# How exactly do the fliers follow the airways/escape routes?

I once sat in the cockpit of a KLM aircraft and we met a coffin exactly on the opposite route, 300 m higher.The cause by which they follow the airways so accurately is that they fly from beacon to Beacon. This is the setting of the pilots in advance. The plane is doing its best on autopilot.

The accuracy in tracking the heart line of the air route has been very high with modern navigation equipment for years.So exact that you can really hit an unforeseen counter-beam at your flight altitude.

The fact is that the maintenance of that correct height has been done with more precision for a number of years.

(I will first repeat the current question text in case something is changed later on: “How exactly do the fliers follow the airways/escape routes?”)

That more accurately maintaining the assigned flight altitude was also needed.Because up to a number of years ago, the flight levels above 290 (29,000 feet or 8.8 km altitude) were still separated by an interlayer of 2,000 feet (610 m) thickness. One has long worked towards entering a height separation of 1,000 feet (305 m), equal to the separation that was already gold below that 8.8 km altitude.

And why is that thinner interlayer necessary?Well, there is more and more air traffic, and for every plane there is actually only one optimal flight altitude (and that is gradually higher as the plane gets lighter on the way by consuming fuel, but aside).

Two Boeings 777 which are at the same time from Hong Kong to Amsterdam resp.London want to have to be planned either at different heights (where there is always one that flies at the less ideal height and thus consumes more), or they have to start scheduled with a certain time interval to the flight so that the number two Sufficiently far behind the number one remains. Flying at a different altitude often also means a slightly different speed, so sometimes the problem dissolves on the road after an hour or something. The wind can also be slightly stronger or less strong at the other altitude, which can sometimes also help.

Higher than the ideal height is usually not feasible, and lower one does not want either.

The reason that the higher flight levels had previously had a greater margin was traditionally located in the natural decrease in the air pressure reduction per 100 meters altitude difference as you get higher.By this I mean that the air pressure if you are going from 100 meters altitude to 200 meters height decreases more strongly than from 8,800 meter altitude to 8,900 meter altitude. Your altitude determination by means of air pressure measurement is therefore high in the air by nature a lot less precisely.

And the meters themselves were good, but the exact outside air pressure measurement also depends on the place of the measuring point (measuring hole) on the skin of the aircraft which, after all, pushes the stationary air around the plane and puts it in motion.The size of the air pressure disturbance caused by the aircraft itself had to be reassessed for many older aircraft types. The altimeter itself (the pointing instrument in the cockpit) knows that for all kinds of flight speeds something different pointing error is not.

And a superficial dent in the fuselage before the measuring point can also help the accuracy of soap while that for the constructive strength does not have to be objectionable.

However, nowadays, in large parts of the airspace, only aircraft that meet the stricter requirements for applying reduced Vertical Separation Minima (RVSM) are allowed.As a result, the number of available flight levels above Flight Level 290 could be doubled: should one first fly on FL 290, 310, 330, 350, 370, 390, and 410, etc., then one could now choose from FL 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400 , and 410, etc. So long as everyone knows how to keep the height accurate. So there is no more ‘ on the hand ‘, but it is always the autopilot that holds the set height tirelessly.

The downside of the coin is that two opposing beams which, by some mistake, of one of them or of the air traffic control are exactly at the same height and fly between the same beacons, make a greater chance of touching each other.This has already happened once with two planes over Brazil, where one of them came off with a torn winglet and could still land, but the other, a Boeing 737, half of the left wing lost and in toll flight (falling as a winding Tree leaf) The ern came down and broke in pieces on the way and crashed into the Brazilian jungle. The other plane was a brand new business jet. Gol Transportes A茅reos Flight 1907-Wikipedia, the free encyclopedia .

And also by following flying exactly the same course line in opposite direction, two large planes over India have come into frontal collision in 1996.There was then one device mistakly dropped further than the traffic control had instructed, and that was in fact already climbing back to its assigned altitude, when it returned exactly on course the altitude where the other plane, a 747, still Had to wait before continuing to climb. 1996 Charkhi Dadri mid-air collision-Wikipedia

There is now happy TCAS, the Traffic alert and Collision Avoidance System that the fliers outside the air traffic control can warn in time for a threatening collision, but that requires alert to intervene manually by the pilots and then Especially (both!) do not obey the then sometimes misleading traffic management, but only follow TCAS, and that has not gone well at the beginning.Airplane Collision 脺berlingen-Wikipedia . In that case, it was two planes on intersecting races, not counter-beams.

So you could conclude that that exact course and altitude can also have disadvantages.(“Every Foor part…”) Of course, this thought is also occurring in front of the people in the planes. Some of them are, on their own initiative, for example one nautical mile (almost 2 km) to the right of the course, so that you will in principle miss an unintentional counter-beam. However, this process was initially recommended only in some areas without radar coverage (‘ range ‘). Modern navigation systems can do this software, just as if each beacon is one nautical mile to the right of the nominal course. A more recent development is that this method is already compulsory over the North Atlantic Ocean.

Perfection is a challenge in this imperfect world… But we are constantly working on it.

Further information:

Dutch Wikipedia link about the various forms of separation (planes sufficiently far apart):

About TCAS: Explanation by Captain Joe: “traffic, traffic” all ABOUT TCAs explained BY CAPTAIN Joe (in aviation do not escape the use of the English language.)

English Wikipedia:

About RVSM: Reduced Vertical Separation minima-Wikipedia .