An ooops that slipped through the cracks...

[scottd]

....................

..............

 

[EdFred]

I usually see VV as VV00n, never VV010.

 

[wsuffa]

Me too. I thought it was strange given a visibility of 1/2SM and FG. This should have been VV001.

'tis possible, though, Scott. I can remember several times in San Antonio being able to see runway lights from 200' up, but less than 1/4 mile in a layer just above the ground. Or stars in the sky but not the house across the street.

One of the more "interesting" landings I had one time was in those conditions. Canceled IFR, runway was fully visible (all lights) on final approach, tower wanted me to go back to approach as they reported field below mins - but gave me a special VFR, at less than 100' off the deck I was on the soup, broke out a few feet later (literally, the soup was about 10-25' thick, I was out before I could apply power) to land with pretty much the entire runway in sight. By the time I got the plane in the hanger, the ground visibility was about 100', but I could look up and see the moon.

Yeah, it's rare, but not unheard of, 'least not is certain parts of Texas.

 

[roncachamp]

One of the more "interesting" landings I had one time was in those conditions. Canceled IFR, runway was fully visible (all lights) on final approach, tower wanted me to go back to approach as they reported field below mins - but gave me a special VFR, at less than 100' off the deck I was on the soup, broke out a few feet later (literally, the soup was about 10-25' thick, I was out before I could apply power) to land with pretty much the entire runway in sight. By the time I got the plane in the hanger, the ground visibility was about 100', but I could look up and see the moon.

Why did you cancel IFR?

 

[rottydaddy]

This is not really so odd, assuming a dense but thin layer of fog. I've seen that.

 

[wsuffa]

Why did you cancel IFR?

Appeard clear in flight, runway, tower and ground in full sight, no evidence of visibility impairment. Dropping IFR meant I could cut some corners (and save a few minutes) since the route into SSF crosses some of the arrivals for SAT.

 

[poadeleted20]

I'm still having trouble understanding why it's not possible to have a vertical visbility of 1000 feet when there's 1/2 mile horizontal visibility in fog.

 

[Cap'n Jack]

Scott- it looks like there are decent sized lakes and rivers in the vicinity (looking at a map). As stated by others, could a thin layer off the water be the culprit?

 

[roncachamp]

Appeard clear in flight, runway, tower and ground in full sight, no evidence of visibility impairment. Dropping IFR meant I could cut some corners (and save a few minutes) since the route into SSF crosses some of the arrivals for SAT.

Ah, so you had canceled before you were near the field.

 

[wsuffa]

Ah, so you had canceled before you were near the field.

Yeah, a few (maybe 5-7) miles out.

 

[jesse]

Since 02/22/2009:

METAR with a VV010 has happened 14,502 times.
METAR with a VV001 has happened 230,024 times.

VV010 on a metar isn't nearly as common - but it happens often enough.

 

[jesse]

Thanks for that check. Out of how many METARs in total?

66,748,129

But it's not just VV010...it does happen...it's VV010 coupled with 1/2SM or less that I am at odds with. I wonder how many of those 14,502 times that the visibility was at or below 1/2SM.

That is a question that could be answered. I could write some code to figure it out, or I could just give you a list of all 14,502 reports if you have the ability to process it.

And the climatology used by the NWS is also based locally, meaning the Lake Charles, LA region for this case. It may happen much more frequently at Nashville, TN than at Lake Charles, for example. So I wonder how many times it has occurred at LCH over the last 30 years.

I only have data back to 02/2009

 

[roncachamp]

Yeah, a few (maybe 5-7) miles out.

Hard to imagine how canceling IFR at that point could have cut many corners or saved many minutes. You should have been cleared for approach by then and on tower frequency.

 

[jesse]

Okay, here are the numbers...

BTW, as you indicated in the e-mail, this includes METARs around the world, not just the U.S.

1/2SM - 736
1/4SM - 258
1/8SM - 25
1/16SM - 2
Total - 1021 (worldwide)

Many of these are cases of +SN, BLSN. BLDU and +TSRA. Only 112 had 1/2SM FG VV010 and no other modifer such as TS, SN, RA, BLSN, etc..

