This article describes the challenges of down-times in Air Traffic Control.

Nine biological systems are working inside the human body. These systems include the respiratory system, circulatory system, nervous system, musculoskeletal system, digestive system, excretory system, endocrine system, reproductive system, and the integumentary system. All these systems work together with a unified goal of sustaining optimum good health.

As long as these systems keep working, the human body is working properly. If a single system stops working the life of humans comes at stake. Whenever there is a requirement to deal with a system through physical intervention there exist proper procedures and protocols to follow.

These procedures and protocols ensure to provide preliminary arrangements at the place of the system which is undergoing treatment. This preliminary arrangement is of vital importance as it keeps the human body running its function. 

Elements of an Air Traffic Control System

The same is the case for Air Traffic Control Services as it is working to ensure the provision of smooth orderly and expeditious flow of air traffic while maintaining safety. Different systems are working together for this cause. Generally speaking, there are three elements of air traffic control services.

  • Ground Control
  • Air Control
  • Flight data and clearance delivery

Ground Control is aimed at avoiding collisions between aircraft that are on the ground. Air control is aimed at preventing mid-air collisions or avoiding the proximity of aircraft while en-route. Flight data and clearance delivery is focused on the exchange of information vital for the safety and regularity of air traffic control services.  

Various systems are working round the clock to ensure the provision of flawless optimum air traffic control services. These sophisticated systems are working with a unified goal of ensuring safety and expeditious flow of air traffic to ensure optimum utilization of air space. As long as these systems are working standards of air traffic control services are met.

Although these systems are working in a standardized manner still the history of air traffic control services has witnessed incidents associated with system downtimes where the main objectives of air traffic control services were jeopardized and standards of safety were compromised.


There is a cost associated with shutting down of an air traffic control system either for scheduled maintenance that may include upgrades or due to system failures. Whenever a system shutdowns the three basic elements of air traffic control services are prone to errors. To cope with this issue air traffic control services employ procedure control services. A procedural control is a method of providing air traffic control services without the use of radar. Although this stands to be an option still there is a risk associated with it. Procedure control service cannot be as efficient as the radar control service because of the lack of visual elaboration of a scenario.

With increased traffic volume the application of procedural control becomes difficult and the probability of error increases. A decrease in efficiency in Air Traffic Control Services can be translated into a disastrous situation like mid-air collision, runway excursion, etc. Apart from these issues, there is a possibility of a loss of aircraft movement data that is directly connected with Air Traffic Service Revenue. Based on these facts it becomes necessary to limit the duration of the shutdown. By decreasing the time duration probability of errors also decreases that can leads to grave consequences. Whenever a system is shut down there is a requirement for a smooth transition of required controls from current technology underuse towards alternate options.

Scenario around Air Traffic Controllers

Let us make challenges more understandable. Consider a scenario in which an air traffic controller is dealing with traffic in a radar environment. Due to scheduled maintenance, secondary surveillance radar services will not be available for a specified period. Air traffic control services cannot be hindered while switching control of aircraft and coordination from the current radar environment to an alternate option.

An alternate option can be another radar system or procedure control. One of the biggest challenges while continuing with the shutdown of the Air Traffic Control System will be managing the transition. The transition of control and coordination from one system to another will be in a smooth manner to retain control of air traffic and coordination with concerned authorities for ensuring the safety of aircraft.

Coming back to our scenario before the scheduled downtime period teams from Air Traffic Control Service as well as the Technical section are working together in close liaison to ensure continuous monitoring off-site as well as on-site for expected errors. As the alternate system is based on the manual working environment in such an environment the dynamics of working are completely altered. There exist chances related to the loss of vital information in form of aircraft movement data.

For this purpose digital flight progress strip that records the movement of aircraft is switched with a manual flight progress strip. Manual flight progress strip generation is dependent on the flight progress strip printer. Coordination was done through the support of VCCS (Voice Communication and Control System). This coordination is switched from VCCS to the manual process. There is a lot of stress to ensure flawless communication with adjacent FIRs and other stakeholders for the exchange of vital information related to aircraft movement data. Hence the equipment required to support the alternate option for continuing provision of air traffic control services is required to be maintained and their performance to be monitored at successive intervals. Audit checks ensure such systems are intact and their support equipment working at optimum.


During downtimes in the air traffic control system, the prime importance is assigned to the smooth transition of the system for retaining the quality of data and information. Duration of downtime is always desired to be minimum to decrease the probability of error. Continuous monitoring is considered to be a vital part of maintaining safety during downtime. Apart from technical aspects continuous coordination and close liaison among all stakeholders is necessary.

Read more in the subsequent article: Avoiding System Down-Times.

If you are an aviation academy of training center, you might be interested in SkyRadar's Pedagogical Monitoring Training System for ATC.

SkyRadar's monitoring environment trains ATSEP on rapidly locating errors or points of system degradation, on rapidly fixing them and keeping downtimes short.


The system includes a pedagogically enhanced monitoring environment and a simulated ATC environment. It connects to the various training laboratories by SkyRadar.

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