Oceanic Arrival

Compare LRNS to ground-based NAVAID (as applicable depending on your equipage). 1. When departing oceanic airspace and acquiring ground-based NAVAIDs, you should note the accuracy of your LRNS compared to the position information provided by those NAVAIDs. 2. You should note discrepancies in your maintenance log.

Source: AC 91-70B, ¶D.2.11.3

Remove strategic lateral offset. You must remove the strategic lateral offset prior to exiting oceanic airspace at coast-in. We recommend you include this as a checklist item.

Source: AC 91-70B, ¶D.2.11.1

Confirm routing beyond oceanic airspace. Before entering the domestic route structure, you must confirm your routing and speed assignment.

Source: AC 91-70B, ¶D.2.11.2

Transition Level. During the approach briefing, you should note the transition level on the approach plate or verify with ATC. You must reset your altimeters to QNH when descending through the transition level. You should confirm whether the altimeter setting is based on inches of mercury or hectopascals.

Source: AC 91-70B, ¶D.2.12.1

• Transition altitude: The altitude at or below which the vertical position of an aircraft is controlled by reference to altitudes.
• Transition Layer: The airspace between the transition altitude and the transition level.
• Transition Level: The lowest flight level available for use above the transition altitude.

Source: ICAO Document 4444, Ch 1

When arriving at your destination gate, you should note any drift or circular error in your LRNS. 1. A GPS primary means system normally should not exceed 0.27 NM for the flight. 2. Some inertial systems may drift as much as 2 NM per hour.

Source: AC 91-70B, ¶D.2.13.1

You must note problems in the altimetry system, altitude alert, or altitude hold in the maintenance log.

Source: AC 91-70B, ¶D.2.14

At the end of each flight, determine the accuracy of the navigational system to facilitate correction of performance. You may perform a check to determine the radial error at the ramp position as soon as the aircraft parks. Radial errors for INSs in excess of 2 NM per hour are generally considered excessive (part 121, appendix G). Keep records on each individual navigation system performance.

Source: AC 91-70A, ¶3-6.t.

1. Record Documentation. Decisions regarding monitoring of an aircraft's navigation performance are largely the prerogative of individual operators. In deciding what records to keep, airlines should consider the stringent requirements associated with special use airspaces such as MNPS. Investigating all errors of 20 NM or greater in MNPS airspace is a requirement for airlines. Whether radar or the flight crew observes these deviations, it is imperative to determine and eliminate the cause of the deviation. Therefore, operators should keep complete flight records so that they can make an analysis. The retention of these documents must include the original and any amended clearances.
2. Documentation Requirements. Operators should review their documentation to ensure that it provides all the information required to reconstruct the flight. These records also satisfy the ICAO standard of keeping a journal. Specific requirements could include, but do not only apply to, the following:
• Record of the initial ramp position (latitude/longitude) in the LRNS, original planned flight track, and levels.
• Record of the LRNS gross error check, RVSM altimeter comparisons, and heading reference cross-checks before entering oceanic airspace.
• Plotting charts to include post waypoint 10-minute plots.
• All ATC clearances and revisions.
• All position reports made to ATC (e.g., voice, data link).
• The master document used in the actual navigation of the flight, including a record of waypoint sequencing allocated to specific points, ETA, and actual times of arrival (ATA).
• Comments on any navigation problems relating to the flight, including any discrepancies relating to ATC clearances or information passed to the aircraft following ground radar observations, including weather deviations or wake turbulence areas.

Source: AC 91-70A, ¶3-12.c.

Decisions regarding the monitoring of aircraft navigation performance are largely the prerogative of individual operators. In deciding what records should be kept, operators should take into account the stringent requirements associated with the NAT HLA. Operators are required to investigate all lateral deviations of 10 NM or greater, and it is imperative, whether these are observed on ground radar, via ADS reports or by the flight crew, that the cause(s) of track deviations be established and eliminated. Therefore, it will be necessary to keep complete in-flight records so that an analysis can be carried-out.

Source: ICAO NAT Doc 007, ¶11.2.1