Solved VFR IMC

[finnerlend]

Hello! METAR for Torp airport (ICAO: ENTO), shows VFR conditions. But it can't be right, because the vertical visibility (VV) is lower than 1500ft (The limit for VFR flight inside the control zone CTR).

[Gkikas LGPZ]

@finnerlend

I think a software automatically showed VFR,
because the visibility is +10 and "no clouds observed" !!!
Unfortunately developers haven't took into account such a case
(vis. +10 km, vertical visibility 010 = 1000 ft).

Maybe the weather observer ought to code the wx. conditions as:
.... 9999 -SN OVC010 ....

the way he/she did today !

[ivo]

Yes this is bug thank you for mentioning it

[Gkikas LGPZ]

@ivo
Please also correct the MVFR criteria you use.
MVFR "needs" Ceilings 1,000 to 3,000 feet.
SCT025 is not a ceiling at 2,500 ft . (BKN025 is)
Ceiling is a measurement of the height of the base of the lowest clouds
that cover MORE THAN half of the sky (more than 4 oktas).
SCT is 3-4 octas.
BKN is 5-7 octas.

LGAV is not MVFR

LGAV is VFR

[ivo]

Just checked the flight rules and see no classification, where VV could change the rules from VFR to other. Do you have link to some rules or document?

[rittels]

hi @ivo

Ceiling: The height above the earth's surface of the lowest layer reported as broken or overcast, or as the vertical visibility into an indefinite ceiling.

google search:

http://profhorn.meteor.wisc.edu/wxwise/weather/lesson6/content.html

[csabatatar]

@ivo
I agree with @Gkikas-LGPZ and @rittels that Ceiling is the lowest cloud base that cover MORE THAN HALF of the sky (more than 4 oktas), so it can be BKN (5-7) or OVC (8/8).
And it is consist of Vertical Visibility too, because its definition is: "Vertical Visibility (VV) shall be reported when the sky is OBSCURED and information on VV is available. The existence of a vertical visibility will constitute an OBSCURED CEILING."
I found it here (on the canadianaviationweather website).

Flight rules are the following:
LIFR: /magenta/
Ceiling: < 500 ft (and/or) VIS: < 1 mile (1,6 km)
IFR: /red/
Ceiling: 500-1000 ft (and/or) VIS: 1-3 mile (1,6-4,8 km)
MVFR: /blue/
Ceiling: 1000-3000 ft (and/or) VIS: 3-5 mile (4,8-8km)
VFR: /green/
Ceiling: > 3000 ft (and/or) VIS: > 5 mile (8 km)

So deducting the conclusions of VV:
• it works the same as Ceiling in practice --> so Windy should treat it in the same manner, even if there is no specified Ceilings in the METAR..
• ceiling term on Windy needs improvement --> to make it match to its definition, as it was mentioned above (BKN, OVC & VV should be included and match with the flight rules limitations)
• and maybe (I'm not sure) Windy using only an "AND" linking operation between the Ceiling and VIS, but if only one of them is exist, the relating rule is going to alive --> that's why there is an "and/or" linking between them in the regulation

I hope it will help in the correction of this bug.

[ivo]

fixed soon