Cross-polar routes
Since 2001, when Russia opened their airspace borders, some airlines thought that flying across the north pole would be much faster, like a shortcut. As a matter of fact, they got right. You can almost save up to 4 hours of flight, flying through the north pole instead of the regular routes.
These regular routes are the PACOTS (Pacific Organized Track System) going from the U.S. west coast to Japan and Honolulu. These are a set of predefined routes (it works like NAT routes), that start within US airspace (a fix) and they finish within Japan airspace (another fix). Between them, there’s just some waypoints defined with coordinates (there are no navaids to define them). So, an airplane departing from JFK had to go to the west coast and then, get en-route in these tracks.
United Airlines, Continental and other Japanese airlines started operating routes through the north pole. Then, they would save time, fuel and consequently money. But it’s not that easy. We all know that in the north pole it’s kinda cold, so it’s pretty likely that kerosene solidify. Nevertheless you can also descend to a lower altitude and modify your original route.
In addition, because of the earth’s magnetic field shape, the cosmic rays are much intense in that area. Therefore, the radiation exposure seems to be greater than the normal quantity. Some expert says that the total radiation exposure up there could be equal to 3 X-ray taken. Here you can appreciate a cross-polar route from JFK to Beijing (Japan) at Great Circle Mapper.
ATC services are not available, since we have no radar coverage. To sum up, it’s really an amazing adventure flying this kind of routes. Pilots must have good skills, and a big coat!
The SELCAL Code
The SELCAL system or Selective Calling system, commonly used in aeronautical communications, is a multiple system that allows the radio ground-based operator to send a signal to the aircraft that wants to establish a communication. In other words, when an ATC want to talk with an airplane flying over the ocean, he pushes a button and the airplane’s crew receive a message. That is kind of worthy in oceanic routes, where HF (High Frequency) communications give a lot of background noise, and pilots usually turn off the squelch until they receive this signal.
In order to identify each single aircraft, a SELCAL code is assigned to each one. This code is made by 2 pairs of letters (using from “A” to “S” excluding “I” and “O”) and each letter has an assigned frequency. Then, when the operator wants to talk with that aircraft, a 4-tone signal is sent with those letters. Everybody who is in that frequency will hear that sound, but only the one with that code will receive a sound alert (bling-blong-like sound) and a light alert.
There are 10920 different SELCAL codes. That’s the reason why there are duplicate codes (two airplanes, same code). Only airplanes operating oceanic routes use that system though. So, when a duplicate code exists, they make certain that those airplanes will operate in widely separate parts of the world.
ARINC (Aeronautical Radio Inc.) issues these codes in the US. You can find real-world SELCAL codes in this website just entering the registration number.
5 commentsNorth Atlantic Routes: I eat beef, you eat fish
Every single day, hundreds of commercial airplanes cross the north atlantic, flying transcontinental routes linking North America and Europe basically, the NAT (North Atlantic Tracks). The performances of these flights are much different and complex due to its distant routes from any kind of airport.
The twin-engine aircrafts operating these flights (usually big ones) must have the ETOPS rating, explained in other post. That is because the nearest alternative airport when flying above the atlantic is 180 minutes far. If an engine failure happens (or any other system), this aircraft should divert to the closest airport immediately.
Another huge problem is the radar coverage. As a matter of fact, this radar coverage does not exist. Radars must be set up on ground or close (not floating over the sea). The main Air Traffic Control facilities (Shanwick Oceanic for European side and Gander Oceanic for US side) are equipped with air traffic management systems that by means of pilot manual position reports, they have some sort of “radar-like” screen with all the airplanes’ positions.
The third and big problem as well (but solved anyway) is about communications. The communicacions between pilots and controllers use VHF (Very High Frequency from 30 MHz to 300MHz) frequency range. VHF waves only reach “line-of-sight” spaces. So, in that case they must use HF (High Frequency from 3 MHz to 30MHz) that bounces off the ionosphere and give coverage to greater distances. Nevertheless, even this advantage, sound quality is much poor.
The NAT routes are designed and published daily. They are defined with an entry waypoint, an exit waypoint and between, waypoints are defined with coordinates (there are no navaids to define them). Early in the morning, westbound routes are published. Then late at night, eastbound routes are published. Europe incoming routes are usually defined at higher latitude, to take advantage of the Jet Stream (high speed wind, will post about this).
By the way, pilots flying these routes cannot eat the same meal. 
Here we can appreciate North Atlantic Routes all the day long