“It was Friday 30th at night. After 90 minutes of normal flight, the airplane was obliged to go back to the departure airport, New York Kennedy. The airplane is brand new, and it’s breaking in. The minor computer trouble caused some lost of accuracy on navigation parameters” an Air France spokesman said.

Air France A380

The Air France A380, the largest double-decker ever, lift his flight a week ago (Friday 20th) from Paris Roissy-Charles de Gaulle to New York – J.F. Kennedy with more than 500 passengers onboard.

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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!

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The right or privilege, in respect of scheduled international air services,…

1st.- …granted by one State to another State or States to fly across its territory without landing.

2nd.- …granted by one State to another State or States to land in its territory for non-traffic purposes 

3rd.- …granted by one State to another State to put down, in the territory of the first State, traffic coming from the home State of the carrier 

4th.- …granted by one State to another State to take on, in the territory of the first State, traffic destined for the home State of the carrier

5th.- …granted by one State to another State to put down and to take on, in the territory of the first State, traffic coming from or destined to a third State

6th.- …via the home State of the carrier, traffic moving between two other States

7th.- …granted by one State to another State, of transporting traffic between the territory of the granting State and any third State with no requirement to include on such operation any point in the territory of the recipient State

8th.- …of transporting cabotage traffic between two points in the territory of the granting State on a service which originates or terminates in the home country of the foreign carrier or (in connection with the so-called Seventh Freedom of the Air) outside the territory of the granting State (consecutive cabotage)

9th.- …of transporting cabotage traffic of the granting State on a service performed entirely within the territory of the granting State (stand alone cabotage)

Freedoms of the air

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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.

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Virgin America will release an in-flight wireless Internet on all his flights by the second quarter of 2009. In fact, they flew a test flight from San Francisco to test the whole system and it kinda works.

This gadget, called GoGo, will not forbid any special content, but there will be some constraints though ( no Skype, no IP voice systems,…). The company’s philosophy is not to edit the content that passengers want to watch, but to offer WiFi in order to let the people choose what to watch. This system will be available above 1000 feet and it works with 3G technology.

Thence, get connected in the airplane will be $10 on short flights, and $13 on longer legs. You just need a laptop to get access. Virgin says that later in 2009 they will include an integrated in-flight entertainment system, that will give connectivity to people who don’t have laptops or PDA’s.

Of course, nowadays, a lot of airlines are willing to incorporate this devices to their birds.

Source: Original Link

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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

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The quick fuel draining system (called Fuel Jettison) is an onboard system in large aircrafts like B747, B767, B777 and some B757 and also A330 and A340.

When an emergency procedure around an airport is carried out, the airplane must be able to land with the Take Off Weight (sometimes Maximum Take Off Weight). Then, the low/mid range airplanes have no problems dealing with that, but long range airplanes does.  

Heavy airplanes usually carry a huge amount of fuel (because of long haul flights). Thence, according to JAR regulation JAR 25.1001 about Airworthiness, these heavy aircrafts must be equipped with a Fuel Jettison system. The regulation require to the system to empty the tanks in 15 minuts, and then leaving enough fuel to keep a 3.2% climb gradient in landing configuration at 1.15 stall speed. For example, a B727 releases 1060 kg (2330 lbs) of fuel per minute, with all tank pumps running. The fuel nozzle is set at the wing tip, in order not to make any damage at the airplane fuselage. 

    Source: Wikimedia

Even though this procedure seems pretty enviromentally harmful, it isn’t much critisized because its low frequency, low amount of sprayed fuel and the procedure conditions. If possible, fuel jettison procedure must be done over the sea.

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The ETOPS (Extended-range Twin-engine Operational Performance Standards) defines the twin-engine aircrafts requirements to operate flights where the nearest enroute alternative airfield is further than 60 minutes.

At the beginning of commercial aviation, because of the lack of regulations concerning alternative airfields further than 60 minutes, the air carriers started putting pressure on Aviation Administrations to be modified,  in order to be able to operate transatlantic routes with twin-engine. Because of that, ICAO and the FAA drawn up a new reguation that allowed to operate those routes. 

Nowadays, there are several ETOPS ratings depending on some parameters. These parameters are including the engines and systems’ reliability, crew training and ratings, manteinance and so on.

Author Andrés Meneses

These are the different ETOPS ratings issued these days by Aeronautical Authorities:

• ETOPS-75
• ETOPS-90
• ETOPS-120/138 (138 minuts is a 15% plus 120 minuts, in order to cover a little part of the Atlantic Ocean, not covered with ETOPS-120)
• ETOPS-180/207

An ETOPS rating is gradual. That means if you want to reach ETOPS-120 rating, first of all the aircraft must have reached the ETOPS-75 rating (with 200 sectors with 98% relieability), then the ETOPS-90 rating (with 300 sectors with 98% reliability), and finally the ETOPS-120. For example, in order to achieve ETOPS-120 rating, the airplane must prove less than 0.05 per mil in-flight shut-down. That means, flying 20.000 flights there’s only one in-flight shut-down (obviously, an airplane does not achieve 20.000 routes in its life).

There’s a tremendous application called Great Circle Mapper where you can compute each ETOPS rating maximum range around the earth.

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