Flight Planning, Weather and NOTAM
The objective of meteorological service for international air navigation shall be to contribute towards the safety, regularity and efficiency of international air navigation. To accomplish the above goals successfully, the aviation meteorological services collect process and produce products for users according to ICAO recommended standards.
Aerodromes weather
Observations report
Aerodromes weather observations shall be made by facilities, tools, and visual calculations. Aerodromes weather reports serve for flight planning, arriving and departing aircraft, en-route flight and other aeronautical operational activities. In addition, the Aerodromes weather observation data is one of the data used for aerodrome weather forecast.
Aerodromes routine reports are being make every 30 minute. In case of significant changes happen beyond criteria, special weather report will be issued in order to ensure that users are updated with aerodromes weather information.
FLIGHT PLANNING
Forecasts, warnings
The aeronautical Meteorological Office provides weather forecasting/warning services for civil aviation activities on their areas of responsibility. Forecasting and warning messages include:
- Aerodrome forecast (TAF, TAF AMD).
- Landing forecast.
- Takeoff forecast.
- Area and air route forecast.
- SIGMET.
- AIRMET.
- Aerodrome warning (AD WRNG).
- Windshear warning (WS WRNG).
1. Aerodrome forecasts
An aerodrome forecast shall be issued at a specified time and consist of a concise statement of the expected meteorological conditions at an aerodrome for a specified period.
Meteorological offices preparing TAF shall keep the forecasts under continuous review and, when necessary, shall issue amendments promptly to to ensure that users are always using the updates.
2. Landing forecasts
A landing forecast shall consist of a concise statement of the expected significant changes in the meteorological conditions at that aerodrome to be appended to a local routine report, local special report, METAR or SPECI. The period of validity of a trend forecast shall be 2 hours from the time of the report which forms part of the landing forecast.
3. Forecasts for take-off
A forecast for take-off should refer to a specified period of time and should contain information on expected conditions over the runway complex in regard to surface wind direction and speed and any variations thereof, temperature, pressure (QNH), and any other elements as agreed locally. They are used for serving aircraft during take-off.
4. En-route weather forecasts
Weather condition forecasts on the flight and flight regions, including additional forecasts, with information on upper winds, temperatures, hazadous weather phenomena, convective clouds…
5. SIGMET Information
SIGMET information shall be issued by the meteorological watch office and shall give a concise description in abbreviated plain language concerning the occurrence or expected occurrence of specified en-route weather and other phenomena in the atmosphere that may affect the safety of aircraft operations, and of the development of those phenomena in time and space. In addition, SIGMET is also used for flight planning.
6. AIRMET Information
AIRMET information shall be issued by the meteorological watch office in accordance with regional air navigation agreement, taking into account the density of air traffic operating below flight level 100. AIRMET information shall give a concise description in abbreviated plain language concerning the occurrence and/or expected occurrence of specified en-route weather phenomena. which may affect the safety of low-level flights, and of the development of those phenomena in time and space Currently, AIRMET not been implemented in Vietnam. However, this information will be made in the future to accommodate the growth of flying activity, especially low-level flight.
7. Aerodrome warnings
Aerodrome warnings shall be issued by the aerodrome meteorological offices and shall give concise information of meteorological conditions which could adversely affect aircraft on the ground, including parked aircraft, and the aerodrome facilities and services.
8. Wind shear warnings and alerts
Wind shear warnings shall be prepared by the aerodrome meteorological offices designated by the meteorological authority concerned for aerodromes where wind shear is considered a factor, in accordance with local arrangements with the appropriate ATS unit and operators concerned. Wind shear warnings shall give concise information on the observed or expected existence of wind shear which could adversely affect aircraft on the approach path or take-off path or during circling approach between runway level and 500 m (1 600 ft) above that level and aircraft on the runway during the landing roll or take-off run. Where local topography has been shown to produce significant wind shears at heights in excess of 500 m.