3.6.2 Adherence to flight plan
3.6.2.1 Except as provided for in 3.6.2.2 and 3.6.2.4, an
aircraft shall adhere to the current flight plan or the applicable
portion of a current flight plan submitted for a controlled flight unless a request for a change has been made and clearance
obtained from the appropriate air traffic control unit, or unless
an emergency situation arises which necessitates immediate
action by the aircraft, in which event as soon as circumstances
permit, after such emergency authority is exercised, the
appropriate air traffic services unit shall be notified of the
action taken and that this action has been taken under
emergency authority.
3.6.2.1.1 Unless otherwise authorized or directed by the
appropriate air traffic control unit, controlled flights shall, in
so far as practicable:
a) when on an established ATS route, operate along the
defined centre line of that route; or
b) when on any other route, operate directly between the
navigation facilities and/or points defining that route.
3.6.2.1.2 Subject to the overriding requirement in
3.6.2.1.1, an aircraft operating along an ATS route segment
defined by reference to very high frequency omnidirectional
radio ranges shall change over for its primary navigation
guidance from the facility behind the aircraft to that ahead of
it at, or as close as operationally feasible to, the change-over
point, where established.
3.6.2.1.3 Deviation from the requirements in 3.6.2.1.1
shall be notified to the appropriate air traffic services unit.
3.6.2.2 Inadvertent changes. In the event that a controlled
flight inadvertently deviates from its current flight plan, the
following action shall be taken:
a) Deviation from track: if the aircraft is off track, action
shall be taken forthwith to adjust the heading of the
aircraft to regain track as soon as practicable.
b) Variation in true airspeed: if the average true airspeed
at cruising level between reporting points varies or is
expected to vary by plus or minus 5 per cent of the true
airspeed, from that given in the flight plan, the
appropriate air traffic services unit shall be so informed.
c) Change in time estimate: if the time estimate for the
next applicable reporting point, flight information region
boundary or destination aerodrome, whichever comes
first, is found to be in error in excess of three minutes
from that notified to air traffic services, or such other
period of time as is prescribed by the appropriate ATS
authority or on the basis of air navigation regional
agreements, a revised estimated time shall be notified as
soon as possible to the appropriate air traffic services
unit.
