High Latitude Operations

• The North Polar Area is defined as the entire area north of latitude 78 degrees North.
• The South Polar Area is defined as the entire area south of latitude 60 degrees South.

Source: Advisory Circular 120-42B, ¶601.

• Controlled airspace within the High Level Airspace is divided into three separate areas. They are the Southern Control Area (SCA), the Northern Control Area (NCA) and the Arctic Control Area (ACA).
• Pilots are reminded that both the NCA and the ACA are within the Northern Domestic Airspace; therefore, compass indications may be erratic, and true tracks are used in determining the flight level at which to fly. In addition, the airspace from FL 330 to FL 410 within the lateral dimensions of the NCA, the ACA and the northern part of the SCA has been designated CMNPS airspace.

Source: Transport Canada Aeronautical Information Manual, ¶ 2.6

Operations in the North Polar Area.] After February 15, 2008, no certificate holder may operate an aircraft in the region north of 78° N latitude (“North Polar Area”), other than intrastate operations wholly within the state of Alaska, unless authorized by the FAA. The certificate holder's operation specifications must include the following:

• The designation of airports that may be used for en-route diversions and the requirements the airports must meet at the time of diversion.
• Except for all-cargo operations, a recovery plan for passengers at designated diversion airports.
• A fuel-freeze strategy and procedures for monitoring fuel freezing for operations
• A plan to ensure communication capability for operations in the North Polar Area.
• An MEL for operations in the North Polar Area.
• A training plan for operations in the North Polar Area.
• A plan for mitigating crew exposure to radiation during solar flare activity.
• A plan for providing at least two cold weather anti-exposure suits in the aircraft, to protect crewmembers during outside activity at a diversion airport with extreme climatic conditions. The FAA may relieve the certificate holder from this requirement if the season of the year makes the equipment unnecessary.

Source: 14 CFR 135, §135.98

All approvals for operations into AMUs are granted by issuing OpSpec B040, and by adding that area of en route operation to the standard OpSpec B050. A checklist for operations in AMUs is available in the guidance subsystem in association with OpSpec B040.

Source: FAA Order 8900, Volume 4, Chapter 1, §5, ¶4-103.D]

Certificate holders must have at least two cold weather anti-exposure suit(s) for the crewmembers on the airplane if outside coordination by a crewmember at a diversion airport with extreme climatic conditions is determined to be necessary. The certificate holder may be relieved of this requirement based on seasonal temperatures that would render the use of such suits unnecessary. This determination must be made with concurrence of the CHDO.

Source: Advisory Circular 135-42, Appendix 3, ¶3.f.

• Fuel quantity indicating system (FQIS), including the fuel tank temperature indicating system;
• APU (when the APU is necessary for an airplane to comply with ETOPS requirements), including electrical and pneumatic supply to its designed capability,
• Autothrottle system;
• Communication systems relied on by the flight crewmember to satisfy the requirement for communication capability; and
• Except for all-cargo operations, an expanded medical kit to include automated external defibrillators (AED).

Source: Advisory Circular 120-42B, ¶603.b.(5)

Before receiving approval to conduct polar operations, a certificate holder must review their MEL for such operations and should amend their MEL. The following systems and equipment should be addressed in the MEL based on specific needs applicable to this operation.

(1) Fuel Quantity Indicating System (to include a fuel tank temperature indicating system).

(2) Communication system(s) needed for effective communications by the flight crewmember while in flight.

(3) Expanded medical kit.

Source: Advisory Circular 135-42, Appendix 3, ¶3.c.

Before conducting polar operations, certificate holders must ensure that flight crewmembers are trained on any applicable passenger recovery plan used in this operation. Certificate holders should also ensure that flight crewmembers are trained on the following items, which should be included in a certificate holder's approved training programs:

(1) Atmospheric pressure at Field Elevation/Barometric pressure for Local Altimeter Setting and meter/feet conversion issues (flight crewmember training).

(2) Training requirements for fuel freeze (maintenance and flight crewmember training).

(3) General polar-specific training on weather patterns and aircraft system limitations (flight crewmember training).

(4) Proper use of the cold weather anti-exposure suit, if required (flight crewmember training).

(5) Radiation exposure (see AC 120-61A, In-Flight Radiation Exposure).

Source: Advisory Circular 135-42, Appendix 3, ¶3.e.

The FAA recognizes the limitations of satellite communications (SATCOM) in the North Polar Area above this latitude, and in such an area an alternate communication system such as HF voice or data link is to be used. The relatively short period of time that the flight is above latitude 82 degrees North in relation to the total planned flight time is a small fraction of the total flight. The ability to use SATCOM for all other portions of the flight, which for some routes could be longer than 15 hours duration, is advantageous to the flight. For flights above 82 degrees North latitude, the operator must also ensure that communications requirements can be met by the most reliable means available, taking into account the potential communication disruption due to solar flare activity. The same philosophy and commensurate requirements apply for ETOPS in the South Polar Area.

