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Why can the following METAR not be abbreviated to "CAVOK"?

DLLO 121550Z 31018G30KT 9999 FEW060TCU BKN070 14/08 Q1016 TEMPO 4000 TS=

(Aerodrome elevation 1 000 ft, MSA for sector 000-190° 5 800 ft, for sector 190-360° 7 300 ft)

  • A
    Because visibility is forecast to be 4 000 m.
  • B
    Because the cloud base is below the highest minimum sector altitude.
  • C
    Because there are gusts reported.
  • D
    Because thunderstorms are forecast temporary for the next 2 hours.

ICAO Annex 3
2.2 Use of CAVOK

When the following conditions occur simultaneously at the time of observation:
a) visibility, 10 km or more, and the lowest visibility is not reported;

Note 1. - In local routine and special reports, visibility refers to the value(s) to be reported in accordance with 4.2.4.2 and 4.2.4.3; in METAR and SPECI, visibility refers to the value(s) to be reported in accordance with 4.2.4.4.

Note 2. - The lowest visibility is reported in accordance with 4.2.4.4 a).

b) no cloud of operational significance;

c) no weather of significance to aviation as given in 4.4.2.3, 4.4.2.5 and 4.4.2.6;
information on visibility, runway visual range, present weather and cloud amount, cloud type and height of cloud base shall be replaced in all meteorological reports by the term "CAVOK".

Cloud of operational significance. A cloud with the height of cloud base below 1500 m (5000 ft) or below the highest minimum sector altitude, whichever is greater, or a cumulonimbus cloud or a towering cumulus cloud at any height.


DLLO 121550Z 31018G30KT 9999 FEW060TCU BKN070 14/08 Q1016 TEMPO 4000 TS=
  • Aerodrome elevation 1 000 ft, MSA for sector 000-190° 5 800 ft, for sector 190-360° 7 300 ft
In this case, requirement b) is not met. The lowest cloud layer is at 6000 ft "FEW060TCU" and the airport elevation is 1000 ft => which means that the lowest cloud layer is at 7000ft, which is below the highest MSA for this airport (7300 ft). Furthermore, Towering cumulus "TCU" are also present.

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