IBAC Bulletin B 02-6

Subject: NAT – Adherence to correct FL at oceanic entry

Aircraft operators/flight crews are reminded of the necessity of being at the correct FL when entering oceanic airspace as specified in their oceanic crossing clearance.

The Minimum Navigation Performance Specifications (MNPS) Operations Manual Chapter 6 states that the pilot is responsible to ensure that he/she enters the Ocean at the FL contained in the Oceanic clearance.

This reminder has been occasioned by instances when the assigned FL in domestic airspace did not correspond with that in the oceanic crossing clearance and the request of the pilot for a clearance to climb to the assigned FL at oceanic entry was denied by ATC due other traffic. The pilot did not follow up, nor apparently did ATC request the pilot to advise his assigned FL for oceanic crossing. As a result the aircraft entered oceanic airspace at the wrong FL and could not be immediately cleared into the airspace

The service providers have therefore requested that flight crews be more assertive in these circumstances to ensure that their clearances are such that they will arrive at the oceanic boundary at the correct gateway, at the correct FL and at the assigned Mach number.

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Sources: NAT Implementation Management Group 21st Meeting.
NAT MNPS Operations Manual.

Prepared by:
Peter R. Ingleton
IBAC Director, ICAO Liaison
10 December 2002