Source: AC 120-42B, ¶303.c.(7)

• The height of the tropopause depends on the location, notably the latitude, as shown in the figure on the right (which shows annual mean conditions). It also depends on the season.
• At latitudes above 60°, the tropopause is less than 9-10 km above sea level; the lowest is less than 8 km high, above Antarctica and above Siberia and northern Canada in winter. The highest average tropopause is over the oceanic warm pool of the western equatorial Pacific, about 17.5 km high, and over Southeast Asia, during the summer monsoon, the tropopause occasionally peaks above 18 km. In other words, cold conditions lead to a lower tropopause, obviously because of less convection.
• Deep convection (thunderstorms) in the Intertropical Convergence Zone, or over mid-latitude continents in summer, continuously push the tropopause upwards and as such deepen the troposphere.
• On the other hand, colder regions have a lower tropopause, obviously because convective overturning is limited there, due to the negative radiation balance at the surface. In fact, convection is very rare in polar regions; most of the tropospheric mixing at middle and high latitudes is forced by frontal systems in which uplift is forced rather than spontaneous (convective). This explains the paradox that tropopause temperatures are lowest where the surface temperatures are highest.

Source: Geerts and Linacre

Fuel Freeze Strategy and Monitoring Requirements for Polar Operations. Certificate holders must develop a fuel freeze strategy and procedures for monitoring fuel freezing for operations in the North Polar Area. A fuel freeze analysis program in lieu of using the standard minimum fuel freeze temperatures for specific types of fuel may be used. In such cases, the certificate holder's fuel freeze analysis and monitoring program for the airplane fuel load must be acceptable to the FAA Administrator. The certificate holder should have procedures for determining the fuel freeze temperature of the actual fuel load on board the airplane. These procedures relative to determining the fuel freeze temperature and monitoring the actual temperature of the fuel on board should require appropriate levels of coordination between maintenance and the flight crewmember.

Source: Advisory Circular 135-42, Appendix 3, ¶3.c.

Less radiation will be received on a lower-latitude flight because of the greater amount of radiation shielding provided by the Earth’s magnetic field. This shielding is greatest near the equator and gradually decreases to zero as one goes north or south. Galactic cosmic radiation levels over the polar regions are about twice those over the geomagnetic equator at the same altitudes. Because solar particle peak energies are much lower than galactic particle peak energies, solar cosmic radiation dose rates are negligible near the geomagnetic equator.

Source: Advisory Circular 120-61B, ¶6.a.

• Space radiation on the ground is very low, but increases significantly with altitude. At 30,000 to 40,000 feet, the typical altitude of a jetliner, exposure on a typical flight is still considered safe – less than a chest X-ray.
• Exposure is considerably higher, however, over the Earth's poles, where the planet's magnetic field no longer provides any shielding. And with a thousand-fold rise in commercial airline flights over the North Pole in the last 10 years, exposure to radiation has become a serious concern.
• A study by Mertens of polar flights during a solar storm in 2003 showed that passengers received about 12 percent of the annual radiation limit recommended by the International Committee on Radiological Protection. The exposures were greater than on typical flights at lower latitudes, and confirmed concerns about commercial flights using polar routes.
• People who work on commercial airline flights are technically listed as "radiation workers" by the federal government – a classification that includes nuclear plant workers and X-ray technicians. But unlike some others in that category, flight crews do not quantify the radiation they are exposed to.

Source: NASA Study, Michael Finneran

Before each flight, certificate holders must designate alternate airports that can be used in case an en route diversion is necessary. The airplane should have a reasonable assurance that the weather during periods when the certificate holder would need the services of the airport are within the operating limits of the airplane. The airplane should be able to make a safe landing and maneuver off the runway at the diversion airport. In addition, those airports identified for use during an en route diversion should be capable of protecting the safety of all personnel by allowing:

(1) Safe offload of passengers and crewmember during possible adverse weather conditions;

(2) Providing for the physiological needs of the passengers and crewmember until a safe evacuation is completed; and

(3) Safe extraction of passengers and crewmember as soon as possible (execution and completion of the recovery should be within 12 to 48 hours following landing).

Source: Advisory Circular 135-42, Appendix 3, ¶3.a.

Operators are expected to define a sufficient set of polar diversion alternate airports, such that one or more can be reasonably expected to be suitable and available in varying weather conditions (AC 120-42A, Extended Range Operation With Two-Engine Airplanes (ETOPS), provides additional guidance for two-engine airplanes).

Source: FAA Order 8900, Volume 4, Chapter 1, §5, ¶4-103.E.

A recovery plan is required that will be initiated in the event of an unplanned diversion. The recovery plan should address the care and safety of passengers and flight crew at the diversion airport and include the plan of operation to extract the passengers and flight crew from that airport.

Source: FAA Order 8900, Volume 4, Chapter 1, §5, ¶4-103.G.