Polar route

A polar route is an aircraft route across the uninhabited polar ice cap regions. The term "polar route" was originally applied to great circle routes between Europe and the west coast of North America in the 1950s.^[1]

The Arctic

History

The Soviet pilot Valery Chkalov was the first to fly non-stop from Europe to the American Pacific Coast. His flight from Moscow, Soviet Union to Vancouver, Washington, United States, via the North Pole on a Tupolev ANT-25 single-engine plane (June 18–20, 1937) took 63 hours to complete. The distance covered was 8,811 kilometres (5,475 mi).^[2]

In September 1945, a long-distance flight was undertaken for public relations purposes: generals Barney M. Giles, Curtis LeMay and Emmett O'Donnell, Jr. piloted three specially modified B-29s from Chitose Air Base in Hokkaidō to Chicago Municipal Airport, continuing to Washington, D.C., the farthest nonstop distance to that date flown by U.S. Army Air Forces aircraft and the first-ever nonstop flight from Japan to the U.S.. The distance covered was approximately 5,839 miles or 9,397 kilometers.^[3][4] Two months later, Colonel Clarence S. Irvine commanded another modified B-29, Pacusan Dreamboat, in a world-record-breaking long-distance flight from Guam to Washington, D.C., traveling 7,916 miles (12,740 km) in 35 hours,^[5] with a gross takeoff weight of 155,000 pounds (70,000 kg).^[6] Almost a year later, in October 1946, the same B-29 flew 9,422 miles nonstop from Oahu, Hawaii, to Cairo, Egypt, in less than 40 hours, further proving the capability of routing airlines over the polar icecap.^[7]

Of the commercial airlines, SAS was first: their Douglas DC-6B flights between Los Angeles and Copenhagen, via Sondre Stromfjord and Winnipeg, started on November 15, 1954.^[8] Canadian Pacific DC-6Bs started Vancouver–Amsterdam in 1955, then Pan Am and TWA started West Coast to Paris/London in 1957. SAS was first again, flying Europe to Tokyo via Anchorage with Douglas DC-7Cs in February 1957; Air France Lockheed L-1649 Starliner (which was the final version of the Lockheed Constellation) and KLM DC-7C aircraft followed in 1958.

During much of the Cold War, the Arctic region was a buffer zone between the Soviet Union and North America; civilian flights from Europe to the Asian Far East were unable to cross the Soviet Union or China and had to use a Middle East route or connect through Alaska across the Arctic region. These Cold War tracks extended from the northern Alaskan coast across Greenland to Europe. Korean Air Lines Flight 902 operated with a Boeing 707 was shot down over the USSR by a Soviet Air Force fighter aircraft in 1978 after the flight crew made gross navigational errors attempting to fly the assigned polar route.

Prior to the advent of today's modern long range jetliners, Anchorage International Airport (ANC) in Alaska was a technical stop for a number of airlines flying the polar route between western Europe and Tokyo. According to the July 1, 1983 edition of the Worldwide Official Airline Guide (OAG), Air France, British Airways, Japan Air Lines (JAL), KLM Royal Dutch Airlines, Lufthansa, Sabena and Scandinavian Airlines (SAS) were all operating flights between Japan and western Europe which included a stop in Anchorage.^[9] Most of these international airlines were operating earlier model Boeing 747 aircraft on the route at this time, although Sabena and SAS were instead operating McDonnell Douglas DC-10-30 aircraft on their respective polar route services via Anchorage. U.S. based air carrier Western Airlines also flew a polar route during the early 1980s between London Gatwick Airport and Honolulu using DC-10-30 aircraft, with these flights also making a stop in Anchorage.^[10]

The main obstacle to flights across Russia was the inadequate Russian air traffic control system and a lack of English communication. To solve these issues, RACGAT (Russian-American Coordinating Group for Air Traffic) was formed in 1993. By summer 1998, the Russian government gave permission to open four cross-polar routes, named Polar 1, 2, 3 and 4.^[11]

Finnair was the first airline to fly non-stop over the polar region between western Europe and Japan. This service began in 1983 and was flown with a McDonnell Douglas DC-10-30 wide body jetliner between Tokyo and Helsinki.^[12][13]

Cathay Pacific Flight 889 from New York John F. Kennedy International Airport, piloted by Captain Paul Horsting on 7 July 1998 — the first arrival to the new Hong Kong International Airport at Chek Lap Kok west of Hong Kong — appears to be the first non-stop flight over the Arctic polar region and over Russian airspace. It was the world's first nonstop transpolar flight from New York to Hong Kong, dubbed Polar One. It took 16 hours to complete, and it was and still is the longest flight Cathay Pacific operates.^[14]

Today

The American Federal Aviation Administration now defines the North Polar area of operations as the area north of 78 deg north latitude,^[15] which is north of Alaska and most of Siberia.

