terminate aircraft resupply operations, station CHARLIE had to be evacuated. Meanwhile, on 7 March 1957, using several 42-foot-long (13 m) commercial house trailers,

4026-604: Was evacuated in May 1965 by the icebreaker USCGC Edisto (WAGB-284) . The station hosted 14 different research projects, including 337 personnel. Upon completion of major restoration of ARLIS II, a full occupation of T-3 by the Arctic Research Laboratory was initiated in September 1965. And by this time, the iceberg had completely circled the Beaufort Gyre . Meanwhile, while the ARLIS II and T-3 ice stations were occupied,

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4092-404: Was hampered by a mix of varying obstacles. Due to the iceberg's constantly moving location, resupply had to be operated from two air bases Point Barrow, Alaska and Thule Air Base , Greenland . At that time, flights were conducted without navigational aids, and the aircraft landing on the constantly moving iceberg T-3 was performed solely by dead reckoning and celestial grid navigation, which

4158-631: Was last visited in 1979. After being satellite-monitored for years, the iceberg eventually drifted through the Fram Strait in 1983. Satellite monitoring had been employed to keep track of the iceberg T-3 since it was abandoned, but meteorologists lost track of it in the autumn of 1982. A request was made to the NOAA flight research team to keep an eye out for T-3. On July 3, 1983, the Associated Press reported U.S. scientists had rediscovered

4224-424: Was located approximately 800 km (500 mi) south of the North Pole , broke away from the coast forming the giant Ayles Ice Island 37 metres (121 ft) thick and measuring around 14 by 5 km (8.7 by 3.1 mi) in size with an area of approximately 66 km (25 sq mi) or 2.6 km (0.62 cu mi) in volume. Fletcher%27s Ice Island Fletcher's Ice Island or T-3

4290-546: Was mostly operated during the winter period while the runway was suitable for aircraft landing. This also indicated operating during the most severe weather conditions, such as very low ceilings and prevailing reduced visibility. Accurate weather forecasting was not available until much later, due to the absence of reporting stations and the distance to travel over remote arctic wastes. Winds in excess of 45 knots and temperatures below minus 30°F (-34°C) had also been recorded at both stations during resupply operations. Resupply for T-3

4356-537: Was often hampered by long periods of twilight , which prevented celestial observation. Also, because the nearest alternate air bases were 475 miles (764 km) away, potential in-flight emergencies could result in fatal outcomes. In this regard, pilots and their crews had to calculate cargo and fuel loads precisely to insure not only a safe landing but also a safe return from the iceberg. Iceberg T-3 had once been reported to have been identified during World War II, but there are several conflicting reports in regard to when

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