Liability in Automated Systems

  • Home 1993 Liability in Automated Systems....

Liability in Automated Systems

32ND ANNUAL CONFERENCE, Christchurch, NZ, 19-23 April 1993

WP No. 128

Liability in Automated Systems


During the 30th Annual Conference in Trinidad, Conference accepted the recommendations of a Standing Committee 4 Working Paper on Automation and the ATCO in as much as the legal aspects of a controller’s responsibilities in respect of automated systems should be clearly defined. At the 31st Annual Conference in Bournemouth the subject of an ATCOs liability in Automated Systems was put on the work programme of Standing Committee 7.


When reliance is placed on computers and automated systems, there follows a natural concern as to what happens in the event of equipment failure, or if the wrong information is delivered to the controller. Controllers using such a system, and placing reliance on it, need to know where the responsibility lies for the provision of correct data 1 on which their appropriate air traffic control decisions are made. Controllers will accept responsibility for their non-automated type operations and decisions, but does a computer have any legal liability for the accuracy of the data it provides?

There is already a dependence on some forms of automated data sent down form aircraft systems. Such as SSR identification and Mode C level information. However, in the case of SSR operations, there is still a requirement for the controller to review the data and ensure that suitable verification procedures are carried out. Controllers’ liability may be compromised unless controls are effected to ensure that the data handled by computers is correct, and fail-safe.

The introduction of computers has brought about many benefits to the aviation world, especially in the areas of aircraft flight control and management systems. The automation of ATC systems is being actively considered and controllers will find themselves placing an increasing reliance on these devices, in order to carry out their duties safely and expeditiously. A subject of particular concern is what happens when an automated system fails and the controller has to recover the situation. During the changeover period back to a non-automated form of ATC, the liability for any incident, which might take place, is not well defined. Failures of any equipment places a high level of stress on the controller and, at these times, errors and omissions may occur.

A further area of concern in an automated system is the difficulty of detecting rare faults that may arise from interaction through a keyboard input device. For example, very occasionally, a key press input on a system keyboard may not be detected by the computer system. Perhaps because of a poor electrical contact. The controller, however, may not notice this rare event and thus incorrect data may be input.

In the use of the Traffic Alert and Collision Avoidance System (TCAS) a conflict of interest can arise when the controller gives one instruction but the TCAS issues another to the pilot. Problems can occur if a resolution advisory is issued to the pilot, unnecessarily and an erosion of separation takes place which is, in effect, caused by the TCAS itself. Present trials with TCAS have highlighted significant problems when aircraft are climbing/descending towards each other, even though ATC separation is being provided.


It is recommended to conference that the following paragraphs be adopted as IFATCA policy and inserted in the IFATCA Manual on Page 4123:

“A controller shall not be held liable for incidents that may occur due to the use of inaccurate data if he is unable to check the integrity of the information received.”

“A controller shall not be held liable for incidents in which a loss of separation occurs due to a resolution advisory issued by an automated system.”


Human Factors in the Ground Control of Aircraft (V. D. Hopkin)

Paper to RAES (U.K. Guild)

Last Update: September 20, 2020  

December 21, 2019   685   Jean-Francois Lepage    1993    

Comments are closed.

  • Search Knowledgebase