Aircraft like the Boeing 747-400, 747-8, 777-200ER, 777-200LR and 777-300ER as well as the Airbus A340, A350 and A380, with ranges of around 7,000 nautical miles (13,000 km) or more, are required in order to travel the long distances nonstop between suitable airports.^[16] Before this era, all flights from North America to Asia were routed around the Communist bloc using a series of tracks between Alaska and Japan.

Arctic polar routes are now common on airlines connecting Asian cities (Bangkok, Beijing, Dubai, Abu Dhabi, Guangzhou, Hong Kong, New Delhi, Mumbai, Seoul, Shanghai, Singapore, Taipei and Tokyo) to North American cities (New York City, Boston, Chicago, Detroit, Houston, Los Angeles, San Francisco, Seattle, Toronto, Vancouver and Washington, D.C.). Emirates flies nonstop from Dubai to the US West Coast (San Francisco, Seattle and Los Angeles), coming within a few degrees of latitude of the North Pole.^[17][18]

Antarctica

Few airlines fly between cities having a great circle route over Antarctica. Direct flights between South Africa and New Zealand would overfly Antarctica, but no airline has scheduled such flights. LATAM Airlines flies nonstop between Auckland, Sydney and Santiago, Air New Zealand flies nonstop between Auckland and Buenos Aires starting December 1, 2015, and Qantas flies nonstop between Sydney and Santiago, the most southerly polar route. Depending on winds, these reach 55 degrees south latitude, but other times 71 degrees, which is enough to cross the polar ice cap.^[19]

Depending on the winds, the Qantas flight QF 63 from Sydney to Johannesburg sometimes flies over the Antarctic Circle to latitude 71 degrees as well and allowing views of the icecap.^[20]

Operational considerations

The FAA's policy letter Guidance for Polar Operations (March 5, 2001) outlines a number of special requirements for polar flight, which includes two cold-weather suits, special communication capability, designation of Arctic diversion airports and firm recovery plans for stranded passengers, and fuel freeze strategy and monitoring requirements.^[15]

Jet fuel freeze temperatures range between −40 and −50 °C (−40 and −58 °F). These temperatures are frequently encountered at cruise altitude throughout the world with no effect since the fuel retains heat from lower elevations, but the intense cold and extended duration of polar flights may cause fuel temperature to approach its freezing point. Jet A grade with a maximum freeze point of −40 °C (−40 °F) is used in the U.S., while Jet A1 grade with a maximum freeze point of −47 °C (−53 °F) is used elsewhere.^[21] Modern long-distance airliners are equipped to alert flight crew when fuel temperatures reach 3 °C (5.4 °F) above these levels. The crew must then change altitude, though in some cases due to the low stratosphere over polar regions and its inversion properties the air may actually be somewhat warmer at higher altitudes.^[15]

The alerts are typically set at 3 °C (5.4 °F) above the specified maximum freeze point. This provides a 3 °C (5.4 °F) safety margin from the solidification temperature. However, fuels produced at the refineries are often better than the spec values; for example, it is not uncommon to find Jet A fuels that have measured freeze point better (colder) than the specified maximum of −40 °C (−40 °F). In that way, the safety margin is even larger than 3 °C (5.4 °F). On the other hand, the temperature probe that delivers fuel temperature information to the flight deck is not located in the coldest part of the fuel tanks. The difference between the recorded and the coldest fuel temperature varies depending on a variety of factors, especially the circulation of fuel in the tanks and duration of cold soak. It is, therefore, prudent to have a safety margin.

For polar flights, FAA allows,^[22] under certain conditions, the measured freeze point be used instead of assuming the spec value in ASTM D1655. This gives the airlines more flexibility in flight planning.

References

External links

• RACGAT website - archived in 2003
• Flightradar24 blog page - Why you flew over Greenland