38TH ANNUAL CONFERENCE, Santiago, Chile, 15-19 March 1999WP No. 166Transfer of Control Functions to Pilots (Legal Aspects) |
Introduction
The Toulouse IFATCA (98) Conference revealed the need to deal with the legal aspects of the transfer of control functions to pilots. The main drivers for change as outlined in the ATM 2000+ strategy document are. The need to create additional capacity in congested airspace areas whilst increasing safety levels, and secondly to provide airspace users with opportunities for greater flight efficiency when possible. To this end is it conceivable that in time some separation functions will be transferred to the cockpit. It is necessary therefore that IFATCA should investigate this subject thoroughly.
Discussion
Separation Assurance
The fundamental principal of ATM is to apply positive separation between aircraft in controlled airspace. The primary method of operation is to preserve minimum separation between aircraft, rather than using collision avoidance tools to simply miss other traffic. The way in which separation assurance is applied, and the allocation of responsibilities to the humans involved has a direct effect on workload.
IFATCA has the following technical and professional policy on the use of ACAS:
| “IFATCA recognises that the development of airborne collision avoidance systems should be encouraged. However it must be accepted that the primary means of collision avoidance within a controlled airspace environment must continue to be the air traffic control system that should be totally independent of airborne emergency devices such as ACAS. TCAS devices should not be a consideration in the provision of adequate air traffic services .”
“Guidelines and procedures shall be established in order to prevent incidents arising from the use of false or misleading information provided by Airborne Collision Avoidance Systems .” |
There are a many options regarding how separation might be applied, who should be responsible and when, and how much technological support can or should be used. The main options fall between structuring traffic and retaining the current tactical controlling methods but, arranging it in orderly and predictable flows to retain the human cognitive process. Or designing systems where human intervention is the exception.
ACAS has already brought a degree of situational awareness to the cockpit. This trend is likely to continue with the introduction of Airborne Separation Assurance Systems (ASAS) and improved cockpit HMI.
Distributed air and ground responsibilities involves ATC sharing the responsibility for separation assurance (SA) with suitably equipped aircraft, thus providing the possibility for a reduction in ATC workload and enhancing flight efficiency. The concept of autonomous operations produces a number of issues that need to be addressed.
a) Feasibility and potential benefits of autonomous operations in busy traffic areas;
b) Ability of these aircraft to negotiate safe trajectories in multi-conflict situations;
c) The separation minima to be adopted;
d) The number of aircraft that would need to be suitably equipped before worthwhile benefits would accrue;
e) The method of transition from one environment to another;
f) The legal aspects of the concept.
In order for SA to be delegated to pilots, various airspace regimes would need to be considered, namely: Managed airspace (MAS), Free Flight Airspace (FFAS) and Unmanaged Airspace. Current ICAO airspace classifications and legislation can be encompassed by these designations, however, if this concept is to proceed it is important that future rules and classifications are common to all states involved in SA delegation in order that pilots and controllers work to an agreed standard set of procedures. It is envisaged that within Managed and Unmanaged airspace the rules and procedures will remain similar to those presently in use. ATC will effectively retain responsibility for SA in MAs, however, the boundaries of this airspace may change in an organised way depending on traffic levels. In addition, suitably equipped aircraft might be allowed to provide their own separation from another for a specific manoeuvre, for example: ‘in trail climb’.
It is proposed that in FFAS ATC will not in general provide SA and responsibility for this task will be transferred to the cockpit. However, there may be situations for example, where multiple conflicts are predicted, that the controller will need to intervene, in order to resolve the situation, this leads us to a major issue for future ATC systems. Is it possible or indeed desirable to arrange the system such that a controller only has to keep a mental picture of a limited portion of the overall traffic situation, and what are the consequences of such a change for ATC and aviation as a whole.
IFATCA has the following Provisional Policy on ASAS:
|
“Where ASAS is implemented, a clear and unambiguous statement of the separation responsibilities of pilots and controllers is required. IFATCA has no fundamental objection to the use of CDTI in areas where it is demonstrated to maintain and improve system safety. Before ASAS applications are put in place, it should be proven that they maintain or improve system safety while providing net cost benefits. IFATCA considers the following to be the minimum attributes of any CDTI system used in Airborne Separation Assurance applications: i) Positive unambiguous identification of all relevant aircraft to the standards currently required of ATC systems and controllers; ii) Sufficient information as to the intent of relevant aircraft to avoid any action taken in maintaining separation from generating additional conflict .” |
Human Factors
The human factors issues raised by the concept identified in paragraph 2.1.8 require careful investigation. This subject is being addressed by SC4.
Legal Matters
From the legal viewpoint, it is essential that the responsibility for Separation Assurance is clearly defined. The majority of problems are likely to occur at the transition from MAS to FFAS or vice- versa. Or when a controller is required to take over responsibility for SA in FFAS when multiple conflicts are predicted.
Before any transfer of responsibility for SA takes place, it would be necessary to:
a) Agree the action with the pilot(s) concerned;
b) Determine the start and end point for the transfer of responsibility;
c) Ensure that contingency plans are in place to ensure adequate separation can be maintained in the case of equipment failure.
IFATCA has the following policy, which is relevant here:
| “The legal aspects of an air traffic controller’s responsibilities must be clearly identified when working with automated systems .” |
Conclusions
As far as delegation of separation is concerned, states must have in place regulations detailing procedures to be followed before responsibility for SA can be transferred to the cockpit. In Order to avoid problems, it will be necessary for these regulations to be standardised globally.
The legal responsibility for SA must be defined in the regulations governing the procedure. It must be very clear when the pilot takes this responsibility and when it is transferred back to the controller. ATC cannot normally be expected to jump in at a moments notice and sort out a confliction, whether this might be possible if sufficient information were provided is a human factors issue and should be addressed by SC4.
IFATCA has the following policy on the use of ACAS:
|
“IFATCA recognises that the development of airborne collision avoidance systems should be encouraged. However it must be accepted that the primary means of collision avoidance within a controlled airspace environment must continue to be the air traffic control system that should be totally independent of airborne emergency devices such as ACAS. TCAS devices should not be a consideration in the provision of adequate air traffic services. Guidelines and procedures shall be established in order to prevent incidents arising from the use of false or misleading information provided by Airborne Collision Avoidance Systems.” |
IFATCA has the following provisional policy regarding separation assurance systems:
| “Where ASAS is implemented, a clear and unambiguous statement of the separation responsibilities of pilots and controllers is required.” |
IFATCA has no fundamental objection to the use of CDTI in areas where it is demonstrated to maintain and improve system safety.
Before ASAS applications are put in place, it should be proven that they maintain or improve system safety while providing net cost benefits.
IFATCA considers the following to be the minimum attributes of any CDTI system used in Airborne Separation Assurance applications:
- Positive unambiguous identification of all relevant aircraft to the standards currently required of ATC systems and controllers;
- Sufficient information as to the intent of relevant aircraft to avoid any action taken in maintaining separation from generating additional conflict.
IFATCA has the following policy on legal liability:
| “The legal aspects of an air traffic controller’s responsibilities must be clearly identified when working with automated systems.” |
SC4 and SC7 will need to continue to monitor this subject in order that policy can be produced or revised to cope with new developments.
Recommendations
States must have in place regulations detailing procedures to be followed before Separation Assurance can be transferred to the cockpit.
The legal responsibility for Separation Assurance must be defined in the regulations governing the use of the procedure.
The Initial and final points at which Separation Assurance is transferred from ATC to the pilot must be accurately defined in all cases.
References
EATCHIP Operational Concept Document – ATM2000+.
Last Update: September 28, 2020