Regulations - General Airspace Commentary

General Information for Regulations - General Airspace


There are a number of regulations  concerning how close you may fly to  various dangerous or noise-sensitive locations. You will probably need to put some effort into remembering all the numbers. I have made some pictures illustrating some of the regulations, but be sure to read the CARs linked to the different questions, in order to see the exact rules. Notice that you are supposed to be TREE thousand feet over burning TREES -- that one isn't on the PSTAR but it has been on the private written exam.  And here's a joke about overflight of forest fires.

A built-up area is anywhere that has mostly buildings and streets on the ground. The downtown area of a city or town, a suburb, an industrial park, and a factory all constitute built up areas. Furthermore, people are not very good at judging the height of an airplane overhead.  Your registration is painted in large letters underneath your wing.  If you annoy people on the ground with your airplane, they will write down your registration and call Transport Canada.  It's an easy way to get a fine and a violation on your licence. Avoid repeated overflight of populated areas at minimum altitudes. The above altitudes represent how far you must fly above the tops of the fire, animals, or buildings, NOT the height ASL shown on your altimeter.

Weather Minima

The rules for weather minima depend on your altitude, whether it is day or night, and whether you are flying fixed wing (airplanes) or rotary wing (helicopters). The pictures here illustrate the Canadian rules from CARs 602.114 and 602.115.  The United States rules are slightly different, but I won't discuss them here.

The basic rule for vertical/horizontal/visibility is 500'/2000'/1 mile. Here are some tricks to help you remember.  VFR aircraft must remain 500' vertically from cloud: that's 500' clearance above and below.  That's not too hard to remember, because five hundred feet per minute is a normal rate of descent or climb, what you see on the VSI whenever you go up or down.  Just remember "500' up or down."  Horizontal cloud clearance is the distance clouds must be from you in any direction at your altitude, or how far you have to pass a cloud off to your side.  In uncontrolled airspace that's 2000' horizontal separation, or a third of a mile. I don't know of a clever way for you to remember this, unless it helps to know that two thousand feet is the length of a typical small runway,  the distance a sex offender must stay away from schools under Iowa law, or the distance a colonial cannon called a minion could fire a three pound ball.  I didn't think so.  Just remember two thousand feet.  Visibility is how far you must be able to see forward in flight, through haze, mist, rain or other obscuration. In uncontrolled airspace, that distance is one mile visibility.

Flight below 1000' agl is a special case. If you're flying less than 1000' above the ground, it's probably because the weather is too bad to fly higher. The rules acknowledge this and no longer specify a particular distance you have to stay from cloud, so long as you remain clear of cloud. But the rules also acknowledge that "scud running," as this is called, is dangerous, so the normal visibility requirement doubles to 2 miles visibility. Helicopters are more manoeuverable, and can stop their forward motion, so their pilots are allowed half the visibility required of airplane pilots, and helicopters can legally fly below 1000' agl with 1 mile visibility.

For a control zone, think of the number three.  A control zone is typically busier than uncontrolled airspace, so the minima are higher. The "500' up or down" rule is the same, but both the horizontal cloud distance and visibility requirements triple in a control zone, so the minimum requirements become 500' vertically from cloud, 1 mile horizontally from cloud, and 3 miles visibility. It so happens that three thousand feet agl is the typical height of a control zone, too.

Night flight is another special case. You can't actually see the clouds at night, but the cloud clearance rules are the same as in the daytime, wherever you are. The visibility requirement at night is always three miles, regardless of whether you are in controlled airspace, uncontrolled airspace, above or below one thousand feet, in a helicopter or in an airplane. 

Here's a question for you. Looking at the aircraft in the night picture, tell me if it is coming towards you or away from you, and whether you should turn to the right, turn to the left, or hold your course if you saw those lights in front of you at night. Click on the picture to see the answer.

Cruising Altitude Orders

To separate aircraft flying in opposite directions, the cruising altitude orders specify permissible altitudes for any given direction of flight. Altitudes are assigned according to the magnetic orientation of the aircraft's track over the ground, not according to the heading (the way the airplane is pointing. That is because aircraft of different speeds are affected differently by the wind, requiring different headings to maintain the same track. Within 3000' of the ground, the cruising altitude orders do not specify altitudes for VFR flight.  Above 3000' agl, you should travel at an altitude matching the table below.

