How Planes Cross the Atlantic: Routes, Jet Stream and Ocean Navigation
A flight from Europe to North America takes 7-9 hours westbound and around 8-11 hours eastbound. The difference comes down to the jet stream, covered below. The route looks straight on the seatback screen, but the plane’s actual path is different – and it changes every day.
Why the route isn’t a straight line
On a flat map, the logical path from London to New York seems to run horizontally along a line of latitude. But the shortest distance between two points on a sphere is a great circle arc. That arc curves northward compared to what a standard Mercator map suggests, often passing near Iceland or Greenland.
But even that arc is just the starting point. The actual route is built around the wind.
The jet stream and NAT tracks
At cruising altitude – around 33,000-40,000 ft (10-12 km) – the jet stream is blowing. It’s a narrow band of air a few hundred kilometers wide, moving west to east at 100-300 km/h. Riding it eastbound to Europe can cut an hour off the flight and burn significantly less fuel. Flying into it westbound costs time and money.
This is why transatlantic routes change daily. The system is called NAT HLA – North Atlantic High Level Airspace. Every day, two control centers – Shanwick and Gander – jointly publish a set of tracks, lettered corridors running from A to Z. Airlines pick the track that suits their direction, departure time, and weather forecast.
Shanwick Oceanic Control is a joint Irish-British facility physically located in Prestwick, Scotland. The name combines Shannon and Prestwick – two centers that historically split the work before being merged. It covers the eastern half of the North Atlantic.
Gander Oceanic Control is a Canadian facility in Newfoundland covering the western half. Gander was a strategic refueling stop as far back as World War II, when aircraft didn’t have the range to cross the Atlantic nonstop.
Shanwick and Gander handle the northern NAT tracks, but they’re not the only centers over the Atlantic. The entire ocean is divided between five control areas. Beyond those two, there are three more:
Reykjavik OACC – Iceland’s oceanic center, responsible for airspace over the northern Atlantic and the Greenland Sea.
New York OACC – the FAA-run center managing the zone east of the US coastline, south of Gander. Routes from the US East Coast and the Caribbean to Europe pass through here.
Santa Maria OACC – a Portuguese center based in the Azores, covering the central Atlantic. Routes from Europe to South America and West Africa run through its airspace. The Azores are also one of the primary diversion airports for transatlantic flights.
All five centers operate without radar – there simply isn’t any over open ocean. Aircraft positions are reported via HF voice radio or satellite, and crews are required to check in every 10-40 minutes.
Westbound tracks (Europe to North America) come out around 23:00 UTC; eastbound tracks (the return direction) around 14:00 UTC. Coordinates and altitudes differ every time. Crews find out their specific routing shortly before departure.
How airspace works without radar
There are no ground-based radars over the Atlantic. The signal doesn’t reach. Until the mid-2010s, oceanic air traffic control relied entirely on voice position reports over HF radio and strict separation rules – aircraft maintained a minimum of 10 minutes between each other on the same track, and 60 nautical miles laterally.
Between 2015 and 2020, that changed. Most long-haul aircraft now carry ADS-B, which continuously broadcasts their position – receivable by satellites on the Iridium network, among others. This allowed controllers to tighten spacing and move more aircraft through the oceanic airspace at once.
Cruising altitude and speed
Cruising altitude is typically 33,000-41,000 ft (10-12.5 km). The exact level depends on aircraft weight: a heavy plane at the start of a long sector can’t reach its optimum altitude right away – it climbs there gradually as it burns off fuel. This is called a step climb.
Cruise speed is around 900 km/h ground speed with a tailwind, 800-850 km/h without. The Mach number crews target is usually 0.84-0.85. That’s not the aircraft’s maximum – it’s the most fuel-efficient speed for the conditions.
Fuel and diversion airports
A transatlantic flight is one of the more demanding fuel-planning exercises in commercial aviation. The aircraft carries fuel for the route, plus a reserve to reach an alternate, plus contingency fuel for the unexpected. At departure, a Boeing 777 or Airbus A350 can be 100-120 tonnes heavier than it will be on landing – just from fuel.
Diversion airports for transatlantic routes are planned in advance. In the middle of the ocean, the nearest options are the Azores (Lajes Field), Gander in Canada, or Reykjavik. When aircraft divert there in emergencies, it’s not random – those airports are already on the flight plan before wheels-up.
Twin-engine aircraft – the Boeing 787, Airbus A350, A330 – cross the Atlantic under ETOPS rules (Extended-range Twin-engine Operations). This certification specifies the maximum time an aircraft can fly on one engine to reach the nearest suitable airport. Most modern types hold ETOPS-180 or ETOPS-240, meaning 3-4 hours on a single engine. Without that certification, the route wouldn’t be legal.
Communications and navigation over the ocean
There’s no cellular coverage over the Atlantic. Aviation communication runs through HF radio and SATCOM – satellite-based voice and data links. Crews report their position, altitude, and estimated time to the next waypoint at regular intervals, even now that ADS-B handles automatic position broadcasting.
Navigation is built on Inertial Reference Systems (IRS) and GPS. IRS needs no external signal – it calculates position from accelerations, starting from the alignment point before departure. GPS corrects the accumulated drift. Both run simultaneously.
Passenger Wi-Fi on transatlantic flights works through satellites – most commonly Viasat or Inmarsat. Speeds are inconsistent, but enough for messaging apps. Over the central Atlantic, expect coverage gaps of 30-60 minutes.
Why eastbound and westbound are different flights
New York to London averages 6.5-7.5 hours. The return runs 8-9.5 hours. On the same route, the difference can reach 2 hours. It’s all the jet stream: eastbound it pushes you along, westbound it pushes back.
When the jet stream is particularly strong, westbound flights sometimes route well south of the usual path – down to the latitude of Spain and Portugal – to avoid the core of the flow entirely. It adds distance but saves time and fuel.
Because the Earth is a sphere and the screen shows a flat projection. The shortest path between two points on a sphere is a great circle arc, which appears to curve upward on a standard Mercator map. That curve is the straight line – it just doesn’t look like one on a flat surface.
The high-latitude routing is the straight path – it’s the great circle arc. The jet stream often reinforces that choice by running in the same direction. Flying over Greenland isn’t a detour; it’s the geometrically shortest route, usually with a tailwind on top.
Crews know their diversion airports before departure. The most common options are the Azores (Portugal), Gander or Goose Bay in Canada, and Reykjavik in Iceland. If needed, the aircraft turns toward the nearest one – depending on where it is along the route, that takes anywhere from 30 minutes to 2 hours.
GPS works fine over the Atlantic – the satellites are still up there. But even without it, the aircraft uses Inertial Reference Systems (IRS), which calculate position from movement and acceleration, starting from a known point before departure. Over 7-8 hours, IRS accumulates a small error; GPS corrects it periodically.
The jet stream blows west to east. Flying from North America to Europe means a tailwind of 150-300 km/h – the aircraft covers ground much faster. The return leg flies into the same wind, which accounts for the 1-2 hour difference.
At the midpoint of the Atlantic, roughly between the Azores and Newfoundland, there is no land within 1,500 km in any direction. It’s the one stretch of the route where the nearest shore is farther away than at any other point in the flight.