Development of Guidelines to Determine the Necessity for Air Traffic Control At Aerodromes

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Development of Guidelines to Determine the Necessity for Air Traffic Control At Aerodromes

25TH ANNUAL CONFERENCE, San José, Costa Rica, 21-25 April 1986

WP No. 61

Development of Guidelines to Determine the Necessity for Air Traffic Control at Aerodromes


At the 1985 Annual Conference following discussion on agenda item AFIS , SC 1 was tasked with the development of “guidelines to determine the necessity for ATC at aerodromes, based on traffic movements, geographical location, weather and terrain”.

ICAO Annex 11, chapter 2, contains the factors that should be considered when determining the need for ATS. These factors include types and density of traffic, meteorological factors as well as any other factor that may be relevant. The stated factors are needless to say of obvious significance. However there is little attempt made at quantifying the different factors.

Some states have established criteria for when ATC should be provided at an aerodrome. These relate in the main to amount and categories of traffic e.g. one state will provide ATC at an aerodrome if the total number of movements (IFR and VFR) exceeds 15,000 pa in two consecutive years. Another state applies a formulae which is based not only on traffic density but which also takes into consideration and differentiates between different categories of operations; commercial air transport, general aviation etc..

Of international organisations that have considered the subject IFALPA is of significant interest. IFALPA POL – STAT 1985 states that “Aerodromes and approach control service should be provided at all regular and alternate aerodromes used in commercial air transport operations”. It is considered reasonable when reviewing the need for ATC at aerodromes to make a distinction between commercial air transport operations and other categories of operations. Commercial air transport operations normally take place on a regular and frequent basis, and usually a considerable number of fare-paying passengers are carried. These passengers rightly expect to be carried from one point to another in a safe, orderly and expeditious manner; obviously the provision of air traffic control at the aerodromes concerned must be considered as a major factor in ensuring maximum flight safety for the fare-paying public.

Clearly there is a large number of aerodromes not involved with commercial air transport operations where there even so may be a need for air traffic control. Those states that have established criteria for the provision of ATC seems to regard the amount of traffic as the decisive – or at least major – factor to be considered, and normally this will be on the basis of total annual number of movements. It may be argued, however, that such figures may not necessarily give an adequate indication of a possible need for ATC, in as much as that total annual number of movements ,may not relate to peak or near-peak traffic density.

It seems a reasonable assumption to make that navigational aids and procedures for IFR operations at an aerodrome will only be provided when traffic density, amount of inclement weather and other related factors make it economically necessary or desirable. It is however, a fact that IFR approach, departure and holding procedures have been implemented at aerodromes without providing protection for such flights through the establishment of controlled airspace. Such practices would not seem to be in the interest of flight safety nor in accordance with the guidelines contained in Attachment A to the ICAO Annex 11 . Furthermore, in such cases there will normally be no provision of air traffic control. Separation of simultaneous IFR flights will therefore have to be achieved by the individual pilots concerned on the basis of flight information provided either by an AFIS unit or direct from pilot to pilot. Under such conditions it seems reasonable to assume that there is a real requirement for the provision of ATC, especially in view of the fact that there are not established any pilot – applied separation standards or procedures.

To Conclude

What may be termed the basic factors to be considered when reviewing the need for air traffic control at aerodromes are contained in the ICAO Annex 11. In addition to those factors one can conclude that the existence of commercial air transport operations and published IFR procedures at an aerodrome indicate a requirement for ATC at that aerodrome.

It is recommended that:

In addition to the provisions contained in Annex 11, chapter 2 , air traffic control service shall be provided at aerodromes that :

a) serve commercial air transport operations, and/or
b) have published IFR approach, departure and holding procedures.

the relevant controlled airspace shall be established for aerodromes at which air traffic control is provided.

Last Update: September 20, 2020  

December 1, 2019   408   Jean-Francois Lepage    1986    

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