General

The subject matter was proposed by ANACNA, Italian MA, during Geneva 2001 Conference.

It addresses the concerns of several MAs to the introduction of types of Apron Management Service (AMS). Consideration is given to the effect of Low Visibility Operations, to the existing requirements of Surface Movement Guidance and Control Systems (SMGCS) and to proposals to introduce Advanced-SMGCS (A-SMGCS).

AMS are a set of services that can be established, on an aerodrome, to cope with the needs of managing the various activities on aprons.

This WP only covers those services, whether provided by ATCOs, related to the guidance of, and communication with, aircraft and, in some circumstances, vehicles and pedestrians; services provided with the purpose of achieving a “safe, orderly and expeditious” flow of traffic, as a link from gates to ATS jurisdiction.

International institutions

ICAO, of course, covers the subject (Ref 5.2, § 9.6). Nevertheless it doesn’t specify nor the organisation of the service neither the subjects responsible of providing it.

Eurocontrol, in the recent past, released the strategy for the years 2000+. In order to cope with growing traffic, a new concept, called “gate to gate”, was introduced, with the intention of rationalising the services providing a continuous environment. This overcame the preceding ICAO concept of terminating ATS at manoeuvring area boundary.

In 1996, The European Commission promulgated a Directive (Ref 5.7) on the commercialisation of ground services at airports. Within such Directive the EC expressed the will of keeping every service relate to the guidance of aircraft on the ground, apron included, with the ATS.

IFATCA

IFATCA, at present, has a policy related to legal liability of aerodrome controllers, where AMS are established and not provided by an aerodrome ATS Unit (IFATCA Manual, page 4414, § 1.2.12). It states:

Functions of Aerodrome Controllers related to AMS

In regard to operations on the surface of an airport, it is generally accepted that air traffic controllers are responsible for the issue of restrictions, clearances, informations and instructions, in order to prevent collisions (in non A-SMGCS environment) or provide safe separation between aircraft and aircraft, and aircraft and vehicles (in A-SMGCS environment). They are also expected to provide information and advice on matters related to the safety of movement on the airport surface, with particular reference to the exact nature of any irregularity that might effect each aircraft or vehicle. Such information may include actual surface conditions, details of any work in progress or notified obstructions, failure of any lighting systems, the closure of any taxiways, etc. In addition, they are expected to liaise with ground agencies in the event of any emergency or incident occurring (Ref. 5.1, §2.2, and 5.3, PartV – §1 and 2). In some countries, such services cover not only the manoeuvring area, but the apron areas as well.

Because of the siting of apron areas, and because of the continuous presence of ground serving vehicles, it is not generally assumed that controllers can effectively be responsible for the safe separation of aircraft and vehicles on these areas of every airport. However, with increase of traffic, and consequent increased need to provide a safe separation service for aircraft moving on these areas, the role of controllers to provide a “control” service will need to be extended and supported by suitable equipment, and procedures, in order for them to undertake their duties effectively.

Factors affecting the responsibilities of Aerodrome Controllers on Aprons

The view over the apron and aircraft parking areas are often obstructed by building developments and controllers, also whether entitled of apron control, are not always able to determine the exact location of aircraft, or their immediate effect to other aircraft movements. In restricted parking areas, such as cul-de-sacs, the issue of push-back and taxi clearances require greater controller awareness and monitoring. This is a common function at most airports. However, the legal liability for the issue of such clearances must be clearly defined to uphold the ICAO position, that controllers only have responsibility for the safe separation of aircraft and vehicles on the manoeuvring areas of an airport. Where such liability has not been suitably determined, controllers should expect their local or national ATS authorities to provide them with all necessary exemptions from liability to avoid any undesirable legal consequences.

Although pilots in command are deemed to retain overall responsibility for the safe operation of their aircraft, the extension of a controller’s responsibility must be considered and the legal liabilities determined. This is especially important where an interaction of controlled aircraft and uncontrolled vehicles and personnel exists. One of the solutions, would be for the ground based handling companies to assume total responsibility for the safe movement of aircraft on aprons, during push- back, coincident with the authority of ATC to clear the commander of the aircraft to push-back from the stand.

A-SMGCS environment

The ICAO definition of “manoeuvring area” excludes the apron areas. ICAO acknowledges that responsibility for the apron areas may be delegated to different control authorities that are not exclusively part of any ATC operation. The responsibility for overall control may therefore vary as a result of the actual weather conditions. But, with A-SMGCS, ICAO proposes “whichever method of control is used, the level of service provided by an A-SMGCS should be consistent from the runway to the stand and vice-versa” (ref. 5.9, Chap. I, § 3.6).

From the controller point of view, if A-SMGCS is implemented, the concept and responsibility for the control of aircraft and vehicles should be seen as an ATC function. The provision of separation, the monitoring of separation using any automated aids, the issue of clearances and instructions, and the responsibility for alerting the emergency services should also be considered ATC functions.

When considering airspace, ATCOs are nominally responsible for the provision of safe separation of IFR/S-VFR/VFR flights (depending on airspace class). On surface, with A-SMGCS, the responsibility for safe separation always covers all aircraft, regardless of weather conditions and their individual flight rules, and vehicles as well. Given that ATC already has an existing and proven responsibility for aircraft and vehicles on the manoeuvring area, it should be accepted that ATC should also remain as the sole authority for the implementation and monitoring of separation of aircraft and vehicles operating within any A-SMGCS area.

Non A-SMGCS environment

Anyway, also when an A-SMGCS is not established and, consequently, separation standards are not published, ATC retains responsibility of issuing restrictions, clearances, information and instructions, in order to prevent collisions, on the manoeuvring area, between aircraft and aircraft, and aircraft and vehicles. Moreover, it also retains responsibility for alerting the emergency services. On apron areas, where the control of aircraft is provided by the ATC, this is usually not responsible for the control of vehicles and pedestrians, being these responsible for their own separation from aircraft.

Apron Management Service – ICAO point of view

Several ICAO Documents (Ref 5.4 Chap. 10, 5.5 Chap. 4, 5.6 Chap. 8) state that there are no specific instructions relating to a service covering the apron areas, but also that apron management is an essential task at any aerodrome and is required to regulate the activities and movement of aircraft, vehicles and personnel on apron areas.

ICAO also states that any decision to implement an apron management service must rest with the aerodrome authority. The reason given is to ensure that flexibility remains with the aerodrome to provide the services they deem necessary and meet their needs. This seems to conflict with preceding statement that an apron management service is essential to regulate the movement of aircraft and vehicles on apron areas. It also removes any implementation of any standards and recommended practices from this “essential” service. Which ultimately means that the level and effectiveness of apron management services can vary from airport to airport and would be entirely dependent on individual airport authorities to decide what is most appropriate for them.

Responsibilities

Where aerodrome controllers are responsible for apron control, their functions, duties and responsibilities must be clearly determined. The legal liability for the issue of push-back and taxi clearances must be clearly defined. Where such liability has not been suitably determined, controllers should expect their local or national ATS authorities to provide them with all necessary exemptions from liability to avoid any undesirable legal consequences.