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Air law – some basics

Studying air law requires a large double-double

I am currently studying air law.  Air law is a big topic and will take some time to cover.  It’s hard to present all this information, so I thought I’d review a few of the very basics.

Material for air law is found in the Canadian Aviation Regulations (CARS). CARS is divided into two parts, the Regulations, which provide the rules, and the Standards, which give us guidance on how to apply the rules.  There are eight parts, or subject areas:

Part 1   General Provisions

Part 2   Aircraft Identification and Registration

Part 3   Aerodromes and Airports

Part 4   Personnel Licensing and Training

Part 5   Airworthiness

Part 6   General Operating and Flight Rules

Part 7   Commercial Air Services

Part 8   Air Navigation Services

Canadian Airspace - Image from Transport Canada (
Canadian Airspace – Image from Transport Canada (

In Canada, airspace is divided into Northern Domestic Airspace (NDA) and Southern Domestic Airspace (SDA). The NDA runs in close proximity to the earth’s pole, and the lines of force dip towards the pole make the compass reading unreliable, because the compass lies in a horizontal plane.  Therefore, aircraft operating in this zone must fly according to true track calculations. Runway numbering is oriented to and surface winds are provided in degrees true. At night or IFR aircraft must be equipped with a gyroscopic direction indicator.

Runway numbering

In SDA, aircraft operate according to their magnetic track.  Runways are numbered according to their magnetic track, and surface winds are also reported in degrees magnetic. Runway markings are numbered to the nearest 10 degree increment, and the last digit is dropped. For example, runway with the heading 163 will be abbreviated 16.

Altimeter Regions

Canada is also divided into an altimeter setting region and a standard pressure region. The limits of the altimeter setting region are the same as for the SDA and vertically below FL180 (flight level 18,000 feet).  In this region, a pilot must set their altimeter to the current altimeter reading for the departing airport and airports along the flight.  The standard pressure region encompasses the NDA and anywhere above FL180.   The altimeter is set to standard sea level pressure (29.92″ Hg). For takeoff and climb for an airport in this region, altimeter should be set to the setting for that particular airport, and reset to standard pressure upon reaching cruising altitude.  For descent and landing, the altimeter setting for that particular airport should be set.

Uncontrolled Airspace

This consists of airspace where there is no air traffic control (ATC).  Because of this, aircraft in close proximity may present a hazard since to monitoring is given, hence pilots are required to monitor the frequency 126.7 continuously broadcast their location, altitude and intention.

Controlled Airspace

Here ATC is provided and consists of high level (above FL180) and low level airspace (below FL180).

High Level Airspace

All airspace above 18,000. This is divided into three regions: (1) Southern Control Area (SCA): same boundaries as SDA, within this area, all traffic (above 18,000 feet) is controlled, the (2) Northern Control Area (NCA) which extends from the northern limits of the SCA to about 72 degrees latitude, and all traffic above FL230 is controlled, and the Arctic Control Area (ACA) which extends from the boundary of the NCA to the North Pole. It controls all the airspace above FL270.

High level airspace includes high level airways which are prescribed tracks between specific navigation aids where ATC is provided, and high level air routes which are the same as airways but no ATC is provided.

 Low Level Airspace

This is Canadian Domestic Airspace below 18,000 feet ASL, not all of which is controlled. Controlled low level airspace includes

Low level airways: routes which aircraft can navigate by following a non directional beacon, and VHF/UHF airways spaced approximately 100 miles apart along the airway.  The basic width is 4 nautical miles on each side.  Low Frequency/Medium frequency airways (LF/MF) are navigated with reference to signals from low frequency transmitters. The width is 4.34 nautical miles on each side.  An airway has it’s base at 2,200 AGL and extends up to the base of the overlying high level airspace.

Control Area Extensions (CAE): are additional control zones established at some busy airports within controlled airspace to handle IFR traffic.  They extend from 2,200 to 18,000 ‘ AGL.

Control Zones: Designated around certain aerodromes to monitor IFR traffic and facilitate the movement of IFR and VFR traffic.  The upper limit is usually 3000′ AGL. They can be classified as B,C,D or E depending on the classification of surrounding airspace. Most with terminal control have a 7 nautical mile radius, others 5, and a few only 3.

Canadian Terminal Control Area (TCA) Airspace. Figure from Transport Canada (
Canadian Terminal Control Area (TCA) Airspace. Figure from Transport Canada (

Terminal Control Areas (TCU): These are established at airports with heavy traffic to provide IFR service to aircraft. They may be A, B, C, D or E and usually extend into high level airspace.  The TCU takes the shape on an inverted wedding cake.  The limits are specified on the figure to the left.

Next, I’ll review the Classification of Canadian Airspace – airspace classes, A, B, C, D, E, F and G.  Read more air law here.