Wednesday, June 25, 2008


Homeostasis (from Greek: ὅμος, homos, "equal"; and ιστημι, histemi, "to stand" lit. "to stand equally"; coined by Walter Bradford Cannon) is the property of either an open system or a closed system, especially a living organism, that regulates its internal environment so as to maintain a stable, constant condition. Multiple dynamic equilibrium adjustments and regulation mechanisms make homeostasis possible. The concept was created by Claude Bernard, often considered as the father of physiology, and published in 1865. (WIKIPEDIA)

Air Traffic Control systems are discreet event dynamic large systems. They are composed of three sub systems the visualization of the traffic data – radar data processing, the planning and partitioning of the operational load – flight data processing, and all the related communications – ATN . There is also the substructure which provides the necessary services for these three subsystems – SYSTEMS. ATC system are also a combination of human and machine elements. There are many operators of different types.

I would like to point out at the homeostasis in the air traffic control systems between the technical and operational groups. The operational group comprises air traffic controllers and the various people in their management hierarchy. Most of these people come from an air traffic controller back ground.
The technical group is composed of a mix of engineers and air traffic controllers… Some of the engineers come from a technical background while some of them come from math and science university education and engineering faculties. Air traffic controllers in the technical group function as interface to the operational group. They work in requirements specification, quality control, configuration management and testing.

The safety created by an air traffic control center is the result of a combination of the work of the operational and technical work done. When the technical side fails, the operational measures are used. For example, seperation is increased. Also, when the technical facilities get old and are out of date, operator load increases. For ex. if the radar views are not good, operators have to cope with this difficulty somehow.

The homeostasis between the technical and operational side works in ATC so that when the technical side goes down the role of the operational side increases or vie versa. When everything is perfact operational side relaxes a little bit.

Why am I writing this note? It is not a big deal up to this point. The interesting phenomenon begins when we observe: If one of the two elements that comprise the homeostasis dominates the relation,
what happens then? For ex. operational side effects the technical decisions for various reasons…
These decisions may vary from setting unrealistic deadlines to deciding which technical systems to buy…

The dynamic nature of the homeostatic balance may determine the sudden or unjustified changes in the balance. In fact the flexibility of the system is designed so that even if the radar views are lost air traffic control can continue with the strips. The risk of losing touch with the technical reality is more on the long run. I believe, it is very difficult to maintain and develop a technically upto date system while carrying on the day to day ATC duties.

There is a tangible risk in ATC which may arise from the tendency of one of the technical and operational groups to dominate the other.

Ali R+

Note: I woke up to the importance of this issue because of the contrast I noticed btw Turkey and Karlsruhe in regards to this matter. Thanks again to Herr Ehrenberger (ECO).