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(Redirected from Navigation: Pre-flight Preparation)
Pre-flight preparation is an essential preliminary to all flights. Usually, it comprises the following five stages, although stages 1. and 2. may be interchanged:
- AIS briefing
- Meteorological Briefing
- Route Selection
- Chart Preparation
- Flight Plan Preparation
AIS Briefing involves identifying all aeronautical information which may affect the flight. This comprises:
- Permanent aeronautical information, contained in national AIPs or commercial flight guides and printed on aeronautical charts; and,
Most aerodromes contain briefing facilities for use by pilots preparing for a flight; however, this may be limited in its geographical coverage. Where this is so, there may be a direct link to a central aeronautical library, or on-line access to aeronautical information may be available.
The contents of AIPs are laid down by ICAO Standards; however, national AIPs are of limited geographical coverage and commercial flight guides are usually more convenient to use.
Meteorological briefing involves determining forecast and actual weather conditions for the route planned and for selected airfields along the route.
En-route weather comprises forecast winds and temperatures at cruising levels along the route together with forecasts of en-route weather conditions, especially cloud conditions and any associated turbulence and/or icing. This information is depicted on special charts.
Airfield weather reports may be either actual reports (METAR) or forecast conditions (TAF). METARs are issued at regular intervals; when a significant change to conditions occurs before the next METAR is due, a special report (SPECI) is issued. In the interests of brevity and clarity, written METARs, SPECIs and TAFs always follow the same format and employ simple self-evident codes (see Further Reading).
If the aerodrome has a fully staffed meteorological office, a forecaster may be available to explain the forecast and any expected hazards.
Where briefing is by reference to printed matter only, a degree of expertise is necessary to decode the various different types of information.
When choosing the route for a flight, the following considerations must be taken into account where applicable:
- Flights across National Boundaries. Flights which will cross national boundaries must obey the relevant regulations contained in national AIPs.
- Controlled Airspace. Flights to be conducted wholly or partly within controlled airspace must follow the provisions of the appropriate national authorities, contained in the national AIP. Other flights must avoid controlled airspace.
- Airspace Restrictions. Flights must avoid airspace restrictions, including danger, prohibited and restricted areas, and other flight restrictions (e.g. VIP flights).
- RVSM Airspace. RVSM airspace must be avoided when operating aircraft for which RVSM approval has not been granted.
- Where possible, the route should avoid areas of forecast extreme weather conditions, e.g. severe turbulence, or moderate or severe icing.
- Weather conditions at the departure, destination and alternate airfields must be better than the specified minima.
- Mode of Navigation.
- Navigation equipment in the aircraft must be adequate for safe operation in accordance with national AIPs. Equipment serviceability must satify the relevant Minimum Equipment List.
- Where visual navigation is to be employed, the route should avoid areas of low cloud or areas where visibility is forecast to be poor;
- Where navigation is to be by use of radio navigation aids, the route may be designed to follow tracks between radio beacons or radials or bearings from radio beacons.
- Over-water Flights. Special rules apply to flights over water:
- Flights across the North Atlantic above specified flight levels must conform to the North Atlantic Track structure. Similar provisions may apply in other geographical areas.
- Flights by twin engined aircraft may be required to route in accordance with ETOPS procedures.
Charts used must be marked with all relevant airspace restrictions, i.e. controlled airspace, danger, prohibited and restricted areas.
Charts printed with aeronautical information must be checked to ensure the currency of depicted information.
Temporary airspace restrictions notified in NOTAMs or AICs must be marked on charts
The route to be flown should be marked on charts, including, where appropriate, topographical charts.
Where appropriate, important bearings or ranges from navigational beacons (e.g. those which define a turning point or entry into controlled airspace) should be marked on the chart. See also Navigation by Radio Aids.
Flight Plan Preparation
Where required by national procedures, an IFR or VFR flight plan should be prepared for submission to ATC authorities. The ATC flight plan must be submitted in good time, as specified in the national AIP.
Whether or not an ATC flight plan is required, a navigation flight plan should be prepared for the route, showing planned levels, minimum safe flight levels, tracks, distances, times, ETAs and fuel requirements and any other information specified by the operator.
- Aircrew Quick Reference to the METAR and TAF Codes is an easily understood explanation of the METAR and TAF codes with examples, produced by USAF.
- The role of meteorological forecast verification in aviation a presentation by Günter Mahringer, Austrocontrol.