[Taken from Canforce Flight Planning Doc]
422. CANADIAN TRACK STRUCTURES
1. Northern Control Area Track Structure a. General
The Northern Control Area (NCA) Track System allows for a reduced lateral separation, and facilitates the application of the Mach number technique. The tracks are contained within the Southern and Northern Control Areas and extend upward from FL280. The system is primarily used by international flights operating North America/Europe (NAT) and North America/Alaska-Orient (PAC). The tracks are described in the Designated Airspace Handbook (TP 1820) and are depicted on Enroute High Altitude Charts.
The mandatory use of NCA tracks and the availability to random route is different for NAT and PAC traffic. The operating conditions for the two traffic flows are indicated in the following paragraphs.
b. Flight Planning Procedures
For flight planning an NCA or Lateral track, the flight plan routing is indicated by using the abbreviation "NCA" or "LAT", as appropriate, followed by the letter or number of the track.
For flights operating within the NCA Track System, position reports are to be indicated by:
(i) the compulsory reporting point designator; or (ii) the code name of the track and the reporting line meridian; the parallel of latitude need not be
included in the position report. Example: Bravo Track at 80W - ““BRAVO 80 AT (time)””
d. NCA Tracks - NAT Traffic (Eastbound and Westbound) During the period from June 1 to September 30, between the hours 1500 and 2000 UTC daily:
(i) aircraft operating at FL280 to FL330 inclusive shall flight plan a NCA track(s); (ii) aircraft operating at FL350 or above may flight plan a random route; and (iii) outsidethisperiod,operatorsmayflightplanarandomroute.
NOTE: The requirement to flight plan and operate using the North American Route (NAR) System, as specified in the CFS, Planning Section, remain in effect.
Document is availabe
here ...