SIGMETS - CAN THEY BE MORE CRYPTIC?

[Yenn]

Don't start me on acronyms!

 

 

[facthunter]

Acronyms.

 

An essential part of a situation where true understanding is professed by a few and outsiders have no idea what is really happening, but are not game to say it, as it will make them look silly.

 

These abbreviated coded messages are OK as a legal back-up, or reminder, where a briefing (verbal) is available as well. They fall far short of providing enough knowledge of the Met. conditions that you might be subject to, to conduct the flight professionally .

 

Regarding the use of CAVOK. My recollection is that it is (cloud) Ceiling And Visibility OK. but I am going back a while and things change sometimes.. or get confused...Nev.

 

 

[Yenn]

CAVOK see AIP Gen 3-5-28 in my version.

 

Visibility 10 kM or more.

 

No cloud below 5000' or highest minimum sector altitude.

 

No precipitation, thunderstorms, fog etc.

 

When all else fails read the instructions.

 

 

[turboplanner]

Just look at the varying opinions on the term CAVOK, then think about the many more obscure terms, sometimes only being used by certain meteorologists.

 

The reason I'm so sentitive to this is that I was caught by the term "Trough".

 

I've seen it many times on TV broadcasts since, but at the time I'd just completed the GA course with near 100% test results, and we had never discussed it, and it wasn't in any of the literature, but it was innocuously sitting within the teletype forecast I picked up from Moorabbin on an early morning with blue skies, in fact CAVOK, and I was heading towards it. Got in to the destination in SA with only a mild change in weather, but was then socked in for three days and made it back to Melbourne in marginal conditions, late for work and a very much wiser person.

 

Footnote: I now find the local RC model aircraft site gives the best information.

 

 

[Admin]

In a couple of weeks when the changes are applied to the site there are pages that will help a great deal in this area

 

 

[facthunter]

Inter & Tempo.

 

Dexter, you have explained it very well, but I am surprised that it wasn't covered thoroughly in your training. Perhaps these "gaps" exist in the knowledge that we should have. The Meteorological situation that caused these showers (or whatever )should be part of the overall "concept" of the situation that you are flying into, and was obtained when you used to get a comprehensive briefing of the area you were going to fly into. you would be aware of systems coming through and the weather generally. The terms "tempo " and "inter" impose a LEGAL requirement for the carriage of fuel, so it is very easy for someone to check your flight plan and see if you have complied with it. You may have through fuel or fuel to divert to another place that does not have any requirements on it, that will cover the situation for you. eg IF you were required to carry 60 mins holding but nominated another aerodrome as an alternate(that did not have holding on it) you could use that if the fuel required to satisfy that requirement was less. Another factor that can catch you out is carrying an alternate when the forecast wind is above the crosswind max for your aircraft type, at your planned destination. Nev

 

 

[ianboag]

If met info had traditionally been in plain language, would we regard a move to gobbledygook as progress?

 

Ian B

 

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CHRISTCHURCH (NZCH):

 

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METAR NZCH 080100Z 24004KT 200V260 9999 FEW025 08/01 Q1021 NOSIG RMK SUGARLOAF 25003KT

 

Report issued 08th 1:00pm

 

Wind: light southwesterly (240°) 4 kt varying from southerly (200°) to westerly (260°)

 

Visibility: 10 km or more Cloud: few at 2500 ft

 

Temperature: 8°C Dewpoint:1°C QNH: 1021 hPa

 

Weather: no significant change expected

 

Remarks : SUGARLOAF Wind: light westerly (250°) 3 kt

 

TAF NZCH 072303Z 0800/0824 22012KT 9999 -SHRA FEW012 SCT025 BECMG 0806/0808 26005KT TEMPO 0812/0824 BKN014 2000FT WIND 22020KT

 

Forecast issued 08th 11:03am valid from 08th midday to 09th midday

 

Wind: moderate southwesterly (220°) 12 kt Visibility: 10 km or more

 

Weather: light showers of rain Cloud: few at 1200 ft - scattered at 2500 ft

 

between 6pm and 8pm becoming

 

Wind: light westerly (260°) 5 kt

 

from time to time between midnight and midday

 

Cloud: broken at 1400 ft

 

2000 ft wind: southwesterly (220°) 20 kt

 

 

[JayKay]

if I'm not the only one who didn't know, is INTER means that the particular weather eg. SHRA (Shower of Rain) could occur for up to 30 mins at a time and TEMPO means that this could occur for up to 60 mins at a time. So therefore one needs to factor in HOLDING fuel for either 30 or 60 mins when intending to land at an AD with either of these 2 words in the TAF. I've since looked back in the VFR Guide and still can't find where that is spelled out in those (or any other for that matter) terms.

Hi Destiny Flyer,

 

Does page 92 of "Visual Flight Rules Guide - Version 2 July 2007" under the heading "Alternate Minima" deal with your question? or maybe AIP ENR 1.1?

 

BTW, TEMPO does NOT mean that "this could occur for up to 60 mins at a time". If that was the meaning it would overlap the meaning of INTER.

 

TEMPO is used to indicate change in prevailing conditions expected to last for periods of between 30 and 60 minutes in each instance [AIP GEN 3.5 (Sec 3.6.5.a.)]