NCC.OP.153 Destination aerodromes – instrument approach operations

PBN OPERATIONS

(a)When the operator intends to use PBN, the operator should either:

(1)demonstrate that the GNSS is robust against loss of capability; or

(2)select an aerodrome as a destination alternate aerodrome only if an IAP that does not rely on a GNSS is available either at that aerodrome or at the destination aerodrome. GNSS ROBUSTNESS AGAINST LOSS OF CAPABILITY — HELICOPTERS

(b)The operator may demonstrate robustness against the loss of capability of the GNSS if all of the following criteria are met:

(1)At flight planning stage, SBAS or GBAS are expected to be available and used.

(2)The failure of a single receiver or system should not compromise the navigation capability required for the intended instrument approach.

(3)The temporary jamming of all GNSS frequencies should not compromise the navigation capability for the intended route. The operator should provide a procedure to deal with such cases unless other sensors are available to continue on the intended route.

(4)The duration of a jamming event should be determined as follows:

(i)Considering the average speed and height of a helicopter flight, the duration of a jamming event may be considered to be less than 2 minutes.

(ii)The time needed for the GNSS system to re-start and provide the aircraft position and navigation guidance should also be considered.

(iii)Based on (i) and (ii) above, the operator should establish the duration of the loss of GNSS navigation data due to jamming. This duration should be no less than 3 minutes, and may be no longer than 4 minutes.

(5)The operator should ensure resilience to jamming for the duration determined in (4) above, as follows:

(i)If the altitude of obstacles on both sides of the flight path are higher than the planned altitude for a given segment of the flight, the operator should ensure that there is no excessive drift on either side by relying on navigation sensors such as an inertial system with performance in accordance with the intended function.

(ii)If (i) does not apply and the operator cannot rely on sensors other than GNSS, the operator should develop a procedure to ensure that a drift from the intended route during the jamming event has no adverse consequences on the safety of the flight. This procedure may involve air traffic services.

(6)The operator should ensure that no space weather event is predicted to disrupt GNSS reliability and integrity at both the destination and the alternate aerodromes.

(7)The operator should verify the availability of RAIM for all phases of flight based on GNSS, including navigation to the alternate aerodrome.

(8)The operator’s MEL should reflect the elements in points (b)(1) and (b)(2).

OPERATIONAL CREDITS

(c)To comply with point NCC.OP.153, when the operator intends to use ‘operational credits’ (e.g. EFVS, SA CAT I, etc.), the operator should select an aerodrome as destination alternate aerodrome only if an approach procedure that does not rely on the same ‘operational credit’ is available either at that aerodrome or at the destination aerodrome.

INTENT OF AMC1

(a)The limitation applies only to destination alternate aerodromes for flights when a destination alternate aerodrome is required. A take-off or en route alternate aerodrome with instrument approach procedures relying on GNSS may be planned without restrictions. A destination aerodrome with all instrument approach procedures relying solely on GNSS may be used without a destination alternate aerodrome if the conditions for a flight without a destination alternate aerodrome are met.

(b)The term ‘available’ means that the procedure can be used in the planning stage and complies with planning minima requirements.

GNSS ROBUSTNESS AGAINST LOSS OF CAPABILITY — HELICOPTERS

(a)Redundancy of on-board systems ensures that no single on-board equipment failure (e.g. antenna, GNSS receiver, FMS, or navigation display failure) results in the loss of the GNSS capability.

(b)Any shadowing of the GNSS signal or jamming of all GNSS frequencies from the ground is expected to be of a very short duration and affect a very small area. Additional sensors or functions such as inertial coasting may be used during jamming events. Jamming should be considered on all segments of the intended route, including the approach.

(c)The availability of GNSS signals can be compromised if space weather events cause ‘loss of lock’ conditions and more than one satellite signal may be lost on a given GNSS frequency. Until space weather forecasts are available, the operator may use ‘nowcasts’ as short-term predictions for helicopter flights of short duration.

(d)SBAS also contributes to the mitigation of space weather effects, both by providing integrity messages and by correcting ionosphere-induced errors.

(e)Even though SBAS should be available and used, RAIM should remain available autonomously. In case of loss of the SBAS, the route and the approach to the destination or alternate aerodrome should still be flown with an available RAIM function.

(f)When available, GNSS based on more than one constellation and more than one frequency may provide better integrity and redundancy regarding failures in the space segment of GNSS, jamming, and resilience to space weather events.