There's been only one occurrence at LCH over the last year...in a thunderstorm with heavy rainfall.

KLCH 241907Z VRB04G17KT 1/2SM +TSRA FG VV010 20/19 A2984

And outside of this case, there has only been five instances at LCH with VV010 of which two of them are the ones I posted earlier. So it is indeed rare - hence unlikely.

I'm confused. How does 14,502 become 1021?

 

[jesse]

When I remove all of the visibilities that are 3/4SM, 1SM, 1 1/2SM, etc. Your file contains all METARs that have VV010 independent of the vis. My point was that a condition of VV010 and 1/2SM (or less) together is very exceptional, not that VV010 is rare. Make sense?

Understand.

 

[wsuffa]

Hard to imagine how canceling IFR at that point could have cut many corners or saved many minutes. You should have been cleared for approach by then and on tower frequency.

I seemed clear and high visibility from the air even on final approach. Why not cancel as opposed to flying out to the SSF VOR and making the turn back in? If there's IFR departure traffic, you help them, too.

Dropping IFR inbound to SSF usually saved time, and really wasn't a bad judgement. The ATIS was still reporting VFR conditions. And frankly, even on IFR, it wouldn't have made any difference - that ground fog would still have been there, and I still would have been able to see through it. However, 2-4 minutes longer in the air would certainly have resulted an issue... in the 15 minutes it would have taken to get to SAT and fly the ILS (fitting into the other traffic) would probably have resulted in a non-landing at SAT, too.

 

[roncachamp]

I seemed clear and high visibility from the air even on final approach. Why not cancel as opposed to flying out to the SSF VOR and making the turn back in? If there's IFR departure traffic, you help them, too.

Dropping IFR inbound to SSF usually saved time, and really wasn't a bad judgement. The ATIS was still reporting VFR conditions. And frankly, even on IFR, it wouldn't have made any difference - that ground fog would still have been there, and I still would have been able to see through it. However, 2-4 minutes longer in the air would certainly have resulted an issue... in the 15 minutes it would have taken to get to SAT and fly the ILS (fitting into the other traffic) would probably have resulted in a non-landing at SAT, too.

Radar outage?

 

[wsuffa]

Radar outage?

Speed with which the ground fog was forming. Beat it in, or go 100 miles away.

 

[xaminmo]

That's basically a haze layer. I've run into them many times, where horizontally, my vis is much poorer than vertically. However, usually it's enroute, and I can climb 1000 and everything is swell. The only times I've had a fog or haze layer near the ground was early in the morning, right before sunup, in spring.

 

[sba55]

'tis possible, though, Scott. I can remember several times in San Antonio being able to see runway lights from 200' up, but less than 1/4 mile in a layer just above the ground. Or stars in the sky but not the house across the street.

Same happened to me in Sacramento once. ASOS was reporting vis 1/4, which was worrisome, especially since I didn't have my IR. But when I got close to the field, it seemed _completely_ clear. Around 100', though, everything disappeared....

 

[Dr. O]

There have been instances where the FAA inspector was at a field and giving out citations to those pilots who canceled their IFR flight plan just because they could see the runway environment while the the airport traffic area was still technically IMC... In that situation you may not cancel the IFR flight plan until you are on the ground and clear of the active runway...
Yes, this is an unusual situation, but not unheard of... You are always best off by completing the landing under the IFR flight plan and clearing the runway before uttering the magic words...

denny-o

 

[RotorAndWing]

There have been instances where the FAA inspector was at a field and giving out citations to those pilots who canceled their IFR flight plan just because they could see the runway environment while the the airport traffic area was still technically IMC... In that situation you may not cancel the IFR flight plan until you are on the ground and clear of the active runway...
Yes, this is an unusual situation, but not unheard of... You are always best off by completing the landing under the IFR flight plan and clearing the runway before uttering the magic words...

denny-o

Need to raise the BS flag on that statement. FAA Inspectors cannot "issue citations" like a traffic cop. If someone is suspected of non compliance the Inspector will open an Enforcement Investigation Report (EIR) and possibly send out a 44709 letter.