The North Atlantic is a busy chunk of airspace. Each day, thousands of aircraft cross the Atlantic Ocean between Europe and North America. We want to tell you a little more about what it is like to fly over it though. What’s going on while the passengers are sitting back enjoying their airplane food and inflight entertainment?
The rules and regulations
First up, the North Atlantic is, for all intents and purposes, broken into two ‘parts’ – the NAT HLA (high level airspace) which includes the track system, and then all the other bits which aren’t NAT HLA. The NAT HLA part has a whole load of rules and regulations linked to it while the other bit has less.
The main reasons for these rules and regs are that a) there is no ATC radar so flying what you’ve been told to fly is really important and b) it is really important because there are loads of other aircraft up there and not a whole lot of separation between them all. So most of them relate to what an aircraft needs to carry onboard in terms of communication, navigation and other mandatory systems. There are also some strict rules on the accuracy of navigation, what to do in case of emergencies, weather avoidance etc.
A look at the NAT HLA
The NAT HLA is from FL285-FL420 inclusive and it is divided up into 6 different FIRs (Flight Information Regions)/OCAs (Oceanic Control Areas). Shanwick looks after the UK/ Ireland section, Gander looks after the Canadian side, Reykjavik has the North, Bodø has the really north (east) part and down south you have New York Oceanic and Santa Maria on each side. There is also a small bit controlled by Nuuk. You can see these on Fightradar24 if you activate the ATC boundaries layer in Settings.
Within the NAT HLA, you have the organized track system which is defined each morning and evening based on where the best jet streams are. There are usually 5 or 6 tracks published, with the westbound ones utilized during the day, and the eastbound by night. The peak flow of traffic heading westbound cross 030° west between 1130 and 1900 UTC, and eastbound it is at its heaviest between 0100-0800 UTC.
Flight planners do not have to plan to use the OTS – they can plan random routes as well. Using the tracks makes for the quickest, most efficient flights, but only if you also get the level you need and they can be fairly full at peak times.
Communications and clearances
Most of what pilots do to cross comes down to communications and clearances. The primary form of communication in the NAT HLA is HF radio, and each section utilizes its own primary and secondary frequencies which change daily (and nightly) and are influenced a lot by ionospheric disruptions. Those big solar storms in early May 2024? Those tend to disrupt HF causing blackouts.
Some of that mandatory equipment we mentioned earlier also includes things like datalink (CPDLC and ADS-C). CPDLC is a type of ‘texting’ system between ATC and aircraft, but one that uses set messages types so controllers can send clearances, and crew can make requests for things like level changes etc. Aircraft must have this and at least 2 forms of long-range communications – hence the HF requirement.
The Oceanic Clearance is (and will be until later in 2024, more on that in a future post) a BIG part of routing through the NAT HLA because before any aircraft enters the area, they need an oceanic clearance. This is requested by the pilots, usually by CPDLC (but they can use voice), to the controlling sector around 60-90minutes prior to entry. In their request, they include their entry point and ETA, requested flight level and speed (Mach number). They then receive a clearance back confirming the routing, speed, level etc.
Who uses the NAT HLA?
Airplanes. Airplanes with a decent range and ETOPS approval, because there isn’t a whole lot of land around if you suddenly need to land.
But this is changing (possibly). From around 2026, other users are expected to be able to start winging their way over the NAT HLA as well. Actually, not necessarily winging it – balloons are on the list of potential new users, along with UAS and UTM traffic.
When things go wrong...
It isn’t always smooth sailing over the North Atlantic. One bad thing is turbulence. In fact, this is some of the most turbulent airspace out there because of the large jet streams that mingle within it. A recent study at the University of Reading shows that the duration of severe clear air turbulence (CAT) has increased by around 55% over the last 40 years.
Because of the lack of quick comms with ATC, and the amount of traffic using the airspace, there are contingencies in place for emergencies and for weather deviations. These are set rules for how crew should descend and divert if it comes to it, and they can’t get hold of ATC. In any other situation, not following the right routing, at the correct level and speed can result in a Gross Navigation Error (GNE).
These are tracked and there are BIG fines applied to any operator whose aircraft strays from the clearance without good reason. The only deviation allowed from the assigned trajectories are a speed change of less than 0.02 Mach, an altitude deviation of less than 300’ (to allow for turbulence) and aircraft can SLOP, meaning they can set an offset of between 0 and 2.0nm right of track. That one is for wake turbulence. So pilots have to ‘think in 3D’, constantly monitoring it all to ensure they aren’t straying into the track of another aircraft.
Where to go in an emergency
There isn’t a whole lot of much out over the North Atlantic, save for a lot of water. If aircraft need to divert they are generally looking at EINN/Shannon, BIKF/Keflavik, one of the Canadian options (CYQX/Gander, CYYR/Goose Bay, CYYT/St Johns or CYJT/Stephenville), or the more southeasterly LPLA/Lajes. There are other places you can go, but they are small/ military/icy/not ideal.
A bit of history
The first flight over the North Atlantic took place way back in 1919. The route only started to get busier for commercial traffic after WWII, and in 1961 they started to worry about aircraft flying into each other and so implemented the first (occasional) use of NAT Tracks. By 1965, they were a daily feature. They are actually based on the old shipping routes which go as far back as 1898.
Fringe benefits
One good thing about routing over the NAT, particularly at higher latitudes, is that crew often get to see the ‘Northern Lights’. These are more prevalent in the winter months and obviously more visible at night, but they can be a beautiful bit of entertainment at 3am when pilots are struggling with boredom!
A standard day crossing the NAT HLA
Flight crew check the weather and NOTAMs well in advance to ensure the available airports are good in case they need them. Additional fuel is often carried to ensure they can accept lower levels and manage weather detours if required. During aircraft checks those systems needed for the crossing are confirmed as working.
In-flight, the crew ensure the route is plotted – this is normally done on electronic flight bags now, but some old school operators might still use the old chart method. Within around 90 minutes of entry, the crew request their clearance and once received, confirm the route they are planning to fly matches what they have been told to fly.
As they enter, they check in on HF and ensure the CPDLC system is logged on and working. Then it is just a case of checking and monitoring. Over each waypoint, the fuel and time is checked, and 10 minutes after each waypoint a plot is made using GPS position to confirm they are on track. Aircraft squawk 2000 once 10 minutes from radar coverage and set 123.45 in the VHF box 1 for communicating with nearby aircraft, and 121.5 in box 2 for emergencies.
The changeover between Shanwick and Gander happens at 030°W, and as they cross into other OCAs they will make contact with that control station. The crossing usually takes several hours, after which they are handed over to a domestic center depending on which land they exit into.
So, there we have it. The North Atlantic is more than just a great big puddle, at least for the pilots flying over it.
