b.
The possibility of a failure of a key aircraft component or related supporting system during the approach or missed approach (e.g., engine failure, electrical generator failure, single hydraulic component failure). Even though a particular failure may in itself be considered too remote based on exposure time (e.g., engine failure), it is nonetheless important to address these considerations since, in practical circumstances, a “go-around” may be due to a factor which relates to or leads to the failure, and thus is not an independent event (e.g., flocking bird

7. RNP AR Operations and Training

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ingestion). This is consistent with the long standing principle of safety of operation of multi-engine aircraft in air carrier operations which notes that after passing V1 on takeoff, until touchdown, the aircraft should typically be able to sustain a failure such as engine failure and still safely be able to continue flight and land.
c.
The possibility of a balked landing or rejected landing at or below DA(H), or MDA(H), as applicable.

d.
The possibility of loss or significant reduction of visual reference, that may result in or require a go-around.

e.
Suitable obstacle clearance following a missed approach, considering applicable aircraft configuration during approach and any configuration changes associated with a go-around (e.g., engine failure, flap retraction).

f.
For special airports identified IAW section 121.445 (e.g., mountainous terrain), or other airports with critical obstacles that have not otherwise been accounted for, the ability to ensure suitable obstacle clearance following a rejected landing; applicable aircraft configuration(s) during approach and any configuration changes associated with a go-around and missed approach should be considered.

g.
Unusual atmospheric or environmental conditions that could adversely affect the safety of the operation (e.g., extreme cold temperatures, known local atmospheric or weather phenomena that introduce undue risk, etc.). When conducting a safety assessment of issues listed above, and uncertainty exists as to aircraft failure condition effects, procedural design intent or margins, aircraft characteristics or capabilities following failure, or other such issues, the operator should consult with an appropriate organization source able to provide reliable and comprehensive information. Typically this includes consultation with one or more of the following as applicable, and as necessary:

Aircraft manufacturer,

Avionics manufacturer;

Procedure designer;

Air Traffic Service provider, or regulatory authority.

The ACD provides the airline with the aircraft manufacturer information necessary to prepare a FOSA. In addition the evaluation conducted by the EASA, during certification as part of the operational readiness, takes into account the probable and remote aircraft system failures for the RNP values determined in abnormal conditions (engine failure or system failures whichever is dimensioning). The use of these RNP values relieves the operator from the need to conduct a formal FOSA for system failures. 
　
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