Guidance concerning Air Navigation in and above the NAT MNPSA
in this category receive a clearance on a route other than originally flight planned, special caution should be exercised to ensure that the co-ordinates of the assigned route and of the associated landfall and subsequent domestic routings are fully understood and correctly inserted into the automated navigation systems. Appropriate cross checks should be carried out. In all cases when an en route re-clearance is requested, the pilot should ensure that the revised ATC clearance includes the new routing from the oceanic exit point to the first landfall point or coastal fix. If at the time of being given a clearance or re-clearance, the pilot has any doubt concerning the subsequent domestic routing, details should be checked with the ATC unit issuing the clearance/re-clearance.
OCEANIC CLEARANCES FOR RANDOM FLIGHTS INTENDING TO OPERATE WITHIN THE NAT REGION AND SUBSEQUENTLY ENTER REGIONS OTHER THAN NAM OR EUR
Oceanic Clearances issued to flights in this category are similar to domestic ATC clearances
in that clearances are to destination on the assumption that co-ordination will be effected ahead of the aircraft's passage. In this case, if necessary, the flight profile may be changed en route, prior to hand-over from one centre to another, subject to traffic conditions in the adjacent area.
OCEANIC FLIGHTS ORIGINATING FROM THE CAR OR SAM REGIONS AND ENTERING NAT MNPS AIRSPACE VIA THE NEW YORK OCA
If a pilot has received the three clearance elements. i.e. a complete route, altitude, and Mach
Number, even if these elements are not issued at the same time, then the pilot has been provided with an Oceanic Clearance and no request for one is necessary. For example: on a flight from Santo Domingo to Europe, Santo Domingo ACC issues a Clearance with a complete route and altitude; later, San Juan CERAP issues the aircraft a clearance to maintain Mach 0.84. At this point, all three required elements (route, Mach Number and flight level) have been received and the flight has an Oceanic Clearance. Subsequent changes to any single element of the Oceanic Clearance does not alter the others.
If the pilot has not received all three elements of an Oceanic Clearance, then a full Oceanic
Clearance should be obtained prior to entering MNPS Airspace. If any difficulty is encountered obtaining the elements of the Oceanic Clearance, the pilot should not hold while awaiting a Clearance unless so instructed by ATC. The pilot should proceed on the cleared route into MNPS Airspace and continue to
request the Clearance elements needed.
ERRORS ASSOCIATED WITH OCEANIC CLEARANCES
Navigation errors associated with Oceanic Clearances fall into several categories of which
the most significant are ATC System Loop errors and Waypoint Insertion errors.
ATC System Loop Errors
An ATC system loop error is any error caused by a misunderstanding between the pilot and
the controller regarding the assigned flight level, Mach Number or route to be followed. Such errors can arise from: incorrect interpretation of the NAT Track Message by dispatchers; errors in co-ordination between OACs; or misinterpretation by pilots of Oceanic Clearances or re-clearances. Errors of this nature, which are detected by ATC from pilot position reports will normally be corrected. However, timely ATC intervention cannot always be guaranteed, especially as it may depend on the use of third-party relayed HF,
GP/VHF or SATCOM Voice communications.
NAT Doc 007