Making the safe decision (AKA "I hate AIRMET ZULU")

Gary Drescher wrote:
: wrote in message
: ...
: I haven't re-read the entire situation, but a 2700' ceiling
: is not really MVFR.

: Yes it is:

: "MVFR means Minimum or Marginal Visual Flight Rules. MVFR criteria means a
: ceiling between 1,000 and 3,000 feet and/or 3 to 5 miles visibility."

: http://www.weather.gov/glossary/glossary.php?letter=m

I stand corrected. The little blue dots on aviationweather.gov always seemed
to go away at 1500'.

-Cory


--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

wrote in message
...
Gary Drescher wrote:
: wrote in message
: ...
: I haven't re-read the entire situation, but a 2700' ceiling
: is not really MVFR.

: Yes it is:

: "MVFR means Minimum or Marginal Visual Flight Rules. MVFR criteria means
a
: ceiling between 1,000 and 3,000 feet and/or 3 to 5 miles visibility."

: http://www.weather.gov/glossary/glossary.php?letter=m

I stand corrected. The little blue dots on aviationweather.gov always
seemed
to go away at 1500'.

That's a handy web site. Here's a link to the cite's guides to the meaning
of its symbols and acronyms:
http://aviationweather.gov/static/info/

--Gary

"Gary Drescher" wrote in message
. ..
That's a handy web site. Here's a link to the cite's guides to the meaning

Er, site's, not cite's.

: : "MVFR means Minimum or Marginal Visual Flight Rules. MVFR criteria means
: a
: : ceiling between 1,000 and 3,000 feet and/or 3 to 5 miles visibility."
:
: : http://www.weather.gov/glossary/glossary.php?letter=m
:
: I stand corrected. The little blue dots on aviationweather.gov always
: seemed
: to go away at 1500'.

: That's a handy web site. Here's a link to the cite's guides to the meaning
: of its symbols and acronyms:
: http://aviationweather.gov/static/info/

As far as the regs go, is "MVFR" even defined? I kinda doubt it... it's
either below minimums (as prescribed by the overly complicated VFR cloud
clearance/visibility rules), or it's not.

In any event, except for mountainous terrain, I wouldn't think twice about
launching VFR into 2700 AGL.

-Cory


--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

On 10/27/2005 13:55, wrote:

: : "MVFR means Minimum or Marginal Visual Flight Rules. MVFR criteria means
: a
: : ceiling between 1,000 and 3,000 feet and/or 3 to 5 miles visibility."
:
: : http://www.weather.gov/glossary/glossary.php?letter=m
:
: I stand corrected. The little blue dots on aviationweather.gov always
: seemed
: to go away at 1500'.

: That's a handy web site. Here's a link to the cite's guides to the meaning
: of its symbols and acronyms:
: http://aviationweather.gov/static/info/

As far as the regs go, is "MVFR" even defined? I kinda doubt it... it's
either below minimums (as prescribed by the overly complicated VFR cloud
clearance/visibility rules), or it's not.

Well, it's defined (at least) in the Handbook of Aeronautical Knowledge
(FAA-H-8083-25) and used throughout that document.

From page 10-15, in the section describing the Weather Depiction Chart:

"Areas of IFR conditions (ceilings less than 1,000 feet and
visibility less than 3 miles) are shown by a hatched area
outlined by a smooth line. MVFR regions (ceilings 1,000 to
3,000 feet, visibility 3 to 5 miles) are shown by a non-hatched
area outlined by a smooth line. Areas of VFR (no ceiling or
ceiling greater than 3,000 feet and visibility greater than
5 miles) are not outlined."

It is also defined in Aviation Weather Services, AC-00-45E:

IFR - Ceiling less than 1,000 feet and/or visibility less
than 3 miles; hatched area outlined by a smooth line.

MVFR (Marginal VFR) - Ceiling 1,000 to 3,000 feet inclusive
and/or visibility 3 to 5 miles inclusive; non-hatched area outlined
by a smooth line.

VFR - No ceiling or ceiling greater than 3,000 feet and visibility
greater than 5 miles; not outlined.




In any event, except for mountainous terrain, I wouldn't think twice about
launching VFR into 2700 AGL.

-Cory




--
Mark Hansen, PP-ASEL, Instrument Airplane
Sacramento, CA

wrote in message
...
: That's a handy web site. Here's a link to the site's guides to the
meaning
: of its symbols and acronyms:
: http://aviationweather.gov/static/info/

As far as the regs go, is "MVFR" even defined? I kinda doubt it... it's
either below minimums (as prescribed by the overly complicated VFR cloud
clearance/visibility rules), or it's not.

True, being MVFR has no particular regulatory significance. But neither do
most of the other terms and symbols that appear in the government's aviation
weather products. Still, they have explicit definitions that are useful to
be familiar with in order to correctly interpret the meteorological
information that's offered.

--Gary