Do stratospheric business and military jets use the North Atlantic Tracks? The North Atlantic Tracks (NATs) are the airways generally used by airliners taking approximate great-circle routes between North America and Europe; due to the wild swings in wind strength and direction over the North Atlantic from day to day and place to place, the NATs are not fixed in position, but, rather, are plotted fresh every morning to allow transatlantic flights as much tailwind (and, thereby, as much groundspeed and as much per-flight fuel efficiency) as possible, and, then, sent to all the airlines preparing aircraft for transatlantic runs.

In contrast, the weather in the stratosphere - the layer of air lying above the tropopause (the upper boundary of the weather-prone troposphere; usually lying between 35 and 50 kilofeet at temperate and polar latitudes, but generally located at a much higher altitude over the tropics) and below the stratopause (the upper boundary of the stratosphere, and the lower boundary of the poorly-known mesosphere; usually located at around 165-180 kft) - is essentially uniform constant from day to day, changing (usually) only slowly, with the seasons.  This removes the raison d’etre for the moving NATs, as no particular stratospheric route is objectively significantly better than any other of comparable length.  For this reason, the Concorde (cruising at flight levels [FLs] 470-600, equating to an altitude of 47-60 kft, give or take a kilofoot or so)1 did not use the NATs, instead following, for open-ocean stratospheric cruise, one of a set of preplotted fixed airways, the locations of which did not change from day to day.

But the Concorde, even when it was still in service, wasn’t the only aircraft to cross the North Atlantic in the stratosphere; business jets (at least the many that are actually capable of doing so) routinely cruise at between FL 450 and FL 550 or so (the exact upper limit depending on the model of bizjet), and some smaller military jets routinely cruise above FL 600 in order to minimise aerodynamic drag on long-distance flights.  These other high-altitude jets would stand to benefit just as much as the Concorde did from being able to use fixed stratospheric airways rather than having to follow the variable and non-stratospheric-aircraft-benefitting NATs; yet, I’ve only ever come across mention of immobile stratospheric routes with reference to the Concorde, and in language that makes it sound like the Concorde was unique in its use of these routes.

So do stratospheric bizjets and military jets have to use the NATs (and, if so, why?), or do they get to use fixed stratospheric routes, like the Concorde did?



1: An aircraft’s flight level is the altitude, in hectofeet, that its barometric altimeter (if properly calibrated, and assuming the aircraft’s pitot-static system is working properly) indicates when set to standard pressure (29.93 inHg).
The tropopause is in the low to mid 30s in the mid-north latitudes that the NATs reside (and is in the 20s in the arctic in winter) so an airliner crossing on a NAT at 55 DegN at FL370 will be well into in the stratosphere.

Concorde didn't use the NATs simply because the NATs top out at FL410.  And in any case, the NATs are a large band of parallel tracks several hundred miles wide which are mostly just shifted more northerly or more southerly to accommodate weather patterns and the locations of polar jets etc.  The routings aren't really customized much more than that.

Anyway, because they top out at 410, if your jet can cruise above 410, like a Global or Gulfsteam, you can avoid the NATs and can pretty much file for whatever custom routing suits you that doesn't conflict with someone else.