NAT

North Atlantic Tracks are a set of transatlantic flight corridors established and managed jointly by Gander Oceanic, Shannon Oceanic, and Shanwick Oceanic control centres. They exist because the North Atlantic has no radar coverage and only limited VHF radio range, so aircraft are organized into fixed routes with defined separation rules. Rather than allow each flight to pick its own path, NATs impose order on what would otherwise be a chaotic, uncontrolled piece of airspace.

Each NAT is a one-way corridor, typically 10 nautical miles wide, running eastbound or westbound at specific flight levels. The routes shift with wind patterns: eastbound tracks (called the East Track Set) are available during local morning hours and exploit the jet stream, while westbound tracks (West Track Set) operate during afternoon and evening windows. A typical North Atlantic crossing might follow track Bravo at Flight Level 350, with other aircraft on the same track spaced at minimum 10-minute intervals or 50 nautical miles. Aircraft file flight plans requesting specific tracks and levels, and oceanic control assigns them based on availability and fuel/performance.

Why NATs matter in maintenance

For maintenance technicians and engineers, NAT operations drive specific certification and equipment requirements. Aircraft must carry HF (high frequency) radio for oceanic communications, inertial reference systems or GPS for accurate position reporting, and CPDLC (Controller Pilot Data Link Communications) equipment on newer aircraft. Navigation accuracy is tighter than domestic flying: crews must maintain track-keeping within 5 nautical miles, which demands serviceable navigation systems and careful preflight checks. Any defect in HF radio, INS drift, or CPDLC compatibility can ground an aircraft from transatlantic service.

Maintenance planning around NATs is seasonal. Winter routing differs from summer because the jet stream position shifts, meaning the optimal tracks change. Airlines plan heavy checks during season transitions when particular aircraft will be out of service. The spacing rules and altitude restrictions also create dispatch pressure: a broken altitude encoder or faulty transponder can prevent a crew from requesting a preferred NAT and flight level, forcing a delay or reroute to avoid costly fuel burn on an alternate path.

The term NAT itself has been in use since organized transatlantic operations expanded in the 1960s and 1970s. It is distinct from CPDLC or RVSM (Reduced Vertical Separation Minima), though all three are linked: RVSM enables the narrower vertical spacing that lets more aircraft use NATs efficiently. Modern developments include the Transition and Initial Approach Procedures (TPAE) that connect NATs to European airspace, which further tighten the integration between oceanic and continental air traffic management.