another question for you USA FAR experts: tetrahedrons

[[email protected]]

Is the tetrahedron at an airport:

1) Supposed to be pinned down to show active runway
2) Allowed to be pinned down to show active runway
3) Supposed to pivot freely with the wind direction

(Background: our club has a long-standing policy to anchor the
tetrahedron. Some of us are really scratching our heads about this
policy and would like to change it. We already know that "the
tetrahedron is not a wind indicator".)

~ted/2NO

[Vaughn Simon]

> wrote in message
ps.com...
> Is the tetrahedron at an airport:
>
> 1) Supposed to be pinned down to show active runway
> 2) Allowed to be pinned down to show active runway
> 3) Supposed to pivot freely with the wind direction
>
> (Background: our club has a long-standing policy to anchor the
> tetrahedron. Some of us are really scratching our heads about this
> policy and would like to change it. We already know that "the
> tetrahedron is not a wind indicator".)

I don't know what (if anything) the FARs say about that, but it is covered
in the AIM (Section 4-3-4) "Pilots are cautioned against using a tetrahedron
for any purpose rather than as an indicator of landing direction." Curiously,
the section seems to be silent on your specific question, but does say that a
wind tee can be manually pointed as long as it is co-located with a wind
indicator.

Thanks for an interesting topic. I learned something.

Vaughn

[Mike the Strike]

"The landing direction indicator--A tetrahedron is installed when
conditions at the airport warrant its use. It may be used to indicate
the direction of landings and takeoffs. A Tetrahedron may be located at
the center of a segmented circle and may be lighted for night
operations. The small end of the tetrahedron points in the direction of
landing. Pilots are cautioned against using the tetrahedron for any
purpose other than as an indicator of landing direction. Further,
pilots should use extreme caution when making runway selection by use
of a tetrahedron in very light or calm wind conditions as the
tetrahedron may not be aligned with the designated calm-wind runway."

Says it all. That's why I call for surface winds before I land.

Mike

Vaughn Simon wrote:
> > wrote in message
> ps.com...
> > Is the tetrahedron at an airport:
> >
> > 1) Supposed to be pinned down to show active runway
> > 2) Allowed to be pinned down to show active runway
> > 3) Supposed to pivot freely with the wind direction
> >
> > (Background: our club has a long-standing policy to anchor the
> > tetrahedron. Some of us are really scratching our heads about this
> > policy and would like to change it. We already know that "the
> > tetrahedron is not a wind indicator".)
>
> I don't know what (if anything) the FARs say about that, but it is covered
> in the AIM (Section 4-3-4) "Pilots are cautioned against using a tetrahedron
> for any purpose rather than as an indicator of landing direction." Curiously,
> the section seems to be silent on your specific question, but does say that a
> wind tee can be manually pointed as long as it is co-located with a wind
> indicator.
>
> Thanks for an interesting topic. I learned something.
>
> Vaughn

[Vaughn Simon]

"Mike the Strike" > wrote in message
ps.com...
> "The landing direction indicator--A tetrahedron is installed when
> conditions at the airport warrant its use. It may be used to indicate
> the direction of landings and takeoffs. A Tetrahedron may be located at
> the center of a segmented circle and may be lighted for night
> operations. The small end of the tetrahedron points in the direction of
> landing. Pilots are cautioned against using the tetrahedron for any
> purpose other than as an indicator of landing direction. Further,
> pilots should use extreme caution when making runway selection by use
> of a tetrahedron in very light or calm wind conditions as the
> tetrahedron may not be aligned with the designated calm-wind runway."
>
> Says it all. That's why I call for surface winds before I land.
>


Still does not answer the OP's specific question.

> > 2) Allowed to be pinned down to show active runway
> > 3) Supposed to pivot freely with the wind direction

The AIM specifically says that a wind tee may be manually pointed (if
another wind direction locator is co-located), but it does not say the same for
a tetrahedron. They may MEAN that it is OK to manually point it, they just
don't say it; and they say nothing about any requirement to co-locate a wind
direction indicator with a tetrahedron.

I say the question is still open.

Vaughn