Portuguese METAR Text, Annex 3 Units, and a Dispatcher's Query
A Brazilian dispatcher sends a query in Portuguese asking whether a flight may depart for an aerodrome whose latest METAR reads: SBCT 121800Z 12008KT 8000 -RA BKN012 OVC025 19/17 Q1015. The dispatcher writes that the aerodrome has a 300 ft decision height and asks whether the conditions are above minima and whether the trend forecast is required. The MET office also receives an English-language query from the operator asking for the meaning of the QNH group and whether the visibility is in metres or statute miles. The forecaster must answer both queries accurately and consistently, and must respect the Annex 3 conventions for units and for the trend forecast.
1. Interpret the METAR in Portuguese and in English, and state whether the conditions are above the 300 ft decision height.
Read the worked answer
O METAR indica vento de 120 graus a 8 nós, visibilidade de 8.000 metros, chuva leve, nuvens fragmentadas a 1.200 pés e encobertas a 2.500 pés, temperatura de 19 °C, ponto de orvalho de 17 °C e QNH de 1.015 hPa. A altura da base das nuvens mais baixas é de 1.200 pés, portanto acima da altura de decisão de 300 pés. A visibilidade de 8.000 metros também está acima dos mínimos usuais. In English, the wind is from 120° at 8 kt, visibility is 8,000 m in light rain, with broken cloud at 1,200 ft and overcast at 2,500 ft, temperature 19 °C, dewpoint 17 °C, and QNH 1,015 hPa. The lowest ceiling is 1,200 ft, which is above the 300 ft decision height, and the visibility is well above minima. The conditions are therefore above minima, but the forecaster should note that the ceiling is broken rather than overcast and that the trend forecast is a separate product.
2. Explain the units and the trend forecast requirement to both the Portuguese-speaking and English-speaking enquirers.
Read the worked answer
A visibilidade no METAR é expressa em metros, conforme a Annex 3, e o grupo Q1015 indica o QNH em hectopascais, que é a pressão reduzida ao nível médio do mar. O QNH é usado para ajustar o altímetro na aproximação. O grupo de tendência é um grupo suplementar que indica as condições esperadas nas duas horas seguintes e é exigido para os aeródromos designados, não para todos. In English, visibility is reported in metres under Annex 3, and the Q group gives the QNH in hectopascals, the altimeter setting reduced to mean sea level. The trend forecast is a supplementary group appended to the METAR that describes expected conditions in the following two hours; it is required for designated aerodromes and is not universal. The dispatcher should be told that the current METAR shows conditions above the 300 ft decision height, but that the trend forecast, if issued, must be consulted separately because it may indicate a deterioration within the two-hour window. Both answers must use the same units and the same interpretation to avoid an operational discrepancy.