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Air law – definitions of Canadian airspace

Canadian Airspace. Image from IVAO.com

Following up on the previous article on air law, let’s review some details about Canadian airspace.

Air law is such a big topic and is very hard to cover in it’s entirety, so if you want more detail or more material refer to From the Ground Up and Canadian Aviation Regulations,  the Canadian Aeronatical Information Manual.

Canadian Domestic Airspace is divided into seven classification, each identified by a single letter.  The rules governing each airspace depend on it’s classification and not by which name the airspace is commonly known.  Control l or terminal areas can be classified B, C, D or E but weather minimums for flying are still related to the common name of the controlled or uncontrolled airspace.

The classification, as you may remember from ground school, looks sort of like an upside down layer cake, where the smallest classifications are nearer the ground and larger zones extend upward.

Class A 

This is all controlled high level airspace, only IFR flight is permitted. It spans from FL180 to FL600, inclusive.  ATC (air traffic control) is provided to all aircraft, and require clearance to enter.

Tower at YBW. Contol zones can be class B, C, D or E.
Tower at YBW. Contol zones can be class B, C, D or E.

Class B

In class B airspace, IFR and VFR traffic is allowed. ATC is provided. It includes all controlled low-level airspace between 12,500 and up to, but not including 18,000. VFR traffic must file a flight plan and request a route to enter.  A pressure altimeter is required (has to have been certified within 24 months) and a transponder with mode C capability.

Class C

IFR and VFR permitted. VFR must be cleared by ATC to enter. Terminal control areas and associated control zones may be classified Class C when the appropriate ATC unit is not in operation.  A 2 way radio and transponder with mode C capability is required.  In case of a communications failure, squawk 7600.  Otherwise,  VFR traffic must use 1200 on transponder.

Class D

Both IFR and VFR traffic are permitted, and VFR must establish radio communications with ATC.  ATC separation is only provided to IFR traffic.  Terminal control zones can be classified Class D, and if there is no ATC they will revert to Class E.

 Class E

This class of airspace exists when none of the requirements for neither A, B, C, D are met. Both IFR and VFR are permitted but again, ATC separation is only provided to IFR traffic. There are no special requirements for VFR traffic.  Low level airways, control area extensions, transition zones and control zones without an operating tower may fall into this category.

Class F

Forbidden or advisory airspace.

Class G

Does not fit into any of the other airspace categories, and ATC has neither the responsability nor obligation to manage traffic. This is uncontrolled airspace.  Low level air routes and aerodrome traffic zones fall into this category.

It’s easy to forget these classifications.  A useful mnemonic to remember these types of airspace and what is associated with each will help you remember!

A = Airliners. IFR only. Between 18,000 and 60,000 feet.

B= IFR.  Between 12,500 and 18,000

C = Clearance required to enter

D = Dialogue is required. Do not enter before talking to a controller.

EEasy for VFR, Everyone gets home from this class of airspace, no need to talk to controllers.

F = Forbidden, or Fancy  – special use airspace.

G = General uncontrolled airspace.

And of course, the U.S. has their own unique system of classification.  Information on the U.S. system can be found in From the Ground Up.

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What is VFR?

IFR Flying Conditions. Image Courtesy of Langley Flying School.

It’s springtime, and out here in Alberta the weather is all over the place. From clear, sunny, calm days arrive strong wings, snow, sleet, rain, low ceilings and all sorts of weather, signifying change of seasons. Yesterday for example we did not have VFR weather here.  In fact, with a visibility of 1/2 SM, vertical visibility of 500 feet and snow at CYBW we have LIFR, or low instrument flight rules conditions – this means ceilings and visibility conditions below IFR minimums. Ceiling is below 500 feet and visibility is less than 1 SM.

There are two kinds of flight rules, visual flight rules and instrument flight rules.  VFR stands for visual flight rules and means the pilot flies the aircraft with visual reference to the ground, using landmarks, roads, avoid aircraft in the vicinity, avoiding terrain and obstacles.  The pilot must know where they are at all times and maintain visual contact with the ground at all times.

Weather minimums have been established to allow the pilot to fly VFR.  These are listed in the table below:

VFR Weather minimum. Image from the AIM and Langley Flying School.
VFR Weather minimum. Image from the AIM and Langley Flying School.

As long as these minimums are observed, the pilot can fly VFR.  Remember that some types of airspace do not allow VFR traffic, or VFR traffic must seek permission in order to enter certain kinds of airspace.

Also applying to VFR traffic are altitude rules. VFR traffic flying at 3000 feet AGL or higher must follow specified rules about altitude depending on direction flown. Cruise altitude is based on magnetic track. The altitudes are:

For headings: 000 degrees – 179 degrees = ODD thousand + 500 feet

For headings: 180 degrees – 359 degrees = EVEN thousand + 500 feet

VFR traffic is not allowed to fly over cities (built up areas) lower than 1000 AGL, and should not descend below 500 feet AGL during flight – of course this does not apply to special flights (police, ambulance) nor during take off or landing phases of flight. This explains why the traffic helicopter always seems to buzz my house!

VFR traffic can use instruments to operate, but are not allowed to rely on them unless they have an IFR rating, and are flying IFR.

Pilots flying VFR are allowed to start a flight that is initially VFR but changing to instrument meteorological conditions (IMC), and where visual flying will not be encountered anymore.  The best thing to do in this situation as a VFR pilot is to either fly straight and level until the conditions improve, or complete a 180 degree turn where you came from to return to visual conditions. Also, if you are near a control zone, you can request SVFR – special VFR.  The aerodrome must have at least 1 mile visibilty and you must remain clear of cloud.

If you are not near a control zone and encounter these conditions, you are forced to fly IFR.  The best solution is to avoid IMC if possible unless you are IFR rated.

Another solution is to fly VFR “over the top” or OTT.   This is a special rating that private pilot license holders can get to fly over cloud cover, maintain visual contact with other airplanes flying IFR while giving VFR pilots greater flexibility. This rating can be added to your PPL with 15 hours of  flight training.

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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 (tc.gc.ca)
Canadian Airspace – Image from Transport Canada (tc.gc.ca)

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

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.