When flight crews transition from the U.S. NAS to another country’s airspace, they should be aware of differences not only in procedures but also airspace. For example, when flying into Canada regarding altimeter setting changes, as depicted in Figure 3-22 on page 3-18, notice the change from QNE to QNH when flying northbound into the Moncton flight information region (FIR), an airspace of defined dimensions where flight information service and alerting service are provided. Transition altitude (QNH) is the altitude in the vicinity of an airport at or below which the vertical position of the aircraft is controlled by reference to altitudes (MSL). The transition level (QNE) is the lowest flight level available for use above the transition altitude. Transition height (QFE) is the height in the vicinity of an airport at or below which the vertical position of the aircraft is expressed in height above the airport reference datum. The transition layer is the airspace between the transition altitude and the transition level. If descending through the transition layer, set the altimeter to local station pressure. When departing and climbing through the transition layer, use the standard altimeter setting (QNE) of 29.92 inches of Mercury, 1013.2 millibars, or 1013.2 hectopascals. Remember that most pressure altimeters are subject to mechanical, elastic, temperature, and installation errors. Extreme cold temperature differences also may require a correction factor.


In addition to acknowledging a handoff to another Center en route controller, there are reports that should be made without a specific request from ATC. Certain reports should be made at all times regardless of whether a flight is in radar contact with ATC, while others are necessary only if radar contact has been lost or terminated. Refer to Figure 3-23 on page 3-19 for a review of these reports.


If radar contact has been lost or radar service terminated, the CFRs require pilots to provide ATC with position reports over designated VORs and intersections along their route of flight. These compulsory reporting points are depicted on NACO IFR en route charts by solid triangles. Position reports over fixes indicated by open triangles are noncompulsory reporting points, and are only necessary when requested by ATC. If on a direct course that is not on an established airway, report over the fixes used in the flight plan that define the route, since they automatically become compulsory reporting points. Compulsory reporting points also apply when conducting an IFR flight in accordance with a VFR-on-top clearance. Whether a route is on airways or direct, position reports are mandatory in a nonradar environment, and they must include specific information. A typical position report includes information pertaining to aircraft position, expected route, and estimated time of arrival (ETA). Time may be stated in minutes only when no misunderstanding is likely to occur. [Figure 3-24 on page 3-20]