NCO.OP.142 Destination alternate aerodromes — instrument approach operations

SBAS-CAPABLE GNSS EQUIPMENT GNSS system which are authorised under (E)TSO-C145 or (E)TSO-C146 or later revisions are SBAScapable. Aircraft certified for RNP APCH to LPV minima are considered compliant.

USE OF RAIM FOR SBAS Where a receiver with RAIM is used to meet the requirement for SBAS, its availability should be predicted by a pre-flight RAIM check, in accordance with AMC1 NCO.GEN.105(c).

IAPs THAT DO NOT RELY ON SBAS This instrument approach can be an RNP APCH to LNAV minima. It can also be an RNP APCH to LNAV/VNAV minima using Baro VNAV if the aircraft is equipped with a Baro VNAV function certified for APV. This requirement is only used for planning purposes to cover the possibility of an SBAS loss; it does not prevent the pilot from flying an approach relying on SBAS if SBAS is available.

APPROPRIATE CONTINGENCY ACTION An appropriate contingency action is an alternative offered in NCO.OP.142(b)(5) to completion of the planned flight to a safe landing, either at the planned destination or a destination alternate, using normal procedures and using navigation equipment meeting the requirements of NCO.IDE.A/H.100, installed for redundancy or as a backup. The contingency action should be considered before flight and take into account the information identified by flight preparation according to NCO.OP.135. It may depend on the flight and availability of navigation solutions (satellites, ground navaids, etc.) and weather conditions (IMC, VMC) along the flight. The contingency action addresses partial loss of navigation capability, such as: loss of the stand-alone GNSS equipment; local loss of GNSS signal-in-space (e.g. local jamming at destination); loss of GNSS signal-in-space. It should take into account what options remain in case of loss of GNSS signal; for instance, (non-GNSS-based) radar vectoring by ATC, non-GNSS-based navigation systems or the possibility to reach VMC. Examples of contingency actions include: seeking navigational assistance from ATS, using communication and surveillance systems that remain operational, to enable safe descent to VMC; the emergency use of navigation equipment not meeting the requirements of NCO.IDE.A/H.100 by making use of the provisions in NCO.GEN.105(e); descent over water or very flat terrain to levels with reduced (but reasonable) obstacle clearance; and unusually long periods of dead reckoning.