Airspace Dimensions

Entry into NAT RVSM airspace requires the holding approvals for both lateral navigation (NAT MNPS Approval) and height keeping performance (RVSM Approval).

NAT MNPS airspace has a base of FL 285 and a ceiling of FL 420 with 1000 ft vertical separation applied to aircraft operating at and between FL 290 and FL 410.

Basic Concept for Contingencies

For oceanic and remote area RVSM applications, where continuous direct controller-pilot communication may not always be possible, a range of contingencies have been considered which allow independent action by flight crews, in general, they permit crews, in exceptional circumstances, to deviate from assigned clearances by selecting flight levels and/or tracks where other aeroplanes are least likely to be encountered. During such deviations, crews are required to make maximum use of aeroplane lighting and to transmit relevant information on all appropriate frequencies, including the distress and emergency frequency. Once contact with ATC has been re-established, the crew will be assisted and issued with new clearances as required. Offset track procedures may be permitted if an encounter with turbulence is considered to be due to wake vortex.

When executing a contingency maneuver the pilot should:

• Watch for conflicting traffic.
• Continue to alert other aircraft using 121.5 MHZ or 131.8 MHZ and
• make maximum use of aircraft lighting.
• Continue to fly tracks or flight levels which are likely to be unoccupied.
• Obtain an ATC clearance as soon as possible.

(c) M.Hanke 2014