World Air Ops | NAT | Doc 007 MNPS Guidance

Guidance concerning Air Navigation in and above the NAT MNPSA CHAPTER 14‣ Never initiate an on-track uncleared level change. If a change of level is essential and priorATC clearance cannot be obtained, treat this situation as a contingency and execute theappropriate contingency offset procedure, when possible before leaving the last cleared flightlevel. Inform ATC as soon as practicable.‣ Do not assume that the aircraft is at a waypoint merely because the alert annunciator soindicates. Cross-check by reading present position.‣ Flight deck drills. There are some tasks on the flight deck which can safely be delegated toone member of the crew, but navigation using automated systems is emphatically not one ofthem, and the Captain should participate in all navigation cross-check procedures. All suchcross-checks should be performed independently by at least two pilots.‣ Initialisation errors. Always return to the ramp and re-initialise inertial systems if the aircraftis moved before the navigation mode is selected. If after getting airborne, it is found that duringinitialisation a longitude insertion error has been made, unless the crew thoroughly understandwhat they are doing, and have also either had recent training on the method or carry writtendrills on how to achieve the objective, the aircraft should not proceed into MNPS Airspace, butshould turn back or make an en route stop.‣ Waypoint loading. Before departure, at least two pilots should independently check that thefollowing agree: computer flight plan, ICAO flight plan, track plotted on chart, and ifappropriate, the track message. In flight, involve two different sources in the cross-checking, ifpossible. Do not be so hurried in loading waypoints that mistakes become likely, and alwayscheck waypoints against the current ATC clearance. Always be aware that the cleared routemay differ from that contained in the filed flight plan. Prior to entering the NAT MNPSAensure that the waypoints programmed into the navigation computer reflect the OceanicClearance received and not any different previously entered planned or requested route.‣ Use a flight progress chart on the flight deck. It has been found that making periodic plots ofposition on a suitable chart and comparing with current cleared track, greatly helps in theidentification of errors before getting too far from track.‣ Consider making a simple use of basic DR Navigation as a back-up. Outside polar regions,provided that the magnetic course (track) is available on the flight log, a check against themagnetic heading being flown, plus or minus drift, is likely to indicate any gross tracking error.‣ Always remember that something absurd may have happened in the last half-hour. There areoften ways in which an overall awareness of directional progress can be maintained; the positionof the sun or stars; disposition of contrails; islands or coast-lines which can be seen directly orby using radar; radio navaids, and so forth. This is obvious and basic, but some of the errorswhich have occurred could have been prevented if the crew had shown more of this type ofawareness.‣ If the crew suspects that equipment failure may be leading to divergence from cleared track, itis better to advise ATC sooner rather than later.In conclusion, navigation equipment installations vary greatly between operators; but lessons learned frompast mistakes may help to prevent mistakes of a similar nature occurring to others in the future.NAT Doc 007 88 Edition 2010