A) When looking at airport information on your VNC Chart what does M122.3 mean?
The M stands for Mandatory Frequency, as per CARS 602.97; "no pilot-in-command shall operate a VFR or IFR aircraft within an MF area unless the aircraft is equipped with radiocommunication equipment..."
B) When can you enter a Mandatory Frequency without the required radio equipment?
CARS 602.97(3) states
(a) a ground station is in operation at the aerodrome;
(b) prior notice of the pilot-in-command's intention to operate the aircraft at the aerodrome has been given to the ground station;
(c) when conducting a take-off, the pilot-in-command ascertains by visual observation that there is no likelihood of collision with another aircraft or a vehicle during take-off; and
(d) when approaching for a landing, the aircraft enters the aerodrome traffic circuit from a position that will require it to complete two sides of a rectangular circuit before turning onto the final approach path.
C) What legs can you join the circuit on in a Mandatory Frequency?
The diagram shows the recommended procedures for joining a circuit at an uncontrolled aerodrome. In addition to the above the Aeronautical Information Manual (AIM) also states for an aerodrome with a Mandatory Frequency;
Aerodromes within an MF area when airport advisory information is available: Aircraft may join the circuit pattern straight-in or at 45°
to the downwind leg or straight-in to the base or final legs
D) When must you make your first radio call if you will be entering a Mandatory frequency Area?
As per CARS 602.101
"before entering the MF area and, where circumstances permit, shall do so at least five minutes before entering the area, giving the aircraft's position, altitude and estimated time of landing and the pilot-incommand's arrival procedure intentions...."
Take note of the wording of this regulation. It says "shall" do so at least 5 minutes before entering. If you are working very close to the edge of the zone this may not be possible. If you have been out of the zone on a cross country or working for an extended amount of time there is no excuse for not reporting on time. Remember if you forget and call only when entering you could be reported.