VFR Cruising Altitudes to 18,000' ASL

Aircraft Magnetic Track



Odd thousand feet, plus 500' ASL
(3500', 5500', 7500', etcetera)

Even thousand feet, plus 500' ASL
(4500', 6500', 8500', etcetera)

For example, if you will be flying on a magnetic track of 218 degrees, you need to select an altitude from the right of the table.  

I know three ways to remember these rules.  One is the saying "Odd people fly east."

Another is the word ONE:
O dd
N orth
E ast

Some people just think of the 0 being like the O in Odd, so they can remember:
0 dd for directions of flight from
0 to 179

Whatever helps you remember that easterly directions of flight correspond to odd altitudes (plus 500' for VFR).

The full rules are more complex, as they include IFR traffic and traffic above 18,000' asl. You're not required to know those rules for the private licence, but you can look them up in CARs 602.34.

Question-by-Question Explanation of Regulations - General Airspace

12.01 The ADIZ (Air Defence Identification Zone) is a region of airspace that rings North America like a moat.  There is a map in the AIP-RAC 2.13, and the exact coordinates are in the Designated Airspace Handbook. In order that approaching hostile aircraft may be identified, aircraft that plan to fly in the ADIZ must file a defence flight plan or defence flight itinerary specifying the time and place that they will penetrate the ADIZ.  Any estimated change in time by more than 5 minutes and any change in the route by more than 20 nm must be reported to ATS.  The ADIZ rules apply to all aircraft, regardless of speed or size. I have abbreviated the rules here, see CARs 602.145 for the details.

12.02 This is the definition of VFR flight: flight with visual reference to the surface. VFR aircraft frequently fly in control zones and aerodrome traffic areas. CARs 602.114 and 602.115.

12.03 Helicopter visibility rules are almost always half of aeroplane ones.

12.04 "Clear of cloud" leaves some room for judgement for the pilot, but it is important to be clear. If you are forced to fly  below 1000' agl and dodge clouds, it is likely that  other aircraft  are too. If you are too close to a cloud, it's like coming suddenly from behind a corner. Have you ever seen two people walk into each other as they both came from opposite directions around a corner?

12.05 CARs 602.23 says only "No person shall create a hazard to persons or property on the surface by dropping an object from an aircraft in flight." This doesn't mean that you can't drop objects, but that you must ensure they won't hurt anyone nor damage anything.

12.06. You need to read CARs 602.27 to know the rules for aerobatic flight, then pick the most correct answer.
(1)  You can get permission to conduct aerobatic manoeuvers in controlled airspace over an airport and you can conduct aerobatic manoevers well over an airport in the uncontrolled airspace above. But this is not the answer they want because there is more to getting permission than just monitoring an appropriate freqency, and there is not necessarily an appropriate frequency to monitor if you are in uncontrolled airspace overhead an airport.
(2) You must be over 2000' agl to do aerobatics, unless you have a special permit, but you may never do aerobatics over a built up area, such as the suburban area of a city.
(3) This is a good answer, as it combines the minimum legal visibility for aerobatics with class F airspace.  Some class F airspace is designated for aerobatics.
(4) 1 mile is too low a visibility for aerobatics, in any class of airspace.

12.07 Many pilots say, "Eight hours, bottle to throttle." If it's been eight hours, but you are still under the influence - still drunk or still hungover - CARs 602.03 forbids you to fly.  The AIP recommends 24 to 48 hours after drinking, and some companies require 12.  

12.08  Here is the definition of day from CARs 101.01: "day" or "daylight" means the time between the beginning of morning civil twilight and the end of evening civil twilight

Civil twilight is the period of time between sunset and when the centre of the sun's disc is six degrees below the horizon. You can't tell this by looking at the horizon or your watch, you have to look it up. It typically last thirty to forty-five minutes, but it can last all night in Canada, depending on your latitude and season. You can get a list of civil twilight times from Flight Services, or from the National Research Council. That last link is on the bottom of the NavCanada flight planning page under Sunrise/Sunset.

