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Guidance concerning Air Navigation in and above the NAT MNPSA



In general terms, the aircraft should be flown at a flight level and/or on a track where other

aircraft are least likely to be encountered. Maximum use of aircraft lighting should be made and a good look-out maintained. If TCAS is carried, the displayed information should be used to assist in sighting

proximate traffic.

    • 12.3


      • 12.3.1

        The general concept of these Oceanic in-flight contingency procedures is, whenever

operationally feasible, to offset from the assigned route by 15 NM and climb or descend to a level which differs from those normally used by 500 ft if below FL410 or by 1000 ft if above FL410.

Initial Action


The aircraft should leave its assigned route or track by initially turning at least 45° to the

right or left whenever this is feasible. The direction of the turn should, where appropriate, be determined by the position of the aircraft relative to any organised route or track system (e.g. whether the aircraft is outside, at the edge of, or within the system). Other factors which may affect the direction of turn are: direction to an alternate airport, terrain clearance, levels allocated on adjacent routes or tracks and any known SLOP off sets

adopted by other nearby traffic.

Subsequent Action


An aircraft that is able to maintain its assigned flight level, after deviating 10 NM from its

original cleared track centreline and therefore clear of any potentially conflicting traffic above or below

following the same track, should :

    • a)

      climb or descend 1000 ft if above FL410

    • b)

      climb or descend 500 ft when below FL410

    • c)

      climb 1000 ft or descend 500 ft if at FL410

      • 12.3.4

        An aircraft that is unable to maintain its assigned flight level should, whenever possible,

initially minimise its rate of descent when leaving its original track centreline and then when expected to be clear of any possible traffic following the same track at lower levels, expedite descent to an operationally feasible flight level, which differs from those normally used by 500 ft if below FL410 (or by 1000 ft if above FL410).


Before commencing any diversion across the flow of adjacent traffic, aircraft should, whilst

maintaining the 15 NM offset track, expedite climb above or descent below the vast majority of NAT traffic (i.e. to a level above FL410 or below FL280), and then maintain a flight level which differs from those normally used: by 1000 ft if above FL410, or by 500 ft if below FL410. However, if the pilot is unable or unwilling to carry out a major climb or descent, then any diversion should be carried out at a level 500 ft different from those in use within MNPS Airspace, until a new ATC clearance is obtained.


If these contingency procedures are employed by a twin engine aircraft as a result of the

shutdown of a power unit or the failure of a primary aircraft system the pilot should advise ATC as soon as practicable of the situation, reminding ATC of the type of aircraft involved and requesting expeditious


NAT Doc 007


Edition 2010

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