CVFR Definition
    Class B Locations
Difference Canada - United States
Transponder Airspace
ATC Clearance
Altitudes
Pilot Responsibilities

CVFR Definition

CVFR is the acronym for Controlled VFR. It is called that because in order to fly VFR in Class B airspace, a pilot must contact ATC, and must receive (and comply with) a clearance from ATC, all the while remaining in Visual Meteorological Conditions (VMC) and still complying with the rules for VFR. This makes the location of Class B airspace very important to a VFR pilot, doesn't it?

Class B Locations

The good news for VFR pilots who don't like working with ATC is that there isn't a lot of Class B airspace in Canada where one would want to fly. Class B airspace in Canada is defined in the Designated Airspace Handbook (DAH) as all controlled low level airspace above 12,500 up to (but not including) 18,000 ASL. Where an airway has an MEA that is higher than 12,500, the MEA on that airway is considered the base of Class B airspace. Note also that with 18,000 being the transition level between altimeter setting region and standard pressure region, 18,000 becomes FL180, which means it is officially high level airspace, and is included in Class A airspace.

Difference Canada - United States

The only difference from one country to the next that I am currently aware of is between Canada and the US. They don't have the same restriction on VFR above 12,500 feet in the US, so VFR aircraft are allowed to fly in the upper reaches of low level airspace with the requirement for ATC clearance. We'll often see VFR transborder flights cruising along at 15,500 or 17,500 which is legal there, but not in Canada. VFR pilots often don't know this little fact either. We're often just as happy to provide the service to them, but they have to contact us, first. Most often, in my experience, pilots flying in those altitudes are talking to US ATC for flight following anyway, so we do get the message to them.

Transponder Airspace

Another thing that becomes important with Class B airspace is that it is wholly contained within Transponder Airspace. This in itself isn't anything of major concern. The Canadian Aviation Regulations (CARs) 601.03 tells us that all aircraft operating in Class A, B, and C airspace must be equipped with a functioning transponder with an automatic pressure altitude reporting device (easier said as MODE C). As a side note, many airspaces are designated as Transponder Airspace in the DAH. These include areas such as many Terminal Control Areas and Control Zones. These areas are depicted on the appropriate charts, which may be included as VFR Terminal Procedure Charts in the Canada Flight Supplement. Transponder Airspace also includes all Class E airspace upwards from 10,000 feet ASL to 12,500 ASL inclusive within radar coverage. So you need a MODE C transponder to be in Class B airspace, but you also need one just to get above 10,000 feet (unless 10,000-12,500 is in uncontrolled airspace or it is Class E and you know you are not within radar coverage).

ATC Clearance

As mentioned earlier, VFR flights wishing to operate in Canada's Class B airspace must be in communication with ATC, and must obtain an ATC clearance before entering Class B airspace. A pilot will receive a clearance limit, a routing and an altitude assignment. As a pilot, you must treat this like an IFR aircraft would treat his clearance, too. That means no deviations from the assigned airspace or altitude without approval from ATC. The reason? ATC will be treating you like an IFR aircraft. They will expect you to comply with the clearance you receive and acknowledge, and they are required to apply IFR separation standards between you and other traffic in Class B airspace, and just outside in many cases. For example, if you're at the bottom of Class B airspace, an IFR aircraft just below you will have IFR separation applied between you and him. There is more to this issue expressed below in a section on pilot responsibilities.

The ATC clearance is will normally be issued within about 1,000 feet below Class B airspace (rather than being issued a clearance off the ground). The AIP RAC 5.6 tells us that this is to give ATC and the pilot the opportunity to check radio functionality, but it also serves as a reminder that the ATC clearance is only valid within Class B airspace and that separation will only be provided between the VFR aircraft and other traffic once there. Another reminder is the standard ATC phraseology, "Maintain VFR" being included in the clearance.

Altitudes

The altitude issue has confused a few pilots and controllers over the years. Since most VFR aircraft don't actually want to fly above 12,500, we don't see a lot of this. However, there are several aircraft that are flown VFR and are capable of cruising efficiently above 12,500, so we do see it on occasion. According to CARs, cruising altitudes for CVFR aircraft are the same as those meant for IFR aircraft. That is to say Westbound aircraft are at even thousands and Eastbound aircraft are at odd thousands. This is, as with IFR, determined by magnetic track (000-179° being considered eastbound and 180-359° being considered westbound). Note that this means a VFR aircraft has only a few choices of altitudes in Class B airspace. This is detailed in the AIP, RAC 2.3.1 including Figure 2.2.

12,000 feet is not in Class B airspace, so it isn't included there. A VFR aircraft would operate at 12,500 which is just outside Class B airspace. 18,000, as mentioned earlier, becomes FL180 and is part of Class A airspace, therefore VFR flight is not permitted at 18,000. The eastbound altitudes are fairly straight forward. If airspace below 12,500 were given the designation of Class B airspace, the same even thousand or odd thousand rule would apply below that to CVFR aircraft as well. At the time of writing, there is no Class B airspace in Canada below 12,500 ASL.

Pilot Responsibilities

The reason they're not called IFR even though they are required to call and obtain a clearance is that CVFR aircraft are still technically VFR in a very important way. As said a few times in Weekly Topics, visibility is life for a VFR aircraft. The goal is to keep a VFR aircraft a VFR aircraft, while at the same time affording extra protection for IFR aircraft operating at higher altitudes. This means giving ATC the authority to move VFR aircraft as required, but also making the VFR pilot keep his eyes out the window. A VFR pilot in Class B airspace must remain clear of IFR weather conditions just the same above 12,500 as below. As mentioned in the past few weeks with VFR receiving flight following, ATC is not always aware of where the bad weather is. This means that before a pilot accepts a clearance to enter Class B airspace, he has to be sure the weather will permit him to fly in the airspace assigned to him, which includes both route and altitude. If it turns out that an accepted clearance would have the CVFR aircraft enter IFR weather, the pilot must advise ATC as soon as possible and obtain a modified clearance which allows him to remain in Visual Meteorological Conditions (VMC), an IFR clearance if the aircraft is so equipped and the pilot is rated for IFR, or, in the case of the Class B airspace being a Control Zone, Special VFR if the conditions permit it.

If he can't talk to ATC (because of controller workload, or communication difficulties, or whatever), and his current route of flight would have him enter IMC (Instrument weather), or the preceding options are not available to him, the pilot is to ensure the aircraft remains in VMC by leaving Class B airspace horizontally or by descending. If the Class B airspace is a control zone, the aircraft must, "land at the aerodrome on which the control zone is based," according to the AIP. I think the nearest suitable aerodrome would suffice, especially if the weather at the aerodrome on which the CZ is based is worse. In any case, as with any clearance from ATC, if it can't be maintained, ATC is to be notified as soon as possible of the action taken and the reason.

Lastly, the pilot must maintain communications with ATC while operating on a clearance in Class B airspace. If he must leave the frequency to talk to radio or whoever else, he must obtain approval from ATC prior to making the switch. It is impossible for ATC to do their job if they can't talk to the aircraft involved.

I hope this week's topic has cleared up a little confusion related to CVFR and Class B airspace. Did I leave anything unanswered? Perhaps a further explanation is desired? Please contact me with questions or comments. My e-mail address is moxner@nbnet.nb.ca. Thanks again for taking the time to read!