Note that it is still officially day AFTER the sun has gone down, and day starts before the sun comes up. Remember: if you can see the sun, it is definitely day

This definition was changed in 2004 and the PSTAR question was changed a couple of years later.

Here is the old rule, presented purely for historical interest.
"day" - means the period beginning one half-hour before sunrise and ending one half-hour after sunset and, in respect of any place where the sun does not rise or set daily, the period during which the centre of the sun's disc is less than six degrees below the horizon

12.09 Night is the period when it's not day, so it's the period ffrom the end of evening civil twilight to the beginning of morning civil twilight. You remember from seeing a sunset that it doesn't instantly become dark the moment the sun disappears. It doesn't instantly become official night, either.

12.10 The purpose of CARs 602.24 seems to be to prevent pilots from spontaneously joining up in formation.  You don't want some stranger on the highway driving right on your bumper, and you don't want someone else in the air suddenly being on your wingtip.  If you prearrange the formation, it's legal, and you can fly side by side wherever you have a clearance.

12.11 The R in CYR stands for restricted. As it says in CARs 601.04, no one may fly in restricted airspace without permission. To get permission you must contact the person responsible for that airspace, listed in a document called the Designated Airspace Handbook. Some people miss this question because they automatically think they can't go in restricted airspace at all, so disregard the idea of having permission.

12.12 Advisory airspace is class F airspace designated by CYA. Advisory means that it's advice, not a rule. The chart is telling you that a certain kind of activity goes on there, and that if you are not participating in that activity, you might not want to be there. The airspace where you go with your instructor to practice stalls is probably Class F advisory airspace designated T (for training) or A (for aerobatics). Look on your VNC or VTA chart and see. 

12.13 This is word-for-word out of CARs 602.14. Note that while a helicopter may get within 500' horizontally of an obstacle, for airplanes the clearance is 2000', the same clearance as for clouds. I have heard of a fixed wing school that re-worded this question, so be on the lookout.

12.14 Also straight from CARs 602.14. That's 500' above or horizontally, and it's the same for helicopters and airplanes.

12.15 According to CARs 602.13, take-offs and landings are only permitted in built up areas if you are landing at an airport, or if you are involved in a police operation, or saving human life. This means that no matter how big your backyard is, if you live in the city, you're not allowed to land there without having it certified as an airport.

12.16 As stated in CARs 602.34. Although 3500' is the lowest cruising altitude, answer (4) is incorrect because aircraft above 3000' must comply with the orders.  3100' is not a proper VFR cruise altitude.

12.17 As 290 is between 180 and 359, an aircraft on a magnetic track of 290° must be at an even thousand altitude, plus 500' (asl) because it is VFR.  (IFR traffic is assigned thousand foot altitudes).

12.18 For some reason, a lot of people get this wrong on the PSTAR, but they always seem to recognize their error right away when I show them.  Read the question carefully.  The track is the path over the ground, the heading is the direction the airplane is pointing.  In the Southern Domestic Airspace, magnetic track is used to dictate altitude.  (In the far north, compasses are not very useful, and true track is used instead).

12.19 The three categories of people who may see your licence are listed in CARs 103.12. "The Minster" refers to the Canadian Minister of Transport, which in effect means his or her delegates: Transport Canada inspectors. Other people might ask to see your pilot licence before allowing you to rent their aircraft, enter their office, or go through their security gates.  The difference is, if you don't want to show the latter people your licence, you can legally walk away and not show it to them. If the cops, customs or Transport Canada officials ask to see it, you must show it, or face legal penalities.

12.20 This question is usually on the Private Pilot written exam, too.
(1) Low level airways are based at 2200' AGL.
(2) Control zone transition areas are based at 700' AGL.
(3) It does extend upward from the surface of the earth, but not just in designated airways.
(4) Up to, but not including, 18,000' ASL.
(1) 2200' AGL represents the floor of class E airspace in a low level airway.
(2) 700' AGL represents the floor of transition areas around control zones.
(3) A control zone normally is the controlled airspace around an airport. It starts at the ground, where the runways are, and a typical height for a control zone is 3000'. Many control zone tops are higher or lower.
(4) The key here is that the control zone starts at the ground. The top of the control zone is a specified height above the surface.

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This page written 8 October 2002 by Robyn Stewart.  Last revised 21 September 2010.

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