Chapter

14

Airspace

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14 Airspace

Airspace 14

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Airspace 14

Introduction

14.1 Division of Airspace. All the airspace within a state must be contained within one or more Flight Information Regions (FIR). This is the basic unit of airspace within which the most basic form of Air Traffic Service, a Flight Information Service, is available. The alerting service is also available in an FIR. It is usual to give each FIR a name i.e. the London FIR, which geographically identifies the location of the FIR and its associated Area Control Centre (ACC) within which the Flight Information Centre is located. Where a State strictly enforces its sovereignty, the boundaries of that State’s FIR(s) usually coincide with the national borders of the state. It is not unusual (in Europe, for instance) for FIR boundaries to be ‘convenient’ (i.e. following Lat/Long or median lines) rather than to follow often convoluted national borders. As well as FIRs, the airspace of a state will be divided into Control Areas (CTAs) and Control Zones (CTRs) and may include restricted, prohibited and danger areas. CTAs can exist in the form of corridors linking other CTAs; these are known as airways. The airspace in the vicinity of an aerodrome is known as an Aerodrome Traffic Zone (ATZ).

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Figure 14.1

14.2Upper Information Regions (UIRs). Where a state applies a division of airspace vertically, the upper portion of the airspace is defined as an Upper Information Region UIR. Such a division facilitates the application of different rules and separation standards to those of the underlying airspace. The basic assumption is that traffic using the UIR will be essentially in transit en route, whereas lower traffic will be arriving or departing and therefore manoeuvring. In Europe the division between the FIR and UIR is at FL195 whereas in the USA it is at FL180. The lower boundary of a UIR will always be a VFR FL.

14.3Open FIR. Airspace within an FIR that is not defined as a CTA, CTR or other ‘restricted’ airspace is known as the open FIR. Within the open FIR the only air traffic services offered are a Flight Information Service and the Alerting Service.

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Figure 14.2

14.4Oceanic Control Areas (OCAs). Over large areas of the world’s Oceans e.g. the North Atlantic, traffic control has special problems (i.e. relatively poor navigation and of necessity HF communications requiring the use of radio operators). To solve the problems, or at least to make them manageable, the airspace above FL55 over the Oceans is designated as OCAs where strict rules are enforced and special navigation procedures are applied.

14.5Prohibited, Restricted and Danger Areas. All Prohibited, Restricted and Danger Areas within a state are contained in the FIR(s) of that state and subject to notification of activity and change in status by NOTAM (see definition). Each area will be assigned an individual designator consisting of the country identifier, the letter P, R or D followed by a number in the range 001 - 999. For example in the UK a danger off the north coast of Cornwall is designated EG D001. EG is the ICAO identifier for the UK; D means a danger area and 001 is the unique number for that area.

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